Torque control methods, actuators, harmonic joint modules and robots

Abstract

This invention belongs to the field of robot motion control technology, specifically relating to torque control methods, actuators, harmonic joint modules, and robots. The method obtains the deviation between the target command torque and the actual output torque, and adjusts a unique offline tuning coefficient α, using a proportional coefficient k. p =α· J m With integral coefficient k i =α·B m The PI controller calculates the target drive current to control the motor. This method overcomes the high-frequency mechanical oscillation and overshoot caused by insufficient stiffness of the harmonic reducer, simplifies the parameter tuning process to single-parameter determination, and significantly improves the high dynamic closed-loop tracking accuracy and motion smoothness of the joint torque.

Description

Technical Field

[0001] This invention belongs to the field of robot motion control technology, specifically involving torque control methods, drivers, harmonic joint modules, and robots. Background Technology

[0002] With the rapid development of intelligent robots, collaborative robots, and industrial automation equipment, harmonic joint modules, as the core power transmission unit of robots, are being used more and more widely. Torque control, as the underlying core technology for harmonic joint modules to achieve high-precision compliant control, collision detection, and force interaction feedback, directly determines the smoothness, accuracy, and safety of the entire robot system's motion.

[0003] In existing technologies, torque control for harmonic joint modules typically relies on classic proportional-integral (PI) or proportional-integral-derivative (PID) controllers. The implementation logic usually involves measuring the difference between the actual output torque and the target command torque to obtain the deviation, which is then processed by independently set proportional and integral gains, ultimately outputting a current control command for driving the motor. However, a harmonic joint module is essentially a typical "two-inertia elastic system" with extremely complex electromechanical mechanisms. The system's flexible, strongly coupled, and multivariable physical model is difficult to reflect in conventional controllers. Summary of the Invention

[0004] In view of this, the present invention proposes a torque control method, a driver, a harmonic joint module and a robot, aiming to improve the control effect of the joint module and the motion control performance of the robot.

[0005] In a first aspect, in the torque control method for a harmonic joint module provided by the present invention, the torque control method includes:

[0006] S11. Obtain the target command torque. F s * and actual output torque F s And obtain the target command torque. F s * Compared with actual output torque F s Torque tracking deviation e ( t ), ;

[0007] S12, Based on the torque tracking deviation e ( t ), and the proportional coefficient of the designed PI controller. kp = α·J m With integral coefficient k i = α·B m The target drive current value is calculated using a PI controller. i q * , ;

[0008] S13, Based on the target drive current value i q * Drive the motor, thereby controlling the actual output torque. F s Tracking and approximating the target command torque F s * ;

[0009] in, J m This refers to the rotor inertia on the motor side. B m The coefficient of friction on the motor side. α This refers to the adjustment coefficient determined during the offline tuning phase.

[0010] The torque control method of the above harmonic joint module has the following technical effects: (1) By adjusting the proportional coefficient of the PI controller... k p and integral coefficient k i Rotor inertia on the motor side J m and coefficient of friction B m Perform binding design ( k p = α·J m and k i = α·B m (2) By using the controller's zero point to cancel the motor's inertial-damped mechanical poles, the strong coupling effect of the motor's inherent hardware parameters on the control dynamic response is effectively eliminated. α The process of repeatedly trying and adjusting the two parameters (proportional coefficient and integral coefficient) of traditional PI control is simplified to the precise determination of a single parameter, which greatly improves the efficiency of engineering debugging. (3) By tracking the closed-loop deviation between the actual output torque and the command torque, the defects of poor accuracy and output fluctuation in the open-loop torque control of the harmonic reducer transmission chain are significantly overcome.

[0011] In a further preferred embodiment of the torque control method provided by the present invention, the adjustment coefficient α The determination process includes:

[0012] S21. Based on the motor-side motion equation, the load-side motion equation, and the coupling equation of the force transmission on the motor side and the load side of the harmonic joint module, construct the electromagnetic driving torque of the motor. F m The actual output torque of the harmonic joint module F s The transfer function of the harmonic joint module;

[0013] S22, Proportional coefficient of the PI controller based on the design k p = α·J m With integral coefficient k i = α·B m The transfer function of the PI controller is obtained.

