阅读说明：本技术 移动体以及移动体的控制方法 (Mobile body and control method for mobile body ) 是由 杉本克文 神川康久 于 2020-02-12 设计创作，主要内容包括：为了改进车轮行驶期间的稳定性,在具有带脚轮的多个支撑腿的移动体中,该移动体包括：多个支撑腿,其基座被附接到本体上并且脚轮被附接到其端部；稳定器；以及脚轮角度控制单元。稳定器基于本体的姿态的目标值来控制多个支撑腿中的每一个的脚轮接地位置。脚轮角度控制单元基于目标值来控制脚轮中的每一个的脚轮角度。(In order to improve stability during wheel traveling, in a moving body having a plurality of support legs with casters, the moving body includes: a plurality of support legs, the base of which is attached to the body and casters are attached to the ends thereof; a stabilizer; and a caster angle control unit. The stabilizer controls a caster ground position of each of the plurality of support legs based on a target value of the posture of the body. The caster angle control unit controls a caster angle of each of the casters based on the target value.)

1. A mobile body, comprising:

a plurality of support legs in which a base is mounted on the body and casters are mounted on the distal end;

a stabilizer configured to control a position at which a caster of each of the plurality of support legs contacts a ground based on a target value of an attitude of the body; and

a caster angle control unit configured to control a caster angle of each of the casters based on the target value.

2. The movable body according to claim 1 wherein, upon transition to a travel mode in which the movable body performs wheel travel, the caster angle control unit obtains a ratio of a height from a road surface to the base to a caster trajectory of the caster and a new target value based on mechanical impedance and torsional rigidity of each of the plurality of support legs.

3. The movable body according to claim 1 wherein the caster angle control unit obtains a mechanical impedance based on the torsional rigidity of each of the plurality of support legs, the target value, the height from the road surface to the base, and a caster trajectory of the caster, when shifting to a walking mode in which the movable body performs walking.

4. The mobile body according to claim 1, further comprising:

a plurality of elevators configured to support the object table; and

an elevator control unit configured to control the plurality of elevators based on the target values.

5. The movable body according to claim 1 wherein the body comprises a front body, a rear body, and a connection unit that connects the front body to the rear body.

6. The movable body according to claim 1 wherein the caster comprises a wheel unit and a damper that expands and contracts in a direction perpendicular to the road surface.

7. The movable body according to claim 1,

wherein each of the plurality of support legs includes a first joint disposed in the base, a second joint, and a third joint disposed in the distal end, an

Wherein the first joint is a biaxial joint.

8. The mobile body of claim 1, wherein the plurality of support legs comprises a pair of front support legs and a pair of rear support legs.

9. The mobile body according to claim 8 wherein an installation angle of a base of each of the pair of front support legs is different from an installation angle of a base of each of the pair of rear support legs.

10. The movable body according to claim 1 wherein the number of the plurality of support legs is two.

11. A method of controlling a mobile body, the method comprising:

a stabilization step of controlling a position at which a caster of each of a plurality of support legs, in which the base is mounted on the body and the caster is mounted on a distal end, is in contact with the ground based on a target value of an attitude of the body; and

a caster angle control step of controlling a caster angle of each of the casters based on the target value.

Technical Field

The present technology relates to a mobile body. In particular, the present technology relates to a moving body that can move using a plurality of support legs, and a method of controlling the moving body.

Background

In the related art, a moving body that operates a plurality of support legs and walks so as to be able to pass over obstacles, steps, and the like is used for various purposes such as carrying a load and providing safety or entertainment. Such a moving body is also called a robot. In general, in the movement of a moving body operating a support leg during traveling, the moving speed is slower than that during traveling of wheels. Therefore, a moving body in which a caster is mounted on a distal end of a support leg so as to be able to perform travel by a travel wheel in addition to traveling has been proposed (for example, see patent document 1).

[ list of references ]

[ patent document ]

[ patent document 1]

JP2009-154256A

Disclosure of Invention

[ problem ] to

The above-described moving body is switched to the running mode in which the running of the running wheels is performed in the movement on a flat ground or the like where the running of the wheels is easy, and is switched to the running mode in the movement on an irregular ground where the running of the wheels is difficult, and therefore compatibility between the improvement of the moving speed and the improvement of the running on the irregular ground can be achieved. However, the mobile body changes the position where the support leg contacts the ground in order to avoid an obstacle or a step on the road surface in the travel mode, thereby changing the posture thereof in some cases. However, in these cases, the mobile body can restore its attitude by temporarily separating the other support legs from the ground and stepping down the steps to stabilize the attitude. However, walking down the steps with support legs during driving risks toppling. When the traveling speed is temporarily reduced, the risk of toppling over when the supporting leg is used for walking down the step can be reduced. However, this is not preferable because the average speed is reduced. Therefore, in the above-described mobile body, it is difficult to improve the stability when running on the running wheels.

The present technology has been devised in view of such a situation, and an object of the present technology is to improve stability of wheel travel of a moving body including a plurality of support legs having casters.

[ solution of problem ]

The present technology is designed to solve the above-described problems, and a first aspect is a moving body including: a plurality of support legs, wherein the base is mounted on the body and the caster is mounted on the distal end; a stabilizer configured to control a position at which a caster of each of the plurality of support legs contacts the ground based on a target value of the attitude of the body; and a caster angle control unit configured to control a caster angle of each of the casters based on the target value. Therefore, an operational effect of controlling the caster angle based on the target value of the posture can be obtained.

According to the first aspect, the caster angle control unit may obtain the ratio of the height from the road surface to the base to the caster track of the caster and a new target value based on the mechanical resistance and the torsional rigidity of each of the plurality of support legs at the time of transition to the travel mode in which the mobile body performs travel on the travel wheels. Therefore, in the traveling mode, the operational effects of the ratio of the height to the caster track and the new target value can be obtained.

According to the first aspect, the caster angle control unit may obtain the mechanical impedance based on the torsional rigidity of each of the plurality of support legs, the target value, the height from the road surface to the base, and the caster trajectory of the caster, when shifting to the walking mode in which the mobile body performs walking. Therefore, an operational effect of obtaining mechanical resistance in the walking mode can be obtained.

According to the first aspect, the moving body may further include: a plurality of elevators configured to support the object table; and an elevator control unit configured to control the plurality of elevators based on the target value. Therefore, an operational effect of controlling the elevator based on the target value can be obtained.

According to the first aspect, the body may include a front body, a rear body, and a connection unit connecting the front body to the rear body. Therefore, an operational effect of independently controlling the postures of the front body and the rear body can be obtained.

According to the first aspect, the caster may include a wheel unit and a damper that extends and contracts in a direction perpendicular to a road surface. Therefore, an operational effect of increasing the caster angle when weight is applied can be obtained.

