Robotic arm and adaptive admittance control system and method thereof, and robot

Abstract

The present invention provides a mechanical arm and its adaptive admittance control system and robot, the adaptive admittance control system includes: an observer, which is used to receive a contact force signal and generate an oscillation amplitude parameter according to the contact force signal; an expected trajectory generator, which is used to adjust the initial environment stiffness when the oscillation amplitude parameter is greater than a preset threshold, and generate the expected posture of the mechanical arm according to the adjusted initial environment stiffness; an admittance controller, which is used to adjust the admittance parameter of the admittance controller according to the oscillation amplitude parameter and the preset threshold when the oscillation amplitude parameter is greater than the preset threshold, and generate the posture deviation of the mechanical arm according to the adjusted admittance parameter; a motion controller, which is used to control the mechanical arm according to the posture deviation and the expected posture. When the interactive environment stiffness suddenly changes, the dynamic response performance and stability of the system can still be ensured, and the reliability is high.

Description

Technical Field

[0001] The present invention relates to the technical field of robot arm control, and in particular to an adaptive admittance control system of a robot arm, an adaptive admittance control method of a robot arm, a robot arm and a robot. Background Art

[0002] The robot force control method based on the admittance control architecture only needs to install a force sensor on the robot arm, and convert the contact force signal into the position or speed deviation of the robot arm through the admittance controller, which is used to correct the motion instructions of the robot arm, and finally rely on a high-precision robot motion controller to achieve precise force control. The robot force control method based on the admittance architecture has the characteristics of high precision and easy implementation, and is widely used in the contact force control of the robot arm and the environment.

[0003] In the related technology, when the traditional admittance control architecture is used to control the force of the robot, when the stiffness of the interactive environment changes suddenly, its dynamic response performance and stability are poor, and the system reliability is low. Summary of the invention

[0004] In order to solve the above technical problems, the present invention provides an adaptive admittance control system for a robotic arm. When an observer observes that the system shows an unstable trend, the initial environmental stiffness in the adaptive algorithm is updated to improve the convergence speed of the adaptive algorithm, and the admittance parameters are adjusted at the same time. Therefore, when the interactive environmental stiffness suddenly changes, the dynamic response performance and stability of the system can still be ensured, and the reliability is high.

[0005] The invention also provides an adaptive admittance control method for a mechanical arm.

[0006] The invention also provides a mechanical arm.

[0007] The invention also provides a robot.

[0008] The technical solution adopted by the present invention is as follows:

[0009] An adaptive admittance control system for a robot arm comprises: an observer, the observer is used to receive a contact force signal and generate an oscillation amplitude parameter according to the contact force signal, wherein the contact force signal is a signal for collecting and acquiring the contact force at the end of the robot arm; an expected trajectory generator, the input end of the expected trajectory generator is connected to the output end of the observer, the expected trajectory generator is used to adjust the initial environment stiffness when the oscillation amplitude parameter is greater than a preset threshold, and generate the expected posture of the robot arm according to the adjusted initial environment stiffness; an admittance controller, the admittance controller is used to adjust the admittance parameter of the admittance controller according to the oscillation amplitude parameter and the preset threshold when the oscillation amplitude parameter is greater than the preset threshold, and generate the posture deviation of the robot arm according to the adjusted admittance parameter; a motion controller, the motion controller is used to control the robot arm according to the posture deviation and the expected posture.

[0010] In one embodiment of the present invention, the observer is specifically used to generate the oscillation amplitude parameter by the following formula:

[0011]

[0012] Among them, η is the smoothing coefficient, is the oscillation amplitude parameter of the previous sampling period, is the first ratio of the high-frequency component to the low-frequency component of the contact force signal in the current sampling period, is a second ratio of the standard deviation of the time domain signal of the contact force signal in the current sampling period when the windowing process is performed to the maximum allowable force, It is the oscillation amplitude parameter of the current sampling period.

[0013] In one embodiment of the present invention, the desired trajectory generator adjusts the initial environment stiffness by the following formula:

[0014]

[0015] in, is the initial environment stiffness, It is the ratio of the change in the actual contact force at the end of the robot arm to the change in the actual posture.