[0014] S23. Combining the transfer function of the harmonic joint module and the transfer function of the PI controller, the open-loop transfer function of the system is obtained;

[0015] S24. Construct the corresponding closed-loop characteristic equation of the system based on the open-loop transfer function of the system;

[0016] S25, Adjustment α The system's closed-loop characteristic equation is configured such that all poles are distributed as a single real root and a pair of conjugate complex roots, satisfying the boundary condition that the real root is close to the imaginary axis and the pair of conjugate complex roots are far from the imaginary axis. This process yields the tuned adjustment coefficients. α .

[0017] The torque control method of the above harmonic joint module has the following technical effects: (1) It comprehensively considers the motor side, load side and transmission coupling dynamics, so that the controller tuning is based on the real physical transmission model, which improves the theoretical accuracy of torque closed-loop control. (2) By configuring the system pole as a real root (the dominant pole close to the imaginary axis) and a pair of conjugate complex roots (the minor poles far from the imaginary axis), the high-order joint coupling dynamic response presents the overdamped or stable characteristics of an approximate first-order system. Theoretically, it overcomes the high-frequency mechanical oscillation and overshoot caused by insufficient stiffness of the harmonic reducer from the root, ensuring that the joint torque output is stable, fast and shock-free.

[0018] In a further preferred embodiment of the torque control method provided by the present invention,

[0019] (1) The equation of motion on the motor side is:

[0020]

[0021] In the formula, J m This refers to the rotor inertia on the motor side. B m The coefficient of friction on the motor side. ω m The speed is the speed on the motor side. For motor-side acceleration, N The reduction ratio of the harmonic reducer. k t The torque constant of the motor. i q For motor q shaft current, F m For electromagnetic driving torque, ;

[0022] (2) The equation of motion on the load side is:

[0023]

[0024] In the formula, J l For the load-side rotor inertia, B l The coefficient of friction on the load side. ω l For load-side speed, For load-side acceleration, T L For external load disturbance torque;

[0025] (3) The coupling equation for the force transmission on the motor side and the load side of the harmonic joint module is:

[0026]

[0027] In the formula, k r The stiffness coefficient of the harmonic reducer Actual output torque F s The derivative of .

[0028] The torque control method of the above harmonic joint module has the following technical effects: (1) By introducing the stiffness coefficient of the harmonic reducer k r and load torque T L The electromechanical energy transfer relationship was clearly defined, and the torque transmission time delay and elastic coupling mechanism in the flexible joint transmission chain were accurately characterized. (2) The reduction ratio was accurately taken into account.N and motor torque constant k t The physical variables provide a solid physical basis for the subsequent rigorous analytical reduction of the transfer function.

[0029] In a further preferred embodiment of the torque control method provided by the present invention, the torque control is constructed from the electromagnetic drive torque of the motor. F m To the actual output torque F s The process of the transfer function of the harmonic joint module is as follows:

[0030] First, based on the motion equations of the motor side, the motion equations of the load side, and the coupling equations of the force transmission on the motor side and the load side of the harmonic joint module, the initial open-loop transfer function of the harmonic joint module is constructed:

[0031]

[0032] in, s For Laplace calculation; the equation neglects the load-side motion equations. T L The reason is T L These are typically constants or slow variables, and the integral term of a PI controller can eliminate them. T L Impact on the results;

[0033] Then based on and To simplify the initial open-loop transfer function, terms of the initial open-loop transfer function are ignored. In J l and B l ; and combined The final transfer function of the harmonic joint module is obtained as follows:

[0034] .

[0035] The torque control method of the above-mentioned harmonic joint module has the following technical effects: Utilizing the physical characteristic that the load inertia and damping at high reduction ratios account for a very small proportion when referred to the motor side, the method reasonably ignores the following terms. J l and B l This yields a concise and refined characteristic transfer function, significantly reducing the analytical complexity of higher-order differential equations and their transfer functions.

