Electromechanical robot manipulator device
阅读说明：本技术 机电机器人操作器装置 (Electromechanical robot manipulator device ) 是由 D·奥托莫 Y·谭 J·方 C·克罗谢尔 于 2018-05-25 设计创作，主要内容包括：一种机电操作器装置,包括：包括多个电机的驱动系统；能够通过驱动系统驱动并具有三个运动自由度的臂；用于将所述驱动系统的驱动力传递到所述臂的绞盘传动装置；连接到所述臂的末端执行器,所述末端执行器配置为与用户接合并具有至少三个旋转自由度；和控制系统,控制系统用于控制所述驱动系统,以在选定的方向上向所述末端执行器提供力。(An electromechanical operator device comprising: a drive system including a plurality of motors; an arm drivable by a drive system and having three degrees of freedom of movement; a winch transmission for transmitting a driving force of the driving system to the arm; an end effector connected to the arm, the end effector configured to engage a user and having at least three rotational degrees of freedom; and a control system for controlling the drive system to provide a force to the end effector in a selected direction.)
1. An electromechanical operator device comprising:
a drive system including a plurality of motors;
an arm drivable by the drive system and having three degrees of freedom of movement;
a winch transmission for transmitting a driving force of the driving system to the arm;
an end effector connected to the arm, the end effector configured to engage with a user and having at least three rotational degrees of freedom; and
a control system for controlling the drive system to provide a force to the end effector in a selected direction.
2. The apparatus of claim 1, wherein the winch drive comprises at least one bushing rotatably drivable by a motor and a corresponding winch wheel, wherein the bushing is configured to rotate the winch wheel corresponding to the bushing via an associated drive line.
3. A device according to claim 2, wherein the or each drive wire is secured to a respective associated bush.
4. A device according to claim 3, wherein the or each drive wire is secured by the drive wire passing through a hole in the bush.
5. A device according to any one of claims 3 and 4, wherein the or each drive wire is secured by a fastening means.
6. A device according to any one of claims 2 to 5, comprising a bush for each degree of freedom of the arm.
7. The apparatus of any preceding claim, wherein the apparatus is configured to engage with an upper limb of a user.
8. The device of claim 7, wherein the device is configured for rehabilitation of the upper limb.
9. The device of any one of the preceding claims, wherein the arms are semi-parallel arms.
10. The device of any of the preceding claims, wherein each degree of freedom of the end effector is not actuated.
11. The device of any one of claims 1-9, wherein at least one degree of freedom of the end effector is actuatable.
12. The device of any one of the preceding claims, wherein the device is controllable by the control system to apply a force to a user to assist movement of the user.
13. The device of any one of the preceding claims, wherein the device is controllable by the control system to compensate for a portion of the weight of the device that a user would otherwise bear, and/or friction within the device.
14. The apparatus of any one of the preceding claims, wherein the apparatus is configured to track a position and/or orientation of the end effector and output one or more signals indicative of the position and/or orientation.
15. The apparatus of claim 14, further comprising one or more sensors arranged to output a signal indicative of the orientation of the end effector.
16. The device of any one of the preceding claims, further comprising a feedback generator for providing feedback indicative of a position and/or orientation of the end effector.
17. The apparatus of any preceding claim, wherein the apparatus is configured to engage with a limb of a user, and further comprising a feedback generator for providing feedback indicative of the position and/or posture of the limb.
18. An apparatus according to any preceding claim, wherein the apparatus is configured for use by a user in interacting with another physical object or a computer input device.
19. A method of rehabilitating, training, or assisting a user, the method comprising:
controlling, by a control system, a device according to any one of claims 1 to 18 and connected to a user to resist inappropriate or less desirable physical movements of the user, to encourage the user to perform more appropriate or desirable physical movements, or to assist targeted movements of the user towards the user's physical movements.
20. The method of claim 19, further comprising connecting a portion of an upper limb of a user to an end effector.
21. A method of exercising, the method comprising:
controlling, by a control system, a device according to any one of claims 1 to 14 and connected to a user to resist less desirable body movements of the user, encourage the user to perform more desirable body movements, or assist a targeted movement of the user towards the user's body movements.
22. The method of claim 21, further comprising connecting a portion of an upper limb of a user to an end effector.
23. A method of assisting a user in interacting with an object, the method comprising:
controlling a device according to any of claims 1 to 18 and connected to a user by a control system to assist target movement of the user towards the user's body movement.
24. The method of claim 23, wherein the object is an item or a computer input device.
25. A weight-reducing device for an electromechanical operator device, the weight-reducing device comprising:
a controller configured to receive inputs indicative of joint angles of a limb, masses of forelimbs and upper limbs of the limb, an inertia matrix of the forelimbs and upper limbs, and lengths of the forelimbs and upper limbs;
wherein the controller is configured to determine forces and moments applied to the limb by the electromechanical operator device from the input in accordance with:
wherein q ishIs the generalized coordinate of the limb, gh(qh) Is a vector corresponding to the torque of the limb joint caused by gravity,is the generalized inverse transposition of the limb jacobian, and the formula is as follows:
wherein M ish(qh) Is an inertia matrix.
26. The weight-reducing apparatus of claim 24, wherein the controller is configured to determine the forces and moments according to the following equations:
27. a weight loss device as claimed in claim 25 or 26, comprising a processor for receiving the spatial orientation of at least three spatial orientation sensors located on the limb and configured to determine therefrom the joint angle of the limb and to communicate the joint angle to the controller.
28. A weight reduction device according to claim 25 or 26, wherein the input indicative of joint angle comprises the spatial orientation of at least three spatial orientation sensors located on the limb, and the controller is configured to determine the joint angle of the limb accordingly.
29. A weight-reducing apparatus according to any one of claims 25 to 28 including at least three spatial orientation sensors.
30. The device of any one of claims 1 to 19, further comprising a weight-reducing device of any one of claims 25 to 29.
31. An electromechanical handle for an electromechanical operator device, the electromechanical handle comprising:
an end effector connectable to an arm of a manipulator device, the end effector configured to have at least three degrees of freedom of movement;
wherein the end effector comprises a wristband configured to engage a user, the wristband being rotatable about an axis coincident with a subject's forelimb corresponding to pronation-supination rotation and to one of the degrees of freedom of motion.
32. The electromechanical handle according to claim 31, wherein the wrist strap comprises an outer shell and an inner shell rotatable within the outer shell.
33. An electromechanical handle according to claim 31 or claim 32 further comprising a motor for controlling the angular orientation of the wristband.
34. An electromechanical handle according to claim 33 when dependent on claim 32 wherein the motor is controllable to control the angular orientation of the inner housing relative to the outer housing.
35. An electromechanical handle according to claim 33 or 34 wherein said motor is controllable to cease controlling the angular orientation of said wristband so as to allow the anterior-posterior joint to rotate freely.
36. An electromechanical handle according to any one of claims 31 to 34 wherein the other two degrees of freedom of movement are lockable.
37. The electromechanical handle of any one of claims 31 to 36, comprising a microcontroller configured to receive the orientation of the passive arm and the electromechanical handle and to generate control commands therefrom to control the angular position of the wristband.
38. An electromechanical operator device comprising:
a drive system including a plurality of motors;
an arm drivable by the drive system and having three degrees of freedom of movement;
a winch transmission for transmitting a driving force of the driving system to the arm;
an end effector connected to the arm, the end effector configured to engage with a user and having at least three degrees of freedom of movement and an ability to control a user's pronation-supination motion; and
a control system for controlling the drive system to provide a force to the end effector in a selected direction.
39. The apparatus of claim 38, wherein the end effector comprises a wristband configured to engage a user, the wristband being rotatable about an axis coincident with a subject's forelimb corresponding to pronation-supination rotation and to one of the degrees of freedom of motion.
40. The device of claim 39, wherein the wristband comprises an outer shell and an inner shell rotatable within the outer shell.
41. The apparatus of claim 39 or claim 40, further comprising a motor for controlling the angular orientation of the wristband.
42. Apparatus according to claim 41 when dependent on claim 40, wherein the motor is controllable to control the angular orientation of the inner housing relative to the outer housing.
43. The device of any one of claims 38 to 42, further comprising a weight-reducing device of any one of claims 25 to 29.
Technical Field
The present invention relates to an electromechanical robotic manipulator device, particularly but by no means exclusively for use as an electromechanical robotic manipulator device for rehabilitation, for example upper limb rehabilitation.