[0016] In one embodiment of the present invention, the expected trajectory generator generates the expected posture of the robotic arm according to the adjusted initial environment stiffness by the following formula:

[0017]

[0018] in, is the environmental stiffness of the current sampling period, γ1 is the first positive scalar constant, γ2 is the second positive scalar constant, f p is the estimated contact force at the pth sampling period, f p is the actual contact force in the pth sampling period, x p is the actual position of the end of the robot arm in the pth sampling period, is the environmental position of the current sampling period, x e,0 is the initial environment position, is the environmental stiffness of the pth sampling period, is the environmental position of the pth sampling period, f k-1 is the estimated contact force in the previous sampling period, is the environmental stiffness of the previous sampling period, x k-1 The actual position of the end of the robot arm in the previous sampling period, is the environmental position of the previous sampling period, is the expected position of the end of the robot arm in the current sampling period, is the environmental position of the current sampling period, is the expected contact force in the current sampling period.

[0019] In one embodiment of the present invention, the admittance parameter includes damping, and correspondingly, the admittance controller is specifically used to adjust the admittance parameter of the admittance controller through the following formula:

[0020]

[0021] Wherein, d(k) is the damping of the current sampling period, d(k-1) is the damping of the previous sampling period, and α is the coefficient corresponding to the admittance controller. is the oscillation amplitude parameter of the current sampling period, and ε is the preset threshold.

[0022] In one embodiment of the present invention, the stable output value of the observer under a 1 Hz input signal is used as the preset threshold.

[0023] In one embodiment of the present invention, the admittance controller is formed using the following formula:

[0024]

[0025] Where M, D, and K are the inertia, damping, and stiffness of the desired second-order system after being updated according to the adjusted admittance parameters, respectively. d is the expected contact force, F c is the actual contact force, x d is the desired position of the robot arm, x ris the reference pose of the robot arm, and E is the desired pose x of the robot arm. d With reference pose x r The posture deviation between them.

[0026] An adaptive admittance control method for a robot arm comprises the following steps: receiving a contact force signal, and generating an oscillation amplitude parameter according to the contact force signal, wherein the contact force signal is a signal acquired by collecting the contact force at the end of the robot arm; when the oscillation amplitude parameter is greater than a preset threshold, adjusting the initial environment stiffness, and generating the desired posture of the robot arm according to the adjusted initial environment stiffness, and adjusting the admittance parameter of the admittance controller according to the oscillation amplitude parameter and the preset threshold, and generating the posture deviation of the robot arm according to the adjusted admittance parameter; and controlling the robot arm according to the posture deviation and the desired posture.

[0027] A robotic arm comprises the adaptive admittance control system of the robotic arm.

[0028] A robot comprises the above-mentioned mechanical arm.

[0029] Beneficial effects of the present invention:

[0030] When the observer observes that the system has an unstable trend, the present invention updates the initial environmental stiffness in the adaptive algorithm to improve the convergence speed of the adaptive algorithm, and adjusts the admittance parameters at the same time, so that when the interactive environmental stiffness suddenly changes, the dynamic response performance and stability of the system can still be ensured, and the reliability is high. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 Schematic diagram of a block diagram of an adaptive admittance control system of a robotic arm according to an embodiment of the present invention;

[0032] Figure 2 Flow chart of an adaptive admittance control method for a robotic arm according to an embodiment of the present invention. DETAILED DESCRIPTION

[0033] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0034] Figure 1 is a block diagram of an adaptive admittance control system of a robotic arm according to an embodiment of the present invention.

[0035] like Figure 1As shown, the adaptive admittance control system of the robot arm according to the embodiment of the present invention may include: an observer 100 , a desired trajectory generator 200 , an admittance controller 300 and a motion controller 400 .

[0036] Among them, the observer 100 is used to receive the contact force signal and generate an oscillation amplitude parameter according to the contact force signal, wherein the contact force signal is a signal for collecting and acquiring the contact force of the end of the robot arm; the input end of the expected trajectory generator 200 is connected to the output end of the observer 100, and the expected trajectory generator 200 is used to adjust the initial environment stiffness when the oscillation amplitude parameter is greater than a preset threshold, and generate the expected posture of the robot arm according to the adjusted initial environment stiffness; the input end of the admittance controller 300 is connected to the output end of the observer 100, and the admittance controller 300 is used to adjust the admittance parameter of the admittance controller according to the oscillation amplitude parameter and the preset threshold when the oscillation amplitude parameter is greater than the preset threshold, and generate the posture deviation of the robot arm according to the adjusted admittance parameter; the input end of the motion controller 400 is respectively connected to the output end of the expected trajectory generator 200 and the output end of the admittance controller 300, and the motion controller 400 is used to control the robot arm according to the posture deviation and the expected posture.