[0036] In a further preferred embodiment of the torque control method provided by the present invention, the proportional coefficient of the designed PI controller is used...k p = α·J m With integral coefficient k i = α·B m The transfer function of the PI controller is obtained as follows:

[0037] ;

[0038] Among them, the transfer function of the harmonic joint module i q Approximately equal to the transfer function of the PI controller i q * The reason is that the motor of the harmonic joint module uses a high-bandwidth current control loop to achieve the output current. i q Tracking at extremely high speeds i q * .

[0039] The torque control method of the above-mentioned harmonic joint module has the following technical effects: it uses a low-level hardware current control loop to track the target drive current with extremely high bandwidth. i q * Its characteristics approximate the actual current to the command current, effectively decoupling the microsecond-level electrical response and millisecond-level mechanical torque response of the motor, reducing the frequency domain analysis difficulty of the outer loop torque controller, and ensuring the dynamic high fidelity of the upper-level algorithm when it is deployed and executed on the actual motor drive hardware platform.

[0040] In a further preferred embodiment of the torque control method provided by the present invention, combining the transfer function of the harmonic joint module and the transfer function of the PI controller, the obtained system open-loop transfer function is:

[0041] .

[0042] The torque control method of the above harmonic joint module has the following technical effects: (1) The standard open-loop transfer function is directly derived through pole cancellation, making the open-loop gain and resonant poles of the system readily apparent in the frequency domain. (2) It provides clear mathematical tools for calculating the open-loop cutoff frequency, phase margin, and gain margin of the system, facilitating rapid evaluation of the system's stability boundary.

[0043] In a further preferred embodiment of the torque control method provided by the present invention, the corresponding closed-loop characteristic equation of the system is constructed based on the open-loop transfer function of the system as follows:

[0044] .

[0045] The torque control method of the above harmonic joint module has the following technical effects: (1) It accurately maps the dynamic closed-loop characteristics of higher-order joints to a single adjustment parameter. α (2) Engineers can directly and accurately calculate the equations that satisfy the critical oscillation conditions and the distribution of dominant poles using algebraic root locus criteria (such as the Routh criterion or Cardan's formula). α Solve the space, completely get rid of blind trial and error, and achieve one-click automated parameter tuning.

[0046] In a second aspect, the driver provided by the present invention includes a memory and a processor, the memory storing a computer program; the processor is configured to, when the computer program is executed, cause the processor to implement the torque control method described in any one of the first aspects.

[0047] The above-mentioned driver has the following technical effects: (1) It integrates the efficient pole placement torque algorithm into the driver microcontroller unit, thereby increasing the calculation frequency of the joint bottom-level closed-loop control (which can reach kilohertz or even higher control cycles). (2) It realizes efficient local closed-loop control of the joint module, which significantly reduces the real-time communication and calculation pressure on the robot's central control computer.

[0048] Thirdly, in the harmonic joint module provided by the present invention, the harmonic joint module includes a motor, a harmonic reducer, a torque sensor, and a driver. The harmonic reducer is connected to the output end of the motor. The torque sensor is disposed at the output end of the harmonic reducer and is used to collect the actual output torque of the harmonic joint module. The driver is the driver described in the second aspect, and the driver is electrically connected to the motor and the torque sensor respectively.

[0049] The above-mentioned harmonic joint module has the following technical effects: (1) It integrates a motor, harmonic reducer, end torque sensor and intelligent driver to form a highly modular intelligent joint product with high dynamic response and excellent compliant force control capability. (2) By using end output torque feedback combined with the internal high-fidelity closed-loop algorithm, the nonlinear mechanical disturbances such as hysteresis, friction and variable stiffness of the harmonic reducer are directly eliminated and canceled within the module level, so that the end user can directly obtain accurate torque output.

[0050] Fourthly, in the robot provided by the present invention, the robot includes a machine body and at least one harmonic joint module as described in the third aspect, the harmonic joint module being mounted at the joint of the machine body.

