Rigid-flexible switching control method and system of robot joint module permanent magnet synchronous motor

Abstract

This invention discloses a method and system for rigid-flexible switching control of a permanent magnet synchronous motor (PMSM) in a robot joint module, relating to the field of robot joint module control technology. The method includes: constructing a relevant coupling model based on the PMSM of the target robot joint module; obtaining state characteristic quantities of the joint module based on the relevant coupling model; constructing a rigid-flexible state discrimination function based on the state characteristic quantities and generating a continuous switching factor; reconstructing the rigid-flexible control parameter set of the PMSM based on the continuous switching factor to obtain a reconstructed control parameter set; performing damping correction and smoothing shaping on the original target torque based on the reconstructed control parameter set to obtain a dual-axis reference current; obtaining a dual-axis voltage reference command based on the reconstructed control parameter set, the dual-axis reference current, and the relevant coupling model; and performing rigid-flexible switching control of the PMSM based on the dual-axis voltage reference command. This achieves adaptive rigid-flexible control of the robot joint under different working conditions.

Description

Technical Field

[0001] This invention relates to the field of robot joint module control technology, and more specifically to a rigid-flexible switching control method and system for permanent magnet synchronous motors in robot joint modules. Background Technology

[0002] With the development of collaborative robots, industrial robots, service robots and embodied intelligent systems, robot joint modules, as core power units, typically use permanent magnet synchronous motors as drive sources to meet diverse task requirements such as high-speed trajectory tracking, precise positioning, compliant assembly, human-machine interaction, and collision buffering. These motors are then combined with transmission mechanisms such as harmonic reducers, planetary reducers, or flexible couplings to achieve high torque output and high-precision control.

[0003] However, in practical engineering, the control requirements of robot joint modules vary significantly depending on the operating conditions. High stiffness and precision are needed during free motion, while compliance is required during contact, collision, or assembly to reduce impact. Existing permanent magnet synchronous motor control methods mostly employ fixed-parameter vector control, making it difficult to simultaneously meet the dual requirements of high stiffness and high compliance under different operating conditions.

[0004] In existing technologies, one type of method suppresses oscillations by online correction of velocity loop parameters, but lacks a unified characterization of multiple operating conditions such as contact and collision, and fails to map operating condition identification to the underlying torque generation and current closed-loop dynamics, leading to sudden torque changes and current spikes during operating condition switching. Another type of method based on model predictive control optimizes the voltage vector by adjusting the weight of the value function, focusing on improving the dynamic and steady-state performance of predictive control, but it does not establish a continuous switching mechanism between rigid and flexible control based on the flexible transmission characteristics of joints, nor does it provide an underlying rigid-flexible integrated control method suitable for vector control structures that balances contact safety and tracking accuracy.

[0005] Furthermore, the flexible transmission characteristics commonly found in joint modules make it difficult for a single fixed stiffness control strategy to adapt to both high-speed operation and compliant contact conditions. If a hard switch is made directly between rigid and flexible control modes, it will lead to abrupt changes in control parameters, abrupt changes in q-axis current reference, and a step jump in output torque, thereby reducing system stability. Therefore, the existing technologies generally have the following shortcomings: (1) lack a multi-feature working condition discrimination mechanism that can reflect the joint contact, collision, and flexible transmission deformation state; (2) lack an integrated method that maps the rigid and flexible control requirements to the underlying torque generation, current closed-loop dynamics, and control parameter reconstruction process; (3) lack a control mechanism that can achieve smooth switching between different working conditions and effectively suppress torque impact and current abrupt changes.

[0006] Therefore, how to achieve adaptive rigid-flexible control of robot joints under different working conditions is a problem that urgently needs to be solved by those skilled in the art. Summary of the Invention

[0007] In view of the above problems, the present invention is proposed to provide a rigid-flexible switching control method and system for permanent magnet synchronous motors of robot joint modules to overcome or at least partially solve the above problems, thereby realizing adaptive rigid-flexible control of robot joints under different working conditions.

