阅读说明：本技术 一种力反馈装置的温度误差补偿系统及方法 (Temperature error compensation system and method of force feedback device ) 是由 张军 陈柳辰 宋爱国 于 2021-09-01 设计创作，主要内容包括：本发明公开了一种力反馈装置的温度误差补偿系统及方法,包括力反馈装置、温度监测单元、温度处理单元,以及温度误差补偿方法；所述的力反馈装置包括三个平动自由度、三个转动自由度、一个开关自由度,以及控制箱；所述的温度监测单元包括温度传感器、采集处理模块和数据发送模块,所述的温度监测单元中温度传感器包括六个,分别安装在所述力反馈装置三个平动自由度和三个转动自由度的驱动电机机身表面；所述的温度处理单元与所述的温度监测单元连接；所述的温度处理单元还与所述的控制箱相连；所述的温度误差补偿方法包括反馈力与温度关系标定、温度实时检测,以及反馈力补偿。本发明力反馈装置的温度误差补偿系统和方法提高了装置的力反馈精度。(The invention discloses a temperature error compensation system and a temperature error compensation method for a force feedback device, wherein the temperature error compensation system comprises the force feedback device, a temperature monitoring unit, a temperature processing unit and a temperature error compensation method; the force feedback device comprises three translational degrees of freedom, three rotational degrees of freedom, one switch degree of freedom and a control box; the temperature monitoring unit comprises six temperature sensors, an acquisition processing module and a data sending module, and the six temperature sensors are respectively arranged on the surfaces of the bodies of the driving motors of the three translational degrees of freedom and the three rotational degrees of freedom of the force feedback device; the temperature processing unit is connected with the temperature monitoring unit; the temperature processing unit is also connected with the control box; the temperature error compensation method comprises the steps of feedback force and temperature relation calibration, temperature real-time detection and feedback force compensation. The temperature error compensation system and method of the force feedback device improve the force feedback precision of the device.)

1. A temperature error compensation system of a force feedback device comprises the force feedback device, a temperature monitoring unit and a temperature processing unit;

the method is characterized in that:

the force feedback device comprises three translational degrees of freedom, three rotational degrees of freedom, one switch degree of freedom and a control box, wherein the three translational degrees of freedom, the three rotational degrees of freedom and the one switch degree of freedom in the force feedback device are all realized by a motor; the motors are all driven by the control box;

the temperature monitoring unit comprises a temperature sensor, an acquisition processing module and a data sending module, wherein the temperature sensor in the temperature monitoring unit is arranged on the outer surface of the motor with three translational degrees of freedom and three rotational degrees of freedom, so that the surface temperature of the motor can be obtained;

the temperature processing unit comprises a data receiving module, a compensation value calculating module and a compensation value sending module;

the temperature monitoring unit is also connected with the temperature processing unit, and the temperature processing unit is also connected with the control box;

the temperature monitoring unit collects data of the temperature sensor through the collection processing module, the temperature data are sent to the temperature processing unit through the data sending module, the temperature processing unit receives the data through the data receiving module, the temperature processing unit calculates a compensation value through the compensation value calculating module, the temperature processing unit sends the compensation value to the control box in the force feedback device through the compensation value sending module, and the control box in the force feedback device is driven by the motor to realize temperature error compensation of the force feedback device.

2. The system of claim 1, wherein the force feedback device comprises: the force feedback device comprises a base, a support frame connected with the base, a second connecting frame arranged on the support frame, a first connecting frame arranged on the second connecting frame, a second translation motor and a third translation motor arranged on the first connecting frame, a parallel link mechanism connected with output shafts of the second translation motor and the third translation motor, a balance weight arranged at the head of the parallel link mechanism, the tail end of a parallel mechanism connected with the tail end of the parallel link mechanism, a first translation motor arranged at the tail end of the parallel mechanism, a diamond mechanism connected with an output shaft of the first translation motor, the tail end of the diamond mechanism connected with the diamond mechanism, a first rotating motor arranged at the tail end of the diamond mechanism, a first rotating mechanism connected with an output shaft of the first rotating motor through a gear structure in the tail end of the diamond mechanism, a second rotating motor connected with the first rotating mechanism, and a second rotating mechanism connected with an output shaft of the second rotating motor, the rotating motor III is connected with the rotating mechanism II through an output shaft, the switch motor bracket is connected with the rotating motor III, the switch motor is arranged on the switch motor bracket, and the switch is connected with the output shaft of the switch motor.