[0051] The above-mentioned harmonic joint module has the following technical effects: (1) By mounting the harmonic joint module at each of its joints, the robot has extremely stable, extremely low overshoot and extremely fast convergence torque self-compliant control capability when in physical contact, assembly operation or collision with people, thereby greatly reducing the risk of physical damage to the robot body and environmental objects caused by external impact. (2) In multi-constraint operation scenarios such as dual-arm cooperation, quadrupedal movement or dexterous operation, it can provide accurate torque servo and dynamic anti-disturbance performance, which significantly improves the overall working accuracy and control stability of the robot. Attached Figure Description

[0052] Preferred embodiments of the present invention will now be described in detail with reference to the accompanying drawings, which will make the above and other features and advantages of the present invention more apparent to those skilled in the art. In the drawings:

[0053] Figure 1 This is a block diagram illustrating the principle of the torque control system of the harmonic joint module in this embodiment.

[0054] Figure 2 This is a schematic diagram of the main process of the torque control method for the harmonic joint module in this embodiment.

[0055] Figure 3 The adjustment coefficient in the PI controller of this embodiment. α A schematic diagram of the main process for determining the [specific element]. Detailed Implementation

[0056] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be described in detail below. Obviously, the described embodiments are merely some embodiments of this invention, and not all embodiments. Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this invention.

[0057] I. System Overall Architecture and Hardware Infrastructure

[0058] As attached Figure 1 As shown, this embodiment provides a highly integrated harmonic joint module and its torque drive control system, which is mainly used in human-robot collaborative robots, quadrupedal robots, or robotic arms. From the overall architecture, the harmonic joint module is mainly composed of two highly integrated components: a mechanical transmission execution unit (motor and harmonic reducer) and a control unit (i.e., driver).

[0059] The mechanical transmission actuator includes a motor (such as a frameless torque motor) and a harmonic reducer rigidly connected to the motor's output shaft. The motor, as the core of the electromechanical energy conversion, outputs electromagnetic torque. F mHarmonic reducers achieve high reduction ratios by utilizing the meshing of a flexible wheel and a rigid wheel. N Torque amplification and speed reduction transmission. A high-precision torque sensor is installed at the end of the harmonic reducer (load side) to monitor and collect the actual output torque of the harmonic joint module in real time. F s .

[0060] The control unit (driver) is electrically connected to the motor and torque sensor. Its core hardware structure includes a memory, a processor (such as a DSP, MCU, or FPGA—a high real-time control chip), a current controller, a PI controller, a vector transformation module (Clarke / Park transformation arithmetic unit), and a power drive arm. Additionally, it includes a position / angle detection module (encoder) and a phase current sampling module (current sensor).

[0061] The memory contains pre-written low-level motor parameters (such as rotor inertia). J m coefficient of friction B m ), transmission parameters (reduction ratio) N Stiffness k r and offline tuned control coefficients α .

[0062] The operation process is as follows: The processor periodically reads the actual output torque from the torque sensor. F s With the target command torque from the system F s * The target is calculated in the internal computing module by using a PI controller with specific zero-pole cancellation. q Shaft current command i q * Subsequently, the electrical angle φ collected by the encoder was combined with... 𝑒 Phase current sampled by a three-phase current sensor The actual vector is obtained through Clarke and Park vector transformations. q shaft current i q Ultimately, the drive voltage command is generated by the ultra-high bandwidth underlying hardware current control loop (current controller). u q It precisely controls the electromagnetic torque output of the motor, completing a closed-loop feedback process of "sensing-computation-drive".

[0063] II. Real-time workflow of torque control method for harmonic joint module

[0064] Combination Figure 2In the torque control method for a harmonic joint module provided in this embodiment, the torque control method includes:

[0065] S11. Obtain the target command torque. F s * and actual output torque F s And obtain the target command torque. F s * Compared with actual output torque F s Torque tracking deviation e ( t ), ;

[0066] S12, Based on the torque tracking deviation e ( t ), and the proportional coefficient of the designed PI controller. k p = α·J m With integral coefficient k i = α·B m The target drive current value is calculated using a PI controller. i q * , ;

[0067] S13, Based on the target drive current value i q * Drive the motor, thereby controlling the actual output torque. F s Tracking and approximating the target command torque F s * ;

[0068] in, J m This refers to the rotor inertia on the motor side. B m The coefficient of friction on the motor side. α This refers to the adjustment coefficient determined during the offline tuning phase.