[0037] Specifically, a force sensor can be set at the end of the robot arm to collect the contact force at the end of the robot arm in real time and generate a corresponding contact force signal F c , and the contact force signal F c It is sent to the observer 100 through the input terminal of the observer 100 .

[0038] Upon receiving the contact force signal F c After that, according to the contact force signal F c Generate the corresponding oscillation amplitude parameters.

[0039] The following describes in detail how to use the contact force signal F c Generate the corresponding oscillation amplitude parameters.

[0040] In one embodiment of the present invention, the observer 100 generates a signal based on the contact force signal F c The steps to generate the corresponding oscillation amplitude parameters are as follows: First, calculate the contact force signal F c The Euclidean second norm after high-frequency filtering and low-frequency filtering, that is, the contact force signal F c The Euclidean second norm after high-frequency filtering ||F h n || and contact force signal F c The Euclidean second norm after low-frequency filtering ||F l n||. Secondly, according to the Euclidean second norm of the contact force signal after high-frequency filtering and low-frequency filtering, the first ratio I of the high-frequency component and the low-frequency component of the contact force signal is calculated. o Specifically, in order to prevent the first ratio I o A sudden change occurs when the contact force signal F c The Euclidean second norm after low-frequency filtering ||F l n || is less than a preset force value (eg, 0.01N), the first ratio I o Set to zero; when the contact force signal F c The Euclidean second norm after low-frequency filtering ||F l n || When it is greater than or equal to the preset force value, the contact force signal F is calculated c The Euclidean second norm after high-frequency filtering ||F h n || and contact force signal F c The Euclidean second norm after low-frequency filtering ||F l n || to obtain the first ratio I o ,Right now

[0041] I0=||F h n || / ||F l n ||. (1)

[0042] Then, the contact force signal F is calculated c The standard deviation of the time domain signal F during windowing and the maximum allowable force F max The second ratio I std Specifically, the second ratio I can be calculated by the following formula: std :

[0043]

[0044] Where, as shown in formula (2), F max Will I std Normalized between 0 and 1, p is the window size for calculating the standard deviation, I std It reflects the change of contact force amplitude within p sampling periods, I std The larger it is, the larger the contact force amplitude is in the corresponding p sampling periods.

[0045] Finally, according to the first ratio I o and the second ratio I std Generate oscillation amplitude parameters. Among them, the first ratio I o and the second ratio Istd They are dimensionless values ​​between 0 and 1.

[0046] In one embodiment of the present invention, the observer 100 may generate the oscillation amplitude parameter by the following formula:

[0047]

[0048] Among them, η is the smoothing coefficient, is the oscillation amplitude parameter of the previous sampling period, is the first ratio of the high-frequency component to the low-frequency component of the contact force signal in the current sampling period, is the contact force signal F of the current sampling period c The standard deviation of the time domain signal F during windowing and the maximum allowable force F max The second ratio, It is the oscillation amplitude parameter of the current sampling period.

[0049] Among them, the oscillation amplitude parameter of the current sampling period can be Update the output of the observer 100, i.e., the oscillation amplitude parameter I os Among them, the oscillation amplitude parameter I os It is a parameter that characterizes the contact force oscillation amplitude and system stability. os The smaller it is, the more stable the system is.

[0050] Furthermore, after the observer 100 generates the oscillation amplitude parameter, the observer 100 may input the oscillation amplitude parameter into the desired trajectory generator 200 and the admittance controller 300 through the output end of the observer 100 from the input end of the desired trajectory generator 200 and the input end of the admittance controller 300 .

[0051] It is understandable that in the traditional adaptive control method, the desired posture of the end of the robot arm is calculated by online estimating the environmental stiffness and environmental position to achieve the desired steady-state contact force. However, the convergence speed of this method is affected by the initial environmental stiffness setting. The smaller the difference between the initial environmental stiffness and the actual environmental stiffness, the faster the interaction contact force converges to the desired contact force, and vice versa.

[0052] To this end, in one embodiment of the present invention, after receiving the oscillation amplitude parameter, the expected trajectory generator 200 can first determine the size of the oscillation amplitude parameter. If the oscillation amplitude parameter is less than or equal to the preset threshold ε, it means that the current system is relatively stable and can be controlled by the traditional adaptive control method; if the oscillation amplitude parameter is greater than the preset threshold ε, it means that the current system has an unstable trend, therefore, the initial environment stiffness in the adaptive algorithm is updated, and the expected posture of the manipulator is generated according to the adjusted initial environment stiffness. Among them, the stable output value of the observer 100 under the 1Hz input signal can be used as the preset threshold ε.