3. A temperature error compensation method of a force feedback device is characterized in that: the method comprises the following specific steps: calibrating the relation between feedback force and temperature, detecting the temperature in real time and compensating the feedback force;

in the method for compensating the temperature error of the force feedback device, the relationship between the feedback force and the temperature is calibrated, and the method comprises the following specific steps:

step 1, installing a force sensor for measuring mechanical quantity information i, i ═ F_x、F_y、F_z、M_x、M_yAnd M_z；

Step 2, keeping the environmental temperature unchanged, and controlling the theoretical feedback force of the three-dimensional translational motion driving motor to be rapidly and directly increased from 0N to N N, wherein N is in the range of 1, 2, 3, … … and N, and N is the maximum feedback force value of the translational motion of the force feedback device; or controlling the feedback moment of the three-dimensional rotary motion driving motor to be rapidly and directly increased from 0 N.m to M N.m, wherein M ranges from 1, 2, 3, … … and M, and M is the maximum feedback moment value of the rotary motion of the force feedback device;

step 3, setting the feedback force/moment to be in the condition of n N M N m M m, keeping the time to be T minutes, setting the feedback force/moment to be zero after the surface of the motor reaches a certain temperature, and synchronously acquiring the feedback force/moment data of the force sensor and the temperature data on the surface of the motor in the process;

step 4, performing surface fitting by taking the feedback force/moment obtained by subtracting the initial temperature from the feedback force/moment as a dependent variable and taking the set value of the feedback force/moment and the temperature as independent variables to obtain relational expressions of the feedback force/moment Fx, Fy, Fz, Mx, My and Mz and the temperature;

the temperature real-time detection in the temperature error compensation method of the force feedback device comprises the following specific steps:

step 5, acquiring current data of the temperature sensor by an acquisition processing module in the temperature monitoring unit, processing the data and converting the data into temperature data;

step 6, a data sending module in the temperature monitoring unit packs the temperature data and then sends the temperature data;

repeating the steps, and periodically collecting and sending the surface temperature of the motor;

the feedback force/moment compensation in the temperature error compensation method of the force feedback device is used for calculating the compensation force/moment through the temperature processing unit, and the method comprises the following steps:

step 7, a data receiving module in the temperature processing unit receives the data, processes the data and unpacks the temperature data;

step 8, a compensation value calculation module in the temperature processing unit calculates the compensation force by taking the current temperature and the set value of the feedback force/moment as input and using the relation between the feedback force/moment and the temperature in the step 4 in the right 8;

step 9, packing the compensation value by a compensation value sending module in the temperature processing unit, and then sending;

and repeating the steps to compensate the feedback force/moment in real time.

Technical Field

The invention belongs to the crossing field of robotics, control science, computer science, man-machine interaction technology and sensing technology, and particularly relates to a temperature error compensation system and method of a force feedback device.

Background

The force feedback device is a man-machine interface device with force perception, and can improve the telepresence of the operation controlled by an operator. On one hand, the robot can be controlled by measuring the position information of the hand of the operator as a control instruction, or the virtual robot in the virtual reality tracks the motion of the hand. On the other hand, the force tactile information fed back by the robot is used as input to control the output force/torque of the motor, so that an operator feels feedback force. Therefore, the 'immersive' force touch telepresence effect on a remote robot work site or a virtual robot work site is generated, control with feeling is achieved, or real touch feeling is generated in a virtual environment.

Therefore, the accuracy of force feedback can greatly affect the realism of force haptics. The existing research on force feedback devices mostly focuses on mechanisms and control methods, such as a 6-degree-of-freedom general heterogeneous robot hand controller (patent application No. 02138700.1), and the research on the force feedback precision change caused by temperature change is less. In fact, most force feedback devices operate over time, and the temperature of the devices changes due to heat generated by the motor. Particularly in applications such as sanding operations where a continuous force feedback output is required, temperature variations can be significant. The change of temperature can cause the motor to have different output torque under the condition of the same input, and if the temperature error compensation is not carried out on the feedback force, the actual feedback force can deviate from the input set value.