[0069] The torque control method of the above harmonic joint module has the following technical effects: (1) By adjusting the proportional coefficient of the PI controller... k p and integral coefficient k i Rotor inertia on the motor side Jm and coefficient of friction B m Perform binding design ( k p = α·J m and k i = α·B m (2) By using the controller's zero point to cancel the motor's inertial-damped mechanical poles, the strong coupling effect of the motor's inherent hardware parameters on the control dynamic response is effectively eliminated. α The process of repeatedly trying and adjusting the two parameters (proportional coefficient and integral coefficient) of traditional PI control is simplified to the precise determination of a single parameter, which greatly improves the efficiency of engineering debugging. (3) By tracking the closed-loop deviation between the actual output torque and the command torque, the defects of poor accuracy and output fluctuation in the open-loop torque control of the harmonic reducer transmission chain are significantly overcome.

[0070] Taking the scenario of collaborative robot end-effector collision detection and precision assembly (such as hole-shaft insertion) as an example, the complete closed-loop working process of the system in this embodiment is described:

[0071] (1) The host computer issues the target torque command to be output by the joint module. F s * ;

[0072] (2) The microcontroller chip built into the joint module acquires the actual contact reaction torque at ultra-high speed through an external torque sensor interface. F s ;

[0073] (3) Instantaneous torque tracking deviation inside the chip e ( t Retrieve intrinsic constants from memory. J m and B m and the pre-calculated dominant pole placement coefficients α The desired current value can be directly solved using the calculation formula. ;

[0074] (4) The underlying motor drive circuit is based on this i q * The duty cycle of the three-phase inverter is precisely adjusted to drive the motor. The entire algorithm is fully embedded and executed at the driver level, ensuring that sudden changes in stiffness caused by external hard impacts can be controlled and responded to within tens of milliseconds, exhibiting excellent mechanical compliance and safety.

[0075] III. Torque Control Principles and Modeling / Solution

[0076] To address the problems of elastic transmission hysteresis and high-frequency mechanical oscillation caused by the inherent low torsional stiffness of harmonic reducers, this preferred embodiment provides a high dynamic torque closed-loop control scheme based on zero-pole cancellation and dominant pole configuration.

[0077] Combination Figure 3 The adjustment coefficient in the above-mentioned torque closed-loop control scheme α The determination process includes:

[0078] S21. Based on the motor-side motion equation, the load-side motion equation, and the coupling equation of the force transmission on the motor side and the load side of the harmonic joint module, construct the electromagnetic driving torque of the motor. F m The actual output torque of the harmonic joint module F s The transfer function of the harmonic joint module;

[0079] S22, Proportional coefficient of the PI controller based on the design k p = α·J m With integral coefficient k i = α·B m The transfer function of the PI controller is obtained.

[0080] S23. Combining the transfer function of the harmonic joint module and the transfer function of the PI controller, the open-loop transfer function of the system is obtained;

[0081] S24. Construct the corresponding closed-loop characteristic equation of the system based on the open-loop transfer function of the system;

[0082] S25, Adjustment α The system's closed-loop characteristic equation is configured such that all poles are distributed as a single real root and a pair of conjugate complex roots, satisfying the boundary condition that the real root is close to the imaginary axis and the pair of conjugate complex roots are far from the imaginary axis. This process yields the tuned adjustment coefficients. α .

[0083] The specific implementation steps and underlying physical derivation process are as follows:

[0084] In step S21, in order to design a controller that accurately matches the physical characteristics, the complete third-order electromechanical coupling motion equations of the harmonic joint module are first constructed:

[0085] (1) Dynamic equations on the motor side:

[0086]

[0087] In the formula, k t The motor torque constant and the electromagnetic drive torque are given. ; ω m and These are the angular velocity and angular acceleration of the motor rotor, respectively. N This is the harmonic deceleration ratio; J m and B m These are the rotor inertia and viscous friction coefficient on the motor side, respectively.

