Industrial robot, control method and device thereof, storage medium and program product

Abstract

The invention discloses a control method and device of an industrial robot, the industrial robot, a storage medium and a computer program product, and the method comprises the steps: designing an observer module, and arranging the observer module at a feedback part of a servo control system; under the condition that the industrial robot runs, observation is carried out through an observer module on the basis of a speed feedback signal of a servo motor and a torque feedback signal of a harmonic speed reducer, and a torque disturbance signal of the industrial robot is obtained; and the torque disturbance signal of the industrial robot is compensated to the torque control of the servo motor on the harmonic speed reducer so as to suppress the tail end vibration of the industrial robot. According to the scheme, the self-adaptive dimensionality reduction state observer is arranged in the feedback part of the servo control system of the industrial robot, the fluctuation torque signal observed by the self-adaptive dimensionality reduction state observer is compensated to the torque control of the servo motor on the harmonic speed reducer, vibration brought by the harmonic speed reducer is restrained, and the control precision of the industrial robot is improved. And dynamic performance of the industrial robot is provided.

Description

Technical Field

[0001] The present invention belongs to the technical field of industrial robots, and specifically relates to a control method, device, industrial robot, storage medium and computer program product for an industrial robot, and more particularly to a vibration suppression method, device, industrial robot, storage medium and computer program product for a servo control system of an industrial robot based on an adaptive dimensionality reduction state observer. Background Art

[0002] With the development of intelligent and industrial robotics technology, industrial robots have been widely used in industrial production, assembly, and other fields. High speed and high precision have always been crucial technical specifications for industrial robots. However, because industrial robot servo systems use harmonic reducers (such as harmonic drive reducers) to connect the motor and articulated arm to achieve deceleration and torque amplification, these harmonic reducers can cause vibration at the end of the industrial robot, affecting its dynamic performance.

[0003] The above content is only used to assist in understanding the technical solution of the present invention and does not constitute an admission that the above content is prior art. Summary of the Invention

[0004] The object of the present invention is to provide a control method, device, industrial robot, storage medium and computer program product for an industrial robot to solve the problem that the harmonic reducer of the industrial robot causes terminal vibration of the industrial robot and affects the dynamic performance of the industrial robot. By setting an adaptive dimensionality reduction state observer in the feedback part of the servo control system of the industrial robot, the fluctuating torque signal observed by the adaptive dimensionality reduction state observer is compensated to the control of the harmonic reducer by the servo motor, thereby suppressing the vibration caused by the harmonic reducer and improving the dynamic performance of the industrial robot.

[0005] The present invention provides a control method for an industrial robot, wherein the industrial robot has a servo motor, a harmonic reducer, and a servo control system. The control method for the industrial robot includes: designing an observer module; and arranging the observer module in a feedback part of the servo control system; when the industrial robot is running, obtaining a speed feedback signal of the servo motor and a torque feedback signal of the harmonic reducer; observing the speed feedback signal of the servo motor and the torque feedback signal of the harmonic reducer through the observer module to obtain a torque disturbance signal of the industrial robot; and compensating the torque disturbance signal of the industrial robot into the torque control of the servo motor on the harmonic reducer to suppress terminal vibration of the industrial robot.

[0006] In some embodiments, the observer module includes: a PI module and an integrator, and the PI module and the integrator are connected in series; wherein, the observer module is used to observe based on the speed feedback signal of the servo motor and the torque feedback signal of the harmonic reducer to obtain the torque disturbance signal of the industrial robot, including: performing PI processing based on the speed feedback signal of the servo motor and the difference between the estimated rotor speed of the servo motor through the PI module to obtain the estimated load torque of the industrial robot as the torque disturbance signal of the industrial robot; performing integrator processing based on the estimated load torque of the industrial robot and the torque feedback signal of the harmonic reducer through the integrator to obtain a new estimated rotor speed of the servo motor; performing PI processing again based on the speed feedback signal of the servo motor and the difference between the new estimated rotor speed of the servo motor through the PI module to obtain a new estimated load torque of the industrial robot as the new torque disturbance signal of the industrial robot; and repeating this cycle to obtain the dynamic estimated load torque of the industrial robot as the dynamic torque disturbance signal of the industrial robot.

[0007] In some embodiments, the expression of the observer module is as follows:

[0008]

[0009] Where d is the differential operator, t is the time, Estimated speed for the servo motor's rotor, is the estimated load torque of the harmonic reducer, B is the preset friction coefficient, J is the system moment of inertia of the servo control system, T e is the electromagnetic torque of the harmonic reducer, k1 is the proportional gain parameter of the observer module, k2 is the integral gain parameter of the observer module, ω m is the mechanical angular velocity of the rotor of the servo motor, Estimate a speed for the rotor of the servo motor.

[0010] In some embodiments, in the expression of the observer module, k1 and k2 are calculated using the gradient descent method, and the expressions of k1 and k2 are as follows:

[0011]

[0012] Among them, ω c is the cutoff frequency of the observer module, and δ is the stability margin of the observer module.

[0013] In some embodiments, the servo control system includes: a position regulator, a speed regulator and a current regulator; wherein, the position regulator is located in the speed loop of the servo control system; the speed regulator and the current regulator are located in the current loop of the servo control system; the output signal of the current regulator can control the action of the servo motor; the observer module is set in the feedback part of the servo control system, including: in the feedback part of the servo control system, according to the torque disturbance signal of the industrial robot output by the observer module and the output signal of the servo motor, the action of the harmonic reducer is controlled.

[0014] In some embodiments, the torque disturbance signal of the industrial robot is compensated into the torque control of the harmonic reducer by the servo motor to suppress the terminal vibration of the industrial robot, including: performing position adjustment by the position regulator based on the position command signal of the servo motor sent by the host computer and the difference between the position feedback signal of the servo motor to obtain the speed command signal of the servo motor; performing speed adjustment by the speed regulator based on the speed command signal of the servo motor and the speed feedback signal of the servo motor to obtain the current command signal of the servo motor; controlling the operation of the servo motor based on the current command signal of the servo motor by the current regulator; when the servo motor is running, the torque command signal of the servo motor can be obtained; in the feedback part of the servo control system, the torque disturbance signal of the industrial robot is obtained by the observer module; performing torque control on the harmonic reducer based on the difference between the torque command signal of the servo motor and the torque disturbance signal of the industrial robot to suppress the terminal vibration of the industrial robot.

[0015] Matching the above method, the present invention provides, on the other hand, a control device for an industrial robot, the industrial robot having a servo motor, a harmonic reducer, and a servo control system; the control device for the industrial robot comprises: a control unit configured to design an observer module; and setting the observer module in the feedback part of the servo control system; an acquisition unit configured to acquire the speed feedback signal of the servo motor and the torque feedback signal of the harmonic reducer when the industrial robot is running; the control unit is further configured to observe based on the speed feedback signal of the servo motor and the torque feedback signal of the harmonic reducer through the observer module to obtain the torque disturbance signal of the industrial robot; the control unit is further configured to compensate the torque disturbance signal of the industrial robot into the torque control of the servo motor on the harmonic reducer to suppress the terminal vibration of the industrial robot.

[0016] In some embodiments, the observer module includes: a PI module and an integrator, and the PI module and the integrator are connected in series; wherein the control unit, through the observer module, observes based on the speed feedback signal of the servo motor and the torque feedback signal of the harmonic reducer to obtain the torque disturbance signal of the industrial robot, including: through the PI module, performing PI processing based on the speed feedback signal of the servo motor and the difference between the estimated rotor speed of the servo motor to obtain the estimated load torque of the industrial robot as the torque disturbance signal of the industrial robot; through the integrator, performing integrator processing based on the estimated load torque of the industrial robot and the torque feedback signal of the harmonic reducer to obtain a new estimated rotor speed of the servo motor; again through the PI module, performing PI processing based on the speed feedback signal of the servo motor and the difference between the new estimated rotor speed of the servo motor to obtain a new estimated load torque of the industrial robot as the new torque disturbance signal of the industrial robot; and repeating this cycle to obtain the dynamic estimated load torque of the industrial robot as the dynamic torque disturbance signal of the industrial robot.

[0017] In some embodiments, the expression of the observer module is as follows:

[0018]

[0019] Where d is the differential operator, t is the time, Estimated speed for the servo motor's rotor, is the estimated load torque of the harmonic reducer, B is the preset friction coefficient, J is the system moment of inertia of the servo control system, T e is the electromagnetic torque of the harmonic reducer, k1 is the proportional gain parameter of the observer module, k2 is the integral gain parameter of the observer module, ω m is the mechanical angular velocity of the rotor of the servo motor, Estimate a speed for the rotor of the servo motor.