Disclosure of Invention

After the force feedback device operates for a period of time, the feedback force error caused by the continuous force feedback output is a problem. In view of the above problems, the present invention is directed to provide a temperature error compensation system and method for a force feedback device with high usability and high versatility, so as to achieve that the force feedback device provides high-precision feedback force under different temperatures.

The invention provides a temperature error compensation system of a force feedback device, which comprises the force feedback device, a temperature monitoring unit and a temperature processing unit:

the force feedback device comprises three translational degrees of freedom, three rotational degrees of freedom, one switch degree of freedom and a control box, wherein the three translational degrees of freedom, the three rotational degrees of freedom and the one switch degree of freedom in the force feedback device are all realized by a motor; the motors are all driven by the control box;

the temperature monitoring unit comprises a temperature sensor, an acquisition processing module and a data sending module, wherein the temperature sensor in the temperature monitoring unit is arranged on the outer surface of the motor with three translational degrees of freedom and three rotational degrees of freedom, so that the surface temperature of the motor can be obtained;

the temperature processing unit comprises a data receiving module, a compensation value calculating module and a compensation value sending module;

the temperature monitoring unit is also connected with the temperature processing unit, and the temperature processing unit is also connected with the control box;

the temperature monitoring unit collects data of the temperature sensor through the collection processing module, the temperature data are sent to the temperature processing unit through the data sending module, the temperature processing unit receives the data through the data receiving module, the temperature processing unit calculates a compensation value through the compensation value calculating module, the temperature processing unit sends the compensation value to the control box in the force feedback device through the compensation value sending module, and the control box in the force feedback device is driven by the motor to realize temperature error compensation of the force feedback device.

As a further improvement of the invention, the force feedback device comprises a base, a support frame connected with the base, a second connecting frame arranged on the support frame, a first connecting frame arranged on the second connecting frame, a second translation motor and a third translation motor arranged on the first connecting frame, a parallel connecting rod mechanism connected with output shafts of the second translation motor and the third translation motor, a balance weight arranged at the head of the parallel connecting rod mechanism, the tail end of a parallel mechanism connected with the tail end of the parallel connecting rod mechanism, a first translation motor arranged at the tail end of the parallel mechanism, a diamond mechanism connected with an output shaft of the first translation motor, the tail end of the diamond mechanism connected with the diamond mechanism, a first rotating motor arranged at the tail end of the diamond mechanism, a first rotating mechanism connected with an output shaft of the first rotating motor through a gear structure in the tail end of the diamond mechanism, a second rotating motor connected with the first rotating mechanism, and a second rotating mechanism connected with an output shaft of the second rotating motor, the rotating motor III is connected with the rotating mechanism II through an output shaft, the switch motor bracket is connected with the rotating motor III, the switch motor is arranged on the switch motor bracket, and the switch is connected with the output shaft of the switch motor.

The invention provides a temperature error compensation method of a force feedback device, which comprises the following specific steps: calibrating the relation between feedback force and temperature, detecting the temperature in real time and compensating the feedback force;

in the method for compensating the temperature error of the force feedback device, the relationship between the feedback force and the temperature is calibrated, and the method comprises the following specific steps:

step 1, installing a force sensor for measuring mechanical quantity information i, i ═ F_x、F_y、F_z、M_x、M_yAnd M_z；

Step 2, keeping the environmental temperature unchanged, and controlling the theoretical feedback force of the three-dimensional translational motion driving motor to be rapidly and directly increased from 0N to N N, wherein N is in the range of 1, 2, 3, … … and N, and N is the maximum feedback force value of the translational motion of the force feedback device; or controlling the feedback moment of the three-dimensional rotary motion driving motor to be rapidly and directly increased from 0 N.m to M N.m, wherein M ranges from 1, 2, 3, … … and M, and M is the maximum feedback moment value of the rotary motion of the force feedback device;

and 3, setting the feedback force/moment to be at the state of n N m M m, keeping the time to be T minutes, and setting the feedback force/moment to be zero after the surface of the motor reaches a certain temperature. In the process, feedback force/torque data of the force sensor and data of the temperature on the surface of the motor are synchronously acquired;

step 4, performing surface fitting by taking the feedback force/moment obtained by subtracting the initial temperature from the feedback force/moment as a dependent variable and taking the set value of the feedback force/moment and the temperature as independent variables to obtain relational expressions of the feedback force/moment Fx, Fy, Fz, Mx, My and Mz and the temperature;

the temperature real-time detection in the temperature error compensation method of the force feedback device comprises the following specific steps:

and 5, acquiring current data of the temperature sensor by an acquisition processing module in the temperature monitoring unit, processing the data and converting the data into temperature data.