[0088] (2) Load-side dynamic equations:

[0089]

[0090] In the formula, J l , B l These are the end load inertia and damping, respectively; ω l , Angular velocity and acceleration were measured for the load. T L This is the disturbance torque caused by the external load.

[0091] (3) Elastic-variable coupling equation of harmonic reducer:

[0092]

[0093] In the formula, k r This is the stiffness coefficient of the harmonic reducer.

[0094] By performing a Laplace transform and joint order reduction solution on the above differential equations, the electromagnetic torque of the motor can be obtained. F m (or drive current) i q (to the actual output torque of the module) F s The initial open-loop transfer function of the harmonic joint module:

[0095]

[0096] Among them, due to external load disturbance T L It exhibits constant or low-frequency slowly varying characteristics. The integral characteristic of the outer-loop PI closed-loop controller can naturally achieve zero steady-state error suppression, so it can be omitted when deriving the open-loop transfer function of the system. T L item.

[0097] Physical simplification and order reduction criteria: In practical engineering, the harmonic joint reduction ratio N Typically large (e.g., N=50~160), then based on and To simplify the initial open-loop transfer function, terms of the initial open-loop transfer function are ignored. In J l and B l ; and combined The final transfer function of the harmonic joint module is obtained as follows:

[0098] .

[0099] In steps S22 and S23, the high-bandwidth electrical loop decoupling and PI zero-pole cancellation structure design are implemented.

[0100] Considering that the motor driver uses a voltage source for driving and the hardware current loop operates at a frequency of tens of kilohertz, its actual current... i q Target current command i q * The tracking bandwidth is much higher than the frequency band of the external mechanical motion response. Therefore, it has extremely accurate steady-state and dynamic tracking accuracy within this control cycle, thus satisfying the constant decoupling condition. i q ≈ i q *

[0101] Based on this, the processor tracks the deviation according to the torque. Calculate the drive instructions. This embodiment designs a PI control structure that is precisely bound to the intrinsic mechanical poles of the motor: The proportional gain of the PI controller is set... k p With integral coefficient k i satisfy:

[0102] k p = α·J m , k i = α·B m

[0103] In the formula, α This is the monotonic adjustment parameter to be tuned. At this point, the transfer function of the PI controller... C ( s Transformed into:

[0104] , and obtain,

[0105] .

[0106] When the PI controller is combined with the final transfer function of the harmonic joint module, the numerator zero of the controller... The mechanical poles that represent the inertial-friction coupling of the motor in the denominator of the transfer function of the transmission object are exactly the same as those of the transmission object. Zero-pole cancellation occurs. After cancellation, the open-loop transfer function of the system is significantly simplified:

[0107]

[0108] In step S24, the dominant pole placement and parameters are determined. α Offline one-click tuning. From the simplified open-loop model above, the closed-loop characteristic equation of the system can be directly derived, which expands into a standard cubic algebraic polynomial:

[0109] .

[0110] In step S25, during engineering commissioning, engineers no longer need to blindly and repeatedly try to adjust the two parameters in complex field environments. Instead, they can directly adjust the single variable during the offline phase using algebraic equation root distribution criteria (such as Cardan's solution formula or Routh-Hurwitz stability boundary analysis). α This allows control over the distribution of the three poles of the closed-loop polynomial. The preferred boundary conditions are:

[0111] (1) Configure the dominant real pole: make one of the real roots s Located immediately to the left of the imaginary axis of the complex plane, it serves as the dominant pole for the system's response speed, determining the step rise time and response bandwidth of joint torque tracking.

[0112] (2) Configure the far conjugate complex poles: make the other two conjugate complex roots The depth moves away from the imaginary axis and enters the high-frequency region of the left half of the complex plane (the absolute value of its real part is much larger than the absolute value of the dominant real root).