[0020] In some embodiments, in the expression of the observer module, k1 and k2 are calculated using the gradient descent method, and the expressions of k1 and k2 are as follows:

[0021]

[0022] Among them, ω c is the cutoff frequency of the observer module, and δ is the stability margin of the observer module.

[0023] In some embodiments, the servo control system includes: a position regulator, a speed regulator and a current regulator; wherein, the position regulator is located in the speed loop of the servo control system; the speed regulator and the current regulator are located in the current loop of the servo control system; the output signal of the current regulator can control the action of the servo motor; the control unit sets the observer module in the feedback part of the servo control system, including: in the feedback part of the servo control system, according to the torque disturbance signal of the industrial robot output by the observer module and the output signal of the servo motor, controlling the action of the harmonic reducer.

[0024] In some embodiments, the control unit compensates the torque disturbance signal of the industrial robot into the torque control of the harmonic reducer by the servo motor to suppress the terminal vibration of the industrial robot, including: performing position adjustment based on the position command signal of the servo motor sent by the host computer and the difference between the position feedback signal of the servo motor through the position regulator to obtain the speed command signal of the servo motor; performing speed adjustment based on the speed command signal of the servo motor and the speed feedback signal of the servo motor through the speed regulator to obtain the current command signal of the servo motor; controlling the operation of the servo motor based on the current command signal of the servo motor through the current regulator; when the servo motor is running, the torque command signal of the servo motor can be obtained; in the feedback part of the servo control system, the torque disturbance signal of the industrial robot is obtained through the observer module; and performing torque control on the harmonic reducer based on the difference between the torque command signal of the servo motor and the torque disturbance signal of the industrial robot to suppress the terminal vibration of the industrial robot.

[0025] Matching the above device, the present invention further provides an industrial robot, comprising: the control device of the industrial robot described above.

[0026] In accordance with the above method, the present invention further provides a storage medium, which includes a stored program, wherein when the program is running, the device where the storage medium is located is controlled to execute the steps of the above-mentioned industrial robot control method.

[0027] In accordance with the above method, the present invention further provides a computer program product, comprising a computer program, which implements the steps of the above method for controlling an industrial robot when executed by a processor.

[0028] Therefore, the solution of the present invention is to design an adaptive dimensionality reduction state observer for the two vibrations caused by the harmonic reducer in the industrial robot (i.e., the terminal vibration caused by the harmonic reducer of the industrial robot, and the resonance that occurs when the natural vibration frequency of the harmonic reducer is close to the natural vibration frequency of the industrial robot); the adaptive dimensionality reduction state observer is added to the feedback part of the servo control system of the industrial robot, and the fluctuating torque signal output by the adaptive dimensionality reduction state observer is compensated to the torque instruction of the servo motor in the servo control system to control the harmonic reducer, so as to suppress the two vibrations caused by the harmonic reducer; thus, by setting the adaptive dimensionality reduction state observer in the feedback part of the servo control system of the industrial robot, the fluctuating torque signal observed by the adaptive dimensionality reduction state observer is compensated to the control of the harmonic reducer by the servo motor, thereby suppressing the vibration caused by the harmonic reducer and improving the dynamic performance of the industrial robot.

[0029] Other features and advantages of the present invention will be set forth in the description which follows, and in part will be obvious from the description, or may be learned by practice of the present invention.

[0030] The technical solution of the present invention is further described in detail below through the accompanying drawings and embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 1. A flow chart of an embodiment of a method for controlling an industrial robot according to the present invention;

[0032] Figure 2 1 is a flow chart of an embodiment of obtaining the torque disturbance signal of the industrial robot by the observer module in the method of the present invention;

[0033] Figure 3 1. A flow chart of an embodiment of the method of the present invention for compensating the torque disturbance signal of the industrial robot into the control of the harmonic reducer by the servo motor;

[0034] Figure 4 1 is a schematic structural diagram of an embodiment of a control device for an industrial robot according to the present invention;

[0035] Figure 5 Schematic diagram of a flow chart of a vibration suppression method based on an adaptive dimensionality reduction state observer of the present invention;

[0036] Figure 6 This is a schematic structural diagram of a vibration suppression structure of a servo control system of an industrial robot according to the present invention;

[0037] Figure 7 Schematic diagram of torque fluctuation simulation observed by the torque observer;

[0038] Figure 8Schematic diagram of the torque observer.

[0039] In conjunction with the accompanying drawings, the reference numerals in the embodiments of the present invention are as follows:

[0040] 102 - acquisition unit; 104 - control unit. DETAILED DESCRIPTION

[0041] To make the objectives, technical solutions, and advantages of the present invention more clear, the technical solutions of the present invention will be clearly and completely described below in conjunction with specific embodiments of the present invention and corresponding drawings. Obviously, the embodiments described are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0042] Considering that harmonic reducers for industrial robots can cause vibration at the end of the robot, affecting its dynamic performance. Due to the unique dual-wave transmission characteristics of harmonic reducers, the flexible gears in the harmonic reducer undergo two meshing processes within a complete rotation cycle. This results in even-multiple frequency components in the output speed. The harmonic reducer generates even-multiple frequency fluctuations in the industrial robot's speed, causing vibration at the end of the industrial robot, affecting the accuracy of the robot's trajectory. Furthermore, the assembly process of harmonic reducers for industrial robots requires high precision. During operation, the periodic meshing of the flexible gear teeth and the rigid gear teeth inevitably generates vibration. When the harmonic reducer speed reaches a certain speed range, the natural vibration frequency of the harmonic reducer approaches that of the industrial robot, causing resonance, which increases the vibration amplitude and causes jitter at the end of the industrial robot, seriously affecting the accuracy of the industrial robot's movement.

[0043] In related solutions, since the terminal vibration caused by the harmonic reducer of the industrial robot cannot be avoided, the design of the flexible gear is often improved to reduce the nonlinear effect of its deformation, or a servo compensation link is added to suppress the vibration.

[0044] Some proposals have revealed an optimized drive structure for industrial robot joints, reducing the weight at the joint end and mitigating the speed fluctuations caused by the harmonic reducer. However, this approach complicates the industrial robot's transmission structure, reduces the drive's control efficiency over the joint arm, and does not completely eliminate the vibrations introduced by the harmonic reducer.

[0045] Other proposals disclose a vibration suppression method and device, a servo drive, and a servo drive system. A current compensation value is determined based on the position difference between the servo motor's rotor position feedback value and the position command. A current regulator controls the servo motor based on the current compensation value, the current feedback value, and the current command to suppress the resonance caused by the harmonic reducer. This approach uses differential calculation of the current compensation value, which produces a certain amount of hysteresis and only suppresses the resonance caused by the harmonic reducer. It does not suppress even-harmonic frequency vibrations caused by the harmonic reducer's dual-wave transmission characteristics.

[0046] Other proposals disclose an anti-interference control method for a harmonic reducer-driven frame system. First, a mathematical model is used to estimate the high-frequency vibration caused by rotor dynamic imbalance in real time. An extended state observer is then designed to estimate the total interference of the harmonic reducer's transmission torque on the drive motor in real time. A backstepping controller is then designed to compensate for and suppress multi-source interference. This method uses an extended observer to observe various interferences and perform multi-band vibration suppression. However, it fails to consider that the even-multiple vibration frequencies generated by the harmonic reducer due to speed changes also change in real time, making effective suppression difficult.

[0047] In related solutions, there are three main methods for suppressing vibrations in industrial robot transmission structures, particularly those caused by harmonic reducers. The first method involves optimizing the joint connection structure to avoid or reduce structurally related vibrations. The second method involves compensating for vibrations based on sensor feedback current or velocity deviation. The third method involves designing an observer to observe various vibration signals to compensate for, reduce, or even eliminate, industrial robot vibrations caused by interference signals. The first method requires modifying the industrial robot structure, resulting in complex design and high assembly requirements. Furthermore, it can only suppress or eliminate a single vibration and cannot completely eliminate the interference vibrations caused by harmonic reducers. The second method is simple to design but suffers from significant hysteresis and cannot effectively compensate for interference fluctuations in torque or current signals. The third method uses an observer to observe the vibration signal, but often uses multiple observers based on a comprehensive observation of the interference signal. This method fails to consider that changes in the interference source can increase the observation error of the original observer, affecting the vibration suppression effectiveness of the servo controller.

[0048] Therefore, the solution of the present invention proposes a control method for an industrial robot, specifically a vibration suppression method based on an adaptive dimensionality reduction state observer. The two vibrations caused by the harmonic reducer in the industrial robot are analyzed, and an adaptive dimensionality reduction state observer is designed as a torque observer. After observing the two vibrations caused by the harmonic reducer in the industrial robot through the torque observer, the vibration signal is reversely compensated to the servo control system, which can effectively suppress the vibration caused by the harmonic reducer and improve the dynamic performance of the industrial robot.

