CN110561427B - Series elastic driver compliance control system and method based on compensation - Google Patents

Series elastic driver compliance control system and method based on compensation Download PDF

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CN110561427B
CN110561427B CN201910775000.1A CN201910775000A CN110561427B CN 110561427 B CN110561427 B CN 110561427B CN 201910775000 A CN201910775000 A CN 201910775000A CN 110561427 B CN110561427 B CN 110561427B
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angle
series elastic
target position
actuator
compensation
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CN110561427A (en
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高亮
钟浩然
李新宇
胡成颢
董昊臻
卢盛雨
李培根
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Huazhong University of Science and Technology
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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B25—HAND TOOLS; PORTABLE POWER-DRIVEN TOOLS; MANIPULATORS
    • B25J—MANIPULATORS; CHAMBERS PROVIDED WITH MANIPULATION DEVICES
    • B25J9/00—Programme-controlled manipulators
    • B25J9/16—Programme controls
    • B25J9/1628—Programme controls characterised by the control loop

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Abstract

The invention belongs to the field of robot compliance control, and particularly discloses a series elastic driver compliance control system and method based on compensation, which are based on an impedance model PkAnd the preset target position of the load end of the serial elastic driver at the current momentAngle/angle
Figure DDA0002174758680000011
To obtain
Figure DDA0002174758680000012
Inverse nominal model based on series elastic driver load dynamic model
Figure DDA0002174758680000013
And the actual position/angle of the load end of the series elastic driver at the current moment
Figure DDA0002174758680000014
To obtain
Figure DDA0002174758680000015
According to
Figure DDA0002174758680000016
And
Figure DDA0002174758680000017
to obtain
Figure DDA0002174758680000018
According to
Figure DDA0002174758680000019
And
Figure DDA00021747586800000110
is calculated to obtain
Figure DDA00021747586800000111
And based on
Figure DDA00021747586800000112
And
Figure DDA00021747586800000113
calculating the actual target position/angle of the actuator at the current moment t
Figure DDA00021747586800000114
Finally, controlling an actuator of the series elastic driver to track the actual target position/angle in real time
Figure DDA00021747586800000115
Therefore, the real-time tracking of the target impedance by the series elastic driver is realized. The invention can realize the flexible control of the series elastic driver and has the advantages of high control precision, good effect and the like.

Description

Series elastic driver compliance control system and method based on compensation
Technical Field
The invention belongs to the field of robot compliance control, and particularly relates to a series elastic driver compliance control system and method based on compensation.
Background
The joint flexible driver can enable the robot to safely interact with people or the environment, a Series Elastic Actuator (SEA) is taken as a typical flexible driver, an Elastic element is structurally introduced, and the robot flexible driver has the advantages of safety, external impact absorption, energy storage, cost reduction and the like, as shown in fig. 1, the Series Elastic driver comprises an actuator and a load, and the actuator and the load are connected through the Elastic element; meanwhile, the robustness of force output can be improved in control. Therefore, the series elastic driver is widely applied to the driving control of the robot joint.
To achieve compliance, the contact resistance is typically varied by adjusting the contact force and position of the actuator tip when in contact with the environment or a person, thereby exhibiting the desired compliance characteristics. Contact impedance is used to describe the behavior of the actuator when interacting with the environment or a person, to describe the flow of energy when interacting with the environment, and therefore impedance control is not equivalent to pure force or position control. Subjectively, the lower the impedance of the controlled object, the softer the person will feel when in contact with it (i.e., the more compliant the controlled object); conversely, the harder (i.e., the stiffer the object being controlled).
Conventional impedance control for series elastic actuators has been biased toward controlling the actuator output force. In the context of robotic applications, however, it is generally desirable that the drive exhibit characteristics that enable accurate position tracking when no contact with the environment or a person occurs; the tracking of the target impedance can be achieved when contact with the environment or a person occurs, thereby exhibiting compliance. Therefore, there is a need for a driver that can simultaneously achieve accurate position tracking and impedance tracking based on the current state. In terms of control accuracy, the system becomes more complex due to the introduction of the elastic element, so that the system is more susceptible to disturbance, thereby causing reduction of control accuracy and robustness. The dynamic characteristics of the load (such as the connecting element, the joint, etc.) can greatly affect the control effect, and the traditional control method does not properly compensate the factors.