[0053] In one embodiment of the present invention, the expected trajectory generator 200 may adjust the initial environment stiffness by the following formula:

[0054]

[0055] in, is the initial environment stiffness, It is the ratio of the change in actual contact force at the end of the robot to the change in actual posture.

[0056] In one embodiment of the present invention, the expected trajectory generator 200 generates the expected posture of the robot arm according to the adjusted initial environment stiffness by the following formula:

[0057]

[0058] in, is the environmental stiffness of the current sampling period, γ1 is the first positive scalar constant, γ2 is the second positive scalar constant, f p is the estimated contact force at the pth sampling period, f p is the actual contact force in the pth sampling period, x p is the actual position of the end of the robot arm in the pth sampling period, is the environmental position of the current sampling period, x e,0 is the initial environment position, is the environmental stiffness of the pth sampling period, is the environmental position of the pth sampling period, f k-1 is the estimated contact force in the previous sampling period, is the environmental stiffness of the previous sampling period, x k-1 The actual position of the end of the robot arm in the previous sampling period, is the environmental position of the previous sampling period, is the expected position of the end of the robot arm in the current sampling period, is the environmental position of the current sampling period, is the expected contact force in the current sampling period. Among them, γ1 and γ2 are positive scalar constants that affect the convergence speed of the adaptive algorithm. The larger the value, the faster the convergence speed, but the system stability becomes worse.

[0059] That is, when the expected trajectory generator 200 determines that the oscillation amplitude parameter is greater than the preset threshold ε, the initial environment stiffness Updated to And according to the updated initial environment stiffness (Size is ) Iterate the formulas in formula group (4) in order to finally obtain the desired position of the end of the robot arm in the current sampling period. And according to the expected position of the end of the robot arm in the current sampling period Update the output of the desired trajectory generator 200, that is, the desired position X of the robot arm d .

[0060] In addition, in order to solve the problem of unstable jitter when the stiffness of the contact environment suddenly increases, an observer is used in the embodiment of the present invention to observe the jitter caused by the sudden increase in the stiffness of the environment, and the contact stability is quickly restored by adjusting the admittance coefficient in the admittance controller. The admittance coefficient may include damping.

[0061] Specifically, in one embodiment of the present invention, the admittance controller 300 is specifically used to adjust the admittance parameter of the admittance controller by the following formula:

[0062]

[0063] Where d(k) is the damping of the current sampling period, d(k-1) is the damping of the previous sampling period, and α is the coefficient corresponding to the admittance controller. is the oscillation amplitude parameter of the current sampling period, and ε is the preset threshold.

[0064] That is, when the oscillation amplitude parameter is greater than the preset threshold value ε, the admittance controller 300 can adjust the damping of the admittance controller 300 through the above formula (5), that is, increase the damping of the current sampling period. At the same time, the inertia and stiffness of the admittance controller 300 of the current sampling period can be assigned to the initial inertia and initial stiffness. Then, the inertia, damping and stiffness of the desired second-order system of the admittance controller 300 are updated according to the damping, inertia and stiffness of the current sampling period, and the admittance controller thus formed is as follows:

[0065]

[0066] Wherein, M, D, and K represent the inertia, damping, and stiffness of the desired second-order system of the admittance controller 300, respectively, that is, the inertia, damping, and stiffness of the desired second-order system updated according to the adjusted admittance parameters, and F d is the expected contact force, F c is the actual contact force (i.e., the contact force signal F in the above embodiment) c ), E is the desired position x of the robot arm d With reference pose x r The posture deviation between them.

[0067] Further, the desired position X of the robot arm output by the desired trajectory generator 200 is d The posture deviation E output by the admittance controller 300 is input from the input and output terminals of the motion controller 400. At this time, the motion controller 400 can calculate the desired posture according to the posture deviation E and the desired posture X. d The robot arm is controlled accordingly in combination with the actual posture X to control the end of the robot arm to contact the environment (e.g., the target contact object).