According to a first aspect, each of the plurality of support legs includes a first joint disposed in the base, a second joint, and a third joint disposed in the distal end. The first joint may be a biaxial joint. Therefore, an operational effect of expanding the movable range of the support leg can be obtained.

According to the first aspect, the plurality of support legs may include a pair of front support legs and a pair of rear support legs. Therefore, the operational effect of controlling the caster angles of the four legs can be obtained.

According to the first aspect, the mounting angle of the base of each of the pair of front support legs is different from the mounting angle of the base of each of the pair of rear support legs. Therefore, an operational effect of making the caster angle in the initial state different between the front side and the rear side can be obtained.

According to the first aspect, the number of the plurality of support legs may be two. Therefore, the operational effect of controlling the caster angles of both legs can be obtained.

Drawings

Fig. 1 is an external view of a mobile body according to a first embodiment of the present technology.

Fig. 2 is a block diagram showing an exemplary configuration of a moving body according to a first embodiment of the present technology.

Fig. 3 is a block diagram showing an exemplary configuration of a caster angle control unit according to a first embodiment of the present technology.

FIG. 4 is a side view showing an exemplary configuration of a support leg according to a first embodiment of the present technology.

Fig. 5 is a diagram showing the rotation axes of the first joint and the third joint according to the first embodiment of the present technology.

Fig. 6 is a block diagram showing an exemplary configuration of a walking mode control unit according to a first embodiment of the present technology.

Fig. 7 is a block diagram showing an exemplary configuration of a travel mode control unit according to a first embodiment of the present technology.

Fig. 8 is a side view showing an example of the installation angle according to the first embodiment of the present technology.

Fig. 9 is a diagram showing a process of traveling on an inclined surface according to the first embodiment of the present technology.

Fig. 10 is a diagram showing an advantageous effect when a caster angle is given according to the first embodiment of the present technology.

Fig. 11 is a diagram showing the control of the control unit according to the first embodiment of the present technology.

Fig. 12 is a diagram showing the control of the stabilizer and the caster angle control unit according to the first embodiment of the present technology.

Fig. 13 is a flowchart showing an example of the operation of the control unit according to the first embodiment of the present technology.

Fig. 14 is a side view showing an exemplary configuration of a moving body according to a second embodiment of the present technology.

Fig. 15 is a block diagram showing an exemplary configuration of a moving body according to a second embodiment of the present technology.

Fig. 16 is a diagram illustrating an elevator control method according to a second embodiment of the present technology.

Fig. 17 is a side view showing an exemplary configuration of a moving body according to a third embodiment of the present technology.

Fig. 18 is a side view showing an exemplary configuration of a moving body according to a fourth embodiment of the present technology.

Fig. 19 is a side view showing an exemplary configuration of a moving body according to a fourth embodiment of the present technology.

Fig. 20 is a sectional view showing an exemplary configuration of a caster according to a sixth embodiment of the present technology.

Fig. 21 is a side view showing an exemplary configuration of a moving body according to a seventh embodiment of the present technology.

Fig. 22 is a side view showing an exemplary configuration of a moving body according to an eighth embodiment of the present technology.

Detailed Description

Hereinafter, a mode for implementing the present technology (hereinafter referred to as "embodiment") will be described. The description will be made in the following order.

1. First embodiment (example of controlling caster angle)

2. Second embodiment (example of controlling the angles of the lifter and the caster)

3. Third embodiment (example in which the body is divided into two parts and the caster angle is controlled)

4. Fourth embodiment (example in which the body is divided into two parts and the angles of the lifter and caster are controlled)

5. Fifth embodiment (example of controlling caster angle by setting front installation angle to be different from rear installation angle)

6. Sixth embodiment (example of providing damper and controlling caster angle)

7. Seventh embodiment (example of providing biaxial joint and controlling caster angle)

8. Eighth embodiment (example of controlling caster angle of both legs)

9. Example of application of Mobile body

<1 > first embodiment >

[ exemplary configuration of moving body ]

Fig. 1 shows an example of an appearance of a moving body 100 according to a first embodiment of the present technology. The moving body 100 is an unmanned robot for various purposes such as carrying objects, providing safety or entertainment, and the moving body 100 includes a body 110 and a plurality of support legs. For example, four support legs 120, 130, 140, and 150 are provided in the moving body 100.

The body 110 is an elongated member, and a control unit 180 that controls four support legs (support legs 120, etc.) is provided inside.

The bases of the support legs 120, 130, 140 and 150 are mounted on the body 110 and the casters 161 to 164 are mounted on the distal end. A member mounted at the distal end of an arm or leg of the robot in this manner is also referred to as an end effector.

When a direction from one side to the other side of both ends of the elongated body 110 is set as a front side, the support legs 120 and 140 are installed on the front side, and the support legs 130 and 150 are installed on the rear side. The support legs 120 and 140 are examples of front support legs described in the claims, and the support legs 130 and 150 are examples of rear support legs described in the claims.

Each support leg 120 includes a plurality of joints and an actuator that drives the joints. The number of joints and joint axes will be described later.

The moving body 100 includes various sensors (not shown), such as a sensor that detects an angle of an actuator, an image sensor that images a road surface, an acceleration sensor, and a gyro sensor. The acceleration sensor and the gyro sensor are provided in, for example, an Inertial Measurement Unit (IMU).

Fig. 2 is a block diagram showing an exemplary configuration of the moving body 100 according to the first embodiment of the present technology. The moving body 100 includes a sensor group 171, a control unit 180, and four support legs (support legs 120, etc.). In each support leg, an actuator group 172 is provided. The control unit 180 includes a stabilizer 181, a road surface condition analysis unit 182, and a caster angle control unit 200.

The sensor group 171 is a sensor group that detects the internal or external condition of the mobile body 100. For example, a sensor for detecting an angle of an actuator, an image sensor for imaging a road surface, an acceleration sensor, a gyro sensor, and the like are provided as the sensor group 171. The sensor group 171 supplies the detected data to the control unit 180.

The actuator group 172 is an actuator group that operates a joint of each of the support legs 120 and the like.

The stabilizer 181 performs a stabilization control (for example, ZMP control) for avoiding toppling. When the ZMP control is performed, the stabilizer 181 controls the landing positions of the leg tips (casters 161 to 164) of the support legs 120 and the like based on the Zero Moment Point (ZMP) and the target value of the posture of the body 110. Here, ZMP refers to the operational center of gravity of vertical ground reaction force, and attitude control performed using ZMP is referred to as ZMP control. The attitude of the body 110 is indicated by, for example, the pitch angle of the body 110.