[0008] To achieve the above objectives, the present invention adopts the following technical solution:

[0009] In a first aspect, embodiments of the present invention provide a rigid-flexible switching control method for a permanent magnet synchronous motor in a robot joint module, comprising: A relevant coupling model is constructed based on the permanent magnet synchronous motor of the target robot joint module; The state feature quantities of the joint module are obtained based on the aforementioned related coupling model; Based on the state feature quantities, a rigid-flexible state discrimination function is constructed and a continuous switching factor is generated; Based on the continuous switching factor, the rigid-flexible control parameter set of the permanent magnet synchronous motor is reconstructed to obtain the reconstructed control parameter set. Based on the reconstructed control parameter set, the target torque is damped and smoothed to obtain a biaxial reference current. Based on the reconstructed control parameter set, the dual-axis reference current, and the related coupling model, the dual-axis voltage reference command is obtained; The permanent magnet synchronous motor is subjected to rigid-flexible switching control based on the dual-axis voltage reference command.

[0010] Preferably, a relevant coupling model is constructed, specifically including: Based on the permanent magnet synchronous motor, the d-axis stator voltage model and the q-axis stator voltage model are constructed in the dq rotating coordinate system, which together form the stator voltage model; Based on the flexible transmission characteristics of the robot joint module, and combined with the output electromagnetic torque, transmission elastic torque and load torque of the permanent magnet synchronous motor, the corresponding motor-side dynamic model and load-side dynamic model are constructed. The motor-side dynamics model and the load-side dynamics model together form a dual-inertia coupling model between the motor side and the load side. The stator voltage model and the dual-inertia coupling model together serve as the relevant coupling model.

[0011] The preferred method for obtaining state feature quantities is as follows: Based on the dual inertia coupling model, the operating status information of the robot joint module is obtained in real time, and the position error, velocity error, equivalent torsional angle difference between the motor side and the load side and q-axis current error, which characterize the operating status of the system are constructed. Based on the load-side dynamic model, and combined with electromagnetic torque, load-side angular velocity, load-side angular acceleration, equivalent inertia of the joint output side, and equivalent damping parameters of the joint output side, the estimated value of the disturbance torque is obtained. The rate of change of disturbance is obtained based on the estimated value of the disturbance torque; The position error, the speed error, the equivalent torsional angle difference between the motor side and the load side, the q-axis current error, and the disturbance change rate together constitute the state characteristic quantity.

[0012] Preferably, the rigid-flexible state discrimination function is constructed, specifically including: After normalizing the position error, speed error, equivalent torsional angle difference between the motor side and the load side, q-axis current error, and disturbance rate of change, the stiffness-flexibility state discrimination function is obtained by weighting and summing them together with the corresponding weighting coefficients.

[0013] The preferred method for obtaining the continuous switching factor is as follows: Set rigid thresholds and flexible thresholds; The discriminant function value is obtained based on the rigid-flexible state discriminant function; Determine whether the value of the discrimination function is greater than or equal to the flexible threshold; If so, the current operating condition is determined to be a flexible control state, and the continuous switching factor is set to 0; Otherwise, determine whether the value of the discrimination function is greater than the rigid threshold; If so, the current operating condition is determined to be a rigid-flexible transition state, and the continuous switching factor is obtained based on the discrimination function value, the rigid threshold, and the flexible threshold; Otherwise, the current operating condition is determined to be a rigid control state, and the continuous switching factor is set to 1.

[0014] Preferably, a hysteresis criterion is introduced for determining the current operating condition: Set rigid entry threshold, rigid exit threshold, flexible entry threshold, and flexible exit threshold; When the previous moment was in a rigid control state, if the value of the discrimination function is greater than or equal to the rigid exit threshold for a preset duration, a switch from the rigid control state to the rigid-flexible transition state is triggered. When the previous moment was in a flexible control state, if the value of the discrimination function is less than or equal to the flexible exit threshold for a preset duration, a switch from the flexible control state to the rigid-flexible transition state is triggered. When the system is in a transitional state, it switches to a rigid control state after the discrimination function value is less than or equal to the rigid entry threshold for a preset duration; and switches to a flexible control state after the discrimination function value is greater than or equal to the flexible entry threshold for a preset duration.