[0068] In summary, if Figure 1 As shown, the control system consists of three parts: the first is an observer 100 based on the contact force signal, which observes the oscillation characteristics of the contact force signal between the end of the robot arm and the environment in real time, and outputs a parameter representing the force oscillation amplitude and the stability of the system, namely, the oscillation amplitude parameter I os ; The second is the admittance controller 300, according to the oscillation amplitude parameter I os Adjust the damping parameters in the admittance control; third, the desired trajectory generator 200, based on the robot position, force error and oscillation amplitude parameter I os Design the adaptive rate and adaptively calculate the desired trajectory of the robot, that is, the desired position X of the robot arm d Finally, based on the desired position X of the robot arm d The robot arm is controlled accordingly based on the posture deviation E output by the admittance controller 300. os A control system is introduced for the design of the expected trajectory generator 200 and the admittance controller 300. When an unstable trend is observed, the initial value of the environmental stiffness in the adaptive algorithm is updated to improve the convergence speed of the adaptive algorithm. At the same time, the parameters of the admittance controller are adjusted to increase the system damping, ultimately improving the contact force dynamic response and system stability.

[0069] According to the adaptive admittance control system of the manipulator of the embodiment of the present invention, the contact force signal is received by the observer, and the oscillation amplitude parameter is generated according to the contact force signal, and the initial environment stiffness is adjusted by the expected trajectory generator when the oscillation amplitude parameter is greater than the preset threshold, and the expected posture of the manipulator is generated according to the adjusted initial environment stiffness, and the admittance controller is used to adjust the admittance parameter of the admittance controller according to the oscillation amplitude parameter and the preset threshold when the oscillation amplitude parameter is greater than the preset threshold, and the posture deviation of the manipulator is generated according to the adjusted admittance parameter, and the motion controller is used to control the manipulator according to the posture deviation and the expected posture. Thus, when the observer observes that the system has an unstable trend, the initial environment stiffness in the adaptive algorithm is updated to improve the convergence speed of the adaptive algorithm, and the admittance parameter is adjusted at the same time, so that when the interactive environment stiffness suddenly changes, the dynamic response performance and stability of the system can still be ensured, and the reliability is high.

[0070] Corresponding to the adaptive admittance control system of the robot arm in the above embodiment, the present invention further proposes an adaptive admittance control method of the robot arm.

[0071] like Figure 2 As shown, the adaptive admittance control method of the robot arm according to the embodiment of the present invention may include the following steps:

[0072] S1, receiving a contact force signal, and generating an oscillation amplitude parameter according to the contact force signal. The contact force signal is a signal acquired by collecting the contact force at the end of the robot arm.

[0073] S2, when the oscillation amplitude parameter is greater than a preset threshold, adjust the initial environment stiffness, and generate the desired posture of the robot arm according to the adjusted initial environment stiffness, and adjust the admittance parameter of the admittance controller according to the oscillation amplitude parameter and the preset threshold, and generate the posture deviation of the robot arm according to the adjusted admittance parameter.

[0074] S3, controlling the robot arm according to the posture deviation and the desired posture.

[0075] In one embodiment of the present invention, the oscillation amplitude parameter is generated by the following formula:

[0076]

[0077] Among them, η is the smoothing coefficient, is the oscillation amplitude parameter of the previous sampling period, is the first ratio of the high-frequency component to the low-frequency component of the contact force signal in the current sampling period, is the second ratio of the standard deviation of the time domain signal of the contact force signal of the current sampling period to the maximum allowable force when the windowing process is performed, It is the oscillation amplitude parameter of the current sampling period.

[0078] In one embodiment of the present invention, the initial environment stiffness is adjusted by the following formula:

[0079]

[0080] in, is the initial environment stiffness, It is the ratio of the change in actual contact force at the end of the robot to the change in actual posture.

[0081] In one embodiment of the present invention, the desired posture of the robot arm is generated according to the adjusted initial environment stiffness by the following formula:

[0082]

[0083] in, is the environmental stiffness of the current sampling period, γ1 is the first positive scalar constant, γ2 is the second positive scalar constant, f p is the estimated contact force at the pth sampling period, f p is the actual contact force in the pth sampling period, x p is the actual position of the end of the robot arm in the pth sampling period, is the environmental position of the current sampling period, x e,0 is the initial environment position, is the environmental stiffness of the pth sampling period, is the environmental position of the pth sampling period, f k-1 is the estimated contact force in the previous sampling period, is the environmental stiffness of the previous sampling period, x k-1 The actual position of the end of the robot arm in the previous sampling period, is the environmental position of the previous sampling period, is the expected position of the end of the robot arm in the current sampling period, is the environmental position of the current sampling period, is the expected contact force in the current sampling period.