The stabilizer 181 acquires the current value of the current attitude (pitch angle, etc.) of the body 110 from the IMU, etc. The stabilizer 181 calculates the position where the currently lifted leg subsequently lands and the force generated in the vertical direction of the currently grounded support leg from the difference between the current value and the target value of the attitude of the ZMP at the position within the support polygon. Here, the raised leg is a support leg whose leg tip is away from the road surface, and the support polygon is a polygon drawn by the leg tip. The stabilizer 181 inputs the calculated value into the inverse kinematics solver together with the current landing position of the leg tip and the mechanical impedance of the leg tip. Here, the inverse kinematics solver is a program that calculates a torque to be applied to the joint when the angle, the angular velocity, and the angular acceleration of the input joint are input.

Then, the stabilizer 181 outputs the value of the torque calculated from the target value of the attitude as the target value of the torque to the corresponding actuator in the actuator group 172. The stabilizer 181 supplies posture information indicating a target value of the posture to the caster angle control unit 200. The stabilizer 181 is an example of a stabilizer described in claims.

The road surface condition analysis unit 182 analyzes the road surface condition using data from the image sensor or the like. The road surface condition analysis unit 182 generates a mode signal indicating one of the traveling mode and the traveling mode based on the analysis result, and outputs the mode signal to the caster angle control unit 200. Here, the traveling mode is a mode in which the mobile body 100 moves by traveling, and the traveling mode is a mode in which the mobile body 100 moves by traveling of wheels. For example, when the road surface is flat and there are few obstacles, the running mode is preferably set. The walking mode is preferably set when the road surface is uneven or there is an obstacle.

The caster angle control unit 200 controls the caster angles of the casters 161 to 164 based on the posture information. The caster angle control unit 200 calculates a target value of the torque based on the control content and outputs the target value to the corresponding actuator in the actuator group 172.

The mobile body 100 switches the mode between the travel mode and the travel mode based on the analysis result of the road surface condition, but the present technology is not limited to this configuration. A communication interface for external communication with the mobile body 100 may be further included to switch the mode according to a command from the outside.

[ exemplary configuration of the caster-angle control unit ]

Fig. 3 is a block diagram showing an exemplary configuration of the caster angle control unit 200 according to the first embodiment of the present invention. The caster angle control unit 200 includes a torsional rigidity map 210 based on the respective postures, a torsional rigidity acquisition unit 220, a walking mode control unit 230, a running mode control unit 240, and a selection unit 250.

The torsional stiffness map 210 based on the respective attitudes stores the respective torsional stiffness of the support leg 120 and the like for each representative attitude of the body 110.

The torsional rigidity acquisition unit 220 obtains the torsional rigidity of each support leg based on the attitude information from the stabilizer 181. The torsional rigidity acquisition unit 220 reads the torsional rigidity corresponding to the posture indicated by the posture information from the torsional rigidity map 210 based on the respective postures. When the torsional rigidity corresponding to the posture is not stored, the torsional rigidity acquisition unit 220 obtains the torsional rigidity by linear interpolation. The torsional rigidity obtaining unit 220 obtains the obtained torsional rigidity K_tTo the walking mode control unit 230 and the traveling mode control unit 240.

When the mode signal from the road surface condition analysis unit 182 indicates the walking mode, the walking mode control unit 230 calculates the mechanical impedance K of the joint satisfying the given condition₁. The walking mode control unit 230 generates actuator control information supporting the angle or torque of the actuator based on the calculation result, and provides the actuator control information to the selection unit 250. The walking mode control unit 230 calculates the mechanical impedance K₁And supplied to the travel mode control unit 240.

When the mode signal indicates the travel mode, the travel mode control unit 240 calculates a parameter related to a caster angle. The contents of the calculated parameters will be described later. The travel mode control unit 240 generates actuator control information based on the calculation result and supplies the actuator control information to the selection unit 250.

The selection unit 250 selects actuator control information of one of the traveling mode control unit 230 and the traveling mode control unit 240 according to the mode signal and supplies the actuator control information to the actuator group 172. In the case of the walking mode, the output of the walking mode control unit 230 is selected. In the case of the travel mode, the output of the travel mode control unit 240 is selected.

[ exemplary configuration of support legs ]

FIG. 4 is a side view showing an exemplary configuration of a support leg 120 according to a first embodiment of the present technology. The support leg 120 includes a first joint 121, a link 122, a second joint 123, a link 124, and a third joint 125.

Hereinafter, an axis parallel to the moving direction of the moving body 100 is referred to as an "X-axis", and a direction perpendicular to the road surface is referred to as a "Z-axis". The axis perpendicular to the X-axis and the Z-axis is referred to as the "Z-axis". When the joint rotates about an axis, the X-axis corresponds to the roll axis, the Y-axis corresponds to the pitch axis, and the Z-axis corresponds to the yaw axis.

The first joint 121 is a joint provided in the base of the support leg 120, and the first joint 121 corresponds to a shoulder joint when the support leg 120 is compared to an arm of a person. When a pitch angle formed between a straight line perpendicular to the axis of the link 122 and a straight line parallel to the longitudinal direction of the body 110 is set as a mounting angle, the first joint 121 is mounted such that the mounting angle becomes a fixed value. The actuator rotates the first joint 121 about a predetermined axis, wherein the angle to the roll axis is. Strictly speaking, whenWhen not "0" degree, the rotation axis of the first joint 121 does not correspond to the roll axis. However, for convenience of description, even in this case, the rotation axis of the first joint 121 is considered as the lower roll axis.

The actuator rotates the second joint 123 about the pitch axis, the second joint 123 corresponding to an elbow joint when the support leg 120 is compared to an arm of a person. The actuator rotates the third joint 125 about the pitch and yaw axes, the third joint 125 corresponding to a wrist joint when the support leg 120 is compared to a human arm.

The link 122 is a member connecting the first joint 121 to the second joint 123. The link 124 is a member that connects the second joint 123 to the third joint 125.

The configuration of each of the support legs 130, 140, and 150 is the same as the configuration of the support leg 120.

Fig. 5 is a diagram showing the rotation axes of the first joint 121 and the third joint 125 according to the first embodiment of the present technology. In the drawing, a is a view of the first joint 121 viewed from the rotational axis (i.e., the roll axis) of the first joint 121. In the drawing, b is a plan view of the caster 161 viewed from a yaw axis between the rotation axes of the third joint 125.

As described above, the stabilizer 181 executes the stabilization control (ZMP control, etc.) to avoid toppling. However, this control may cause the leg tip of the support leg to widen (or narrow) as compared to the initial state. During traveling, interference may be applied to the caster 161 and the like, and the position may be slightly deviated in some cases. When it is assumed that the moving body 100 is traveling straight ahead, a force is applied to the caster 161 and the like in a direction perpendicular to the side surface (in other words, a horizontal direction). This force is hereinafter referred to as "horizontal force". Here, a condition that the direction or posture of the caster 161 has been restored without dispersion or vibration and a specific direction or posture converges when a horizontal force occurs during forward straight traveling can be conceived.