Disclosure of Invention
In order to overcome the defects or the improvement requirements in the prior art, the invention provides a series elastic driver compliance control system and a series elastic driver compliance control method based on compensation, which convert the tracking of target impedance into the tracking of the position of a driver, avoid the load modeling of the actuator by carrying out closed-loop position control on the actuator, effectively compensate the system disturbance and the load dynamic characteristics by combining a disturbance observer and a feedback compensation controller, and realize high-precision compliance control applicable to various actuators.
To achieve the above object, according to one aspect of the present invention, there is provided a compensation-based compliance control system for a series elastic actuator, comprising an impedance control loop, a disturbance observer, a feedback compensation controller, and an actuator control loop, wherein:
the impedance control loop is used for controlling the impedance according to an impedance model PkAnd a preset currentTarget position/angle of load end of series elastic driver at time t
Figure BDA0002174758660000021
Obtaining the actual target position/angle of the series elastic driver at the current moment t
Figure BDA0002174758660000022
The disturbance observer is used for inverse nominal model according to series elastic driver load dynamic model
Figure BDA0002174758660000023
And the actual position/angle of the load end of the series elastic driver at the current moment
Figure BDA0002174758660000024
Obtaining the compensation quantity of the current moment
Figure BDA0002174758660000025
The feedback compensation controller is used for connecting the actual target position/angle of the elastic driver in series according to the current moment t
Figure BDA0002174758660000026
And actual position/angle
Figure BDA0002174758660000027
Obtaining the compensation quantity of the current moment
Figure BDA0002174758660000028
The actuator control loop is used for controlling
Figure BDA0002174758660000029
And
Figure BDA00021747586600000210
calculating to obtain the target position/angle of the actuator at the current moment
Figure BDA00021747586600000211
And based on
Figure BDA00021747586600000212
And
Figure BDA00021747586600000213
calculating the actual target position/angle of the actuator at the current moment t
Figure BDA00021747586600000214
Finally, controlling an actuator of the series elastic driver to track the actual target position/angle in real time
Figure BDA00021747586600000215
Therefore, the real-time tracking of the target impedance by the series elastic driver is realized.
Further preferably, the impedance model PkThe specific relation is as follows:
Figure BDA0002174758660000031
wherein, KsAnd DsRespectively desired stiffness and damping for a predetermined series elastic drive, FtFor the external load force at the present moment,. DELTA.ltThe target position/angle variation of the load end at the current moment t.
As a further preference, the actual target position/angle of the elastic actuator is connected in series at the present moment t
Figure BDA0002174758660000032
The method specifically comprises the following steps:
1) first according to an impedance model PkAnd the external load force F at the present momenttObtaining the variation delta l of the target position/angle of the load end at the current momentt；
2) Based on the preset target position/angle l of the load end of the serial elastic driver at the current momentt dAnd a variation amount DeltaltObtain a series elastic driverInter target position/angle
Figure BDA0002174758660000033
As a further preferred, the disturbance observer includes a first second order butterworth filter and a first proportional controller, which calculates the compensation amount at the current time t using the following formula
Figure BDA0002174758660000034
Figure BDA0002174758660000035
Wherein Q is1(s) is the transfer function of the first second order Butterworth filter, p1Which is a control parameter of the first proportional controller,
Figure BDA0002174758660000036
the actual target position/angle of the actuator at the previous time t-1.
Further preferably, the feedback compensation controller includes a second-order butterworth filter and a second proportional controller, which calculates the compensation amount at the current time t using the following formula
Figure BDA0002174758660000037
Figure BDA0002174758660000038
Wherein Q is2(s) is the transfer function of the second quadratic Butterworth filter, p2Is a control parameter of the second proportional controller.
It is further preferred that the actuator control loop comprises a PID controller for controlling the action of the actuator, by which control of the actuator to the actual target position/angle/is achievedrAccurate tracking of.