[0084] In one embodiment of the present invention, the admittance parameter includes damping. Correspondingly, the admittance parameter of the admittance controller is adjusted by the following formula:

[0085]

[0086] Where d(k) is the damping of the current sampling period, d(k-1) is the damping of the previous sampling period, and α is the coefficient corresponding to the admittance controller. is the oscillation amplitude parameter of the current sampling period, and ε is the preset threshold.

[0087] In one embodiment of the present invention, the stable output value of the observer under a 1 Hz input signal is used as the preset threshold.

[0088] In one embodiment of the present invention, the following formula is used to form the admittance controller:

[0089]

[0090] Where M, D, and K are the inertia, damping, and stiffness of the desired second-order system after being updated according to the adjusted admittance parameters, Fd is the desired contact force, and F c is the actual contact force, x d is the desired position of the robot arm, x r is the reference pose of the robot arm, and E is the desired pose x of the robot arm. d With reference pose x r The posture deviation between them.

[0091] It should be noted that a more specific embodiment of the adaptive admittance control method of the robot arm of the present invention can refer to the adaptive admittance control system of the robot arm in the above embodiment, and will not be described in detail here to avoid redundancy.

[0092] According to the adaptive admittance control method of the robot arm of the embodiment of the present invention, a contact force signal is received, and an oscillation amplitude parameter is generated according to the contact force signal, and when the oscillation amplitude parameter is greater than a preset threshold, the initial environmental stiffness is adjusted, and the desired posture of the robot arm is generated according to the adjusted initial environmental stiffness, and the admittance parameter of the admittance controller is adjusted according to the oscillation amplitude parameter and the preset threshold, and the posture deviation of the robot arm is generated according to the adjusted admittance parameter, and the robot arm is controlled according to the posture deviation and the desired posture. Thus, when the observer observes that the system has an unstable trend, the initial environmental stiffness in the adaptive algorithm is updated to improve the convergence speed of the adaptive algorithm, and the admittance parameter is adjusted at the same time, so that when the interactive environmental stiffness suddenly changes, the dynamic response performance and stability of the system can still be ensured, and the reliability is high.

[0093] Corresponding to the adaptive admittance control system of the robot arm in the above embodiment, the present invention further proposes a robot arm. The robot arm in the embodiment of the present invention may include the adaptive admittance control system of the robot arm.

[0094] According to the robotic arm of an embodiment of the present invention, based on an adaptive admittance control system, when an observer observes that the system shows an unstable trend, the initial environmental stiffness in the adaptive algorithm is updated to improve the convergence speed of the adaptive algorithm, and the admittance parameters are adjusted at the same time, so that when the interactive environmental stiffness suddenly changes, the dynamic response performance and stability of the system can still be ensured, and the reliability is high.

[0095] Corresponding to the mechanical arm of the above embodiment, the present invention further proposes a robot. The robot of the embodiment of the present invention may include the above mechanical arm.

[0096] According to the robot of the embodiment of the present invention, based on the adaptive admittance control system, when the observer observes that the system shows an unstable trend, the initial environmental stiffness in the adaptive algorithm is updated to improve the convergence speed of the adaptive algorithm, and the admittance parameters are adjusted at the same time, so that when the interactive environmental stiffness suddenly changes, the dynamic response performance and stability of the system can still be ensured, and the reliability is high.

[0097] In the description of the present invention, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include one or more of the features. "Multiple" means two or more, unless otherwise clearly and specifically defined.

[0098] In the present invention, unless otherwise clearly specified and limited, the terms "installed", "connected", "connected", "fixed" and the like should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0099] In the present invention, unless otherwise clearly specified and limited, a first feature being "above" or "below" a second feature may mean that the first and second features are in direct contact, or the first and second features are in indirect contact through an intermediate medium. Moreover, a first feature being "above", "above" or "above" a second feature may mean that the first feature is directly above or obliquely above the second feature, or simply means that the first feature is higher in level than the second feature. A first feature being "below", "below" or "below" a second feature may mean that the first feature is directly below or obliquely below the second feature, or simply means that the first feature is lower in level than the second feature.

[0100] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art may combine and combine the different embodiments or examples described in this specification and the features of the different embodiments or examples, unless they are contradictory.

[0101] Any process or method description in a flowchart or otherwise described herein may be understood to represent a module, segment or portion of code that includes one or more executable instructions for implementing the steps of a specific logical function or process, and the scope of the preferred embodiments of the present invention includes alternative implementations in which functions may not be performed in the order shown or discussed, including performing functions in a substantially simultaneous manner or in the reverse order depending on the functions involved, which should be understood by those skilled in the art to which the embodiments of the present invention belong.