First, it is conceivable to apply a moment (i.e., torque) about the rolling axis of the first joint 121, as shown by a in the drawing, and to apply a moment about the caster 161, as shown by b in the figure. Torque T of the former₁Against a horizontal force F applied in the lateral direction (i.e., Y-direction) of the caster 161_SIs balanced, the following equation holds.

In the above formula, the torque T₁The unit of (d) is, for example, newton meters (Nm). Here, p_zIs the height from the road surface to the base of the support leg 120, in units of meters (m), for example. cos () indicates a sine function.Is an angle (in other words, a pitch angle) formed between the longitudinal direction of the body 110 and the road surface. Δ θ is a small change in the yaw angle of caster 161.And Δ θ is in units of radians (rad), for example. Horizontal force F_SThe unit of (d) is, for example, newton (N).

When K is_tIs the torsional stiffness of the support leg 120 and the yaw angle of the caster 161 due to the horizontal force F_SChange beta by the posture change caused_FThen, the following equation is established.

K_tβ_F＝F_Sp_xFormula 2

In the above formula, the torsional rigidity K_tThe unit of (d) is, for example, newtons per meter (N/m). Angle beta_FThe unit of (d) is, for example, radian (rad).

When beta is_θWhen the roll angle of the first joint 121 changes θ, the following equation holds due to geometric constraints.

In the above equation, tan is a tangent function and sin is a cosine function. Angle of rotationβ_θAnd θ is in units such as radians (rad).

Here, when β is an angle of sideslip around the yaw axis occurring in the caster 161, the following equation holds.

β＝β_θ-β_FFormula 4

When formulae 2 and 3 are substituted for formula 4, the following formulae are obtained.

In the above equation, atan () is an arctangent function. Herein, p is_xIs the distance between the point on the X-axis where the line along the link 124 intersects the road surface and the base, and is in units of meters (m), for example. p is a radical of_xCommonly referred to as caster trail.

When the angle θ is Δ θ, equation 5 is replaced with the following equation.

When formula 1 is substituted into formula 6, the following formula is obtained.

When the angle is changedWhen the value is sufficiently small, equation 7 can be approximated as follows.

For horizontal force F_SThe direction from the outside to the inside of the body 110 is a forward direction. For the angle β, the polarity of the change from the inside to the outside of the body 110 is positive. In this case, due to the horizontal force F_SWhen referring to the right side of equation 8, belowWhen the conditional expression is established, a restoring moment is generated, and the caster 161 is kept stable without sideslip.

When formula 9 is modified, the following formula is obtained.

The following is conceivable: height p of front support legs 120 and 140_zAnd caster track p_xAre controlled such that they have the same value. Height p of rear support legs 130 and 150 during control of the front support legs_zAnd caster track p_xAre controlled such that they have a fixed value. In this case, the following equation is established according to the movable range or the telescopic range of the support legs 120 and 140.

In the above equation, f () is an index of the ratio p_z/p_xThe smaller, the pitch angleA predetermined function of the greater relationship.

While controlling the height p of the rear support legs 130 and 150_zAnd caster track p_xThe height of the front support leg may be fixed during control, etc.

In the walking mode, the walking mode control unit 230 sets the torsional rigidity K_tAnd the current height p_zThe ratio to the caster track px is substituted for equation 10 to calculate the maximum mechanical impedance K satisfying equation 10₁. The walking mode control unit 230 controls the torque or angle of each joint based on the calculated value.

On the other hand, in the running mode, the running mode control unit 240 sets the current mechanical impedance K₁Torsional rigidity K_tAnd formula 11 is substituted for formula 10 to calculate the minimum p satisfying formula 10_z/p_xAnd controls the torque of each joint, etc. to obtain the value. Calculated p_z/p_xThe larger the caster angle α of the caster 161. Here, the caster angle α is an angle formed between a straight line parallel to the link 124 and a perpendicular line perpendicular to the road surface. Setting the caster angle α to be greater than "0" degrees is generally expressed as "giving the caster angle".

Regarding the posture (yaw angle) of the caster, it is assumed that the moving body 100 advances straight. However, control may be performed such that stabilization is achieved at a specific attitude (yaw angle) assuming a turning time or the like.

Regarding the attitude of the support leg of the fixed caster (pitch angle of the joint, etc.), it is also assumed that the moving body moves straight. However, any attitude in designing a turn or the like may be considered. In this case, the calculation may be sequentially performed according to the posture at the time of the transition, the turning, or the like.

In the above calculation, the mechanical resistance that is stable in the wheel running is obtained by the single-axis resistance control. However, architectures such as closed link or Stewart (Stewart) platforms can be used to implement impedance control for virtual axes expressed as a result of two or more axes. By setting the torsional rigidity of the support leg to be variable and changing the torsional rigidity, control of the running mode can be achieved.

[ exemplary configuration of Walking mode control Unit ]

Fig. 6 is a block diagram showing an exemplary configuration of the walking mode control unit 230 according to the first embodiment of the present technology. The walking mode control unit 230 includes a parameter calculation unit 231, a mechanical impedance calculation unit 232, and an actuator control unit 233.

The parameter calculation unit 231 calculates the attitude (pitch angle)) Calculating the ratio p_z/p_x. When the attitude from the stabilizer 181 is input, the parameter calculation unit 231 calculates the ratio p using equation 11_z/p_xAnd the ratio p is_z/p_xIs provided to the mechanical impedance calculation unit 232.

The mechanical impedance calculating unit 232 calculates the mechanical impedance K of the joint₁. When the attitude from the stabilizer 181 is input, the mechanical impedance calculation unit 232 calculates the attitude, the torsional rigidity K from the torsional rigidity acquisition unit 220_tAnd the ratio p from the parameter calculation unit 231_z/p_xInput into equation 11. Then, the mechanical impedance calculation unit 232 calculates the maximum mechanical impedance K satisfying equation 11₁. The mechanical impedance calculation unit 232 calculates the mechanical impedance K at a given period in the travel mode₁And supplies the calculated values to the actuator control unit 233 and the travel mode control unit 240.

Actuator control unit 233 is based on mechanical impedance K₁To control the torque or angle of the joint. The actuator control unit 233 holds in advance the mechanical impedance K assuming the walking operation as the current value₀. When recalculating the mechanical impedance K₁The actuator control unit 233 controls the torque of the joint and the like using the actuator such that the impedance gain K in the range of the assumed speed is obtained₁/K₀Held at the given value.

[ exemplary configuration of travel mode control Unit ]

Fig. 7 is a block diagram showing an exemplary configuration of the travel mode control unit 240 according to the first embodiment of the present technology. The running mode control unit 240 includes a parameter calculation unit 241, a mechanical impedance calculation unit 242, and an actuator control unit 243.