[0049] In a servo system, the output end of the servo motor is connected to the load through a transmission device - a harmonic reducer and drives it. The industrial robot servo system receives the position command of the host computer and outputs a control signal to drive the load movement. Because the harmonic reducer as a transmission device in the industrial robot has a low-frequency vibration natural frequency due to assembly reasons, when the operating frequency of the motor is the same as the natural frequency of the harmonic reducer, the servo motor and the harmonic reducer will resonate. At the same time, this vibration will be transmitted to the connected industrial robot load end, causing the vibration and dynamic performance of the industrial robot end to decline. In addition, due to the unique double-wave transmission characteristics of the harmonic reducer, the flexible gear will undergo two meshing processes in a complete rotation cycle. The harmonic reducer generates even-multiple frequency fluctuations in the industrial robot speed, causing vibration at the industrial robot end and affecting the dynamic performance of the industrial robot. The solution of the present invention proposes a vibration suppression solution for an industrial robot servo control system based on an adaptive dimensionality reduction state observer. The main effect achieved is to solve the industrial robot end vibration caused by the harmonic reducer structure in the related solution and improve the dynamic performance of the industrial robot.

[0050] According to an embodiment of the present invention, a control method for an industrial robot is provided. Figure 1 The industrial robot has a servo motor, a harmonic reducer, and a servo control system; in the solution of the present invention, as shown in FIG. Figure 1 As shown, the control method of the industrial robot includes: steps S110 to S140.

[0051] In step S110 , an observer module, such as an adaptive dimensionality reduction state observer, is designed in advance; and the observer module is set in the feedback part of the servo control system.

[0052] In step S120 , when the industrial robot is running, a speed feedback signal of the servo motor is obtained, and a torque feedback signal of the harmonic reducer is obtained.

[0053] In step S130 , the observer module observes the speed feedback signal of the servo motor and the torque feedback signal of the harmonic reducer to obtain a torque disturbance signal of the industrial robot.

[0054] At step S140, the torque disturbance signal of the industrial robot is compensated into the torque control of the harmonic reducer by the servo motor to suppress the terminal vibration of the industrial robot, that is, to suppress the vibration caused by the harmonic reducer and improve the dynamic performance of the industrial robot.

[0055] The solution of the present invention aims at the industrial robot vibration caused by interference in the transmission structure of the industrial robot, proposes a vibration suppression scheme based on an adaptive dimensionality reduction state observer for the servo control system of the industrial robot, analyzes the two vibrations caused by the harmonic reducer in the industrial robot, and designs an adaptive dimensionality reduction state observer as a torque observer; a torque observer is added to the servo control system of the industrial robot, and the observation value of the adaptive dimensionality reduction state observer can better fit the real disturbance waveform, significantly improve the dynamic performance of the industrial robot, and can specifically suppress the even-multiple frequency vibration and resonance caused by the harmonic reducer in the transmission structure of the industrial robot, thereby improving the control accuracy of the servo controller over the industrial robot. The solution has strong engineering practicality, flexible structure, and strong anti-interference ability.

[0056] Figure 5 The figure is a flow chart of a vibration suppression method based on an adaptive dimensionality reduction state observer of the present invention. The solution of the present invention suppresses the vibration of the industrial robot terminal from the harmonic reducer by designing an adaptive dimensionality reduction state observer and adding it to the servo control system, effectively improving the dynamic performance of the industrial robot. The adaptive adjustment observer can adapt to various operating environments and has better stability. The vibration suppression flow chart is shown in FIG. Figure 5 As shown. It should be noted that the solution of the present invention is not only applicable to the vibration caused by the harmonic reducer in the industrial robot, but the vibration caused by other interference sources can also be suppressed by the solution of the present invention and the servo system. In principle, the vibration observed by the adaptive dimensionality reduction state observer designed by the solution of the present invention is not only the vibration caused by the harmonic reducer, but also the vibration caused by various possible interference sources of the industrial robot. It is just that the vibration caused by the harmonic reducer is specially processed for adaptive adjustment; therefore, for other vibrations, the adaptive dimensionality reduction state observer designed by the solution of the present invention can also observe and feedback to the servo control system for suppression.

[0057] In the solution of the present invention, the adaptability is reflected in the use of the gradient descent method to update the state observer parameters of the system according to the speed, etc., so as to suppress the even-multiple frequency fluctuations of the speed in the harmonic reducer and improve the dynamic performance and stability of the industrial robot. Other vibrations include mechanical resonance generated when the operating frequency of the robot system is close to its natural frequency; robot vibration caused by external interference such as load transformation; the adaptive dimensionality reduction state observer in the solution of the present invention estimates the actual torque of the motor in real time; and feeds back the estimated value of the actual torque of the motor to the control system, which can help adjust the driving torque of the motor to avoid entering the resonant frequency range, thereby reducing the vibration caused by it. The torque observer can estimate the impact of external disturbances on the motor torque. By monitoring the torque changes in real time, it can detect the changes in external disturbances and feedback compensation to the torque control in real time to offset the impact of external disturbances and reduce its vibration.

[0058] In some implementations, the observer module includes a PI module and an integrator, and the PI module and the integrator are connected in series.

[0059] Among them, in step S130, the specific process of obtaining the torque disturbance signal of the industrial robot by observing the speed feedback signal of the servo motor and the torque feedback signal of the harmonic reducer through the observer module is described in the following exemplary embodiment.

[0060] The following combination Figure 2 The flowchart of an embodiment of obtaining the torque disturbance signal of the industrial robot through the observer module in the method of the present invention further illustrates the specific process of obtaining the torque disturbance signal of the industrial robot through the observer module in step S130, including: steps S210 to S240.

[0061] In step S210 , the PI module performs PI processing based on the speed feedback signal of the servo motor and the difference between the estimated rotor speeds of the servo motor to obtain the estimated load torque of the industrial robot as the torque disturbance signal of the industrial robot.

[0062] In step S220 , the integrator performs integrator processing based on the estimated load torque of the industrial robot and the torque feedback signal of the harmonic reducer to obtain a new estimated rotor speed of the servo motor.

[0063] In step S230, the PI module is used to perform PI processing again based on the speed feedback signal of the servo motor and the difference between the new estimated rotor speed of the servo motor to obtain a new estimated load torque of the industrial robot as a new torque disturbance signal of the industrial robot.

[0064] In step S240 , the estimated load torque of the dynamic industrial robot is obtained by looping as a torque disturbance signal of the dynamic industrial robot.

[0065] An adaptive state observer is an observer that can estimate the state online and automatically adjust its parameters. The observer designed in the solution of the present invention is composed of a PI link and an integrator connected in series. Figure 8 Schematic diagram of the torque observer.

[0066] like Figure 8 As shown, the rotor mechanical angular velocity ω m , and the estimated rotor speed at the previous moment After the comparator, the speed difference is obtained; the speed difference is passed through the k1J module to obtain the first processed value, and the speed difference is passed through the k1 / s module to obtain the second processed value; the first processed value and the second processed value are passed through the comparator to obtain the estimated load torque The estimated load torque Electromagnetic torque T e The torque difference is obtained after the comparator; the torque difference is obtained after the 1 / (sJ+B) module to obtain the current rotor estimated speed

[0067] The solution of the present invention proposes a vibration suppression scheme for a servo control system of an industrial robot based on an adaptive dimensionality reduction state observer. The scheme analyzes the two vibrations caused by the harmonic reducer in the industrial robot and designs a dimensionality reduction state observer to suppress the two vibrations of the industrial robot, thereby reducing computational complexity. In addition, the solution of the present invention does not require external sensors, reducing costs and simplifying the design.

[0068] Considering that the even-harmonic frequency vibration of the harmonic reducer is difficult to effectively observe using a single observer, the solution of the present invention adds a nonlinear optimization-gradient descent method to tune the observer. This allows the adaptive observer to adjust the optimal state observer parameters according to dynamic parameters such as speed, thereby obtaining a more realistic disturbance signal. In this way, the servo control system can effectively suppress the vibration of the industrial robot caused by the harmonic reducer, improve the accuracy and reliability of the industrial robot's operation, and extend the life of the industrial robot.

[0069] The shaper method used in related solutions can only suppress vibrations with known amplitudes and periods, and different trajectory protocols require readjustment of the shaper. The solution of the present invention uses an observer to observe the vibration signal in real time, thereby compensating the servo control system. It has strong adaptability and has a good vibration suppression effect for different trajectories and even working conditions, thereby enhancing the robustness and efficiency of the industrial robot.