[0102] The logic and / or steps represented in the flowchart or otherwise described herein, for example, can be considered as an ordered list of executable instructions for implementing logical functions, and can be embodied in any computer-readable medium for use by an instruction execution system, device or apparatus (such as a computer-based system, a system including a processor, or other system that can fetch instructions from an instruction execution system, device or apparatus and execute instructions), or in combination with these instruction execution systems, devices or apparatuses. For the purposes of this specification, a "computer-readable medium" can be any device that can contain, store, communicate, propagate or transmit a program for use by an instruction execution system, device or apparatus, or in combination with these instruction execution systems, devices or apparatuses. More specific examples of computer-readable media (a non-exhaustive list) include the following: an electrical connection with one or more wires (electronic devices), a portable computer disk box (magnetic device), a random access memory (RAM), a read-only memory (ROM), an erasable and programmable read-only memory (EPROM or flash memory), a fiber optic device, and a portable compact disk read-only memory (CDROM). In addition, the computer-readable medium may even be paper or other suitable medium on which the program is printed, since the program may be obtained electronically, for example, by optically scanning the paper or other medium and then editing, interpreting or processing in other suitable ways if necessary, and then stored in a computer memory.

[0103] It should be understood that the various parts of the present invention can be implemented by hardware, software, firmware or a combination thereof. In the above-mentioned embodiments, a plurality of steps or methods can be implemented by software or firmware stored in a memory and executed by a suitable instruction execution system. For example, if implemented by hardware, as in another embodiment, it can be implemented by any one of the following technologies known in the art or their combination: a discrete logic circuit having a logic gate circuit for implementing a logic function for a data signal, a dedicated integrated circuit having a suitable combination of logic gate circuits, a programmable gate array (PGA), a field programmable gate array (FPGA), etc.

[0104] A person skilled in the art may understand that all or part of the steps in the method for implementing the above-mentioned embodiment may be completed by instructing related hardware through a program, and the program may be stored in a computer-readable storage medium, which, when executed, includes one or a combination of the steps of the method embodiment.

[0105] In addition, each functional unit in each embodiment of the present invention may be integrated into a processing module, or each unit may exist physically separately, or two or more units may be integrated into one module. The above-mentioned integrated module may be implemented in the form of hardware or in the form of a software functional module. If the integrated module is implemented in the form of a software functional module and sold or used as an independent product, it may also be stored in a computer-readable storage medium.

[0106] The storage medium mentioned above may be a read-only memory, a magnetic disk or an optical disk, etc. Although the embodiments of the present invention have been shown and described above, it can be understood that the above embodiments are exemplary and cannot be understood as limiting the present invention. A person of ordinary skill in the art may change, modify, replace and modify the above embodiments within the scope of the present invention.

Claims

1. An adaptive admittance control system for a robotic arm, characterized in that: include: An observer is used to receive a contact force signal and generate an oscillation amplitude parameter according to the contact force signal, wherein the contact force signal is a signal acquired by collecting the contact force at the end of the robot arm; wherein the observer is specifically used to generate the oscillation amplitude parameter by the following formula: Among them, η is the smoothing coefficient, is the oscillation amplitude parameter of the previous sampling period, is the first ratio of the high-frequency component to the low-frequency component of the contact force signal in the current sampling period, is a second ratio of the standard deviation of the time domain signal of the contact force signal in the current sampling period when the windowing process is performed to the maximum allowable force, is the oscillation amplitude parameter of the current sampling period; An expected trajectory generator, wherein the input end of the expected trajectory generator is connected to the output end of the observer, and the expected trajectory generator is used to adjust the initial environment stiffness when the oscillation amplitude parameter is greater than a preset threshold, and generate the expected posture of the robot arm according to the adjusted initial environment stiffness; wherein the expected trajectory generator adjusts the initial environment stiffness by the following formula: in, is the initial environment stiffness, is the ratio of the change in the actual contact force at the end of the manipulator to the change in the actual posture; the expected trajectory generator generates the expected posture of the manipulator according to the adjusted initial environmental stiffness through the following formula: in, is the environmental stiffness of the current sampling period, γ1 is the first positive scalar constant, γ2 is the second positive scalar constant, F p is the estimated contact force at the pth sampling period, f p is the actual contact force in the pth sampling period, x p is the actual position of the end of the robot arm in the pth sampling period, is the environmental position of the current sampling period, x e,0 is the initial environment position, is the environmental stiffness of the pth sampling period, is the environmental position of the pth sampling period, F k-1 is the estimated contact force in the previous sampling period, is the environmental stiffness of the previous sampling period, x k-1 The actual position of the end of the robot arm in the previous sampling period, is the environmental position of the previous sampling period, is the expected position of the end of the robot arm in the current sampling period, is the environmental position of the current sampling period, is the expected contact force in the current sampling period; An admittance controller, wherein the input end of the admittance controller is connected to the output end of the observer, and the admittance controller is used to adjust the admittance parameter of the admittance controller according to the oscillation amplitude parameter and the preset threshold value when the oscillation amplitude parameter is greater than the preset threshold value, and generate the posture deviation of the robot arm according to the adjusted admittance parameter; A motion controller, wherein the input end of the motion controller is respectively connected to the output end of the desired trajectory generator and the output end of the admittance controller, and the motion controller is used to control the robotic arm according to the posture deviation and the desired posture.