Parameter calculation unit 241 calculates ratio p_z/p_x. Upon conversion into the travel mode, the parameter calculation unit 241 calculates the mechanical impedance K from the travel mode control unit 230₁Torsional rigidity K from the torsional rigidity acquisition unit 220_tAnd equation 11 is substituted for equation 10 to calculate the minimum ratio p satisfying equation 10_z/p_x. Parameter calculation section 241 calculates and calculates ratio p using equation 11_z/p_xCorresponding new attitude (pitch angle)). The parameter calculation unit 241 supplies the calculated values to the mechanical impedance calculation unit 242 and the actuator control unit 243.

The mechanical impedance calculation unit 242 calculates the mechanical impedance K at a given period in the travel mode₁. The mechanical impedance calculating unit 242 obtains the pitch angle from the parameter calculating unit 241Corresponding new torsional rigidity K_t. The torsional stiffness K is obtained, for example, by linear interpolation or reading from the torsional stiffness map 210 based on the respective attitude_t。

Then, the mechanical impedance calculation unit 242 calculates the acquired torsional rigidity K_tRatio p from parameter calculation unit 241_z/p_xAnd a pitch angleSubstituting equation 10 to recalculate the maximum mechanical impedance K satisfying equation 10₁. The mechanical impedance calculation unit 242 supplies the calculated values to the parameter calculation unit 241 and the actuator control unit 243.

The parameter calculation unit 241 monitors the mechanical impedance K from the mechanical impedance calculation unit 242₁. When the value deviates from the range decided at the design stage, the parameter calculation unit 241 recalculates the ratio p_z/p_xEtc., and supplies the recalculated values to the mechanical impedance calculation unit 242 and the actuator control unit 243.

The actuator control unit 243 controls the torque or angle of the joint based on the value calculated by the parameter calculation unit 241 or the mechanical impedance calculation unit 242.

As described with reference to fig. 1 to 7, the bases of the support legs 120, 130, 140 and 150 are mounted on the body 110, and the casters 161 to 164 are mounted on the distal end. The stabilizer 181 controls the landing positions of the casters 161 to 164 based on the target values of the postures of the ZMP and the body 110. The caster angle control unit 200 controls the caster angles of the casters 161 to 164 based on the target values.

Traveling mode control unit 230 in caster angle control unit 200 based on torsional rigidity K_tTarget value of attitude (pitch angle)Etc.) and the ratio p at the time of conversion into the walking mode_z/p_xTo obtain the mechanical impedance K of the joint₁。

Upon conversion to the travel mode, the travel mode control unit 240 in the caster angle control unit 200 is based on the mechanical resistance K₁And torsional rigidity K_tTo obtain the ratio p_z/p_xAnd a target value for the new pose.

Fig. 8 is a side view showing an example of the installation angle according to the first embodiment of the present technology. In the drawings, a is an installation angle of the support leg less than 90 degreesA side view of the mobile body 100 mounted thereon. In the drawings, b is an installation angle of the support leg at 90 degreesA side view of the mobile body 100 mounted thereon.

In the drawings, as shown by a, when the angle is setLess than 90 degrees, the caster angle α is greater than "0" degrees in the initial state. That is, the caster angle is given in this state.

On the other hand, in the drawings, as shown by b, when the angle is setAt 90 degrees, the caster angle α is "0" degrees in the initial state. Here, in this case, the caster angle may also be given under the control of the control unit 180.

In general, the larger the caster angle α, the better the running stability of the mobile body in the linear motion, but the minimum rotationThe radius of curvature increases. Determining an appropriate installation angle in consideration of characteristics。

Fig. 9 is a diagram showing a process of traveling on an inclined surface according to the first embodiment of the present technology. In the drawings, the angle formed between a plane perpendicular to gravity and a slope around the Y-axis (i.e., pitch axis) is referred to as a gradient. When traveling on such an inclined plane, the control unit 180 obtains a gradient using an IMU or the likeAnd the gradient is adjustedAttitude (pitch angle) added to the body 110) The above. Then, the control unit 180 uses the added value as in equation 11To calculate the ratio pz/px or the mechanical impedance K₁. The control unit 180 may also obtain the gradient using a magnetic sensor, a Global Positioning System (GPS) sensor, or the like。

An inclined surface having a gradient around the Y axis is assumed, but the moving body 100 may also travel on an inclined surface having a gradient around the X axis. In this case, when the width of the caster in the left-right direction is sufficiently narrow as in a two-wheeled vehicle, it is not necessary to consider the variation of the ground contact surface. The control unit 180 independently controls the left and right support legs so that the mobile body 100 can be stably operated.

Fig. 10 is a diagram showing an advantageous effect when a caster angle is given according to the first embodiment of the present technology. In the drawings, a is a side view showing a road surface resistance applied when a caster angle α is given. In the drawings, b is a plan view showing the caster 161 to describe the restoring moment of the road resistance. In the drawing, c is a plan view showing the caster 161 in a stable state due to the restoring moment.

In the drawing, as illustrated in a, the control unit 180 gives the caster angle α to the caster 161 by controlling the actuator in the traveling mode. In this case, when the caster 161 rubs the road surface, the road surface resistance occurs on the landing surface in the direction opposite to the moving direction. The larger the caster angle α, the greater the road resistance. The open arrows in the figure indicate the road surface resistance.

As a result of the stabilization control (ZMP control, etc.), as illustrated in b of the drawing, a horizontal force is applied to the caster 161, and the caster 161 is oriented in a direction different from the moving direction. Here, the direction of the caster 161 is a direction indicated by a straight line parallel to the road surface (i.e., indicated by a one-dot chain line in the drawing) and perpendicular to the axis of the caster 161. When the surface resistance is generated, the restoring moment described above is applied in a direction opposite to the direction in which the caster 161 is oriented. The larger the road surface resistance, the larger the restoring moment. In the drawing, a thick dotted line indicates a restoring moment.

When the restoring moment is sufficiently large, as illustrated in c of the drawing, the direction of the caster 161 is the same as the moving direction due to the restoring moment, thereby preventing the caster 161 from sideslipping.

In this way, when a horizontal force is applied, the mobile body 100 can apply a restoring moment corresponding to the road surface resistance by increasing the caster angle α and generating the road surface resistance. The direction of the caster 161 is returned to the moving direction due to the restoring moment, thereby preventing the sideslip.

Fig. 11 is a diagram showing the control of the control unit 180 according to the first embodiment of the present technology. In the drawing, a is an external view of an example of the state of the mobile body 100 in the travel mode. In the drawings, b is a front view of the moving body 100 in a state of a in the drawings when viewed from the front. In the drawing, c is an external view showing an example of a state where the support legs 120 are opened. In the drawings, d is a front view showing the moving body 100 in a state of c in the drawings when viewed from the front.