[0113] Through this pole configuration, the joint exhibits smooth control dynamics similar to a first-order overdamped system under high-order transmission, perfectly absorbing and eliminating the harmonic stiffness at the physical level. k r The induced elastic resonance and response overtuning enable high-precision, zero-oscillation compliant torque tracking.

[0114] IV. Examples of Other Implementation Methods

[0115] (1) Replacement embodiment of torque sensing end

[0116] In the preferred embodiment described above, the actual torque F s The torque is measured directly by a physical torque sensor installed at the output of the harmonic reducer; however, in alternative embodiments where cost is limited or weight reduction is stringent, a physical torque sensor may not be configured. Instead, dual photoelectric / magnetic encoders are configured simultaneously on the motor rotor side and the reducer load side to collect the angular displacement difference between the two ends of the transmission. Based on the known stiffness of the reducer k r The equivalent torque feedback is obtained by directly calculating and observing using the elastic Hooke's law. This feedback value also applies to the zero-pole cancellation PI closed-loop equation in this method.

[0117] (2) Isomorphic extension of actuators and transmission mechanisms

[0118] Although this embodiment focuses on the typical application of a motor in conjunction with a harmonic reducer, the control concept of "based on rotor inertia cancellation and reduced-order dominant pole tuning" of this invention is also fully applicable to other precision joint drive structures that use RV reducers, precision cycloidal pinwheel reducers, or have the characteristic of flexible long shaft transmission with drive. It is only necessary to equivalently replace the corresponding coupling stiffness with the formula in the equation. k r That's all.

[0119] (3) Algorithm enhancement and online adaptive deformation of parameters

[0120] Considering that under long-term extreme operation, the temperature rise on the motor side of the robot may lead to a decrease in the coefficient of friction. B m Slow drift. As a further preferred implementation variation, an online parameter identification observer (such as an adaptive Kalman filter or least squares algorithm) can also run in parallel within the drive to slowly adjust the actual rotor inertia over a slow clock cycle. J m and coefficient of friction B m Perform rolling estimation updates. In this case, the PI controller parameters are adjusted online in real time. , This enables dynamic adaptive zero-pole precise cancellation throughout the entire lifecycle.

[0121] (4) Friction compensation composite control

[0122] To further improve torque tracking accuracy at extremely low speeds, the target drive current calculated in the closed loop can be optionally... i q * Based on this, an additional feedforward term for nonlinear friction compensation current is superimposed, constructed from the Coulomb friction model and the viscous friction model.i comp This makes the final output instruction become This is to overcome the zero-crossing crawling or phase hysteresis caused by the static friction dead zone.

[0123] It should be understood that although this specification is described according to various embodiments, not every embodiment or implementation method contains only one independent technical solution. This way of describing the specification is only for clarity. Those skilled in the art should regard the specification as a whole. The technical solutions in each embodiment can also be appropriately combined to form other implementation methods that can be understood by those skilled in the art.

[0124] The above descriptions are merely illustrative embodiments of this application and are not intended to limit the scope of the embodiments of this application. Any equivalent changes, modifications, and combinations made by those skilled in the art without departing from the concept and principles of the embodiments of this application should fall within the protection scope of the embodiments of this application.

Claims

1. A torque control method for a harmonic joint module, characterized in that, include: Obtain the target command torque F s * and actual output torque F s And obtain the target command torque F s * With actual output torque F s The torque tracking deviation e(t), ; Based on the torque tracking deviation e(t) and the proportional coefficient k of the designed PI controller p =α· J m With integral coefficient k i =α·B m The target drive current value i is calculated using a PI controller. q * , ; Based on the target drive current value i q * Drive the motor, thereby controlling the actual output torque F s Tracking and approximating the target command torque F s * ; Among them, J m B is the rotor inertia on the motor side. m Here, α is the friction coefficient on the motor side, and α is the adjustment coefficient determined during the offline tuning phase.