2. The adaptive admittance control system of the robot arm according to claim 1, characterized in that: The admittance parameter includes damping. Correspondingly, the admittance controller is specifically used to adjust the admittance parameter of the admittance controller through the following formula: Wherein, d(k) is the damping of the current sampling period, d(k-1) is the damping of the previous sampling period, and α is the coefficient corresponding to the admittance controller. is the oscillation amplitude parameter of the current sampling period, and ε is the preset threshold.

3. The adaptive admittance control system of the robot arm according to claim 2, characterized in that: The stable output value of the observer under a 1 Hz input signal is used as the preset threshold.

4. The adaptive admittance control system of a robot arm according to claim 2, characterized in that: The admittance controller is formed using the following formula: Where M, D, and K are the inertia, damping, and stiffness of the desired second-order system after being updated according to the adjusted admittance parameters, respectively. d is the expected contact force, F c is the actual contact force, x d is the desired position of the robot arm, x r is the reference pose of the robot arm, and E is the desired pose x of the robot arm. d With reference pose x r The posture deviation between them.

5. An adaptive admittance control method for a robotic arm, characterized in that: The following steps are involved: A contact force signal is received, and an oscillation amplitude parameter is generated according to the contact force signal, wherein the contact force signal is a signal acquired by collecting the contact force of the end of the robot arm; wherein the oscillation amplitude parameter is generated by the following formula: Among them, η is the smoothing coefficient, is the oscillation amplitude parameter of the previous sampling period, is the first ratio of the high-frequency component to the low-frequency component of the contact force signal in the current sampling period, is a second ratio of the standard deviation of the time domain signal of the contact force signal in the current sampling period when the windowing process is performed to the maximum allowable force, is the oscillation amplitude parameter of the current sampling period; When the oscillation amplitude parameter is greater than a preset threshold, the initial environment stiffness is adjusted, and the desired posture of the robot arm is generated according to the adjusted initial environment stiffness, and the admittance parameter of the admittance controller is adjusted according to the oscillation amplitude parameter and the preset threshold, and the posture deviation of the robot arm is generated according to the adjusted admittance parameter; wherein the initial environment stiffness is adjusted by the following formula: in, is the initial environment stiffness, is the ratio of the change in the actual contact force at the end of the robot arm to the change in the actual posture; the expected posture of the robot arm is generated by the following formula according to the adjusted initial environmental stiffness: in, is the environmental stiffness of the current sampling period, γ1 is the first positive scalar constant, γ2 is the second positive scalar constant, F p is the estimated contact force at the pth sampling period, f p is the actual contact force in the pth sampling period, x p is the actual position of the end of the robot arm in the pth sampling period, is the environmental position of the current sampling period, x e,0 is the initial environment position, is the environmental stiffness of the pth sampling period, is the environmental position of the pth sampling period, F k-1 is the estimated contact force in the previous sampling period, is the environmental stiffness of the previous sampling period, x k-1 The actual position of the end of the robot arm in the previous sampling period, is the environmental position of the previous sampling period, is the expected position of the end of the robot arm in the current sampling period, is the environmental position of the current sampling period, is the expected contact force in the current sampling period; The robot arm is controlled according to the posture deviation and the desired posture.

6. A robotic arm, characterized in that: An adaptive admittance control system comprising a robotic arm according to any one of claims 1-4.

7. A robot, characterized in that: Comprising a robotic arm according to claim 6.

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