[0070] In some embodiments, the expression of the observer module is as follows:

[0071]

[0072] Where d is the differential operator, t is the time, Estimated speed for the servo motor's rotor, is the estimated load torque of the harmonic reducer, B is the preset friction coefficient, J is the system moment of inertia of the servo control system, T e is the electromagnetic torque of the harmonic reducer, k1 is the proportional gain parameter of the observer module, k2 is the integral gain parameter of the observer module, ω m is the mechanical angular velocity of the rotor of the servo motor, Estimate a speed for the rotor of the servo motor.

[0073] In the solution of the present invention, the adaptive observer used in the servo system is a reduced-dimensional torque state observer based on nonlinear optimization. First, the reduced-dimensional torque observer is designed. According to the principle of dynamics, the mechanical motion equation of the motor can be obtained as follows:

[0074]

[0075] Where, J is the system moment of inertia; T e is the electromagnetic torque; ω m is the rotor mechanical angular velocity; B is the friction coefficient; θ m is the mechanical angle; T L is the load torque; d is the differential operator; t is the time.

[0076] The controller sampling period is at the microsecond level, and it can be approximately considered that the load torque T in one sampling period is L is a constant value, so the torque observer can be constructed as follows:

[0077]

[0078] Where k1 and k2 are the proportional and integral gain parameters of the designed observer, Estimated speed for the servo motor's rotor, To estimate the load torque, d is the differential operator, and the load torque can be obtained by simplification: The estimated equation is:

[0079]

[0080] Where s is a complex frequency variable.

[0081] In the solution of the present invention, a torque observer is added to the servo control system of the industrial robot. This torque observer observes the resonance between the harmonic reducer and the natural frequency of the industrial robot and then reverse-compensates the vibration signal to the servo control system. Furthermore, because the harmonic reducer generates vibration signals with even-multiple speed frequencies due to its dual-wave transmission characteristics, the torque observer in the servo control system of the industrial robot obtains its optimal parameters using a nonlinear optimization-gradient descent method. This solution provides better observation of the varying harmonic reducer disturbances, effectively suppressing the vibrations caused by the harmonic reducer and improving the dynamic performance of the industrial robot.

[0082] In some embodiments, in the expression of the observer module, k1 and k2 are calculated using the gradient descent method, and the expressions of k1 and k2 are as follows:

[0083]

[0084] Among them, ω c is the cutoff frequency of the observer module, δ is the stability margin of the observer module, k1 is the proportional gain parameter of the observer module, k2 is the integral gain parameter of the observer module, and J is the system moment of inertia of the servo control system.

[0085] In the solution of the present invention, the observer parameters k1 and k2 shown in formula (3) or formula (4) are calculated as follows:

[0086]

[0087] Where, ω c is the cutoff frequency of the load torque observer; δ is the stability margin of the load torque observer; J is the system moment of inertia.

[0088] Figure 7 The load torque observer is designed, and the simulation verifies the accuracy of the torque fluctuation observation caused by the harmonic reducer. Figure 7 As shown, Figure 7 The meanings of the curves in the upper right corner are, from top to bottom, the simulation diagram of the real torque, the simulation diagram of the real torque fluctuation observed when the load torque observer gain k1 = 1500, the simulation diagram of the real torque fluctuation observed when the load torque observer gain k1 = 3000, the simulation diagram of the real torque fluctuation observed when the load torque observer gain k1 = 5000, and the simulation diagram of the real torque fluctuation observed when the load torque observer gain k1 = 10000. Figure 7 The simulation diagram of the real torque fluctuation observed when the load torque observer gain k1 is displayed shows that the larger the load torque observer gain k1, the better the torque fluctuation observed by the load torque observer follows; but if the gain is too high, high-frequency interference will appear in the observation signal, and after compensating it into the servo motor control torque, new vibration will be introduced. Therefore, it is necessary to set a suitable observer parameter to suppress the vibration. At the same time, because the harmonic reducer has not only the resonance of the natural frequency, but also the even-multiple frequency fluctuation that changes with the motor speed, different frequency speed wave signals require different observer gain parameters k1. Therefore, the gradient descent method is used to enable the observer to obtain the optimal observer gain corresponding to the motor speed, so as to suppress the even-multiple frequency fluctuation of the speed in the harmonic reducer and improve the dynamic performance of the industrial robot. The core parameter update formula of the gradient descent method is:

[0089]

[0090] Where, β t and β t-1are the parameters of the current moment and the parameters of the previous moment, i.e., the observer gain k1 and speed; η is the learning rate, i.e., the step size of the control update, ▽f(β t-1 ) is the gradient of the observer torque error at the previous moment (i.e., the partial derivative vector).

[0091] The steps to design the adaptive parameter adaptation of the adaptive dimensionality reduction state observer are as follows:

[0092] Step 1: Initialization, input motor parameters and initial speed, and get initial parameter β t-1 , and connect the observer to the servo control.

[0093] Step 2: Calculate the gradient. After the industrial robot starts running, calculate the gradient of the vibration error of the industrial robot terminal at the previous parameter ▽f(β t-1 ).

[0094] Step 3: Update the parameters and use formula (6) to get the new parameter β t Update the observer parameters again.

[0095] Step 4: Repeat steps 2 and 3 to make the torque fluctuation observed by the observer close to the industrial robot terminal vibration caused by the harmonic reducer. The obtained observer is as follows: Figure 8 shown.

[0096] In the solution of the present invention, the adaptive dimensionality reduction state observer after the above-mentioned nonlinear optimization is connected to the servo control system, and the torque fluctuation error observed by the compensation observer is compensated, so that the two vibrations caused by the harmonic reducer can be eliminated. The compensation effect is independently controllable and not affected by other regulator parameters. It is easy to implement and greatly improves the dynamic performance of the industrial robot servo control system.

[0097] In some embodiments, the servo control system includes: a position regulator, a speed regulator, and a current regulator.

[0098] Wherein, the position regulator is located in the speed loop of the servo control system; the speed regulator and the current regulator are located in the current loop of the servo control system; the output signal of the current regulator can control the action of the servo motor.

[0099] In step S110, the observer module is set in the feedback part of the servo control system, including: in the feedback part of the servo control system, the action of the harmonic reducer is controlled according to the torque disturbance signal of the industrial robot output by the observer module and the output signal of the servo motor.

[0100] Figure 6 Schematic diagram of the structure of the servo control system of the industrial robot of the present invention to suppress vibration. Figure 6 As shown in the figure, the difference between the position command issued by the host computer and the position feedback of the servo motor is obtained through a comparator, and then the speed command is obtained through the position regulator. The difference between the speed command and the speed feedback of the servo motor is obtained through a comparator, and then the current command is obtained through the speed regulator. The current command is output to the current regulator after the comparator, and the current regulator adjusts the current of the servo motor. The adaptive state observer outputs a torque disturbance signal based on the speed feedback of the servo motor and the torque fluctuation of the harmonic reducer. The difference between the torque command output by the servo motor and the torque disturbance signal output by the adaptive state observer is output to the harmonic reducer after a comparator, and then the difference is output to the harmonic reducer, which controls the end load. Among them, there is a direct relationship between current and torque, and the torque fluctuation of the harmonic reducer will be fed back into the current signal. By processing the feedback current fluctuation signal, the torque disturbance signal can be obtained.

[0101] In the above embodiment, an adaptive dimensionality reduction state observer method is incorporated into the industrial robot servo control system to suppress two types of vibrations caused by the harmonic reducer in the industrial robot servo motor drive. The above embodiment addresses the suppression of vibrations caused by the harmonic reducer in the industrial robot, and this design can also be used to suppress other vibrations of the industrial robot. The above embodiment can also observe the system torque disturbance caused by other similar vibration sources of the industrial robot and feed back the torque fluctuations into the servo system control to suppress vibrations, thereby reducing the vibration of the industrial robot terminal and improving the dynamic performance of the industrial robot.

[0102] In the above-mentioned embodiments, the servo motor output command, speed feedback, position feedback signal, and torque disturbance signal output by the observer may contain high-frequency disturbance noise when connected to the servo system. These signals can be filtered, including but not limited to low-pass or band-pass filters. The use of a low-pass filter is simple in design and can effectively filter out high-frequency noise in the signal, making the system response smoother and improving the reliability and dynamic performance of the system. The use of a band-pass filter can specifically remove high-frequency noise in the signal, reducing the impact on the useful signal compared to a low-pass filter, increasing the accuracy of the servo control signal, and enhancing the reliability of the system.

[0103] In some embodiments, in step S140, the torque disturbance signal of the industrial robot is compensated into the torque control of the harmonic reducer by the servo motor to suppress the terminal vibration of the industrial robot. For the specific process, see the following exemplary description.