[0015] Preferably, the reconstructed control parameter set is obtained, specifically including: Based on the motor parameters, reduction ratio, load inertia, transmission stiffness, driver bandwidth and target operating conditions of the permanent magnet synchronous motor, a rigid parameter set and a flexible parameter set are pre-tuned and used together as the rigid-flexible control parameter set. The rigid-flexible control parameter set is reconstructed based on the continuous switching factor to obtain the reconstructed control parameter set. The reconfiguration control parameter set includes: reconfiguration speed loop proportional coefficient, reconfiguration speed loop integral coefficient, reconfiguration current loop proportional coefficient, reconfiguration current loop integral coefficient, reconfiguration damping compensation coefficient, and upper limit of reconfiguration torque change rate.

[0016] Preferably, obtaining the biaxial reference current specifically includes: Based on the reconstructed speed loop proportional coefficient, the reconstructed speed loop integral coefficient, and the speed error at the previous moment, the basic torque command output by the speed loop is obtained as the original target torque. Based on the reconstructed damping compensation coefficient, a damping correction term is obtained, and the original target torque command is damped to obtain a corrected target torque command. Based on the modified target torque command, the rate of change is constrained to obtain the torque increment; Based on the upper limit of the reconstructed torque change rate and the torque increment, construct the allowable torque increment after limiting; Based on the allowable torque increment and the torque reference value at the previous moment, the torque reference value after the rate of change constraint is obtained. The final torque reference value is generated by first-order filtering based on the torque reference value. Based on the final torque reference value and relevant motor parameters, the d-axis reference current and q-axis reference current corresponding to the permanent magnet synchronous motor are obtained, which together form the dual-axis reference current.

[0017] Preferably, the rigid-flexible switching control of the permanent magnet synchronous motor based on the dual-axis voltage reference command specifically includes: Based on the reconstructed current loop proportional coefficient, the reconstructed current loop integral coefficient, the d-axis reference current and the q-axis reference current, and combined with the stator voltage model, the d-axis voltage reference command and the q-axis voltage reference command are obtained, which together form the dual-axis voltage reference command. Based on the dual-axis voltage reference command, an inverter switching drive signal is generated through inverse Park transform, inverse Clarke transform, and space vector pulse width modulation. Closed-loop control of the electromagnetic torque of the permanent magnet synchronous motor is achieved based on the inverter switching drive signal.

[0018] In a second aspect, embodiments of the present invention provide a rigid-flexible switching control system for a permanent magnet synchronous motor of a robot joint module, used to execute the rigid-flexible switching control method for a permanent magnet synchronous motor of a robot joint module as described in any of the first aspects, comprising: a coupling model construction module, a state feature acquisition module, a rigid-flexible state discrimination module, a control parameter reconstruction module, a reference current acquisition module, and a rigid-flexible state switching module. The coupling model construction module is used to construct a relevant coupling model based on the permanent magnet synchronous motor of the target robot joint module. The state feature acquisition module is used to acquire the state feature quantities of the joint module based on the relevant coupling model; The rigid-flexible state discrimination module is used to construct a rigid-flexible state discrimination function based on the state feature quantity and generate a continuous switching factor. The control parameter reconstruction module is used to reconstruct the rigid-flexible control parameter set of the permanent magnet synchronous motor based on the continuous switching factor to obtain the reconstructed control parameter set. The reference current acquisition module is used to perform damping correction and smoothing shaping on the target torque based on the reconstructed control parameter group to obtain a biaxial reference current. The rigid-flexible state switching module is used to obtain a dual-axis voltage reference command based on the reconfigured control parameter group, the dual-axis reference current, and the related coupling model; and to perform rigid-flexible switching control on the permanent magnet synchronous motor based on the dual-axis voltage reference command.

[0019] As can be seen from the above technical solution, compared with the prior art, the present invention discloses a rigid-flexible switching control method and system for a permanent magnet synchronous motor of a robot joint module, which has the following beneficial effects: 1. This invention establishes a motor-transmission-load coupling model, which can accurately describe the dynamic behavior of robot joint modules under flexible transmission conditions.

[0020] 2. This invention achieves real-time identification of the operating conditions of robot joints by constructing a rigid-flexible state discrimination function composed of position error, velocity error, torsional angle difference, disturbance change rate and current error.

[0021] 3. By introducing a continuous switching factor, this invention reconstructs the speed loop parameters, current loop parameters, damping compensation coefficient, and upper limit of torque change rate online, thus avoiding the problem of sudden changes in control parameters caused by hard switching between traditional rigid and flexible modes.