Background
Motor recovery after nerve injury is achieved by repeating intensive treatments of targeted motor. Over the past 20 years, many robotic devices have been designed for upper limb rehabilitation in patients with impaired neurological function [1 ]. Such devices mechanically interact with the patient as the patient attempts to perform the motor action, thereby assisting or challenging the patient in a structured manner to accelerate and promote rehabilitation of the patient. The specific purpose and mode of interaction with the human user dictates a set of design criteria for an ideal upper limb rehabilitation robot, as described in [2 ]. The main features of the desired combination of characteristics are transparency of the device (which allows the force applied by the user to affect the motion of the robot), ease of installation for each patient, large working space and sufficient static load. The trade-off between transparency and static load capacity is also affected by the inertial bandwidth of the mechanism. However, it has been recognized that the motions required in rehabilitation training are slow to moderate, and therefore can be traded off in a set of other very stringent (and expensive) design requirements.
Existing physical aids are generally divided into two categories: a robot manipulator and an exoskeleton. The manipulator interacts with the user at only one point (typically by means of a handle or support strapped to the wrist or forearm); they include devices such as MIT Manus [3] and MIME [4 ]. The kinematic design of the exoskeleton conforms to the kinematics of the skeletal system of the limbs and therefore should include one matching degree of freedom for each modeled physiological degree of freedom. Examples of exoskeletons include ARMin [5], ArmeoPower (Hocoma, Switzerland) and ABLE platform [6 ].
However, existing manipulators do not fully adjust the posture of the patient's arm, which can lead to situations where pathological synergies cannot be taken into account in the patient's movements [7 ]. Furthermore, most existing manipulators do not allow for non-planar movement during exercise, which often occurs in everyday life.
Exoskeleton devices have been used to generate 3D (spatial) arm movements in rehabilitation. However, this comes at the expense of other aspects of the equipment. Existing exoskeletons also have difficulty providing a good match between the kinematics of the robot and the human user. When the axis of motion of the device is not perfectly aligned with the axis of motion of the user, mechanical constraints can arise, impeding the motion. Furthermore, due to the changing arm and body shape of the patient, more complex setup is required, as the length of the robotic links of the exoskeleton must be adjusted for each patient. Furthermore, due to the series of kinematic principles of the exoskeleton required to accommodate the limbs, the mechanical inertia introduced by the drive motors and various rigid links is typically distributed along the series of arms, thereby reducing the dynamic transparency of the robot (allowing the user to apply forces to affect the motion of the robot). This situation is further amplified due to the large joint torque required, resulting in significant motor inertia in the moving parts of the robot. This problem is usually solved by introducing a high gear ratio to the motor, but this gives way to the back drive capability of the device. Finally, exoskeletons often have a high cost due to their relatively complex construction.
In addition, in rehabilitation of nerve injuries, gravity compensation or weight loss of the (upper) limb is often required, as such weight loss allows movement when the patient's muscle activity is limited. That is, the force generated by these muscles is not sufficient to overcome the effects of gravity before acceleration of the limb occurs. With the existing upper limb robotic devices, the method of providing weight reduction is relatively simple. For example, the exoskeleton can apply compensation torque joint by joint, and the two-dimensional manipulator can reduce weight by the nature of its planar design. Weight reduction with three-dimensional robotic manipulators is more complicated because there is no direct equivalent relationship between the forces that can be applied to the patient and the weight reduction torque required for each joint.
Disclosure of Invention
According to a first broad aspect of the present invention, there is provided an electromechanical operator device comprising:
a drive system including a plurality of motors;
an arm drivable by a drive system and having three degrees of freedom of movement;
a winch transmission for transmitting a driving force of the driving system to the arm;
an end effector connected to the arm, the end effector configured to engage with a user and having at least three rotational degrees of freedom; and
a control system for controlling the drive system to provide a force to the end effector in a selected direction.
In one embodiment, the winch drive comprises at least one bushing rotatably drivable by means of a motor and a respective winch wheel, wherein the bushing is configured to rotate the winch wheel corresponding to the bushing by means of an associated drive line. The or each drive line may be secured to a respective associated bush. The or each drive wire may be secured by the drive wire passing through a hole in the bush. The or each drive line may be secured by a fastening means. There may be a bushing for each degree of freedom of the arm.
In one embodiment, the device further comprises a support for supporting the actuation mechanism system.
In a certain embodiment, the device is configured to engage with an upper limb of a user. The device may be configured for rehabilitation of an upper limb. In particular embodiments, the device is configured to rehabilitate a user, or to assist a user in performing exercises or training.
In one embodiment, the device may be controlled by the control system to resist inappropriate or less desirable body movements by the user and thus encourage more appropriate or desirable body movements.
The arms may be semi-parallel arms. In one embodiment, each degree of freedom of the end effector is not actuated. In another embodiment, at least one degree of freedom of the end effector is actuatable.
In one embodiment, the device is controllable by the control system to apply a force to the user to assist in the movement of the user.
In a certain embodiment, the device may be controlled by the control system to compensate for a portion of the weight of the device that the user would otherwise be subjected to (thus providing gravity compensation) and/or friction within the device.
In another embodiment, the apparatus is configured to track a position and/or orientation of the end effector and output one or more signals indicative thereof. The apparatus may comprise one or more sensors arranged to output a signal indicative of the orientation of the end effector.
In one embodiment, the apparatus further comprises a feedback generator for providing feedback indicative of the position and/or orientation of the end effector.
In one embodiment, the apparatus is configured to engage with a limb of a user, and the apparatus further comprises a feedback generator for providing feedback indicative of the position and/or posture of the limb.
In one embodiment, the apparatus is configured for use by a user in interacting with another physical object (such as tableware or crockery) or a computer input device (such as a touch screen).
According to a second broad aspect of the present invention, there is provided a method of rehabilitating, training or assisting a user, the method comprising:
the apparatus according to the first aspect and connected to the user is controlled by the control system to counteract inappropriate or less desirable body movements of the user, to encourage the user to perform more appropriate or desirable body movements, or to assist in targeted movement of the user towards the user's body movements.
The method may further include connecting a portion of the user's upper limb to the passive end effector.
According to a third broad aspect of the present invention, there is provided a method of exercising, the method comprising: the apparatus according to the first aspect and connected to the user is controlled by the control system to resist less desirable body movements of the user, encourage the user to perform more desirable body movements, or assist the user in target movements towards the user's body movements.
The method may further include connecting a portion of the user's upper limb to the passive end effector.
According to a fourth broad aspect of the present invention, there is provided a method of assisting a user in interacting with an object, the method comprising: the apparatus according to the first aspect and connected to the user is controlled by a control system to assist the target movement of the user towards the body movement of the user.
In one embodiment, the object is an item (e.g., tableware or crockery) or a computer input device (e.g., a touch screen).
According to a fifth broad aspect of the present invention, there is provided a weight-reducing device for an electromechanical robotic manipulator device, the weight-reducing device comprising:
a controller configured to receive inputs indicative of joint angles of a limb, masses of forelimbs and upper limbs of the limb, an inertia matrix of the forelimbs and upper limbs, and lengths of the forelimbs and upper limbs;
wherein the controller is configured to determine forces and moments applied to the limb by the electromechanical robotic manipulator device from the input in accordance with:
wherein q ishIs the generalized coordinate of the limb, gh(qh) Is a vector corresponding to the torque of the limb joint caused by gravity,is the generalized inverse transpose of the Jacobian (Jacobian) of a limb, and the formula is as follows:
wherein M ish(qh) Is an inertia matrix.
In one embodiment, the controller is configured to determine the forces and moments according to the following formulas:
the weight reduction device may comprise a processor for receiving the spatial orientation of at least three spatial orientation sensors located on the limb and configured to determine therefrom the joint angle of the limb and to communicate the joint angle to the controller.
In another embodiment, said input indicative of joint angle comprises the spatial orientation of at least three spatial orientation sensors located on the limb, and said controller is configured to determine the joint angle of the limb therefrom.
In one embodiment, the weight-reducing device comprises at least three spatial orientation sensors.
According to a sixth broad aspect of the present invention, there is provided an apparatus according to the first broad aspect, further comprising a weight-reducing apparatus according to the fifth broad aspect.
According to a seventh broad aspect of the present invention, there is provided an electromechanical handle for an electromechanical operator device, the electromechanical handle comprising:
an end effector connectable to an arm of the manipulator device, the end effector configured to have at least three degrees of freedom of movement;
wherein the end effector comprises a wristband configured to engage a user, the wristband being rotatable about an axis coincident with a subject's forelimb corresponding to pronation-supination rotation and to one of the degrees of freedom of motion.
It should be noted that the end effector may be considered an electromechanical handle.
In one embodiment, the wristband includes an outer shell and an inner shell rotatable within the outer shell.
In another embodiment, the electromechanical handle further comprises a motor for controlling the angular orientation of the wristband.
In certain embodiments, the wristband comprises an outer shell and an inner shell rotatable within the outer shell, and the motor is controllable to control the angular orientation of the inner shell relative to the outer shell.
The motor may be controllable to stop controlling the angular orientation of the wristband, thereby leaving the pronation-supination joint free to rotate.