[0104] The following combination Figure 3The flowchart of an embodiment of the method of the present invention in which the torque disturbance signal of the industrial robot is compensated into the control of the harmonic reducer by the servo motor is shown, further illustrating the specific process of compensating the torque disturbance signal of the industrial robot into the control of the harmonic reducer by the servo motor in step S140, including: steps S310 to S340.

[0105] In step S310 , the position regulator performs position adjustment based on the position command signal of the servo motor sent by the host computer and the difference between the position feedback signal of the servo motor to obtain a speed command signal of the servo motor.

[0106] Step S320 : performing speed regulation based on the speed command signal of the servo motor and the speed feedback signal of the servo motor by the speed regulator to obtain a current command signal of the servo motor.

[0107] In step S330 , the servo motor is controlled to operate based on the current command signal of the servo motor through the current regulator; when the servo motor is operating, a torque command signal of the servo motor can be obtained.

[0108] In step S340, in the feedback part of the servo control system, the torque disturbance signal of the industrial robot is obtained through the observer module; based on the difference between the torque command signal of the servo motor and the torque disturbance signal of the industrial robot, the torque of the harmonic reducer is controlled to suppress the terminal vibration of the industrial robot.

[0109] like Figure 5 As shown in Figure 2, the specific implementation process of a vibration suppression method based on an adaptive dimensionality reduction state observer is as follows:

[0110] Step S1: The servo control system of the industrial robot receives a position command from the host computer. The servo control system drives the end-user of the industrial robot by controlling a motor with a harmonic reducer. The rotor inside the servo motor is a permanent magnet. The three-phase power controlled by the servo driver in the servo control system of the industrial robot forms an electromagnetic field. This magnetic field rotates the servo motor's rotor. Simultaneously, the servo motor's built-in encoder measures the rotor's position and generates a feedback signal to the servo control system of the industrial robot.

[0111] In step S2, during the servo motor control process, in addition to sending a torque control signal to the transmission device - harmonic reducer, the servo motor will also use the encoder to feedback the position and speed of the motor in order to more accurately control the motion state of the end of the industrial robot. The position feedback is subtracted from the position instruction of the host computer and sent to the position regulator in the servo system, while the speed feedback is subtracted from the speed instruction output by the position regulator and then sent to the speed regulator. After receiving the current instruction issued by the speed regulator after the combined effect of the instruction and feedback, the current regulator outputs torque / current to the servo motor. The servo motor ultimately controls the movement of the end of the industrial robot through the transmission device harmonic reducer, where the harmonic reducer plays the role of amplifying torque and deceleration, such as Figure 6 The command, feedback and torque control parts of the servo control system.

[0112] Step S3, when the industrial robot terminal is operating under the control of the servo control system described above, the output end of the servo motor is connected to the terminal through the transmission device-harmonic reducer and driven, because the control system driven by the harmonic reducer will produce two parts of industrial robot vibration: 1) One part of the vibration is because there is a natural frequency of low-frequency vibration in the assembly process of the industrial robot. When the operating frequency of the motor is the same as the natural frequency of the harmonic reducer, the servo motor and the harmonic reducer will resonate. 2) In addition, due to the unique double-wave transmission characteristics of the harmonic reducer, the flexible gear will undergo two meshing processes in a complete rotation cycle, which causes the output speed to fluctuate with an even multiple of the frequency, causing the industrial robot to vibrate. Both parts of the vibration signal will be transmitted to the connected industrial robot terminal. If the industrial robot is controlled by relying solely on the control part described in step 2 above, it will be impossible to effectively eliminate the vibration caused by the two parts of the harmonic reducer, which will cause vibration at the industrial robot terminal and affect the dynamic performance of the industrial robot.

[0113] In response to these two parts of vibration, the solution of the present invention adds an adaptive dimensionality reduction state observer module to the feedback part of the servo control system; the state observer in the related solution only performs overall state observation on the interference in the servo motor of the industrial robot, and there are few studies that analyze the source of vibration interference and design state observers. Some studies have analyzed the vibration in the harmonic reducer, but they all classify it as a type of vibration, ignoring the fluctuation of the even-multiple frequency of the speed caused by the double-wave characteristics of the harmonic reducer. Therefore, most of them believe that their vibrations are single-frequency fluctuations, and use a single state observer to observe the error, without considering that the error vibration frequency will change with the change of the motor speed, and cannot effectively suppress the vibration caused by the harmonic reducer; therefore, it is necessary to design an adaptive dimensionality reduction state observer and add it to the servo control system, and its output fluctuating torque signal is compensated to the servo motor to control the harmonic reducer to suppress the two vibrations caused by the harmonic reducer, such as Figure 6 shown.

[0114] Step S4: The adaptive observer used in the servo system in the solution of the present invention is a dimension-reduced torque state observer based on nonlinear optimization.

[0115] In the solution of the present invention, the designed adaptive dimensionality reduction state observer can be applied to the servo control system described in the solution of the present invention, and can also be used for other industrial robot servo motor control systems with harmonic reducers. The source of vibration is resonance and even-multiple frequency fluctuations of speed, and the vibration suppression method is an adaptive dimensionality reduction state observer. The solution of the present invention designs a servo control system for an industrial robot, and designs a more effective adaptive state observer in the servo control system of the industrial robot for the even-multiple frequency vibration and resonance brought by the harmonic reducer of the industrial robot. The solution has strong engineering practicality, high reliability and stability. The designed dimensionality reduction observer has a simple structure and strong adaptability, and can well observe the torque fluctuations in the control system. The adaptive observer designed by the gradient descent method can well suppress the even-multiple frequency fluctuations in the harmonic reducer that change with speed, thereby greatly improving the dynamic performance of the servo controller for the industrial robot.

[0116] By adopting the technical solution of this embodiment, an adaptive dimensionality reduction state observer is designed for the two vibrations caused by the harmonic reducer in the industrial robot (i.e., the terminal vibration caused by the harmonic reducer of the industrial robot, and the resonance that occurs when the natural vibration frequency of the harmonic reducer is close to the natural vibration frequency of the industrial robot); the adaptive dimensionality reduction state observer is added to the feedback part of the servo control system of the industrial robot, and the fluctuating torque signal output by the adaptive dimensionality reduction state observer is compensated to the torque instruction of the servo motor in the servo control system to control the harmonic reducer, so as to suppress the two vibrations caused by the harmonic reducer; thus, by setting the adaptive dimensionality reduction state observer in the feedback part of the servo control system of the industrial robot, the fluctuating torque signal observed by the adaptive dimensionality reduction state observer is compensated to the control of the harmonic reducer by the servo motor, thereby suppressing the vibration caused by the harmonic reducer and improving the dynamic performance of the industrial robot.

[0117] According to an embodiment of the present invention, a control device for an industrial robot corresponding to the control method for the industrial robot is also provided. Figure 4 The schematic diagram of the structure of an embodiment of the device of the present invention is shown in FIG. The industrial robot has a servo motor, a harmonic reducer, and a servo control system; in the solution of the present invention, as Figure 4 As shown, the control device of the industrial robot includes: an acquisition unit 102 and a control unit 104.

[0118] The control unit 104 is configured to pre-design an observer module, such as an adaptive dimensionality reduction state observer, and place the observer module in the feedback portion of the servo control system. The specific functions and processing of the control unit 104 are described in step S110.

[0119] The acquisition unit 102 is configured to acquire the speed feedback signal of the servo motor and the torque feedback signal of the harmonic reducer when the industrial robot is running. The specific functions and processing of the acquisition unit 102 are shown in step S120.

[0120] The control unit 104 is further configured to observe, through the observer module, the speed feedback signal of the servo motor and the torque feedback signal of the harmonic reducer to obtain a torque disturbance signal of the industrial robot. The specific functions and processing of the control unit 104 are further described in step S130.

[0121] The control unit 104 is further configured to compensate the torque disturbance signal of the industrial robot for the torque control of the harmonic reducer by the servo motor, thereby suppressing the vibration of the terminal of the industrial robot, that is, suppressing the vibration caused by the harmonic reducer, and improving the dynamic performance of the industrial robot. The specific functions and processing of the control unit 104 are further described in step S140.

[0122] The solution of the present invention aims at the industrial robot vibration caused by interference in the transmission structure of the industrial robot, proposes a vibration suppression scheme based on an adaptive dimensionality reduction state observer for the servo control system of the industrial robot, analyzes the two vibrations caused by the harmonic reducer in the industrial robot, and designs an adaptive dimensionality reduction state observer as a torque observer; a torque observer is added to the servo control system of the industrial robot, and the observation value of the adaptive dimensionality reduction state observer can better fit the real disturbance waveform, significantly improve the dynamic performance of the industrial robot, and can specifically suppress the even-multiple frequency vibration and resonance caused by the harmonic reducer in the transmission structure of the industrial robot, thereby improving the control accuracy of the servo controller over the industrial robot. The solution has strong engineering practicality, flexible structure, and strong anti-interference ability.