In the driving mode, as shown in a and b of the drawings, it is assumed that the pitch angle of the body 110 is "0" degree and the caster angle is α₁. For example, when the mobile body 100 is traveling, it is assumed that the mobile body 100 detects the presence of the front obstacle 500 by analyzing image data captured by an image sensor, for example.

In this case, in order to prevent the mobile body from falling down, for example, as illustrated in fig. c and d, the control unit 180 may open the toe by controlling the support legs 120. In order to avoid the step, the moving body 100 expands its support legs in some cases, except for the obstacle 500. Alternatively, the support legs may collide with obstacles or steps during traveling, and the support legs may be opened in some cases.

Fig. 12 is a diagram illustrating the control of the stabilizer 181 and the caster angle control unit 200 according to the first embodiment of the present technology. In the drawing, a is an external view showing the control of the stabilizer 181. In the drawings, b is a front view of the moving body 100 in a state of a in the drawings when viewed from the front. In the drawings, c is an external view showing the control of the caster angle control unit 200.

When the control unit 180 opens the tips of the support legs 120 as illustrated in a and b of the drawings to stabilize the mover 100, the stabilizer 181 opens the tips of the support legs 140 to the same degree as the support legs 120. Pitch angle of the body 110 when the tips of the support legs 120 and 140 are spread apartAnd is increased. In this case, a horizontal force is applied to the toe (caster) of the support legs 120 and 140 toward the outside. In the drawings, an arrow indicated by a solid line indicates a horizontal force. When the horizontal force is large, the caster is inclined in a direction different from the moving direction, and thus there is a fear that the toe gradually opens.

At this time, the caster angle control unit 200 controls the actuator to follow the caster angle with the pitch angleIs increased as illustrated in c of the drawing. For example, the caster angle is controlled to α₂Alpha of the₂Greater than the value alpha before the spread of the tip of the leg₁。

The greater the caster angle, the greater the road resistance exerted on the caster. The direction of the caster is returned to the moving direction due to the restoring moment corresponding to the road surface resistance, thereby preventing the toe from being further spread.

Here, a comparative example in which the caster angle control unit 200 is not provided in the moving body 100 will be assumed. In this comparative example, as illustrated in a of the drawings, when the leg tip is opened, the stabilizer may also cause the support leg to temporarily leave the ground and go down the step by the stabilization control (ZMP control) to stabilize the posture, so that the posture of the body 110 may be restored. However, walking down the steps with the legs during driving risks toppling. When the driving speed is temporarily reduced, the risk of toppling when walking down the steps with the legs can be reduced. However, since the average speed is reduced, it is not preferable.

However, in the moving body 100 including the caster angle control unit 200, when disturbance is applied during the wheel traveling, the direction of the caster can also be corrected without increasing the torque by controlling the caster angle. Therefore, by compensating for the influence of the disturbance or the manufacturing error applied to the leg tip, stable running can be achieved. Compensation is achieved by controlling the caster angle when the leg tips deflect due to interference during travel. Therefore, it is not necessary to consider walking down a step or the like. The above benefits can be achieved within the scope of a normal control system without the need to add actuators or add special mechanisms or sensors.

When the caster angle control unit 200 is provided, it is not necessary to strongly perform mechanical resistance control on the leg tip to maintain the position of the leg tip relative to the body as in the comparative example. Therefore, the disturbance is less transmitted to the body, thereby reducing the influence of the disturbance generated on the road surface on the motion of the mobile body 100. In addition to such advantageous effects, it is possible to reduce the load applied to the link or joint that joins the body with the tip of the leg, and to reduce the strength or rigidity. Therefore, the weight of the connecting rod can be reduced.

[ exemplary operation of the control Unit ]

Fig. 13 is a flowchart showing an example of the operation of the control unit 180 according to the first embodiment of the present technology. This operation starts, for example, when a predetermined application for moving the mobile body 100 is executed.

The control unit 180 causes the stabilizer 181 to execute ZMP control (step S901), and calculates the torsional rigidity K_t(step S902). Then, the control unit 180 determines whether the current mode is the travel mode (step S903).

In the case of the travel mode (yes in step S903), the control unit 180 calculates a parameter (p) related to the caster angle_z/p_x、Etc.) (at step S904). In contrast, in the case of the travel mode (no in step S903), the control unit 180 calculates the mechanical impedance K₁(step S905). After step S904 or S905, the control unit 180 controls the actuator based on the calculated value (step S906). After step S906, the control unit 180 ends the operation.

The control unit 180 may perform control in consideration of not only the stability characteristics of the relative position or posture of the leg tip but also the dynamic characteristics of the tire expressed by the magic formula tire model and the like so that the stability is ensured only for the disturbance having a specific frequency bandwidth. For example, by constructing the control system according to the loop shaping method, it is possible to design to suppress a desired frequency band. Specifically, immediately before step S906 in the drawing, the control unit 180 may adjust the calculated value of S904 or S905 when interference having a specific frequency bandwidth occurs.

In this way, according to the first embodiment of the present technology, the control unit 180 controls the support leg based on the target value of the attitude and the ZMP and controls the caster angle based on the target value. Therefore, the road surface resistance can be generated according to the caster angle. Due to the road surface resistance, a restoring moment will be applied to the caster, and therefore the stability during the running of the wheel can be improved.

<2 > second embodiment

In the first embodiment described above, the mobile body 100 changes its posture without assuming that the object is carried. However, when the moving body 100 changes its posture when carrying the object, there is a fear that the object falls. The moving body 100 of the second embodiment differs from the moving body 100 of the first embodiment in that it further includes a stage and an elevator that horizontally holds the stage.

Fig. 14 is a side view showing an exemplary configuration of the mobile body 100 according to the second embodiment of the present technology. The moving body 100 of the second embodiment is different from the moving body of the first embodiment in that lifters 191 and 192 and a stage 193 are further included.

The stage 193 is a flat plate-like member on which a subject is placed. The lifters 191 and 192 are members supporting the stage 193. The lifter 191 is provided at the front of the body 110, and the lifter 192 is provided at the rear. Each of the elevators 191 and 192 includes, for example, two links and a joint connecting the links. The joint may be rotated about a pitch axis by an actuator. The pitch angles of the joints of the elevators 191 and 192 are controlled for extension and contraction so that the front and rear portions of the stage 193 are raised and lowered independently.

The lifts 191 and 192 each include a link and a joint, but the present technique is not limited to this configuration as long as the stage can be raised and lowered. For example, a link that is extended and retracted along the Z-axis by an actuator may also be used as the lifters 191 and 192.