Step 6, a data sending module in the temperature monitoring unit packs the temperature data and then sends the temperature data;

repeating the steps, and periodically collecting and sending the surface temperature of the motor;

the feedback force/moment compensation in the temperature error compensation method of the force feedback device is used for calculating the compensation force/moment through the temperature processing unit, and the method comprises the following steps:

and 7, receiving the data by a data receiving module in the temperature processing unit, processing the data and unpacking the temperature data.

And 8, calculating by a compensation value calculating module in the temperature processing unit, taking the current temperature and the set value of the feedback force/moment as input, and calculating the compensation force by using the relation between the feedback force/moment and the temperature in the step 4 in the right 8.

And 9, packing the compensation value by a compensation value sending module in the temperature processing unit, and then sending.

And repeating the steps to compensate the feedback force/moment in real time.

Has the advantages that:

according to the temperature error compensation system and method of the force feedback device, the temperature sensor is arranged on the surface of the motor, the original structure of the force feedback device is not changed, and the force feedback device is easy to use and maintain; the feedback force/torque and temperature relation calibration method adopted by the invention can be suitable for most force feedback devices and has universality; the temperature error compensation system and method of the force feedback device improve the force feedback precision of the device.

Drawings

FIG. 1 is a schematic diagram of the system of the present invention;

FIG. 2 is a schematic view of the force feedback device mechanism of the present invention;

FIG. 3 is a schematic diagram of the force feedback device mechanism of the present invention;

FIG. 4 is a schematic view of the installation of a feedback force and temperature relationship calibration experiment sensor according to the present invention;

FIG. 5 is a flow chart of a temperature error compensation method of the present invention;

FIG. 6 shows the result of the calibration experiment of the relationship between the feedback force and the temperature according to the present invention;

FIG. 7 shows the results of the temperature real-time detection and feedback force compensation experiment of the present invention without compensation;

FIG. 8 shows the compensation result of the temperature real-time detection and feedback force compensation experiment of the present invention.

In the figure: 1. a force feedback device; 1-1-1, a first translation motor; 1-1-2 and a second translation motor; 1-1-3, a third translation motor; 1-2, a diamond mechanism, 1-3 and a counterweight; 1-4, a parallel link mechanism; 1-5-1, a first connecting frame; 1-5-2 and a second connecting frame; 1-5-3, a support frame; 1-5-4, a base; 1-6, the tail end of the translation mechanism; 1-7 ends of diamond-shaped mechanisms; 1-8-1, rotating a first motor; 1-8-2, rotating a motor II; 1-8-3, rotating a motor III; 1-9, a switch motor bracket; 1-10, a switch; 1-11-1 and a first rotating mechanism; 1-11-2 and a second rotating mechanism; 1-12, switching the motor; 2. a temperature monitoring unit; 2-1-1, a first temperature sensor; 2-1-2 and a temperature sensor II; 2-1-3, and a third temperature sensor; 2-1-4, and a temperature sensor IV; 2-1-5, a temperature sensor five; 2-1-6, a temperature sensor six; 2-2, an acquisition processing module; 2-3, a data sending module; 3. a temperature processing unit; 3-1, a data receiving module; 3-2, a compensation value calculating module; 3-3, a compensation value sending module; 4. a diamond mechanism end connector; 5. a force sensor; 6. fixing the connecting piece; 7. and a fixing member.

Detailed Description

The invention is described in further detail below with reference to the following detailed description and accompanying drawings:

the invention aims to provide a temperature error compensation system and a temperature error compensation method of a force feedback device with high usability and high universality, so that the force feedback device can provide high-precision feedback force under different temperature conditions.