According to another aspect of the present invention, there is provided a compensation-based compliance control method for a series elastic driver, comprising the steps of:
s1 according to the impedance model PkAnd the preset target position/angle of the load end of the series elastic driver at the current moment t
Figure BDA0002174758660000041
Calculating the actual target position/angle of the series elastic driver at the current moment t
Figure BDA0002174758660000042
S2 inverse nominal model based on series elastic driver load dynamic model
Figure BDA0002174758660000043
And the actual position/angle of the load end of the series elastic driver at the current moment
Figure BDA0002174758660000044
Calculating the compensation amount of the current time
Figure BDA0002174758660000045
S3 connecting elastic driver with actual target position/angle in series according to current time t
Figure BDA0002174758660000046
And actual position/angle
Figure BDA0002174758660000047
Calculating the compensation amount of the current time
Figure BDA0002174758660000048
S4 is according to
Figure BDA0002174758660000049
And
Figure BDA00021747586600000410
calculating to obtain the target position/angle of the actuator at the current momentDegree of rotation
Figure BDA00021747586600000411
And based on
Figure BDA00021747586600000412
Figure BDA00021747586600000413
And
Figure BDA00021747586600000414
calculating to obtain the actual target position/angle of the actuator at the current moment t
Figure BDA00021747586600000415
S5 controlling actuators of series elastic drivers to track actual target position/angle in real time
Figure BDA00021747586600000416
Therefore, the real-time tracking of the target impedance by the series elastic driver is realized.
Further preferably, the impedance model PkThe specific relation is as follows:
Figure BDA00021747586600000417
wherein, KsAnd DsRespectively desired stiffness and damping for a predetermined series elastic drive, FtFor the external load force at the present moment,. DELTA.ltThe target position/angle variation of the load end at the current moment t.
As a further preference, step S1 includes the following sub-steps:
s11 according to the impedance model PkAnd the external load force F at the present momenttObtaining the variation delta l of the target position/angle of the load end at the current momentt；
S22 series elastic driver load end target position/angle based on preset current time
Figure BDA00021747586600000418
And a variation amount DeltaltObtaining the actual target position/angle of the series elastic driver
Figure BDA00021747586600000419
More preferably, the compensation amount at the current time t
Figure BDA00021747586600000420
Calculated using the following formula:
Figure BDA00021747586600000421
wherein Q is1(s) is the transfer function of the first second order Butterworth filter, p1Which is a control parameter of the first proportional controller,
Figure BDA00021747586600000422
is the actual target position/angle of the actuator at the previous moment t-1;
preferably, the compensation amount at the current time t
Figure BDA00021747586600000423
Calculated using the following formula:
Figure BDA0002174758660000051
wherein Q is2(s) is the transfer function of the second quadratic Butterworth filter, p2Is a control parameter of the second proportional controller.
Generally, compared with the prior art, the above technical solution conceived by the present invention mainly has the following technical advantages:
1. the invention is achieved by using an impedance model PkAnd the preset target position/angle of the load end of the series elastic driver at the current moment t
Figure BDA0002174758660000052
Obtaining the actual target position/angle of the series elastic driver at the current moment t
Figure BDA0002174758660000053
The method has the advantages that the tracking of the target impedance is effectively converted into the tracking of the position of the driver, so that the load modeling of the actuator is avoided through the position control of the actuator, and the simultaneous tracking of the impedance and the position can be realized through the position control.
2. The invention calculates corresponding compensation quantities by utilizing the disturbance observer and the feedback compensation controller, and compensates the two compensation quantities into the tracking control of the series elastic driver so as to realize effective compensation of disturbance and load dynamic characteristics, effectively improve the control precision, eliminate external disturbance, improve the robustness of the system and realize high-precision flexible control applicable to various actuators.
3. The invention also carries out research and design on the disturbance observer, adds the proportional controller, and can effectively improve the system performance by adjusting the control parameters of the proportional controller.
4. The disturbance observer is designed based on the dynamic characteristics of the load end (compensation quantity is calculated based on the inverse nominal model of the load dynamic model of the series elastic driver), the influence of the dynamic characteristics of the driver on a system is eliminated, the design process of the disturbance observer is simplified, and the system performance is improved.
5. The invention obtains the actual target position/angle of the series elastic driver based on the target position/angle and the variable quantity of the load end of the series elastic driver so as to convert the position control of the load end into the position control of the actuator, the position control of the load end is inconvenient to be directly controlled due to the existence of the elastic element, and the position control of the load end is indirectly realized by converting the position of the load end into the position of the actuator so as to ensure that the control is easier and more accurate.
6. The invention has less control parameters, and decouples the position inner ring control and other control rings, thereby simplifying the process of setting the control parameters. When the method is applied, the parameters of the inner ring position control PID controller can be set firstly, and then the parameters of the disturbance observer and the feedback controller are set according to the working condition after the parameters are finished, so that the method is convenient for practical application.