In some embodiments, the other two degrees of freedom of motion are lockable.
The electromechanical handle may include a microcontroller configured to receive the orientation of the driven arm and the electromechanical handle and generate control commands therefrom to control the angular position of the wristband.
According to an eighth broad aspect of the present invention, there is provided an electromechanical operator device comprising:
a drive system including a plurality of motors;
an arm drivable by a drive system and having three degrees of freedom of movement;
a winch transmission for transmitting a driving force of the driving system to the arm;
an end effector connected to the arm, the end effector configured to engage a user and having at least three degrees of freedom of movement and an ability to control a user's pronation-supination motion; and
a control system for controlling the drive system to provide a force to the end effector in a selected direction.
In one embodiment, the end effector includes a wristband configured to engage a user, the wristband being rotatable about an axis coincident with a subject's forelimb corresponding to pronation-supination rotation and to one of the degrees of freedom of motion.
In one embodiment, the wristband includes an outer shell and an inner shell rotatable within the outer shell.
The apparatus may further comprise a motor for controlling the angular orientation of the wristband. The wristband may comprise an outer shell and an inner shell rotatable within the outer shell, and the motor is controllable to control the angular orientation of the inner shell relative to the outer shell.
The apparatus may further comprise a weight-reducing device according to the fifth aspect.
It should be noted that any of the various individual features of each of the above-described aspects of the invention, as well as any of the various individual features of the embodiments described herein, including the claims, may be combined as appropriate.
Drawings
In order that the invention may be more clearly defined, embodiments will now be described, by way of example, with reference to the accompanying drawings, in which:
figures 1A and 1B are left and right side views, respectively, of an electromechanical robotic manipulator device for upper limb rehabilitation according to one embodiment of the present invention;
FIG. 1C is a rear view of the actuating mechanism of the device of FIGS. 1A and 1B;
FIGS. 2A and 2B are schematic diagrams of the kinematic structure of the device shown in FIGS. 1A and 1B;
FIG. 2C is a photograph of a prototype device constructed in accordance with the embodiment shown in FIGS. 1A and 1B, showing a user;
FIGS. 3A and 3B are top and right side views, respectively, of the system workspace and body arm workspace of the apparatus of FIGS. 1A and 1B for users with limb lengths of 0.34m and 0.27 m;
FIG. 4 is a schematic diagram of the software and electronic structure of the apparatus shown in FIGS. 1A and 1B;
figures 5A to 5E show the variation in the metrics peak velocity, time to peak velocity (TTP), smoothness, curvature and accuracy between a motion performed within the prototype device shown in figure 2C and the same motion performed outside the prototype device shown in figure 2C;
fig. 6 shows a comparison of the change (percentage) in the metric when performed in the prototype device shown in fig. 2C and when performed in AreoPower (trade mark);
FIG. 7 is a schematic view of a human arm in the sagittal plane as a two-bar linkage;
figures 8A and 8B show the magnitude of the gravity compensation force required by the prototype device of figure 2C at its end effector, when applied to point W in figure 7, and the difference between the vertical force required at that point and the maximum vertical robot force;
FIG. 9 depicts a mathematical approximation of an upper limb model;
FIG. 10 is a schematic illustration of an upper limb modeled according to International Society of Biomechanics (ISB) recommendations;
FIGS. 11A and 11B plot the calculated forces at a plurality of poses in the sagittal (vertical) plane and transverse (horizontal) plane of the upper extremity, respectively;
FIG. 12 shows the percentage of uncompensated torque with respect to the medial/lateral rotation angle for different poses of the upper limb;
FIG. 13 is a view of a robotic arm constructed in accordance with the model of FIG. 10, in accordance with an embodiment of the present invention;
FIG. 14 shows the position of the end effector of the electromechanical robotic manipulator device of FIGS. 1A and 1B over time, i.e., the position of the point of contact between the device and the wrist;
FIG. 15A is a schematic diagram of a controller for implementing a weight loss control strategy according to an embodiment of the present invention;
FIG. 15B is a schematic illustration of a weight-reduced robotic manipulator apparatus having upper limbs and external sensors, according to an embodiment of the present invention;
figure 16 shows a comparison of a weight loss control strategy according to an embodiment of the invention with another weight loss control strategy that takes into account an incomplete manikin;
FIGS. 17A and 17B are views of an electromechanical robotic manipulator device with an electromechanical handle, according to an embodiment of the present invention;
18A-18E are schematic illustrations of an electromechanical handle according to variations of the embodiment of the device shown in FIGS. 17A and 17B;
FIG. 19A depicts three degrees of freedom of the wrist;
FIG. 19B illustrates the pronation-supination joint and its rotation from supination to neutral to pronation position;
FIG. 20 is a schematic diagram of a microcontroller of a version of the electromechanical handle of the device of FIG. 17, according to an embodiment of the present invention;
FIG. 21 illustrates an arrangement of bushings and their associated position drive lines according to one embodiment; and
figure 22 shows the arrangement of the bush, capstan wheel and drive line.
Detailed Description
Fig. 1A and 1B are left and right side views, respectively, of an electromechanical robotic manipulator device 10 for upper limb rehabilitation according to an embodiment of the present invention. Fig. 1C is a rear view of the actuation mechanism of device 10.
The apparatus 10 is configured to provide assistance for rehabilitation of the upper extremities (particularly patients suffering from neurological movement disorders, such as those resulting from stroke). While the apparatus 10 is configured for upper limb rehabilitation, it should be understood that alternative embodiments may be configured for other purposes, such as rehabilitation for other movable parts (e.g., lower limbs, forelimbs, hind limbs, neck, back, pelvis), for training purposes (e.g., encouraging proper movement of upper limbs in sports or performance arts), or for exercise.
Advantages of the apparatus 10 may include one or more of the following: (1) large working space of 3D; (2) each patient is simple and convenient to install; and (3) high transparency. For users with certain arm movement functions (e.g., patients), this transparency may enable passive detection and interaction methods, allowing the apparatus 10 to be used as an evaluation device and to adjust the safety forces applied during exercise. The device 10 has, for example, a semi-parallel mechanism (described below) and provides high back-driveability.
Referring to fig. 1A-1C, the device 10 has a support in the form of a base 12 (although the support may alternatively comprise, for example, a frame), an arm 14 (which is typically a semi-parallel passive arm 14, as shown), and an end effector. In one embodiment, the end effector is in the form of a spherical wrist unit 16 connected to the passive arm 14. In general, in this context, it should be assumed that reference to wrist unit 16 is synonymous with reference to an end effector. The device 10 also comprises a reversibly drivable mechanical system 18 in the form of a drive system comprising three motors 20a, 20b, 20c which impart three degrees of freedom of movement (corresponding to axes q1, q2, q3) on the arm 14. Base 12 supports an actuation mechanism 18.
Wrist unit 16 includes a wristband 22 and a series of at least three rotational joints (in this embodiment, four joints 24a, 24b, 24c, 24d are provided). The rotational joints 24a, 24b, 24c, 24d form a spherical joint mechanism centered about the intended center of the user's wrist and provide the wristband 20 (and thus the user's wrist) with respective degrees of freedom of movement corresponding to the respective axes q4, q5, q6, q 7. In one embodiment, wrist unit 16 is not actuated, but its motion is measured (as described below). In another embodiment, one or more of the axes q4, q5, q6, q7 may be actuated. In this embodiment, actuation axes q4, q5, q6, q7 may be configurable such that, as a matter of choice during use, any or all of actuation axes q4, q5, q6, q7 are not actually actuated (i.e., no actuation force is applied to axes q4, q5, q6, q 7).
Actuating mechanical system 18 is a mechanically transparent (or at least substantially transparent) mechanism, actuating mechanical system 18 being designed to operate in a working space of, for example, at least 0.8m x 1.0m in one embodiment suitable for hand movement. Transparency may be achieved by a reversible drive mechanism driven by impedance control.
Actuating mechanical system 18 includes three rotational joints 26a, 26b, 26c to facilitate rotation about axes q1, q2, q 3. First joint 26a rotates about vertical axis q 1; the second and third joints 26b, 26c actuate the parallel mechanism of the arm 14 (including the beams 28a, 28 b). To achieve the desired transparency, the joints 26a, 26b, 26c are actuated using a capstan wheel drive (described below). Additionally, the joints 26a, 26b, 26c are back-drivable.
The actuating mechanism 18 includes electric (e.g., DC) motors 20a, 20b, 20c, which typically can directly control torque and can be equipped with rotary encoders to measure motor position.
Threaded winch bushings 30a, 30b, 30c are attached to the shafts of motors 20a, 20b, 20c, respectively. The bushings 30a, 30b, 30C are typically threaded to properly position the drive lines 32a, 32b, 32C (described below) to be wound around the bushings 30a, 30b, 30C (see fig. 1C), respectively.