[0022] 4. This invention effectively suppresses sudden changes in q-axis current, electromagnetic torque spikes, and joint output chattering by applying damping correction, slope constraint, and filtering shaping to the target torque command.

[0023] 5. This invention uses vector control to achieve closed-loop regulation and drive output of the permanent magnet synchronous motor current, thereby completing the continuous rigid-flexible switching control of the robot joint module between free motion and contact conditions.

[0024] 6. This invention constructs a rigid-flexible integrated control link for flexible transmission robot joints, which includes "working condition discrimination - switching factor generation - parameter group reconstruction - torque reference shaping - current closed-loop execution". This enables the continuous mapping and adaptive switching of rigid control performance and compliant contact performance under a unified control architecture. It has both high free motion tracking accuracy and good contact compliance performance, and has strong engineering practicality and promotion value. Attached Figure Description

[0025] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the provided drawings without creative effort.

[0026] Figure 1 This is a flowchart of the rigid-flexible switching control method for the permanent magnet synchronous motor of the robot joint module provided in this embodiment of the invention.

[0027] Figure 2 This is a flowchart of the online reconfiguration process for control parameters provided in an embodiment of the present invention.

[0028] Figure 3 This is a schematic diagram of the rigid-flexible switching control system for the permanent magnet synchronous motor of the robot joint module provided in an embodiment of the present invention. Detailed Implementation

[0029] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0030] Example 1 like Figure 1 As shown, to achieve adaptive rigid-flexible control of robot joints under different working conditions such as free movement, contact collision, and assembly operations, this invention discloses a rigid-flexible switching control method for a permanent magnet synchronous motor of a robot joint module, including the following steps. For ease of description, these steps are numbered S1 to S7, which are not used to limit the sequential relationship between the various steps of this invention: S1 constructs a related coupling model based on the permanent magnet synchronous motor of the target robot joint module.

[0031] Furthermore, a relevant coupling model is constructed, specifically including: Based on the permanent magnet synchronous motor, the d-axis stator voltage model and the q-axis stator voltage model are constructed in the dq rotating coordinate system, which together form the stator voltage model; Based on the flexible transmission characteristics of robot joint modules, and combined with the output electromagnetic torque, transmission elastic torque and load torque of permanent magnet synchronous motors, corresponding motor-side dynamic models and load-side dynamic models are constructed. The motor-side dynamics model and the load-side dynamics model together form a dual-inertia coupling model between the motor side and the load side. The stator voltage model and the dual-inertia coupling model are used together as the relevant coupling model.

[0032] Furthermore, the stator voltage model is as follows: ; in, u d and u q They are respectively represented as d Shaft stator voltage and q Shaft stator voltages, respectively corresponding to d Shaft stator voltage model and q Shaft stator voltage model; i d and i q They represent d Shaft stator current and q Shaft stator current; R s Indicates stator resistance; L d and L q They represent d Shaft inductance and q Shaft inductance; ω e Indicates electric angular velocity; ψ f This indicates the magnetic flux linkage of a permanent magnet.

[0033] Furthermore, the dual-inertia coupling model between the motor side and the load side is specifically as follows: ; ; in, J m and J lThese represent the moment of inertia on the motor side and the moment of inertia on the load side, respectively. ω m and ω l These represent the mechanical angular velocity on the motor side and the mechanical angular velocity on the load side, respectively. and These represent the differential calculation quantities of the mechanical angular velocity on the motor side and the mechanical angular velocity on the load side, respectively. B m and B l These represent the viscous damping coefficient on the motor side and the viscous damping coefficient on the load side, respectively. T s Indicates the transmission elastic torque; T L Indicates load torque; K s and B s These represent the equivalent torsional stiffness and the equivalent damping coefficient, respectively. θ m and θ l These represent the angular displacement on the motor side and the angular displacement on the load side, respectively. N Indicates the reduction ratio; T e This indicates the output electromagnetic torque of the permanent magnet synchronous motor; p n Represents the extreme logarithm.

[0034] Furthermore, Represents the dynamic model of the motor side. This represents the load-side dynamics model.

[0035] S2 obtains the state features of the joint module based on the relevant coupling model.