Referring to fig. 1, in a specific application example, the temperature error compensation system of the force feedback device of the present invention includes a force feedback device 1, a temperature monitoring unit 2, and a temperature processing unit 3; the force feedback device comprises three translation motors which are respectively a translation motor I1-1-1, a translation motor II 1-1-2 and a translation motor III 1-1-3, three rotating motors which are respectively a rotating motor I1-8-1, a rotating motor II 1-8-2, a rotating motor III 1-8-3, a switch motor 1-12 and a control box 1-13; the temperature monitoring unit comprises six temperature sensors, namely a first temperature sensor 2-1-1, a second temperature sensor 2-1-2, a third temperature sensor 2-1-3, a fourth temperature sensor 2-1-4, a fifth temperature sensor 2-1-5, a sixth temperature sensor 2-1-6, an acquisition processing module 2-2 and a data sending module 2-3; the temperature processing unit 3 comprises a data receiving module 3-1, a compensation value calculating module 3-2 and a compensation value sending module 3-3.

Referring to attached drawings 2 and 3, the force feedback device 1 comprises a base 1-5-4, a support frame 1-5-3 connected with the base 1-5-4, a connecting frame II 1-5-2 arranged on the support frame 1-5-3, a connecting frame I1-5-1 arranged on the connecting frame II 1-5-2, a translation motor II 1-1-2 and a translation motor III 1-1-3 arranged on the connecting frame I1-5-1, a parallel link mechanism 1-4 connected with output shafts of the translation motor II 1-1-2 and the translation motor III 1-1-3, a counterweight 1-5 arranged at the head part of the parallel link mechanism 1-4, and a parallel mechanism tail end 1-6 connected with the tail end of the parallel link mechanism 1-4, a translation motor I1-1-1 arranged at the tail end 1-6 of the parallel mechanism, a diamond mechanism 1-2 connected with an output shaft of the translation motor I1-1-1, a diamond mechanism tail end 1-7 connected with the diamond mechanism 1-2, a rotating motor I1-8-1 arranged at the tail end 1-7 of the diamond mechanism, a rotating mechanism I1-11-1 connected with an output shaft of the rotating motor I1-8-1 through a gear structure in the diamond mechanism tail end 1-7, a rotating motor II 1-8-2 connected with the rotating mechanism I1-11-1, a rotating mechanism II 1-11-2 connected with an output shaft of the rotating motor II 1-8-2, a rotating motor III 1-8-3 connected with the rotating mechanism II 1-11-1 through an output shaft, a switch motor bracket 1-9 connected with the rotating motor III 1-8-3, a switch motor 1-12 arranged on the switch motor bracket 1-9, and a switch 1-10 connected with the output shaft of the switch motor 1-12.

Further, referring to fig. 1, the motors are driven by control boxes 1-13.

Further, referring to fig. 1, six temperature sensors are arranged in the temperature monitoring unit 2, wherein the temperature sensors are respectively a first temperature sensor 2-1-1, a second temperature sensor 2-1-2, a third temperature sensor 2-1-3, a fourth temperature sensor 2-1-4, a fifth temperature sensor 2-1-5 and a sixth temperature sensor six 2-1-6, and are installed on the surface of a corresponding motor, so that the surface temperature of the corresponding motor can be obtained; the temperature monitoring unit 2 is also connected with the temperature processing unit 3; the temperature processing unit 3 is also connected with the control boxes 1-13.

Further, referring to fig. 1, the collection processing module 2-2 in the temperature monitoring unit 2 collects data corresponding to the temperature sensor, the data sending module 2-3 sends the temperature data to the temperature processing unit 3, the temperature processing unit 3 receives the data through the data receiving module 3-1, the temperature processing unit 3 calculates a compensation value through the compensation value calculating module 3-2, the temperature processing unit 3 sends the compensation value to the control box 1-13 in the force feedback device 1 through the compensation value sending module 3-3, and the control box 1-13 in the force feedback device 1 drives the corresponding motor to realize temperature error compensation of the force feedback device.

Referring to fig. 5, in an application example of compensating the translation motor two 1-1-2, a temperature error compensation method of the force feedback device includes feedback force and temperature relationship calibration S1, temperature real-time detection S11, and feedback force compensation S15.

The temperature relationship calibration S1 includes the following steps:

s2: referring to the attached figure 4, a diamond mechanism tail end connecting piece 4 is arranged on the tail ends 1-7 of the diamond mechanism, a force sensor 5 is arranged on the diamond mechanism tail end connecting piece 4, a fixed connecting piece 6 is arranged at the other end of the force sensor 5, and a fixing piece 7 is connected with the fixed connecting piece 6; the diamond-shaped end 1-7 of the mechanism is now fixed and the mechanical variable information i, i ═ F can be measured by the force sensor 5_y。

S3: the force feedback setpoint y is initially set to 0.