Fig. 15 is a block diagram showing an exemplary configuration of the moving body 100 according to the second embodiment of the present technology. The moving body 100 of the second embodiment is different from the moving body of the first embodiment in that the control unit 180 further includes an elevator control unit 183.

The stabilizer 181 according to the second embodiment also provides the attitude information to the elevator control unit 183. The sensor group 171 according to the second embodiment further includes a sensor that detects an angle of each of the elevators 191 and 192, and supplies sensor data to the elevator control unit 183. The actuator group 172 according to the second embodiment further includes actuators that drive the joints of each of the elevators 191 and 192.

The elevator control unit 183 controls the elevators 191 and 192 based on the attitude indicated by the attitude information so that the stage 193 is kept horizontal. When the pitch angle of the body 110 is greater than '0' degree, the elevator control unit 183 makes the height of one of the elevators 191 and 192 higher than that of the other elevator by controlling the actuator according to the angle. .

Fig. 16 is a diagram illustrating a method of controlling the elevators 191 and 192 according to the second embodiment of the present technology. As illustrated in the drawing, when the height of the front of the body 110 is lower than that of the rear, the elevator control unit 183 expands the front elevator 191 and contracts the rear elevator 192. Therefore, the stage 193 can be kept horizontal to prevent the object from falling.

When the height of the front of the body 110 is higher than that of the rear, the elevator control unit 183 may contract the front elevator 191 and expand the rear elevator 192.

In this way, according to the second embodiment of the present technology, the elevator control unit 183 controls the elevators 191 and 192 based on the postures. Therefore, when the posture is changed, the stage 193 can also be kept horizontal, so that the stage can be prevented from falling.

<3 > third embodiment

In the first embodiment described above, the body 110 is constituted by one member, but the body 110 may be divided into two parts. The moving body 100 of the third embodiment is different from the moving body of the first embodiment in that the body is divided into two parts.

Fig. 17 is a side view showing an exemplary configuration of the mobile body 100 according to the third embodiment of the present technology. The moving body 100 of the third embodiment is different from the moving body of the first embodiment in that the body 110 includes a front body 111, a rear body 112, and a connection unit 310.

The front body 111 is a member mounting the support legs 120 and 140 and is disposed at the front side of the moving body 100. The rear body 112 is a member mounting the support legs 130 and 150 and is disposed at the rear side of the moving body 100.

The connection unit 310 connects the front body 111 to the rear body 112. The connection unit 310 includes an anterior joint 311, a link 312, and a posterior joint 313.

The front joint 311 is a joint connecting the front body 111 to the link 312, and can be pivoted about a pitch axis by an actuator. The rear joint 313 is a joint connecting the rear body 112 to the link 312, and can be pivoted about the pitch axis by an actuator. The link 312 is a member connecting the front joint 311 to the rear body 112.

In the above configuration, the control unit 180 may independently control the posture of the front body 111 and the posture of the rear body 112. Therefore, when the posture of one of the front body 111 and the rear body 112 is slightly changed, such a change does not significantly affect the posture of the other body. Therefore, the stability of the entire moving body 100 can be further improved.

In this way, according to the third embodiment of the present technology, the control unit 180 independently controls the posture of each of the front body 111 and the rear body 112. Therefore, the stability of the entire moving body 100 can be further improved.

<4 > fourth embodiment

In the third embodiment described above, the mobile body 100 changes its posture without assuming that the object is carried. However, when the moving body 100 changes its posture when carrying the object, there is a fear that the object falls. The moving body 100 of the fourth embodiment is different from the moving body 100 of the third embodiment in that it further includes a stage and an elevator for horizontally holding the stage.

Fig. 18 is a side view showing an exemplary configuration of the moving body 100 according to the fourth embodiment of the present technology. The moving body 100 according to the fourth embodiment is different from the moving body 100 of the third embodiment in that elevators 194 and 195 and a stage 193 are further included. The lifters 194 and 195 support the stage 193 and are configured by one link that extends and contracts in the Z direction.

The configuration of the control unit 180 of the fourth embodiment is the same as that of the control unit 180 of the second embodiment.

In this way, according to the fourth embodiment of the present technology, the elevator control unit 183 controls the elevators 191 and 192 based on the postures. Therefore, when the posture is changed, the stage 193 is kept horizontal, so that the stage can be prevented from falling.

<5 > fifth embodiment

In the first embodiment described above, in the moving body 100, the caster angles in the initial state are set to be the same between the front caster angles and the rear caster angles by making the mounting angles of the front support legs 120 and 140 the same as the mounting angles of the rear support legs 130 and 150. However, the larger the caster, the larger the minimum turning radius. Thus, to facilitate cornering, in particular the castors of the front support legs are preferably smaller than the castors of the rear support legs. The fifth embodiment is different from the first embodiment in that the installation angle of the front support legs 120 and 140 is different from that of the rear support legs 130 and 150.

Fig. 19 is a side view showing an exemplary configuration of a moving body 100 according to a fifth embodiment of the present technology. The moving body 100 of the fifth embodiment is different from the moving body 100 of the first embodiment in that the installation angle of the front support legs 120 and 140Different from the mounting angles of the rear support legs 130 and 150. For example, front mounting angleIs set to be smaller than the rear mounting angleThe value of (c). Thus, in the initial state, the front caster angle may be less than the rear caster angle. Therefore, the mobile body 100 is easy to turn when the front installation angle is the same as the rear installation angle.

By angling the frontIs set to be larger than the rear installation angleThe linear motion stability of the front support legs 120 and 140 may be superior to that of the rear support legs. In this way, by changing the front mounting angle and the rear mounting angle, it is possible to adjust the rotation characteristic or the straightness when the interference occurs.

Each of the first to fourth embodiments may be applied to the fifth embodiment.

Thus, according to the fifth embodiment of the present technology, the installation angle of the front support legs 120 and 140 is different from that of the rear support legs 130 and 150. Therefore, in the initial state, the caster angle may be set to be different forward and backward.

<6 > sixth embodiment

In the first embodiment described above, the control unit 180 controls the caster angle to improve the stability of the moving body 100. However, when unevenness or steps on the road surface are equal to or larger than the assumed unevenness or steps, there is a fear that the posture may be changed. The moving body 100 of the sixth embodiment is different from the moving body 100 of the first embodiment in that dampers are provided in the casters to improve stability.

Fig. 20 is a sectional view showing an exemplary configuration of a caster 161 according to a sixth embodiment of the present technology. The caster 161 according to the sixth embodiment includes a wheel unit 166 and a damper 165.

The wheel unit 166 is a circular member mounted on the shaft. The damper 165 is a member that extends and contracts in the Z direction perpendicular to the road surface. A damper 165 is disposed between the shaft and the distal end of the link 124. For example, an elastic body (spring, oil damper, etc.) is used as the damper 165.