[0036] Furthermore, the method for obtaining state feature quantities is as follows: Based on the dual inertia coupling model, the operating status information of the robot joint module is obtained in real time, and the position error, velocity error, equivalent torsional angle difference between the motor side and the load side and q-axis current error are constructed to characterize the system operating status. Based on the load-side dynamic model, and combined with electromagnetic torque, load-side angular velocity, load-side angular acceleration, equivalent inertia of the joint output side, and equivalent damping parameters of the joint output side, the disturbance torque estimate is obtained. The rate of change of disturbance is obtained based on the disturbance torque estimate; Position error, speed error, equivalent torsional angle difference between the motor side and the load side, q-axis current error, and disturbance change rate together constitute the state characteristic quantities.

[0037] Furthermore, position errore θ Speed ​​error e ω The equivalent torsional angle difference Δ between the motor side and the load side θ and q-axis current error e i The corresponding is: ; ; ; ; in, Indicates the given value of the load-side location; This indicates the load-side speed setpoint; express q Shaft current reference value; express q Shaft current feedback value.

[0038] Furthermore, the disturbance torque estimate Specifically: ; in, J eq and B eq These represent the equivalent inertia on the output side of the joint and the equivalent damping parameter on the output side of the joint, respectively.

[0039] Furthermore, the rate of change of the disturbance Specifically: ; in, ( k () represents the estimated value of the disturbance torque at time k; ( k- 1) Represents the estimated value of the disturbance torque at time k-1; T ω This indicates the sampling period of the velocity loop.

[0040] S3 constructs a rigid-flexible state discrimination function based on state feature quantities and generates a continuous switching factor.

[0041] Furthermore, a rigid-flexible state discrimination function is constructed, specifically including: After normalizing the position error, speed error, equivalent torsional angle difference between the motor side and the load side, q-axis current error, and disturbance change rate, the stiffness-flexibility state discrimination function is obtained by weighting and summing the corresponding weighting coefficients.

[0042] Furthermore, to ensure that state variables with different dimensions can be uniformly weighted, this embodiment employs a normalized rigid-flexible state discrimination function: ; in, This represents the normalized position error; This indicates the normalized speed error; This represents the normalized difference in equivalent torsional angle between the motor side and the load side; Indicates normalization q Shaft current error; This represents the normalized rate of change of the perturbation. α 1. α 2. α 3. α 4 and α 5 represents the weighting coefficient.

[0043] Furthermore, the method for obtaining the continuous switching factor is as follows: Set rigid thresholds and flexible thresholds; Obtain the discriminant function value based on the rigid-flexible state discriminant function; Determine whether the discriminant function value is greater than or equal to the flexible threshold; If so, the current operating condition is determined to be flexible control state, and the continuous switching factor is set to 0; Otherwise, determine whether the value of the discrimination function is greater than the rigid threshold; If so, the current operating condition is determined to be a rigid-flexible transition state, and a continuous switching factor is obtained based on the discriminant function value, rigid threshold, and flexible threshold. Otherwise, the current operating condition is determined to be a rigid control state, and the continuous switching factor is set to 1.

[0044] Furthermore, such as Figure 2 As shown, in this embodiment, the rigid threshold J r Flexible threshold J f Based on the discriminant function value J ( k ) for the current running state ( k Identify: .

[0045] Furthermore, to prevent the control state from frequently changing near the threshold, a hysteresis criterion is introduced to determine the current operating condition: Set rigid entry threshold Rigid exit threshold Flexible entry threshold and flexible exit threshold ,satisfy: ; When the previous time step was in a rigid control state, if the discriminant function value is greater than or equal to the rigid exit threshold... After a preset duration, a transition from rigid control to a rigid-flexible transition state is triggered. When the previous time step was in flexible control state, if the discriminant function value is less than or equal to the flexible exit threshold... After a preset duration, a transition from flexible control to rigid-flexible transition is triggered. When the system is in a transitional state, the discriminant function value is less than or equal to the rigid entry threshold. After a preset duration, it switches to rigid control mode; when the discrimination function value is greater than or equal to the flexible entry threshold... After a preset duration, it switches to flexible control mode.