Drawings
FIG. 1 is a basic structural framework of a tandem elastic actuator;
FIG. 2 is a diagram of a compliance control overall control framework for a series elastic actuator;
FIG. 3 is a typical hydraulic SEA system consisting of servo-valve controlled hydraulic cylinders;
FIG. 4 is a graph of position tracking effect without external load;
FIG. 5 is a graph showing the result of the variation of the target position under an external load;
FIG. 6 is a graph of the effect of position tracking under an external load;
fig. 7 is a graph showing an actual stiffness tracking effect.
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is described in further detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention. In addition, the technical features involved in the embodiments of the present invention described below may be combined with each other as long as they do not conflict with each other.
As shown in fig. 2, an embodiment of the present invention provides a compliance control system of a series elastic driver based on compensation, which includes an impedance control loop, a disturbance observer, a feedback compensation controller, and an actuator control loop, where the disturbance observer, the feedback compensation controller, and the actuator control loop form a position control loop of the present invention, and the compliance control of the series elastic driver is implemented through the mutual cooperation of the above modules.
The following description is divided into modules.
(1) Impedance control loop
The basic structural framework of a series elastic drive is shown in FIG. 1 and includes an actuator and a load connected by an elastic element, wherein the actuator end outputsPosition/angle la(the left side of the elastic element is the angle when the actuator is a rotary actuator (e.g. rotary motor, rotary hydraulic motor) and the position when the actuator is a linear actuator (e.g. linear motor, linear hydraulic cylinder)), causing the elastic element to deform, the stiffness of the elastic element is K, and the end position/angle of load is lbThe load is moved by the combined action of the spring force and the external load force F.
If the desired rigidity K of the series elastic driver is to be metsAnd damping DsThen, based on the detection of a different F, the desired position/angle/of the load endcShould satisfy the condition that delta l is F (F, K)s,Ds) Specifically, it is represented as:
Figure BDA0002174758660000071
defining an impedance model Pk＝Δl/F Pk(the impedance model refers to the relationship between Δ l and F, i.e., equation (1)), therefore, the stiffness K expected by the actuator can be presetsAnd damping DsObtaining an impedance model Pk。
According to an impedance model PkAnd the measured external load force F can obtain the real-time target variation delta l of the expected position/angle of the load end, namely, the measured external load force F is substituted into the delta l which can be calculated in the formula (1).
The external load force F can be detected by a sensor, and also can be obtained by the rigidity K of the elastic element and the compression amount of the elastic element, specifically:
F＝(la-lb)K
the tracking of the desired impedance is translated into an actual target input/to the drivercBased on the target position/angle l of the load end of the preset series elastic driverdActual target position/angle l of the series elastic actuatorcThe following formula is obtained:
lc＝ld-Δl
if the elastic series driver can accurately track the actual target position/angle l of the drivercTracking of the target impedance can be achieved. Therefore, the tracking accuracy of the desired impedance is completely dependent on the tracking accuracy of the driver position/angle.
(2) Position control ring
The actuator control loop, the feedback compensation controller and the disturbance observer are constructed to enable the driver to realize accurate position control.
(2.1) disturbance observer design
Based on the load mass M and the rigidity K of the elastic element, a dynamic model of the load position of the driver is established as follows:
according to the actual actuator end position/angle la(on the left side of the elastic element, the position/angle is measured by a displacement sensor/angle sensor), the actual position/angle l of the load endb(adopt displacement sensor/angle sensor to measure position/angle), the external load force F that the load receives, load mass M, elastic element rigidity K, there are the following dynamic models:
Figure BDA0002174758660000081
nominal model P defining a dynamic model of a loadln＝lb/la(the nominal model means lbAnd laThe relation of (a), equation (2)),
Figure BDA0002174758660000082
is an inverse nominal model.
From the model, a disturbance observer is designed as shown in fig. 2, where q(s) is a first order Butterworth filter having a transfer function of the form:
Figure BDA0002174758660000083
wherein, ω isfWhich is the cut-off frequency of the filter, is one of the control parameters, and s is the complex variable in the laplace transform.