[0123] The solution of the present invention suppresses the terminal vibration of the industrial robot from the harmonic reducer by designing an adaptive dimensionality reduction state observer and adding it to the servo control system, effectively improving the dynamic performance of the industrial robot. The adaptive adjustment observer can adapt to various operating environments and has better stability. The vibration suppression flow chart is shown in the figure. Figure 5As shown. It should be noted that the solution of the present invention is not only applicable to the vibration caused by the harmonic reducer in the industrial robot, but the vibration caused by other interference sources can also be suppressed by the solution of the present invention and the servo system. In principle, the vibration observed by the adaptive dimensionality reduction state observer designed by the solution of the present invention is not only the vibration caused by the harmonic reducer, but also the vibration caused by various possible interference sources of the industrial robot. It is just that the vibration caused by the harmonic reducer is specially processed for adaptive adjustment; therefore, for other vibrations, the adaptive dimensionality reduction state observer designed by the solution of the present invention can also observe and feedback to the servo control system for suppression.

[0124] In some implementations, the observer module includes a PI module and an integrator, and the PI module and the integrator are connected in series.

[0125] The control unit 104 obtains the torque disturbance signal of the industrial robot by observing the speed feedback signal of the servo motor and the torque feedback signal of the harmonic reducer through the observer module, including:

[0126] The control unit 104 is further configured to perform PI processing based on the speed feedback signal of the servo motor and the difference between the estimated rotor speed of the servo motor through the PI module to obtain the estimated load torque of the industrial robot as the torque disturbance signal of the industrial robot. The specific functions and processing of the control unit 104 are further described in step S210.

[0127] The control unit 104 is further configured to perform integrator processing based on the estimated load torque of the industrial robot and the torque feedback signal of the harmonic reducer via the integrator to obtain a new estimated rotor speed of the servo motor. The specific functions and processing of the control unit 104 are further described in step S220.

[0128] The control unit 104 is further configured to perform PI processing again using the PI module based on the difference between the speed feedback signal of the servo motor and the new estimated rotor speed of the servo motor, thereby obtaining a new estimated load torque of the industrial robot as a new torque disturbance signal of the industrial robot. The specific functions and processing of the control unit 104 are further described in step S230.

[0129] The control unit 104 is further configured to perform this cycle to obtain the dynamic estimated load torque of the industrial robot as the dynamic torque disturbance signal of the industrial robot. The specific functions and processing of the control unit 104 are further described in step S240.

[0130] An adaptive state observer is an observer that can estimate the state online and automatically adjust its parameters. The observer designed in the solution of the present invention is composed of a PI link and an integrator connected in series.

[0131] like Figure 8 As shown, the rotor mechanical angular velocity ω m , and the estimated rotor speed at the previous moment After the comparator, the speed difference is obtained; the speed difference is passed through the k1J module to obtain the first processed value, and the speed difference is passed through the k1 / s module to obtain the second processed value; the first processed value and the second processed value are passed through the comparator to obtain the estimated load torque The estimated load torque Electromagnetic torque T e The torque difference is obtained after the comparator; the torque difference is obtained after the 1 / (sJ+B) module to obtain the current rotor estimated speed

[0132] The solution of the present invention proposes a vibration suppression scheme for a servo control system of an industrial robot based on an adaptive dimensionality reduction state observer. The scheme analyzes the two vibrations caused by the harmonic reducer in the industrial robot and designs a dimensionality reduction state observer to suppress the two vibrations of the industrial robot, thereby reducing computational complexity. In addition, the solution of the present invention does not require external sensors, reducing costs and simplifying the design.

[0133] Considering that the even-harmonic frequency vibration of the harmonic reducer is difficult to effectively observe using a single observer, the solution of the present invention adds a nonlinear optimization-gradient descent method to tune the observer. This allows the adaptive observer to adjust the optimal state observer parameters according to dynamic parameters such as speed, thereby obtaining a more realistic disturbance signal. In this way, the servo control system can effectively suppress the vibration of the industrial robot caused by the harmonic reducer, improve the accuracy and reliability of the industrial robot's operation, and extend the life of the industrial robot.

[0134] The shaper method used in related solutions can only suppress vibrations with known amplitudes and periods, and different trajectory protocols require readjustment of the shaper. The solution of the present invention uses an observer to observe the vibration signal in real time, thereby compensating the servo control system. It has strong adaptability and has a good vibration suppression effect for different trajectories and even working conditions, thereby enhancing the robustness and efficiency of the industrial robot.

[0135] In some embodiments, the expression of the observer module is as follows:

[0136]

[0137] Where d is the differential operator, t is the time, Estimated speed for the servo motor's rotor, is the estimated load torque of the harmonic reducer, B is the preset friction coefficient, J is the system moment of inertia of the servo control system, T e is the electromagnetic torque of the harmonic reducer, k1 is the proportional gain parameter of the observer module, k2 is the integral gain parameter of the observer module, ω m is the mechanical angular velocity of the rotor of the servo motor, Estimate a speed for the rotor of the servo motor.

[0138] In the solution of the present invention, the adaptive observer used in the servo system is a reduced-dimensional torque state observer based on nonlinear optimization. First, the reduced-dimensional torque observer is designed. According to the principle of dynamics, the mechanical motion equation of the motor can be obtained as follows:

[0139]

[0140] Where, J is the system moment of inertia; T e is the electromagnetic torque; ω m is the rotor mechanical angular velocity; B is the friction coefficient; θ m is the mechanical angle; T L is the load torque; d is the differential operator; t is the time.

[0141] The controller sampling period is at the microsecond level, and it can be approximately considered that the load torque T in one sampling period is L is a constant value, so the torque observer can be constructed as follows:

[0142]

[0143] Where k1 and k2 are the proportional and integral gain parameters of the designed observer, Estimated speed for the servo motor's rotor, To estimate the load torque, d is the differential operator, and the load torque can be obtained by simplification: The estimated equation is:

[0144]

[0145] Where s is a complex frequency variable.

[0146] In the solution of the present invention, a torque observer is added to the servo control system of the industrial robot. This torque observer observes the resonance between the harmonic reducer and the natural frequency of the industrial robot and then reverse-compensates the vibration signal to the servo control system. Furthermore, because the harmonic reducer generates vibration signals with even-multiple speed frequencies due to its dual-wave transmission characteristics, the torque observer in the servo control system of the industrial robot obtains its optimal parameters using a nonlinear optimization-gradient descent method. This solution provides better observation of the varying harmonic reducer disturbances, effectively suppressing the vibrations caused by the harmonic reducer and improving the dynamic performance of the industrial robot.

[0147] In some embodiments, in the expression of the observer module, k1 and k2 are calculated using the gradient descent method, and the expressions of k1 and k2 are as follows:

[0148]

[0149] Among them, ω c is the cutoff frequency of the observer module, δ is the stability margin of the observer module, k1 is the proportional gain parameter of the observer module, k2 is the integral gain parameter of the observer module, and J is the system moment of inertia of the servo control system.

[0150] In the solution of the present invention, the observer parameters k1 and k2 shown in formula (3) or formula (4) are calculated as follows:

[0151]

[0152] Where, ω c is the cutoff frequency of the load torque observer; δ is the stability margin of the load torque observer; J is the system moment of inertia.

[0153] The load torque observer is designed, and simulation verifies the accuracy of the observer in observing the torque fluctuation caused by the harmonic reducer. Figure 7 As shown, Figure 7 The meanings of the curves in the upper right corner are, from top to bottom, the simulation diagram of the real torque, the simulation diagram of the real torque fluctuation observed when the load torque observer gain k1 = 1500, the simulation diagram of the real torque fluctuation observed when the load torque observer gain k1 = 3000, the simulation diagram of the real torque fluctuation observed when the load torque observer gain k1 = 5000, and the simulation diagram of the real torque fluctuation observed when the load torque observer gain k1 = 10000. Figure 7The simulation diagram of the real torque fluctuation observed when the load torque observer gain k1 is displayed shows that the larger the load torque observer gain k1, the better the torque fluctuation observed by the load torque observer follows; but if the gain is too high, high-frequency interference will appear in the observation signal, and after compensating it into the servo motor control torque, new vibration will be introduced. Therefore, it is necessary to set a suitable observer parameter to suppress the vibration. At the same time, because the harmonic reducer has not only the resonance of the natural frequency, but also the even-multiple frequency fluctuation that changes with the motor speed, different frequency speed wave signals require different observer gain parameters k1. Therefore, the gradient descent method is used to enable the observer to obtain the optimal observer gain corresponding to the motor speed, so as to suppress the even-multiple frequency fluctuation of the speed in the harmonic reducer and improve the dynamic performance of the industrial robot. The core parameter update formula of the gradient descent method is:

[0154]

[0155] Where, β t and β t-1 are the parameters of the current moment and the parameters of the previous moment, i.e., the observer gain k1 and speed; η is the learning rate, i.e., the step size of the control update, ▽f(β t-1 ) is the gradient of the observer torque error at the previous moment (i.e., the partial derivative vector).