2. The torque control method according to claim 1, characterized in that, The process of determining the adjustment coefficient α includes: Based on the motor-side motion equations, load-side motion equations, and the coupling equations of force transmission on the motor and load sides of the harmonic joint module, a system is constructed to determine the electromagnetic driving torque F of the motor. m The actual output torque F of the harmonic joint module s The transfer function of the harmonic joint module; Based on the proportional coefficient k of the designed PI controller p =α· J m With integral coefficient k i =α·B m The transfer function of the PI controller is obtained. By combining the transfer function of the harmonic joint module and the transfer function of the PI controller, the open-loop transfer function of the system is obtained; Construct the corresponding closed-loop characteristic equation of the system based on the open-loop transfer function of the system. Adjust α so that all poles of the closed-loop characteristic equation of the system are distributed as one real root and a pair of conjugate complex roots, and satisfy the boundary test condition that the real root is close to the imaginary axis and the pair of conjugate complex roots are far from the imaginary axis, and finally obtain the tuned adjustment coefficient α.

3. The torque control method according to claim 2, characterized in that, (1) The equation of motion on the motor side is: In the formula, J m B is the rotor inertia on the motor side. m ω is the coefficient of friction on the motor side. m The speed is the speed on the motor side. N is the acceleration on the motor side, N is the reduction ratio of the harmonic reducer, and k is the acceleration on the motor side. t Let i be the motor torque constant. q F is the q-axis current of the motor. m For electromagnetic driving torque, ; (2) The equation of motion on the load side is: In the formula, J l For load-side inertia, B l ω is the coefficient of friction on the load side. l For load-side speed, For the load-side acceleration, T L For external load disturbance torque; (3) The coupling equation for the force transmission on the motor side and the load side of the harmonic joint module is: In the formula, k r The stiffness coefficient of the harmonic reducer The actual output torque F s The derivative of .

4. The torque control method according to claim 3, characterized in that, Constructing from the electromagnetic drive torque F of the motor m To the actual output torque F s The process of the transfer function of the harmonic joint module is as follows: First, based on the motion equations of the motor side, the motion equations of the load side, and the coupling equations of the force transmission on the motor side and the load side of the harmonic joint module, the initial open-loop transfer function of the harmonic joint module is constructed: Where s is the Laplace equation; the external load disturbance torque T in the load-side motion equation is ignored. L The reason is T L Typically, these are constants or slow variables; the integral term of a PI controller can eliminate T. L Impact on the results; Then based on and To simplify the initial open-loop transfer function, terms of the initial open-loop transfer function are ignored. J in l and B l ; and combined The final transfer function of the harmonic joint module is obtained as follows: 。 5. The torque control method according to claim 4, characterized in that, Based on the proportional coefficient k of the designed PI controller p =α· J m With integral coefficient k i =α·B m The transfer function of the PI controller is obtained as follows: ； Among them, i in the transfer function of the harmonic joint module q The i in the transfer function of the PI controller is approximately equal to q * The reason is that the motor of the harmonic joint module uses a high-bandwidth current control loop to achieve the output current i q Tracking i at extremely high speed q * .

6. The torque control method according to claim 5, characterized in that, Combining the transfer function of the harmonic joint module and the transfer function of the PI controller, the system open-loop transfer function is obtained as follows: 。 7. The torque control method according to claim 6, characterized in that, Based on the open-loop transfer function of the system, the corresponding closed-loop characteristic equation of the system is constructed as follows: 。 8. A driver, characterized in that, include: A memory, wherein a computer program is stored; A processor configured to, when executing the computer program, cause the processor to implement the torque control method as described in any one of claims 1 to 7.

9. A harmonic joint module, characterized in that, include: Electric motor; A harmonic reducer is connected to the output end of the motor for transmission. A torque sensor is installed at the output end of the harmonic reducer to collect the actual output torque of the harmonic joint module; The driver as claimed in claim 8 is electrically connected to both the motor and the torque sensor.

10. A robot, characterized in that, It includes a machine body and at least one harmonic joint module as described in claim 9, the harmonic joint module being mounted at a joint of the machine body.

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