Disturbance observer phase adopted by the inventionCompared with the traditional disturbance observer, a proportional controller P is added1By adjusting its control parameter p1Improving system performance, controlling parameter p1And selecting according to the actual working condition, and when the control parameter is 1, the control parameter is consistent with that of the traditional disturbance observer. From the detected actual position/angle/of the load endbObtaining the compensation quantity delta l of the disturbance observer as the input of the disturbance observerdob：
Figure BDA0002174758660000084
Wherein p is1As a control parameter of the first proportional controller, Δ ldobIs 0, and is then calculated from the above formula (3), wherein Δ ldobAnd lbCorresponding to the parameter at the current time t,/rCorresponding to the parameter at the last time t-1.
(2.2) feedback Compensation controller design
The invention adds a feedback compensation controller in the feedback loop of the system, which comprises a proportional controller P2Second order Butterworth filters Q(s) and inverse nominal model
Figure BDA0002174758660000091
As shown in fig. 2, which is defined by the end position/angle error err of the loadb＝(lc-lb) As an input, the compensation quantity Deltal of the feedback compensation controller is obtainedf：
Figure BDA0002174758660000092
Wherein Q is2(s) is the transfer function of the second quadratic Butterworth filter, which coincides with the transfer function of the filter in the disturbance observer, p2For the control parameter of the second proportional controller, control parameter p2The value is selected according to the actual working condition.
(2.3) actuator control Ring
By the actual target bit of the driverSetting/angle lcAnd inverse nominal model
Figure BDA0002174758660000093
Obtaining actuator target position/angle
Figure BDA0002174758660000094
Based on the compensation amount delta l of the disturbance observerdobAnd the compensation amount Deltal of the feedback compensation controllerfObtaining the actual target position/angle l of the actuatorrThe process is as follows:
lr＝lp+Δlf-Δldob
wherein,. DELTA.ldobThe initial value is 0, and the actual target position/angle of the actuator at the current moment t can be calculated through the initial value
Figure BDA0002174758660000095
The
Figure BDA0002174758660000096
As the next moment
Figure BDA0002174758660000097
Is calculated as a parameter of
Figure BDA0002174758660000098
The actuator control loop comprises a PID controller for controlling the actuator, the PID controller and the actuator form a closed loop position control loop, and the actual position/angle l of the actuator is realized through PID controlaFor actual target position/angle of actuator
Figure BDA0002174758660000099
Accurate tracking of.
The control system is applied to the control of the series elastic driver, compensation is realized while control is carried out, and the control precision is improved, and the control system specifically comprises the following steps:
s1 according to the impedance model PkAnd a preset currentTarget position/angle of load end of series elastic driver at time t
Figure BDA0002174758660000101
Calculating the actual target position/angle of the series elastic driver at the current moment t
Figure BDA0002174758660000102
This step translates the tracking of the desired impedance into tracking of the target position/angle:
s11 according to the impedance model PkAnd the external load force F at the present momenttObtaining the variation delta l of the target position/angle of the load end at the current momenttI.e. FtSubstitution in formula (1) to give Δ lt；
S22 series elastic driver load end target position/angle based on preset current time
Figure BDA0002174758660000103
And a variation amount DeltaltObtaining the actual target position/angle of the series elastic driver
Figure BDA0002174758660000104
S2 inverse nominal model based on series elastic driver load dynamic model
Figure BDA0002174758660000105
And the actual position/angle of the load end of the series elastic driver at the current moment
Figure BDA0002174758660000106
Calculating the compensation amount of the current time
Figure BDA0002174758660000107
S3 connecting elastic driver with actual target position/angle in series according to current time t
Figure BDA0002174758660000108
And actual position/angle
Figure BDA0002174758660000109
Calculating the compensation amount of the current time
Figure BDA00021747586600001010
S4 is according to
Figure BDA00021747586600001011
And
Figure BDA00021747586600001012
calculating to obtain the target position/angle of the actuator at the current moment
Figure BDA00021747586600001013
And based on
Figure BDA00021747586600001014
Figure BDA00021747586600001015
And
Figure BDA00021747586600001016
calculating to obtain the actual target position/angle of the actuator at the current moment t
Figure BDA00021747586600001017
S5 controlling actuators of series elastic drivers to track actual target position/angle in real time
Figure BDA00021747586600001018
Therefore, the real-time tracking of the series elastic driver to the target impedance is realized, and the compliance control is realized.