The configuration of each of the casters 162 to 164 is the same as that of the caster 161.

The damper 165 is contracted according to the load, aerodynamic weight, or the like, and thus the caster track is enlarged and the caster angle is increased. Accordingly, when the unevenness or the step is overcome, the linear motion stability of the moving body 100 may be improved.

Each of the first to fourth embodiments may be applied to the sixth embodiment.

Thus, according to the sixth embodiment of the present technology, the damper 165 is extended and contracted. Accordingly, by increasing the caster angle according to the weight, the stability of the moving body 100 can be improved.

<7 > seventh embodiment

In the first embodiment described above, the support leg 120 or the like includes the first joint 121 that pivots only about one axis (rolling axis). In this configuration, there is a fear that the movable range of the first joint cannot be sufficiently ensured. The moving body 100 of the seventh embodiment is different from the moving body 100 of the first embodiment in that a first joint that pivots about two axes is provided to expand the movable range.

Fig. 21 is a side view showing an exemplary configuration of a moving body 100 according to a seventh embodiment of the present technology. The moving body 100 of the seventh embodiment is different from the moving body 100 of the first embodiment in that a first joint 126 is provided in the support leg 120 instead of the first joint 121.

The first joint 126 is a biaxial joint that pivots about two axes (a roll axis and a pitch axis). Each of the support legs 130, 140, and 150 also includes a dual axis first joint as in support leg 120.

When the first joint 126 is a biaxial joint, the first joint 121 can expand the movable range of the support leg 120 as compared with the uniaxial joint of the first embodiment.

Each of the first to sixth embodiments may be applied to the seventh embodiment.

Thus, according to the seventh embodiment of the present technology, a biaxial first joint 126 is provided. Therefore, the movable range of the support leg can be enlarged as compared with the case where the single-axis first joint is provided.

<8 > eighth embodiment

In the first embodiment described above, four support legs are mounted on the body 110. However, the greater the number of support legs, the greater the number of components. Therefore, there is a fear that the manufacturing cost of the moving body 100 increases. The greater the number of support legs, the greater the area of the support polygon. Therefore, there is a fear that it is difficult to move to a narrow place. The moving body 100 of the eighth embodiment is different from the moving body 100 of the first embodiment in that the number of support legs is reduced to two.

Fig. 22 is a side view showing an exemplary configuration of the moving body 100 according to the eighth embodiment of the present technology. The moving body 100 of the eighth embodiment is different from the moving body 100 of the first embodiment in that support legs 120 and 140 are mounted on a body 110.

As illustrated in the drawings, two support legs are provided. Therefore, the manufacturing cost is further reduced and it is easier to move to a narrow place than in the case where four support legs are provided.

The sixth embodiment or the seventh embodiment may be applied to the eighth embodiment.

In this way, in the eighth embodiment of the present technology, two support legs are provided. Therefore, the manufacturing cost is further reduced and it is easier to move to a narrow place, compared to the case where four support legs are provided.

The above embodiments have been described as examples for implementing the present technology, and matters in the embodiments have a correspondence with inventive specific matters in the claims. Similarly, the inventive specific matters in the claims have correspondence with matters having the same name of the embodiment of the present technology. Here, the present technology is not limited to the embodiments, and various modifications may be made to the embodiments within the scope of the present technology without departing from the gist of the present technology.

The processing procedure in the above-described embodiment may be determined as a method including a series of procedures, or may be determined as a program causing a computer to execute a series of procedures, or a recording medium storing the program. As the recording medium, for example, a Compact Disc (CD), a Mini Disc (MD), a Digital Versatile Disc (DVD), a memory card, a blu-ray (registered trademark) disc, or the like can be used.

The benefits described in this specification are exemplary only, and not limiting, and other benefits may be realized.

The present technology can be configured as follows.

(1) A mobile body, comprising:

a plurality of support legs in which a base is mounted on the body and casters are mounted on the distal end;

a stabilizer configured to control a position at which a caster of each of the plurality of support legs contacts a ground based on a target value of an attitude of the body; and

a caster angle control unit configured to control a caster angle of each of the casters based on the target value.

(2) The moving body according to (1), wherein, upon transition to a travel mode in which the moving body performs wheel travel, the caster angle control unit obtains a ratio of a height from a road surface to the base to a caster trajectory of the caster and a new target value based on mechanical impedance and torsional rigidity of each of the plurality of support legs.

(3) The movable body according to (1) or (2), wherein the caster angle control unit obtains a mechanical impedance based on the torsional rigidity of each of the plurality of support legs, the target value, the height from the road surface to the base, and a caster track of the caster, at the time of transition to a walking mode in which the movable body performs walking.

(4) The moving body according to any one of (1) to (3), further comprising:

a plurality of elevators configured to support the object table; and

an elevator control unit configured to control the plurality of elevators based on the target values.

(5) The moving body according to any one of (1) to (4), wherein the body includes a front body, a rear body, and a connecting unit that connects the front body to the rear body.

(6) The moving body according to any one of (1) to (5), wherein the caster includes a wheel unit and a damper that expands and contracts in a direction perpendicular to the road surface.

(7) The moving body according to any one of (1) to (6),

wherein each of the plurality of support legs includes a first joint disposed in the base, a second joint, and a third joint disposed in the distal end, an

Wherein the first joint is a biaxial joint.

(8) The movable body according to any one of (1) to (7), wherein the plurality of support legs includes a pair of front support legs and a pair of rear support legs.

(9) The moving body according to (8), wherein an installation angle of a base of each of the pair of front support legs is different from an installation angle of a base of each of the pair of rear support legs.

(10) The movable body according to any one of (1) to (7), wherein the number of the plurality of support legs is two.

(11) A method of controlling a mobile body, the method comprising:

a stabilization step of controlling a position at which a caster of each of a plurality of support legs, in which the base is mounted on the body and the caster is mounted on a distal end, is in contact with the ground based on a target value of an attitude of the body; and

a caster angle control step of controlling a caster angle of each of the casters based on the target value.

[ list of reference numerals ]

100 moving body

110 body

111 front body

112 rear body

120. 130, 140, 150 support leg

121. 126 first joint

122. 124, 312 connecting rod

123 second joint

125 third joint

161 to 164 Caster wheel

165 damper

166 wheel unit

171 sensor group

172 actuator group

180 control unit

181 stabilizer

182 road surface condition analyzing unit

183 Elevator control Unit

191. 192, 194, 195 elevator

193 object stage

200 caster angle control unit

210 torsional stiffness map based on respective attitude

220 torsional rigidity acquisition unit

230 walking mode control unit

231. 241 parameter calculating unit

232. 242 mechanical impedance calculating unit

233. 243 actuator control unit

240 running mode control unit

250 selection unit

310 connecting unit

311 anterior joint

313 posterior joint