The first capstan wheel 34a (about the first axis q1) realizes the drive and adopts a reduction ratio. The first capstan wheel 34a may be configured as a complete circle or as an angular sub-section of a wheel, depending on the maximum extent of its intended rotation. The first axis q1 has a vertical rotation axis, and positions the parallel mechanisms 28a, 28b in a vertical plane.
The second capstan wheel 34b (about second axis q2) is similar in design to the first capstan wheel 34a, but actuates the upper beam 28a of the parallel mechanism 28a, 28 b.
The third capstan wheel 34c (about a third axis q3) is similar in design to the first capstan wheel 34a, but actuates the lower beam 28b of the parallel mechanism 28a, 28 b.
The drive lines 32a, 32b, 32c serve as a mechanism for driving between the winch bushings 30a, 30b, 30c and the respective winch wheels 34a, 34b, 34c and are advantageously made of a material with minimal elongation, such as steel.
This embodiment includes side brackets 36a, 36b, with side brackets 36a, 36b providing a support structure that supports spindle 38, which spindle 38 in turn supports second and third capstan wheels 34b, 34c (and thus defines axis q2), and also provides a mount for second and third motors 20b, 20c and associated motor electronics (not shown). It is desirable that the side brackets 36a, 36b be constructed of a lightweight material, such as aluminum, to minimize inertia.
According to this embodiment, the upper beam 28a is the first main component of the parallel mechanism of the arm 14 and is driven by the second capstan wheel 34 b. The upper beam 28 is constructed of a lightweight but rigid material to minimize weight, such as aluminum tubing.
According to this embodiment, the lower beam 28b is the second of the four main components of the parallel mechanism of the arm 14 and is driven by the third capstan wheel 34 c. The lower beam 28b is also made of a lightweight but rigid material to minimize weight, such as aluminum tubing.
A distal beam 40 is pivotably connected to the upper and lower beams 28a, 28b and connected at a distal end of the distal beam 40 to the wrist unit 16. According to this embodiment, the distal beam 40 is the third of the four main components of the parallel mechanism of the arm 14 and is made of a lightweight but rigid material to minimize weight, such as aluminum tubing.
According to this embodiment, the passive joints 42a, 42b, 42c are the fourth of the four main components of the parallel mechanism of the arm 14; the passive joints 42a, 42b facilitate pivoting of the distal beam 40 relative to the upper and lower beams 28a, 28 b; a passive joint 42c connects the lower beam 28b to the third capstan wheel 34c and facilitates pivoting of the lower beam 28b relative to the third capstan wheel 34 c; the passive joints 42a, 42b, 42c, which are typically unmeasured, comprise double row ball bearings.
The reduction ratio of each capstan wheel 34a, 34b, 34c is defined by the ratio of its diameter to the diameter of its respective capstan wheel hub 30a, 30b, 30c (in the range of 10: 1 to 30: 1). The capstan wheels 34a, 34b, 34c are made of a suitable rigid material, and are preferably made of a lightweight material to limit their inertia (e.g., a hard plastic material such as PVC or aluminum).
According to one embodiment, wrist unit 16 includes a passive spherical joint attachable to the user's wrist or forearm. The arrangement of joints 24a, 24b, 24c, 24d allows rotation in any direction while maintaining the position of the wrist center or equivalent in approximately the same position. In this embodiment, the user's wrist or forearm is attached to wrist unit 16 by a wristband 22 or splint or other suitable structure, which allows the hand to remain free, allowing the patient to interact with objects directly during the rehabilitation exercise, including objects such as everyday objects (e.g., cutlery, cups, pens), or (for virtual rehabilitation purposes) through a physical computer interface (e.g., a touch screen, keyboard or mouse).
According to another embodiment, one joint 24a, 24b, 24c, 24d (e.g., the joint corresponding to axis q 6) is an actuated joint and may be released or controlled, allowing the user's hand to be held in a functional posture (e.g., for a grasping task) while the remaining joints 24 (corresponding to axes q4 and q5, respectively) remain unactuated. This unactuated spherical joint means that the overall posture of the user's arm is not physically adjusted. This may be an advantage when the clinician encourages active and conscious participation in correcting the motor posture, physical constraints increasing the risk of injury.
The spherical joint is equipped with a potentiometer (not shown) to allow measurement of the angular rotation of the wrist, but in this embodiment is not actuated, so the user can freely rotate the direction of the wrist. The spherical joints implemented by the rotary joints 24a, 24b, 24c, 24d have rotational axes q4, q5, q6, q7 that intersect at the center of the joint (e.g., the center of the splint).
Although not shown in this figure, device 10 also includes a control system for controlling actuated mechanical system 18 to apply force to wrist unit 16 in a selected direction.
Fig. 2A and 2B are left schematic views of the kinematic structure 50 of the device 10, and generally correspond to the view of fig. 1A. For clarity, fig. 2B omits wrist unit 16 and shows the passive arm 14 in two different orientations (shown at 14 and 14'). Fig. 2C is a photograph of a prototype device 60 with a user 62 constructed in accordance with this embodiment: like reference numerals are used to indicate like features.
Mechanical design: kinematics
According to one embodiment, wrist unit 16 has six degrees of freedom (DOF) in its motion. Wherein the first three degrees of freedom (axes q1 to q3) are actuated. These degrees of freedom are associated with the actuated mechanical system 18 and are used for translation of the wrist unit 16. The first axis q1 corresponds to rotation about a vertical axis. The second and third axes q2 and q3 actuate a four-bar linkage arrangement of the parallel mechanism of the arm 14 that corresponds to motion in a vertical plane, as positioned by the first axis q1 (see fig. 2A and 2B). This allows most of the motor inertia to be located at the base 12 of the device 10, thereby reducing the effective moving inertia of the robot. It should be understood that for ease of description, the term "vertical" is used herein; more generally, the vertical axis may correspond to any suitable axis as desired.
The user's wrist is connected to the device 10 by a wristband 22 or splint. Typically, the center of the wrist corresponds to the end effector point and the center of rotation of the passive joint (possibly similar to that set forth in [10 ]). The design of the ball joint and splint typically leaves the user's hand free; this facilitates direct interaction with the physical object, as the environment is important in effective rehabilitation exercises [11 ]. In one embodiment, the apparatus 10 includes a potentiometer (described below) for measuring the rotation of the passive joints q4 through q7 to provide a signal indicative of the forearm posture (i.e., wrist position and forearm orientation) of the patient. This unactuated spherical joint means that the overall posture of the user's arm is not physically adjusted. This may be advantageous because clinicians are often encouraged to actively and consciously engage in correction of athletic posture, while physical constraints may increase the risk of injury.
In one embodiment, as described above, the length of the links provided by beams 28a, 28b, 40 is selected to allow access to a working space of 0.8m x 1m, which covers a substantial portion of the human wrist working space. FIGS. 3A and 3B are top and right side views, respectively, of a system workspace 70 and a body arm workspace 72 of device 10 for users with limb lengths of 0.34m and 0.27m 12. Points (O) and (S) represent the robot origin and user shoulder positions, respectively. One extreme configuration 74 of the device 10 is shown in the front view of fig. 3B. Notably, the system workspace 70 includes a majority of the human arm workspace 72.
Mechanical design: actuation and transmission
In one embodiment, each of the three actuation shafts is directly driven by a dc motor (without a reducer) through a capstan wheel transmission. The capstan wheel assembly provides 23 by adjusting the size of the capstan wheel and bushing mounted on the motor shaft: a gear ratio of 1. Advantageously, the device 10 can achieve relatively high torque capacity while maintaining backdriveability.
The bushing may have threads on an outer surface of the bushing such that the winch line is located in a groove of the threads. This advantageously has a lower friction than the gear or belt drive options, since there is no friction component in the motion. The parallel configuration and subsequent positioning of the motor further reduces the inertia of the device and allows the use of high power (and heavy) motors. Finally, it is preferable that the moving arm constituting the semi-parallel driven arm 14 is constituted by a lightweight hollow aluminum pipe.
FIG. 21 illustrates features of a winch drive mechanism according to one embodiment. A bushing 30a associated with first joint 23a is shown. The drive line 32a associated with the bushing 30a is secured to the bushing. In the illustrated embodiment, the drive wire 32a passes through a hole 33a in the bushing 30a (e.g., through the central axis of the bushing). The through bore 33a preferably extends through (or substantially near) the central axis of the bushing 30 a. Alternatively or additionally, the drive wire 32a may be fixedly secured to the bushing 30a using a fastening device, such as by using a grub screw (not shown). An advantage of this embodiment may be that slippage of the drive line 32a during operation of the winch drive is reduced or eliminated. Another advantage is that slip can be reduced or eliminated with a smaller contact area between the drive line 32a and the bushing 30 a. Generally, according to this embodiment, any one or more of the bushings 30a, 30b, 30c, and preferably all of the bushings 30a, 30b, 30c, may have their associated drive lines 32a, 32b, 32c securely fixed as described.