[0156] The steps to design the adaptive parameter adaptation of the adaptive dimensionality reduction state observer are as follows:

[0157] Step 1: Initialization, input motor parameters and initial speed, and get initial parameter β t-1 , and connect the observer to the servo control.

[0158] Step 2: Calculate the gradient. After the industrial robot starts running, calculate the gradient of the vibration error of the industrial robot terminal at the previous parameter ▽f(β t-1 ).

[0159] Step 3: Update the parameters and use formula (6) to get the new parameter β t Update the observer parameters again.

[0160] Step 4: Repeat steps 2 and 3 to make the torque fluctuation observed by the observer close to the industrial robot terminal vibration caused by the harmonic reducer. The obtained observer is as follows: Figure 8 shown.

[0161] In the solution of the present invention, the adaptive dimensionality reduction state observer after the above-mentioned nonlinear optimization is connected to the servo control system, and the torque fluctuation error observed by the compensation observer is compensated, so that the two vibrations caused by the harmonic reducer can be eliminated. The compensation effect is independently controllable and not affected by other regulator parameters. It is easy to implement and greatly improves the dynamic performance of the industrial robot servo control system.

[0162] In some embodiments, the servo control system includes: a position regulator, a speed regulator, and a current regulator.

[0163] Wherein, the position regulator is located in the speed loop of the servo control system; the speed regulator and the current regulator are located in the current loop of the servo control system; the output signal of the current regulator can control the action of the servo motor.

[0164] The control unit 104 sets the observer module in the feedback part of the servo control system, including: the control unit 104 is specifically configured to control the action of the harmonic reducer in the feedback part of the servo control system according to the torque disturbance signal of the industrial robot output by the observer module and the output signal of the servo motor.

[0165] like Figure 6 As shown in the figure, the difference between the position command issued by the host computer and the position feedback of the servo motor is obtained after the comparator, and the speed command is obtained after the position regulator; the difference between the speed command and the speed feedback of the servo motor is obtained after the comparator, and the current command is obtained after the speed regulator; the current command is output to the current regulator after the comparator, and the current regulator adjusts the current of the servo motor; the adaptive state observer outputs a torque disturbance signal based on the speed feedback of the servo motor and the torque fluctuation of the harmonic reducer; the difference between the torque command output by the servo motor and the torque disturbance signal output by the adaptive state observer is obtained after the comparator, and is output to the harmonic reducer, and the terminal load is controlled by the harmonic reducer.

[0166] In the above embodiment, an adaptive dimensionality reduction state observer method is incorporated into the industrial robot servo control system to suppress two types of vibrations caused by the harmonic reducer in the industrial robot servo motor drive. The above embodiment addresses the suppression of vibrations caused by the harmonic reducer in the industrial robot, and this design can also be used to suppress other vibrations of the industrial robot. The above embodiment can also observe the system torque disturbance caused by other similar vibration sources of the industrial robot and feed back the torque fluctuations into the servo system control to suppress vibrations, thereby reducing the vibration of the industrial robot terminal and improving the dynamic performance of the industrial robot.

[0167] In the above-mentioned embodiments, the servo motor output command, speed feedback, position feedback signal, and torque disturbance signal output by the observer may contain high-frequency disturbance noise when connected to the servo system. These signals can be filtered, including but not limited to low-pass or band-pass filters. The use of a low-pass filter is simple in design and can effectively filter out high-frequency noise in the signal, making the system response smoother and improving the reliability and dynamic performance of the system. The use of a band-pass filter can specifically remove high-frequency noise in the signal, reducing the impact on the useful signal compared to a low-pass filter, increasing the accuracy of the servo control signal, and enhancing the reliability of the system.

[0168] In some embodiments, the control unit 104 compensates the torque disturbance signal of the industrial robot into the torque control of the servo motor on the harmonic reducer to suppress the terminal vibration of the industrial robot, including:

[0169] The control unit 104 is further configured to perform position adjustment via the position regulator based on the difference between the position command signal of the servo motor sent by the host computer and the position feedback signal of the servo motor, thereby obtaining a speed command signal for the servo motor. The specific functions and processing of the control unit 104 are further described in step S310.

[0170] The control unit 104 is further configured to perform speed regulation based on the speed command signal of the servo motor and the speed feedback signal of the servo motor through the speed regulator to obtain a current command signal of the servo motor. The specific functions and processing of the control unit 104 are also shown in step S320.

[0171] The control unit 104 is further configured to control the operation of the servo motor based on the current command signal of the servo motor via the current regulator, and to obtain the torque command signal of the servo motor when the servo motor is operating. The specific functions and processing of the control unit 104 are further described in step S330.

[0172] The control unit 104 is further configured to obtain a torque disturbance signal of the industrial robot through the observer module in the feedback portion of the servo control system; and to perform torque control on the harmonic reducer based on the difference between the torque command signal of the servo motor and the torque disturbance signal of the industrial robot to suppress vibration of the terminal end of the industrial robot. The specific functions and processing of the control unit 104 are further described in step S340.

[0173] like Figure 5 As shown in Figure 2, the specific implementation process of a vibration suppression method based on an adaptive dimensionality reduction state observer is as follows:

[0174] Step S1: The servo control system of the industrial robot receives a position command from the host computer. The servo control system drives the end-user of the industrial robot by controlling a motor with a harmonic reducer. The rotor inside the servo motor is a permanent magnet. The three-phase power controlled by the servo driver in the servo control system of the industrial robot forms an electromagnetic field. This magnetic field rotates the servo motor's rotor. Simultaneously, the servo motor's built-in encoder measures the rotor's position and generates a feedback signal to the servo control system of the industrial robot.

[0175] In step S2, during the servo motor control process, in addition to sending a torque control signal to the transmission device - harmonic reducer, the servo motor will also use the encoder to feedback the position and speed of the motor in order to more accurately control the motion state of the end of the industrial robot. The position feedback is subtracted from the position instruction of the host computer and sent to the position regulator in the servo system, while the speed feedback is subtracted from the speed instruction output by the position regulator and then sent to the speed regulator. After receiving the current instruction issued by the speed regulator after the combined effect of the instruction and feedback, the current regulator outputs torque / current to the servo motor. The servo motor ultimately controls the movement of the end of the industrial robot through the transmission device harmonic reducer, where the harmonic reducer plays the role of amplifying torque and deceleration, such as Figure 6 The command, feedback and torque control parts of the servo control system.

[0176] Step S3, when the industrial robot terminal is operating under the control of the servo control system described above, the output end of the servo motor is connected to the terminal through the transmission device-harmonic reducer and driven, because the control system driven by the harmonic reducer will produce two parts of industrial robot vibration: 1) One part of the vibration is because there is a natural frequency of low-frequency vibration in the assembly process of the industrial robot. When the operating frequency of the motor is the same as the natural frequency of the harmonic reducer, the servo motor and the harmonic reducer will resonate. 2) In addition, due to the unique double-wave transmission characteristics of the harmonic reducer, the flexible gear will undergo two meshing processes in a complete rotation cycle, which causes the output speed to fluctuate with an even multiple of the frequency, causing the industrial robot to vibrate. Both parts of the vibration signal will be transmitted to the connected industrial robot terminal. If the industrial robot is controlled by relying solely on the control part described in step 2 above, it will be impossible to effectively eliminate the vibration caused by the two parts of the harmonic reducer, which will cause vibration at the industrial robot terminal and affect the dynamic performance of the industrial robot.

[0177] In response to these two parts of vibration, the solution of the present invention adds an adaptive dimensionality reduction state observer module to the feedback part of the servo control system; the state observer in the related solution only performs overall state observation on the interference in the servo motor of the industrial robot, and there are few studies that analyze the source of vibration interference and design state observers. Some studies have analyzed the vibration in the harmonic reducer, but they all classify it as a type of vibration, ignoring the fluctuation of the even-multiple frequency of the speed caused by the double-wave characteristics of the harmonic reducer. Therefore, most of them believe that their vibrations are single-frequency fluctuations, and use a single state observer to observe the error, without considering that the error vibration frequency will change with the change of the motor speed, and cannot effectively suppress the vibration caused by the harmonic reducer; therefore, it is necessary to design an adaptive dimensionality reduction state observer and add it to the servo control system, and its output fluctuating torque signal is compensated to the servo motor to control the harmonic reducer to suppress the two vibrations caused by the harmonic reducer, such as Figure 6 shown.