In the following description of the specific embodiments, fig. 3 shows a typical hydraulic SEA system consisting of servo-controlled hydraulic cylinders. Setting expected rigidity and damping to obtain expected impedance model PkAnd obtaining a tracking graph and a position tracking graph of the expected impedance under the action of the external load force by changing the magnitude of the end load force. According to the invention, there is no need to establish the dynamics of the hydraulic systemThe model is controlled by using the control frame of fig. 2, in this embodiment, the target position is a sine curve with an amplitude of 40mm, an offset distance of 0 and a frequency of 5Hz, and the control results are shown in fig. 4-7.
Fig. 4 is a diagram of the position tracking effect under the condition of no external load, that is, the actuator is controlled by the control method based on compensation (position control after compensation in the diagram) in the free movement state that the actuator is not in contact with the outside, and the series elastic actuator can accurately track the target position.
FIG. 5 shows the external load force F being 20N, following the desired stiffness KsThe amplitude is 1N/mm, the offset is 1N/mm, the frequency is 5Hz, and the variation delta l of the target position is expected under the condition that the damping is 1N s/mmtThe variation of (2). When F is 0, i.e. no external force is applied, Δ ltIs constant and equal to 0, there is no concept of flexibility, and the driver is pure position tracking even if the impedance model is preset. Fig. 6 shows the control result when the external load force F is 20N, and it can be seen that the series elastic actuator can accurately track the corrected target position (position tracking after compensation in the figure) by using the control method based on compensation proposed by the present invention.
FIG. 7 is a graph of the actual stiffness tracking effect, the compliance control method for converting target impedance tracking into position tracking according to the present invention is effective (stiffness tracking after compensation in the graph), and the series elastic driver can accurately track the dynamic expected stiffness Ks. The position tracking precision of the series elastic driver is improved, so that higher-precision impedance tracking is realized, the flexible control of the series elastic driver can be realized, and the series elastic driver has the advantages of high control precision, good effect and the like.
It will be understood by those skilled in the art that the foregoing is only a preferred embodiment of the present invention, and is not intended to limit the invention, and that any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the scope of the present invention.

Claims (10)

1. A series elastic driver compliance control system based on compensation, comprising an impedance control loop, a disturbance observer, a feedback compensation controller and an actuator control loop, wherein:
the impedance control loop is used for controlling the impedance according to an impedance model PkAnd the preset target position/angle of the load end of the series elastic driver at the current moment t
Figure FDA0002667229530000011
Obtaining the actual target position/angle of the series elastic driver at the current moment t
Figure FDA0002667229530000012
The disturbance observer is used for inverse nominal model according to series elastic driver load dynamic model
Figure FDA0002667229530000013
And the actual position/angle of the load end of the series elastic driver at the current moment
Figure FDA0002667229530000014
Obtaining the compensation quantity of the current moment
Figure FDA0002667229530000015
The feedback compensation controller is used for connecting the actual target position/angle of the elastic driver in series according to the current moment t
Figure FDA0002667229530000016
And actual position/angle
Figure FDA0002667229530000017
Obtaining the compensation quantity of the current moment
Figure FDA0002667229530000018
The actuator control loop is used for controlling
Figure FDA0002667229530000019
And
Figure FDA00026672295300000110
calculating to obtain the target position/angle of the actuator at the current moment
Figure FDA00026672295300000111
And based on
Figure FDA00026672295300000112
And
Figure FDA00026672295300000113
calculating the actual target position/angle of the actuator at the current moment t
Figure FDA00026672295300000114
Finally, controlling an actuator of the series elastic driver to track the actual target position/angle in real time
Figure FDA00026672295300000115
Therefore, the real-time tracking of the target impedance by the series elastic driver is realized.
2. The compensation-based series elastic actuator compliance control system of claim 1, wherein the impedance model PkThe specific relation is as follows:
Figure FDA00026672295300000116
wherein, KsAnd DsRespectively predetermined stiffness expected for the series elastic driveAnd damping, FtFor the external load force at the present moment,. DELTA.ltThe target position/angle variation of the load end at the current moment t.