FIG. 22 illustrates features of a winch drive mechanism according to one embodiment. Bushing 30a and capstan wheel 34a are shown in association with first joint 23 a. According to this embodiment, the end of the position transmission line 32a is firmly fixed to the first capstan wheel 34a at the fixing points 35a, 35 b.
In one embodiment, each shaft q1-q 3 is driven by a 86BL71 brushless Motor (filling Motor) with a rated torque of 0.7Nm and a peak torque of 2.1Nm, driven by Copley 503. The reduction ratio of each capstan is 300/13-23, resulting in a peak output torque of 48.5Nm for each joint 26a, 26b, 26 c. This embodiment provides an average maximum force of wrist unit 16 in its available working space of 48N in the horizontal plane and 38N in the vertical plane. In other embodiments, the average maximum force may be adjusted by adjusting the size of the motor or capstan wheel arrangement. However, the arrangement of this embodiment is sufficient to support an 80 kg user's arm (as described below).
In another embodiment, each shaft q1-q 3 is driven by a 86BL98 brushless Motor (filling Motor) with a rated torque of 1.4Nm and a peak torque of 4.2Nm, driven by CPP-A12V 80. The reduction ratio of each capstan is 300/13-23, resulting in a peak output torque of 96.6Nm for each joint 26a, 26b, 26 c. This embodiment provides an average maximum force of wrist unit 16 in its available working space of 90N in the horizontal plane and 76N in the vertical plane. In other embodiments, the average maximum force may be adjusted by adjusting the size of the motor or capstan wheel arrangement. However, the arrangement of this embodiment is sufficient to support the arm of a 140 kg user (as described below).
Electrical, electronic and software design
In one embodiment, the apparatus 10 utilizes a CompactRIO or sbRIO real-time embedded industrial controller (national instruments corporation) that includes a microprocessor running real-time (RT) Linux and input/output channels connected by Field Programmable Gate Arrays (FPGAs). The controller is connected via ethernet to a host computing device running user interface software. The Analog Output (AO) is used to command the motor driver. The apparatus 10 is equipped with incremental encoders on each motor shaft; these incremental encoders are connected by a high speed Digital Input (DI). Each axis q1-q7 is also equipped with a potentiometer, enabling absolute angle measurements to be made for each of the 6 axes connected to the Analog Input (AI).
The software is designed hierarchically, the time-critical process with high priority runs on the faster, defined hardware and defined software threads, and the task with low priority runs on the host as non-RT software. This arrangement is shown at 80 in fig. 4. Specifically, software limits (angle, speed and torque limits), open loop (feed forward) gravity and friction compensation [13] and impedance controllers [14] run at 10khz on the FPGA, while higher level controllers (including path and trajectory planners) run at 1khz on the RT controller. A personal computer running the Windows operating system (Microsoft, USA) acts as the host PC for the user interface. The software was written in LabVIEW (trade Mark).
Examples of the invention
I. Transparency evaluation
The role of robotic devices in neurorehabilitation is to apply force to a user as the user attempts to complete a movement to encourage the use of certain movement or muscle activation patterns. Prototype device 60 is constructed to be as mechanically transparent as possible to minimize the application of unintentional forces to prevent such unintentional forces from promoting unintended movement patterns in the user.
Known methods of assessing transparency involve the use of force and torque sensors to measure the force exerted on the end effector while performing a given motion. In this case, the smaller the magnitude of the (force and torque) is, the better. Alternatively, in the context of upper limb rehabilitation, transparency may also be assessed by letting the human user perform a stretching action while being attached or not attached to the rehabilitation robot. The motion trajectories for these two conditions can then be compared. In an ideal case, the trajectories for the same intended motion would be the same, i.e., the device 10 would not affect the user's motion. Similar previous studies on existing rehabilitation devices emphasize how much change in the movement pattern [15], [16], [17] may occur. Here, the latter method is employed to evaluate the transparency of the prototype device 60.
A. Experimental methods
After providing consent, five healthy users participated in the experiment. Then a protocol similar to that used by the author of [16] was used. The user is required to reach the virtual target in two cases: in the prototype device 60 and outside the prototype device 60. A magnetic sensor (3d guide trakSTAR, Ascension Corp) was attached to the user's elbow and wrist. The position of the wrist is mapped to the virtual cursor and the user is asked to reach one of the six targets-directly forward, left and right, and the same action in vertical height-from a fixed starting position (in a sagittal plane in line with the shoulders, the elbow bends about 45 degrees). The user is required to reach each goal within one second.
Two conditions were tested:
(1) the user is completely free to move, not connected in any way to the prototype device 60, only the magnetic sensor ("free") is attached; and
(2) the user connects to the prototype device 60 using a wrist splint ("robot"), where the prototype device 60 is set to its transparent mode (i.e., to compensate for its own weight and friction).
In both cases, each user reached each target 10 times. The order in which the conditions are presented is random among users.
As described in [16], the effect of the prototype device 60 on the user's performance is measured using only five metrics, depending on wrist position: (1) peak velocity: maximum velocity (as calculated in real world coordinates, using a first order euler approximating the position data); (2) peak velocity time: peak velocity time relative to the start of motion; (3) smoothness: spectral Arc Length (SAL) smoothness, defined as [18 ];
(4) curvature: measured as the integral of the extended trajectory distance from a straight line (t ═ 1s) connecting the starting position and the final position; and (5) precision: the distance between the cursor and the target in the virtual coordinate is defined as the shortest distance when t is 1 s.
These indicators were chosen because they are associated with rehabilitation [19 ]. The metric is evaluated in two ways. First, the Wilcoxon signature level test was used to compare motion under "free" and "robotic" conditions. Next, the data provided herein for prototype device 60 was compared to data provided in previous work for using ArmeoPower (Hocoma, switzerland) [16 ].
B. Results of the experiment
Fig. 5A to 5E illustrate the variation in the measurements of peak velocity, time to peak velocity (TTP), smoothness, curvature and accuracy, respectively, by comparing the measurements between the motion performed within the prototype apparatus 60 and the motion performed under two extended conditions when the same motion is performed outside the prototype apparatus 60. It is worth noting that performing actions within the prototype device 60 does affect the significant differences in motion patterns shown by these metrics. "x" indicates a significant difference in probability p < 0.001.
Fig. 6 illustrates the percentage change of the ArmeoPower and prototype device 60 from "robot" to "free" including the metrics of peak velocity (PS), TTP, smoothness (S), curvature (C) and accuracy (a). It can be seen that the prototype device 60 has less effect on the measurements in all measurements except for the curvature, indicating that the prototype device 60 provides a more mechanically transparent environment for rehabilitation.
It was found that the movements performed within the prototype device 60 were different from the movements performed outside thereof. However, these variations are relatively small, with less than 15% effect on peak velocity, time to peak velocity, smoothness and curvature. The accuracy is affected more, which is a 50% reduction. However, the absolute change is of the order of 3 mm. The limited impact on these metrics suggests that although the user is aware of the attachment to the prototype device 60, it has little impact. Nevertheless, these changes are not directly caused by force; the user may adapt the interaction forces in some way and/or slightly change their way of movement due to changes in the environment. In any event, these small effects indicate that the interaction forces are minimal; at a minimum, the user can easily overcome these forces to "correct" the change.
It was also compared to the commercial rehabilitation (active) exoskeleton ArmeoPower. In this comparison, it can be seen that the change in the metric introduced by the prototype device 60 is 2-4 times lower than ArmeoPower. There are many reasons. First, ArmeoPower is a complete exoskeleton and is therefore attached to the arm at multiple points. This provides additional locations where force can be applied on the user, resulting in a change in the movement pattern. Secondly, the series configuration of the ArmeoPower naturally leads to a heavier system, and therefore greater inertia must be compensated for, especially in the relatively fast movements considered here. The majority of the mass of the prototype device 60 is at its bottom, so there is less mass to move as the arm moves, again reducing the force applied to the user's arm.
Thus, studies have shown that the movements when using the prototype device 60 are affected compared to movements performed in free extension conditions, but the effect of the design of the prototype device 60 is much less than that of an exoskeleton-based rehabilitation robot device (in this case represented by Armeo Power), allowing for finer interaction with the user and greater ability to detect or react to movements.
II. Gravity compensation
One known and useful function in rehabilitation robots is to be able to "lighten" the arm [20], so that the force threshold of the movement is low, that is, the muscles do not need to overcome the weight of the arm before the arm accelerates.