[0178] Step S4: The adaptive observer used in the servo system in the solution of the present invention is a dimension-reduced torque state observer based on nonlinear optimization.

[0179] In the solution of the present invention, the designed adaptive dimensionality reduction state observer can be applied to the servo control system described in the solution of the present invention, and can also be used for other industrial robot servo motor control systems with harmonic reducers. The source of vibration is resonance and even-multiple frequency fluctuations of speed, and the vibration suppression method is an adaptive dimensionality reduction state observer. The solution of the present invention designs a servo control system for an industrial robot, and designs a more effective adaptive state observer in the servo control system of the industrial robot for the even-multiple frequency vibration and resonance brought by the harmonic reducer of the industrial robot. The solution has strong engineering practicality, high reliability and stability. The designed dimensionality reduction observer has a simple structure and strong adaptability, and can well observe the torque fluctuations in the control system. The adaptive observer designed by the gradient descent method can well suppress the even-multiple frequency fluctuations in the harmonic reducer that change with speed, thereby greatly improving the dynamic performance of the servo controller for the industrial robot.

[0180] Since the processing and functions implemented by the device of this embodiment basically correspond to the embodiments, principles and examples of the aforementioned method, for any details not fully described in this embodiment, please refer to the relevant descriptions in the aforementioned embodiments and will not be repeated here.

[0181] According to an embodiment of the present invention, an industrial robot corresponding to the control device of the industrial robot is also provided. The industrial robot may include: the control device of the industrial robot described above.

[0182] Since the processing and functions implemented by the industrial robot of this embodiment basically correspond to the embodiments, principles and examples of the aforementioned devices, for any details not fully described in this embodiment, please refer to the relevant descriptions in the aforementioned embodiments and will not be repeated here.

[0183] According to an embodiment of the present invention, a computer program product corresponding to the control method of an industrial robot is also provided, including a computer program. When the computer program is executed by a processor, the steps of the control method of the industrial robot described above are implemented.

[0184] Since the processing and functions implemented by the product of this embodiment basically correspond to the embodiments, principles and examples of the aforementioned method, for any details not fully described in this embodiment, please refer to the relevant descriptions in the aforementioned embodiments and will not be repeated here.

[0185] According to an embodiment of the present invention, a storage medium corresponding to the control method of an industrial robot is also provided, wherein the storage medium includes a stored program, wherein when the program is running, the device where the storage medium is located is controlled to execute the steps of the control method of the industrial robot described above.

[0186] Since the processing and functions implemented by the storage medium of this embodiment basically correspond to the embodiments, principles and examples of the aforementioned method, for any details not fully described in this embodiment, please refer to the relevant descriptions in the aforementioned embodiments and will not be repeated here.

[0187] In summary, it is easy for those skilled in the art to understand that, under the premise of no conflict, the above-mentioned advantageous methods can be freely combined and superimposed.

[0188] The foregoing description is merely an embodiment of the present invention and is not intended to limit the present invention. Those skilled in the art will readily appreciate that various modifications and variations of the present invention are possible. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present invention are intended to be within the scope of the claims.

Claims

1. A control method for an industrial robot, characterized in that: The industrial robot comprises a servo motor, a harmonic reducer, and a servo control system; and the control method of the industrial robot comprises: Designing an observer module; and arranging the observer module in the feedback part of the servo control system; When the industrial robot is running, obtaining a speed feedback signal of the servo motor and a torque feedback signal of the harmonic reducer; The observer module observes the speed feedback signal of the servo motor and the torque feedback signal of the harmonic reducer to obtain a torque disturbance signal of the industrial robot; The torque disturbance signal of the industrial robot is compensated into the torque control of the servo motor on the harmonic reducer to suppress the terminal vibration of the industrial robot.

2. The control method of the industrial robot according to claim 1, characterized in that: The observer module includes: a PI module and an integrator, wherein the PI module and the integrator are connected in series; wherein, The method comprises: obtaining a torque disturbance signal of the industrial robot by observing the speed feedback signal of the servo motor and the torque feedback signal of the harmonic reducer through the observer module, including: performing PI processing based on a speed feedback signal of the servo motor and a difference between an estimated rotor speed of the servo motor and the PI module to obtain an estimated load torque of the industrial robot as a torque disturbance signal of the industrial robot; Performing integrator processing based on the estimated load torque of the industrial robot and the torque feedback signal of the harmonic reducer by the integrator to obtain a new estimated rotor speed of the servo motor; performing PI processing again by the PI module based on the speed feedback signal of the servo motor and the difference between the new estimated rotor speed of the servo motor to obtain a new estimated load torque of the industrial robot as a new torque disturbance signal of the industrial robot; In this cycle, the estimated load torque of the dynamic industrial robot is obtained as the dynamic torque disturbance signal of the industrial robot.

3. The control method of an industrial robot according to claim 1 or 2, characterized in that: The expression of the observer module is as follows: Where d is the differential operator, t is the time, Estimated speed for the servo motor's rotor, is the estimated load torque of the harmonic reducer, B is the preset friction coefficient, J is the system moment of inertia of the servo control system, T e is the electromagnetic torque of the harmonic reducer, k1 is the proportional gain parameter of the observer module, k2 is the integral gain parameter of the observer module, ω m is the mechanical angular velocity of the rotor of the servo motor, A speed is estimated for the rotor of the servo motor.

4. The control method of the industrial robot according to claim 3, characterized in that: In the expression of the observer module, the gradient descent method is used to calculate k1 and k2, and the expressions of k1 and k2 are as follows: Among them, ω c is the cutoff frequency of the observer module, and δ is the stability margin of the observer module.

5. The control method of an industrial robot according to any one of claims 1 to 4, characterized in that: The servo control system includes: a position regulator, a speed regulator and a current regulator; wherein, The position regulator is located in the speed loop of the servo control system; the speed regulator and the current regulator are located in the current loop of the servo control system; the output signal of the current regulator can control the action of the servo motor; The observer module is arranged in the feedback part of the servo control system, comprising: In the feedback part of the servo control system, the action of the harmonic reducer is controlled according to the torque disturbance signal of the industrial robot output by the observer module and the output signal of the servo motor.

6. The control method of the industrial robot according to claim 5, characterized in that: Compensating the torque disturbance signal of the industrial robot into the torque control of the harmonic reducer by the servo motor to suppress the terminal vibration of the industrial robot includes: The position regulator performs position adjustment based on the position command signal of the servo motor sent by the host computer and the difference between the position feedback signal of the servo motor to obtain the speed command signal of the servo motor; The speed regulator performs speed regulation based on the speed command signal of the servo motor and the speed feedback signal of the servo motor to obtain a current command signal of the servo motor; The servo motor is controlled to operate based on the current command signal of the servo motor through the current regulator; when the servo motor is operating, a torque command signal of the servo motor can be obtained; In the feedback part of the servo control system, the torque disturbance signal of the industrial robot is obtained through the observer module; based on the difference between the torque command signal of the servo motor and the torque disturbance signal of the industrial robot, the torque of the harmonic reducer is controlled to suppress the terminal vibration of the industrial robot.

7. A control device for an industrial robot, characterized in that: The industrial robot comprises a servo motor, a harmonic reducer, and a servo control system; the control device of the industrial robot comprises: A control unit is configured to design an observer module; and arrange the observer module in a feedback part of the servo control system; an acquisition unit, configured to acquire a speed feedback signal of the servo motor and a torque feedback signal of the harmonic reducer when the industrial robot is running; The control unit is further configured to obtain a torque disturbance signal of the industrial robot by observing the speed feedback signal of the servo motor and the torque feedback signal of the harmonic reducer through the observer module; The control unit is further configured to compensate the torque disturbance signal of the industrial robot into the torque control of the servo motor on the harmonic reducer to suppress the terminal vibration of the industrial robot.

8. An industrial robot, characterized in that: include: The control device for an industrial robot as claimed in claim 7.

9. A storage medium, characterized in that: The storage medium includes a stored program, wherein when the program is executed, the device where the storage medium is located is controlled to execute the control method for the industrial robot according to any one of claims 1 to 6.

10. A computer program product comprising a computer program, characterized in that When the computer program is executed by a processor, the steps of the method for controlling an industrial robot according to any one of claims 1 to 6 are implemented.

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