3. The compensation-based series elastic actuator compliance control system of claim 1, wherein the current time t series elastic actuator actual target position/angle
Figure FDA00026672295300000117
The method specifically comprises the following steps:
1) first according to an impedance model PkAnd the external load force F at the present momenttObtaining the variation delta l of the target position/angle of the load end at the current momentt；
2) Based on the preset target position/angle of the load end of the serial elastic driver at the current moment
Figure FDA0002667229530000021
And a variation amount DeltaltObtaining the actual target position/angle of the series elastic driver
Figure FDA0002667229530000022
4. The compensation-based compliance control system for a series elastic actuator according to claim 1, wherein said disturbance observer comprises a first second order butterworth filter and a first proportional controller, which calculates the amount of compensation at the current time t using the following formula
Figure FDA0002667229530000023
Figure FDA0002667229530000024
Wherein Q is1(s) is the transfer function of the first second order Butterworth filter, p1Is firstThe control parameters of the proportional controller are,
Figure FDA0002667229530000025
the actual target position/angle of the actuator at the previous time t-1.
5. The compensation-based compliance control system for a series elastic actuator of claim 1, wherein said feedback compensation controller comprises a second order butterworth filter and a second proportional controller that calculates the amount of compensation at the current time t using the following equation
Figure FDA0002667229530000026
Figure FDA0002667229530000027
Wherein Q is2(s) is the transfer function of the second quadratic Butterworth filter, p2Is a control parameter of the second proportional controller.
6. The compensation-based series elastic drive compliance control system of any one of claims 1-5, wherein the actuator control loop comprises a PID controller for controlling the action of the actuator, and the PID controller controls the actuator to achieve the actual target position/angle/, whererAccurate tracking of.
7. A series elastic driver compliance control method based on compensation is characterized by comprising the following steps:
s1 according to the impedance model PkAnd the preset target position/angle of the load end of the series elastic driver at the current moment t
Figure FDA0002667229530000028
Calculating the actual target position/angle of the series elastic driver at the current moment t
Figure FDA0002667229530000029
S2 inverse nominal model based on series elastic driver load dynamic model
Figure FDA00026672295300000210
And the actual position/angle of the load end of the series elastic driver at the current moment
Figure FDA0002667229530000031
Calculating the compensation amount of the current time
Figure FDA0002667229530000032
S3 connecting elastic driver with actual target position/angle in series according to current time t
Figure FDA0002667229530000033
And actual position/angle
Figure FDA0002667229530000034
Calculating the compensation amount of the current time
Figure FDA0002667229530000035
S4 is according to
Figure FDA0002667229530000036
And
Figure FDA0002667229530000037
calculating to obtain the target position/angle of the actuator at the current moment
Figure FDA0002667229530000038
And based on
Figure FDA0002667229530000039
Figure FDA00026672295300000310
And
Figure FDA00026672295300000311
calculating to obtain the actual target position/angle of the actuator at the current moment t
Figure FDA00026672295300000312
S5 controlling actuators of series elastic drivers to track actual target position/angle in real time
Figure FDA00026672295300000313
Therefore, the real-time tracking of the target impedance by the series elastic driver is realized.
8. The compensation-based series elastic actuator compliance control method of claim 7, wherein the impedance model PkThe specific relation is as follows:
Figure FDA00026672295300000314
wherein, KsAnd DsRespectively desired stiffness and damping for a predetermined series elastic drive, FtFor the external load force at the present moment,. DELTA.ltThe target position/angle variation of the load end at the current moment t.
9. The compensation-based series elastic driver compliance control method of claim 7, wherein step S1 includes the sub-steps of:
s11 according to the impedance model PkAnd the external load force F at the present momenttObtaining the variation delta l of the target position/angle of the load end at the current momentt；
S22 series elastic driver load end target position/angle based on preset current time
Figure FDA00026672295300000315
And a variation amount DeltaltObtaining the actual target position/angle of the series elastic driver
Figure FDA00026672295300000316
10. The compensation-based compliance control method for a series elastic actuator according to any one of claims 7 to 9, wherein the compensation amount at the current time t
Figure FDA00026672295300000317
Calculated using the following formula:
Figure FDA00026672295300000318
wherein Q is1(s) is the transfer function of the first second order Butterworth filter, p1Which is a control parameter of the first proportional controller,
Figure FDA00026672295300000319
is the actual target position/angle of the actuator at the previous moment t-1;
compensation of current time t
Figure FDA00026672295300000320
Calculated using the following formula:
Figure FDA0002667229530000041
wherein Q is2(s) is the transfer function of the second quadratic Butterworth filter, p2Is a control parameter of the second proportional controller.
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