A. 3D operator specific problems
The configuration of the apparatus 10 affects how gravity compensation must be achieved. For example, horizontal plane operation does not require active gravity compensation-the structure of the device itself limits movement in the vertical direction. On the other hand, the exoskeleton needs active compensation. This compensation can be achieved by estimating the mass of each arm part (upper arm, forearm, hand) and using the torque at each robot joint to compensate the associated gravity.
By design, the three-dimensional manipulator provides a directional force on only one point of the patient's arm. As a result, the method for gravity compensation involves calculating and applying a force at this point to cancel the torque required by the shoulder to counteract the arm weight.
In this analysis, the arm was modeled as a fixed two-bar linkage: upper arm and forearm, each of length luaAnd lfa. Assuming each link is a point mass, centered at points U and F along the link, denoted m respectivelyuaAnd mfa. FIG. 7 is a schematic view of a human arm in the sagittal plane as a two-bar linkage. W represents the position of the wrist or wrist,
Shoulder torque required to support weightCan be expressed as:
note that the required shoulder torque is variable and depends on the posture of the arm. Therefore, to calculate the appropriate gravity compensation force, the system needs to measure the pose, not just the forearm pose. This can be achieved in a number of ways using external sensors (e.g. IMU, RGBD camera or magnetic sensors, such as those used in the experiments in section III).
B. Proposed gravity compensation
In order to make the 3D operator compensate for the shoulder torque tausgThe equivalent force that must be applied at the end effector point (i.e., wrist center W)
the solution to the minimum norm is given by:
the theoretical analysis shows that the gravity compensates the force
For these parameters, even in this limited workspace, the required gravity compensation force is in the range of 0N to 38N, which means that the pose of the human arm must be taken into account when providing gravity compensation. Fig. 8B shows the difference between the required vertical force and the maximum vertical robot force. Figure 8B shows that the capabilities of the current prototype are sufficient to generate this force. In view of the known upper limb posture, the proposed solution therefore proposes a method of providing arm gravity compensation for a 3D manipulator (e.g. the apparatus 10).
However, according to another embodiment, an electromechanical robotic manipulator device for upper limb rehabilitation (compared to the device 10) is provided with an alternative weight-reduction mechanism. The system of interest can be characterized as comprising two components: (1) a robotic device that provides for gravity reduction, and (2) upper limbs whose weight and power are to be compensated for. The two components are connected by tying the upper limb to the end effector (see wrist unit 16) of the robotic device. In the following discussion, the type of robotic device under consideration is described, a mannequin is constructed, and a definition of "weight reduction" is presented.
A. Robot device
The robotic device considered herein is a three-dimensional end effector-based device, commonly referred to as a manipulator, and is comparable to the device 10 of fig. 1A and 1B. A feature of this device (as opposed to an exoskeleton) is that it is connected to a person's arm in a single position and allows movement in three dimensions. Through resistanceAnti-or admittance control, the force fr and moment mr applied to the human arm may be considered adjustable by the robot control strategy of this aspect of the invention. In the case that forces and moments in all directions can be applied, their dimensions are respectivelyAnd
The operator device 10 of fig. 1A and 1B is an example of such a system, with 3 degrees of actuation, capable of generating a translational force only at the contact location. It allows the forearm to move with 6 degrees of freedom; the directional degrees of freedom (the remaining 3 joints) are not driven but are equipped with angular displacement sensors. Thus, the following description identifies the device 10 as a robotic device that is additionally provided with a weight-reducing mechanism in this embodiment.
B. Arm model
The human arm is modeled as a two-link series (sphere-rotation) mechanism. It consists of a shoulder joint modeled as a spherical joint (3DOF, with all three axes of rotation having a common intersection point) and a rotating elbow joint. Thus, the two rigid links consist of an upper limb (in this case the upper arm) and a forelimb (in this case the forearm) and the associated mass m, respectivelyuaAnd mfaAnd (4) forming.
Similar to fig. 7, fig. 9 depicts a mathematical approximation of an upper limb model in the form of a two-bar model with a spherical joint at the shoulder S and a revolute joint at the elbow E. The upper limb (e.g. upper arm) and the forelimb (e.g. forearm) are each formed by a length lua，lfaAnd mass mua，mfaAre approximated (as being located at the mid-point of the limb). The position of the shoulder S is assumed to be known in inertial space so that its position can be quasi-statically updated. The wrist joint is not considered because the device 10 is assumed to be attached to the end of the forearm of the subject. Mathematically, the shoulder and elbow joints were modeled according to the recommendations of the International Society of Biomechanics (ISB) [28](ii) a Figure 10 shows an upper limb modeled in this way with three revolute joints q1, q2, q3 in the shoulder and one revolute joint q4 in the elbow. Although the model does not fully represent all possible degrees of freedom of the upper limb, it can model the degrees of freedom of the maximum range of motion in the upper limb, thus providing a suitable model for this aspect of the invention.
According to this model, the equation of motion of the human arm can be written as:
wherein q ish，
C. Weight reduction
When the device 10 is combined with an upper extremity model, the resulting end-effector force (f)r) Sum moment (m)r) At point CApplied to the upper limb. This provides additional force to the dynamics of the device 10, which can be adjusted by the robotic control strategy. As a result, the kinetics were modified to:
wherein R isr(fr，mr) The effect of robot forces and moments on the upper limbs is described.
Mechanical force f for weight loss of upper limbsrSum moment mrTo compensate for the gravity gh(qh) Thus requiring zero torque at the shoulder and elbow joints to maintain a given upper limb posture. Partial weight loss may occur and result in some torque remaining in the shoulder and elbow joints. Note that this reduction in required torque is analogous to reducing the amount of muscle force required to compensate for this weight.
III weight loss control strategy
In this section, a weight reduction control strategy is proposed for the general class of 3D manipulators for joint torque commands, capable of generating command end effector wrenches. This presents a unique problem definition when using the Jacobian matrix (in relation to the upper limb). This problem requires the identification of the end effector force (now considered the actuation force) to produce the required torque (zero) at the joint. This is in contrast to the common robot Jacobian, which associates the actuation joint space with the task defined in the end effector space.
A. General case 6 degree of freedom robot mechanism
In order to compensate for g due to gravityh(qh) Resulting in torque in the upper limb joint, the robot manipulator provides the appropriate force (f) at the contact locationr) Sum moment (m)r)。
From equation (2), it can be said that:
Rr(fr,mr)＝gh(qh), (3)
this is the end effector force and moment that the device 10 needs to generate.
The forces and moments can then be calculated from the upper limb model as:
whereinIs the generalized inverse of the Jacobian matrix for the human arm and is given by the following formula (see [29]])：
The upper extremity Jacobian matrix has dimensions of 6 x 4, where 6 is the size of the end effector space and 4 is the number of upper extremity joints considered in the model. It should be noted that from the perspective of the upper limb, the end effector is actuated, and the joint space of the upper limb is the regulated motion. As a result, the system is redundant.
It should also be noted that the generalized inverse above is a dynamic consistent inverse, and takes into account the effect of the task space inertia matrix, which acts to null the acceleration of the end effector due to any torque projected into null space of the device 10. This provides a versatile method of reducing weight in any end effector-based device with full actuation of both force and torque. In this case, the Jacobian determinant is full rank at positions other than the singular point, and thus g (q) can be completely compensated forh) The influence of (c). This also has an impact on the application of other joint-based control strategies, which may also be implemented in such end effector-based devices.
This result indicates that the 3D end effector-based robotic device can substantially fully compensate for the effects of gravity on the subject's upper limb dynamics, providing a device for this function that can be less complex in mechanical design than an exoskeleton.
B. In an under-actuated robot apparatus: examples of application to the apparatus 10
To simplify the robotic mechanism for upper limb rehabilitation, it is now considered to apply weight reduction strategies to under-actuated robots, such as the device 10. The device 10 has 3 degrees of actuation, enabling adjustment of the translational degree of freedom of the end effector. The spherical joint is placed on an end effector (wrist unit 16) equipped with an angular displacement sensor.
In this case, the Jacobian matrix is rewritten to consider only the translational force component of the end effector (as actuation), while still adjusting the 4 joints considered in the upper limb model. Thus, the end effector forces that the device 10 must produce to reduce weight are:
this method of upper limb weight loss results in a change in the force of the upper limb posture. Secondly, the use of only three controllable forces on a system with 4 generalized coordinates results in under-drive-not all gravitational effects can be fully compensated.
At the first point of change in the overall workspace, it can be seen from equation (6) that the force depends on both the gravity g (q)h) The influence of (2) is also dependent on JacobianJh(qh) Both depending on the subject qhThe posture of (1). The result of this is that the required force varies in both magnitude and direction across the workspace. A visualization of this situation can be seen in fig. 11A and 11B, which plots the calculated forces in a number of poses in the sagittal (vertical) plane and the transverse (horizontal) plane. In each posture, the force changes, requiring more force to achieve more elbow extension and more shoulder elevation. It should be noted, however, that the amplitude and direction do not vary significantly with changes in the transverse plane associated with the elevation angle of the shoulder S.