S4: keeping the ambient temperature unchanged at 25 ℃, and setting the theoretical feedback force of the motor to be directly increased from 0N to y N.

S5: actual feedback force data of the force sensor is collected.

S6: and collecting the temperature data on the surface of the translation motor II 1-1-2.

S7: judging whether the temperature reaches 46 ℃, if not, entering step S5, and continuing to perform periodic collection; if the temperature reaches 46 ℃, the round of acquisition is ended, and the process proceeds to step S8.

S8: the force feedback set point y is increased by 1.

S9: judging whether the force feedback set value y exceeds 15, if not, recovering the motor temperature to be the same as the ambient temperature, and entering step S4 for next collection; if the value exceeds 15, the flow proceeds to step S10.

S10: and performing surface fitting by taking the actual feedback force as a dependent variable z when the initial temperature is subtracted from the actual feedback force and taking the feedback force set value y and the temperature x as independent variables to obtain a relational expression of the feedback force and the temperature.

The real-time temperature detection S11 comprises the following steps:

s12: the acquisition processing module 2-2 acquires the current data of the temperature sensor 2-1-2.

S13: the acquisition processing module 2-2 processes data and converts the data into temperature data.

S14: the data sending module 2-3 packs the temperature data and then sends the temperature data; the flow advances to step S12 to continue the real-time acquisition.

The feedback force compensation S15 includes the following steps:

s16: the data receiving module 3-1 receives the data and unpacks the temperature data.

S17: the compensation value calculation module 3-2 calculates the compensation force from the feedback force-temperature relational expression obtained in step S10, using the current temperature and the feedback force set value as inputs.

S18: the compensation value sending module 3-3 packs the compensation values and then sends the compensation values; the flow advances to step S16 to continue real-time compensation.

Referring to fig. 6, the 15-round calibration data shows that as the temperature increases, the actual feedback force gradually decreases, and the rate of decrease gradually decreases.

Further, the larger the force feedback set value n, the more the actual feedback force drops with the same temperature rise.

Further, a relation between the feedback force and the temperature is obtained through surface fitting:

normalization: x ═ x-38.53)/5.596; y-5.17)/3.706.

Fitting formula:

z＝p00+p10*x+p01*y+p20*x^2+p11*x*y+p02*y^2+p30*x^3+p21*x^2*y+p12*x*y^2+p03*y^3+p40*x^4+p31*x^3*y+p22*x^2*y^2+p13*x*y^3+p04*y^4+p50*x^5+p41*x^4*y+p32*x^3*y^2+p23*x^2*y^3+p14*x*y^4+p05*y^5

fitting coefficient:

p00＝0.1119(0.1118,0.1119)

p10＝0.02602(0.02598,0.02607)

p01＝0.06871(0.06865,0.06878)

p20＝-0.01681(-0.01688,-0.01674)

p11＝0.02836(0.0283,0.02842)

p02＝0.03527(0.03518,0.03535)

p30＝-0.002808(-0.002845,-0.002771)

p21＝-0.00728(-0.007322,-0.007238)

p12＝0.009211(0.009167,0.009255)

p03＝0.01718(0.01712,0.01724)

p40＝0.007621(0.007587,0.007655)

p31＝-0.01347(-0.0135,-0.01344)

p22＝0.01278(0.01274,0.01282)

p13＝-0.002126(-0.002172,-0.00208)

p04＝-0.02811(-0.02818,-0.02804)

p50＝0.003139(0.003126,0.003153)

p41＝-0.004447(-0.00446,-0.004435)

p32＝0.003814(0.003801,0.003827)

p23＝-0.002322(-0.002335,-0.002309)

p14＝-0.001062(-0.001075,-0.001048)

p05＝0.006869(0.006852,0.006886)

as shown in fig. 7 and 8, after the compensation of the temperature error compensation system and method of the force feedback device of the present invention, the force feedback accuracy of the force feedback device is significantly improved, and the feedback force does not substantially decrease with the temperature increase.

The above description is only one of the preferred embodiments of the present invention, and is not intended to limit the present invention in any way, but any modifications or equivalent variations made in accordance with the technical spirit of the present invention are within the scope of the present invention as claimed.