Secondly, the system considered is not fully driven: in three directions onlyUpper control force, but upperLimbs are modeled as having four joints
By projecting the effect of the driving force back into the human joint space (i.e. the generalized coordinates), the result of applying the current weight reduction method to a manipulator device controlling only the end effector and not the moment can be determined:
as a result, the component of the gravity term that is not compensated by the weighting algorithm can be expressed as:
wherein I4Is a 4 x 4 identity matrix.
Numerical calculations of this expression show that when no moment is available at the contact position, the weight-reducing torque at the elbow joint E is sufficiently compensated, but some component of the shoulder torque is not compensated. This can be seen in fig. 12, which shows the percentage of uncompensated torque versus the inner/outer rotational angle for different postures of the upper limb (i.e. around q 3). It can be observed that these uncompensated torques are: (1) zero (full compensation) when the inside/outside rotation angle of the shoulder is 0 degrees (i.e. elbow directly down); (2) otherwise depending on the full arm posture, including elbow extension (i.e. not expressible in the shoulder frame only).
The uncompensated torques lie in the dynamic null space of the arm, which means that these torques do not affect any linear acceleration of the hand. It is noted that this null is different from the motion null of an arm placed along the rotation angle axis (defined in [30] and used for interaction analysis between human and bone) (discussed further below).
IV, demonstration of ability
The example of the apparatus 10 is used as an experimental platform for implementing a weight-loss controller. The experiments and experimental platforms presented herein provide a demonstration of the platform and control strategy functionality.
A. Device for measuring the position of a moving object
The robotic arm was constructed according to the model identified in fig. 10 and is shown at 90 in fig. 13, along with an exemplary end effector 92 of the device 10 used in these experiments. The robot arm 90 comprises two links 94, 96 connected to each other by a rotary joint 98; the rotary joint 98 includes a ball bearing and represents the elbow E. The proximal end 100 of the arm 90 passes through a ball joint (in this example, Igus)TMBall bearing) is attached to a fixed frame 102 (not shown) representing a shoulder S, and a distal end 104 is attached to the end effector 92 of the device 10. Weight m11kg and m21kg is fixed in the centre of each link 94, 96.
Magnetic sensors (trakSTAR, Ascension Technologies) are used to measure the orientation of the links 94, 96; orientation for real-time (at 30 Hz) computation of the mechanical arm qhThe posture of (1). These results are used in conjunction with the estimation of the model, calculating the required robot force according to equation (6).
B. Procedure for measuring the movement of a moving object
The device was used to perform validation experiments and demonstrate the feasibility of weight loss control strategies in this application.
In this experiment, the apparatus 10 moved the end effector 92 to four different positions within the workspace in position control. These positions are limited by the range of motion of the arm 90, but the positions are selected so that they represent as wide a range as possible. After each position is reached, control will switch to a weight loss strategy. To this point, the response of the system is recorded.
C. Results
Fig. 14 shows the position of the end effector 92 of the device 10 over time, i.e. the position of the contact point between the device 10 and the wrist point C of the arm 90. It can be seen that the system enables each arm 90 to stabilize the posture to which it is moved. When the system switches from position control to gravity compensation, drift may be observed in certain poses. This is not surprising given that the proposed strategy relies only on open loop control and that both the robotic arm and the robotic device are highly back-drivable. Thus, drift may be accounted for by differences between the model and the actual robotic arm 90 and errors in the attitude measurements. However, this drift is negligible, especially for rehabilitation applications, where even a passive human arm cannot be driven backwards due to muscles, ligaments and tendons at the joints.
Fig. 15A is a schematic diagram of the controller 110 for implementing a weight-reduction control strategy according to this aspect of the invention. Referring to fig. 15A, the controller 110 is in the form of a real-time controller, the controller 110 receiving upper limb parameters specifying the dynamics of the upper limb, including the mass, inertia and length of each segment, and upper limb posture parameters defining a representation of the upper limb in space. The controller 110 outputs force and moment parameters [ f, m ] according to equation (6), which are the forces and moments applied by the device 10 (or other similar robotic system) at the point of contact to compensate for the weight of the upper limb, thereby reducing the weight of the upper limb.
Fig. 15B is a schematic diagram of a weight-reduced robotic manipulator apparatus 120 according to this aspect of the invention, showing upper limbs 122 about to be reduced in weight. The apparatus 120 used in the above experiment includes a controller 110 (see fig. 15A), an operator apparatus 124 (see apparatus 10), three 3-degree-of-freedom sensors Sa, Sb, Sc (connected to the upper limb 122) that output their absolute directions in space, respectively, and a processor 126 that receives the outputs of the sensors Sa, Sb, Sc and outputs θ 1, θ 2, θ 3, θ 4 specifying the joint angles of the upper limb 112 to the controller 110. θ 1, θ 2, θ 3, θ 4 are shoulder elevation plane, shoulder elevation, shoulder in/out rotation, and elbow flexion and extension, respectively.
The controller 110 also has a forelimb (e.g., forearm) mass and an upper limb (e.g., upper arm) mass Mua，MfaInertia matrix I of forelimb and upper limbua，IfaAnd length l of forelimb and upper limbuaAnd lfa. From these inputs, the controller 110 determines the force and moment [ f, m ] to be applied by the device 124 according to equation (6)]。
Other devices and clinical applications
Weight loss is commonly used for rehabilitation of patients with neurological dysfunction; instead of devices, therapists often perform this manually, and there are passive devices designed to provide only weight loss support, such as armeoresprings (Hocoma, switzerland) and SaeboMASTM (Saebo, usa). Such devices may be mechanically tuned to provide different levels of support, but are unable to give or implement other control strategies.
Some existing mobile manipulator apparatuses also provide some weight reduction functionality. The two-dimensional manipulator provides a weight-reduction function by its planar design, but only in a limited working space. Exoskeletons provide maximum flexibility in weight reduction and control strategies, but can be difficult to set up and use in a clinical setting. The results show that a properly designed end effector-based device can provide equivalent weight reduction support to an exoskeleton. It is envisaged that extending these findings to other control strategies (such as those discussed in [21], [31 ]) implemented primarily in exoskeleton-based robotic devices should allow more advanced, more efficient strategies to be developed on simpler platforms, accelerating their conversion to clinical practice.
However, there are still other aspects of device support issues; for example, the analysis provided herein only addresses the joint torque required for each position, without considering the interaction forces (assuming that the shoulder and elbow joints are ideal spherical and rotational joints, respectively). In fact, the physiological joints are connected by ligaments and muscles, which do not always reflect the ideal form of expression, in particular for stroke patients, due to conditions such as subluxation. Further analysis may be constructed to estimate this.
A weight loss control strategy is set forth in [26 ]. In this work, the weight reduction strategy implemented assumed a different model of the arm-a model of the rigid elbow. Therefore, the torque about the elbow is not compensated. [26] The weight loss control strategy described in detail in (a) is compared to one of the methods presented herein, and is illustrated in fig. 16 by dashed and solid arrows, respectively. It can be seen that there is a significant difference between the two: the magnitude of the force proposed by the simplified solution (dashed arrow) is smaller than the force of the proposed solution (solid arrow); the simplified solution has a force that is always orthogonal to the vector between the shoulder and the contact position. The proposed solution includes a force component of the same magnitude and same direction as the simplified solution, but also includes an orthogonal component that accounts for the fact that the elbow is now considered a joint. This can "pull" the elbow joint outward so that it does not bend due to gravity. Although no hardware implementation was proposed in previous work [26], it is clear that this implementation does not completely eliminate the gravitational effects around the elbow joint.
Limitations and practical considerations
Uncompensated torque: as mentioned above, the incomplete drive characteristics of the system result in the gravity torque being uncompensated. However, these torques are of little importance in the dynamic null space of the arm, as they do not have an effect on the contact point and any linear acceleration of the subject's hand. Furthermore, the total elbow joint torque is compensated, which seems to be suitable for upper limb rehabilitation applications, since patients often exhibit significant elbow joint motion limitation, usually compensated by shoulder and torso motion [32 ].
The mere use of force-controlled devices does not physically prevent the patient from moving with this unnatural synergy. As a result, if the purpose of the treatment is to prevent such synergy, another method of reducing such synergy is required, as proposed in [33 ]. It is to be noted that this is not necessarily disadvantageous: physically blocking exercise does not prevent the muscle activation pattern, but inhibits its effect, and blocking the activation pattern from the outset may be counterproductive.
Measurement requirements: a second limitation in applying this work to practice is the requirement to know Jacobian Jh(qh) And gravity vector g (q)h). This requires knowledge of the physical characteristics of the patient and real-time measurement of his posture. It should be noted, however, that the inherent physical damping is relatively strong against such knowledge errors and noise, as a result of having a person in the loop. Measurements may be made by various sensors, including sensors on robotic devices, in operationMagnetic sensors for use or Inertial Measurement Unit (IMU) based sensors.
According to another aspect of the present invention, an end effector in the form of an electromechanical handle is provided that may be used with a 3D end effector based arm rehabilitation device (e.g., device 10 or device 120). The characteristics of such electromechanical handles are suitable for use as components of such devices: when tying the human subject in the 3D manipulator device, the hand will remain free (and therefore can be grasped) and can be rotated in various directions, leaving the forearm direction unrestricted. For example, in rehabilitation applications, it is desirable that a subject can perform rehabilitation exercises with his/her hands in a "functional grip posture" even if the subject cannot actively control his/her hand pronation-supination. This is particularly important when the exercise involves real world movements and may affect the healing effect. Furthermore, the subject should be provided with sufficient support of the entire arm. The electromechanical handle desirably inhibits rotation of an upper limb (e.g., arm) in a vertical plane when desired.
Thus, fig. 17A and 17B are views of an electromechanical robotic manipulator device 130, comparable to the device 10 of fig. 1A and 1B, but including an electromechanical handle 132, according to an embodiment of the invention. The electromechanical handle 132 is connected to a distal beam 134 of the manipulator device 130. The electromechanical handle 132 is in fact a wrist-type handle that functions equivalent to the wrist unit 16 of the device 10 of fig. 1A and 1B. The electromechanical handle 132 includes a wristband 136, the wristband 136 being configured to engage a wrist of the subject. In use, the subject's forearm is mounted on a wrist splint (not shown) and then passed through a suitable attachment (e.g. Velcro @)TMStraps (not shown)) are attached to the wristband 136. The wristband 136 and the subject's wrist splint allow the subject's hand to freely extend into and grasp, but may optionally surround the subject's thumb.
Fig. 18A-18E are schematic views of a portion of an electromechanical handle 132 and distal beam 134 according to a minor variation of the version shown in fig. 17A and 17B, and therefore like reference numerals are used to identify like features.
The electromechanical handle 132 of fig. 17A, 17B, and 18A-18E includes a first link 138A and a second link 138B. The first link 138a is rigidly connected to the distal beam 134; the second link 138b is rotatably connected to the first link 138a and the wristband 136 through first and second rotary joints 140a, 140b, respectively, with thrust bearings; their rotation is measured with a potentiometer (not shown). The first and second rotary joints 140a, 140b are positioned such that their axes are orthogonal to each other; the two shafts may be locked in place by a locking mechanism (not shown).
The wrist cover 136 includes: an outer housing 142 and an inner housing 144, the second rotary joint 140b being connected to the outer housing 142, the inner housing 144 being rotatably mounted within the outer housing 142 and the user interface being connected to the inner housing 144. The housing 142 contains the motor, cable reduction system (bushings), potentiometer and electronics (not shown). The inner housing 144 is rotatable within the outer housing 142 about an axis aligned with the forearm (i.e., the pronation-supination joint) of the subject and is actuated by a cable (not shown) wound around a bushing on the motor shaft (also orthogonal to the two first axes). A series of rolling bearings (not shown) in the inner housing 144 facilitate rotation of the inner housing 144 and/or are supported by the outer housing 142. In this example, the wrist splint is by VelcroTMThe strap is tied to the inner shell 144.
The electromechanical handle 132 has three rotational degrees of freedom. As shown in fig. 19A, these three degrees of freedom correspond to the degrees of freedom of the wrist; the rotational degrees of freedom a, b, c are centered about the approximate center of the subject's wrist joint and allow the hand to rotate freely about that point. According to this embodiment, the electromechanical handle 132 includes sensors (not shown) that measure all three rotations, outputting data that is representative of the full 3D orientation of the subject's forearm.
The last rotation c is made about an axis in line with the subject's forearm, resulting in a pronation-supination rotation. The pronation-supination joint and its rotation are schematically illustrated in fig. 19B, with the supination, neutral, and pronation positions shown from left to right. The rotation of the wristband 136 is motorized and may be controlled such that the subject's palm is always in a functional position, such that, for example, the axis directly out of the subject's palm is always perpendicular to the vertical axis. If desired, the anterior-posterior joint may instead be freely rotated, and thus, its orientation controlled by the subject, since the wristband 136 may be back-driven.
The other two degrees of freedom (b and c) are not motorized and therefore can rotate freely. However, these two degrees of freedom may be mechanically locked in a desired position to fully retain the forearm of the subject.
The electronics of the electromechanical handle 132, including the microcontroller, employ the orientation of the distal beam 134 and the electromechanical handle 132 to generate control commands to control the angular position of the driven pronation-supination joint (i.e., the rotational position of the inner housing 144 relative to the outer housing 142) as desired. The electronics of the electromechanical handle 132 report the forearm orientation (represented by the frame of reference of the operator device 130) back to the controller of the operator device via an I2C communication link.
The housing 142 is provided with one or more controls (e.g., buttons) for controlling the behavior of the operator device 130 (i.e., to demonstrate movement, repetition, stoppage, etc.) and an alert mechanism (e.g., one or more LEDs and/or a buzzer) to provide a user interface for the electromechanical handle 132, for example, for use by a therapist.
While all of the processing required to control the electromechanical handle 132 may be performed by the aforementioned controller of the operator device 130, the electromechanical handle 132 may alternatively be equipped with a microcontroller to perform this task. Thus, fig. 20 is a schematic diagram of a version of the microcontroller 150 of the electromechanical handle 132, which may be located, for example, within the housing 142 or on the distal beam 134. (alternatively, the microcontroller 150 may be considered to depict the same functionality, but is implemented by the controller of the operator device 130). The microcontroller 150 receives input (in the form of joint orientation) and control commands (from the controls described above) and communicates with (i.e., communicates with) the controller of the operator device 130. The microcontroller 150 outputs motor commands to the motor of the housing 142 of the electromechanical handle 132 and issues an alarm (e.g., to the aforementioned LED and/or buzzer).
Conclusion
The dynamics of the device 10 have less effect on the movements made by the arm and the working space is large enough not to cover the range of motion of a healthy user. The device 10 provides the ability to exert forces over a large 3D workspace while remaining transparent, which means that the device 10 can create the proper balance between the various categories of existing upper limb rehabilitation systems (exoskeletons and planar operations).
It is contemplated that other embodiments may include upper limb rehabilitation specific control embodiments. Thus, a motorized and dynamically transparent platform can actually implement in a workspace the various repetitive motions studied in robotically-assisted rehabilitation literature (as described in [21 ]), as well as the implementation of assistance strategies such as [22] and [23 ].
In addition, the device 10 is designed to allow free hand movement. Although most robotic devices for rehabilitation utilize virtual environments, studies have shown the importance of the environment in effective rehabilitation exercises [21 ]. The use of virtual environments is useful for incentives (exercises can be "gambled") and additional mapping between the real world and the virtual world is required, so the general problem with these exercises still remains. Furthermore, traditional rehabilitation exercises are often targeted, for example, using a spoon to feed oneself. As a result, the ability to freely work with physical objects is an advantageous feature of the apparatus 10.
Furthermore, the disclosed control strategies for reducing the weight of a patient's arm in a three-dimensional end effector-based device may be used to minimize or eliminate the effects of gravity on a 4-degree-of-freedom arm model. Furthermore, this strategy is not implemented on the device 10 because it does not provide torque on the end effector. In addition to moments about an axis connecting the shoulder and the point of contact, this arrangement may be used to minimize or eliminate the effects of gravity.
This work can be further undertaken to more fully address the effects of other configurations of incomplete drive (e.g., devices that are only capable of applying torque in certain directions), as well as the ability of the device to apply other dynamic conditions to the patient. In implementing this control strategy for healthy subjects and patients, application-based experimental work can be done to observe whether and how these interaction forces alter the behavior of the subject, and to measure changes in muscle activity in this case.
Modifications within the scope of the invention may be readily effected by those skilled in the art. It is to be understood, therefore, that this invention is not limited to the particular embodiments described by way of example hereinabove. For example, although the embodiments described in detail above relate to a communications cable, it will be apparent that the invention may also be applied to other types of cables, including for power transmission.
In the claims hereof, as well as in the foregoing description, and unless the context requires otherwise by express language or necessary implication, the word "comprise" or variations such as "comprises" or "comprising" is used in an inclusive sense, i.e. to specify the presence of the stated features, but not to preclude the presence or addition of further features in various embodiments of the invention.
Furthermore, any reference herein to prior art is not intended to imply that such prior art forms or forms part of the common general knowledge in any country.
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