[0046] Furthermore, a preset duration is used to suppress transient noise and misjudgments caused by single impacts; in this embodiment, multiple velocity loop sampling periods are used. Through the above three-state discrimination and hysteresis switching mechanism, the stability and reliability of operating condition identification can be improved while ensuring response speed.

[0047] Furthermore, based on the rigid-flexible state discrimination results, a continuous switching factor is defined. : ; in, Indicates rigid control mode. Indicates flexible control mode. This indicates a rigid-flexible continuous transition mode.

[0048] S4 reconstructs the rigid-flexible control parameter set of the permanent magnet synchronous motor based on the continuous switching factor, and obtains the reconstructed control parameter set.

[0049] Furthermore, the reconstructed control parameter set is obtained, specifically including: Based on the pre-tuning of the motor parameters, reduction ratio, load inertia, transmission stiffness, driver bandwidth and target operating conditions of the permanent magnet synchronous motor, a rigid parameter set and a flexible parameter set are obtained, which together serve as the rigid-flexible control parameter set. The rigid-flexible control parameter set is reconstructed based on the continuous switching factor to obtain the reconstructed control parameter set. The reconfigurable control parameter set includes: reconfigurable speed loop proportional coefficient, reconfigurable speed loop integral coefficient, reconfigurable current loop proportional coefficient, reconfigurable current loop integral coefficient, reconfigurable damping compensation coefficient, and upper limit of reconfigurable torque change rate.

[0050] Furthermore, the rigid parameter set P r With flexible parameter set P f They are respectively: ; in, and These represent the proportional coefficient and integral coefficient of the velocity loop in the rigid parameter set, respectively. and These represent the proportional coefficient and integral coefficient of the current loop in the rigid parameter group, respectively. This represents the damping compensation coefficient in the rigid parameter set; S r This represents the upper limit of the rate of change of torque in the rigid parameter group; These represent the speed loop proportional coefficient, speed loop integral coefficient, current loop proportional coefficient, current loop integral coefficient, damping compensation coefficient, and upper limit of torque change rate in the flexible parameter group, respectively.

[0051] Furthermore, the rigid parameter set and the flexible parameter set are not fixed empirical constants, but are pre-tuned based on the parameters of the permanent magnet synchronous motor used in the robot joint module, the reduction ratio, the load inertia, the transmission stiffness, the driver bandwidth, and the target working condition requirements. Among them, the rigid parameter set focuses on the high bandwidth and high tracking accuracy control requirements under free motion conditions, while the flexible parameter set focuses on the low impact and high damping compliance control requirements under contact, collision, or assembly conditions.

[0052] Furthermore, the control parameters are reconstructed online based on the switching factor: ; The corresponding result is: ; in, , , , , and These represent the continuous switching factors at the current time. The reconstructed reconstructed speed loop proportional coefficient, reconstructed speed loop integral coefficient, reconstructed current loop proportional coefficient, reconstructed current loop integral coefficient, reconstructed damping compensation coefficient, and upper limit of reconstructed torque change rate are obtained.

[0053] Furthermore, instead of correcting the controller parameters after oscillation, the rigid control requirements and flexible control requirements are continuously mapped to the underlying control parameter set based on the operating condition judgment results, thus achieving a smooth transition at the parameter level.

[0054] S5 performs damping correction and smoothing shaping on the target torque based on the reconfigured control parameter set to obtain the biaxial reference current.

[0055] Furthermore, the biaxial reference current is obtained, specifically including: Based on the reconstructed speed loop proportional coefficient, the reconstructed speed loop integral coefficient, and the speed error at the previous moment, the basic torque command output by the speed loop is obtained as the original target torque. The damping correction term is obtained based on the reconstructed damping compensation coefficient, and the original target torque command is damped to obtain the corrected target torque command. The torque increment is obtained by constraining the rate of change based on the modified target torque command; Based on the reconstructed upper limit of torque change rate and torque increment, construct the allowable torque increment after limiting; Based on the allowable torque increment and the torque reference value at the previous moment, the torque reference value after the rate of change constraint is obtained; The final torque reference value is generated by first-order filtering based on the torque reference value; Based on the final torque reference value and relevant motor parameters, the d-axis reference current and q-axis reference current corresponding to the permanent magnet synchronous motor are obtained, which together form the dual-axis reference current.

[0056] Furthermore, the original target torque Specifically: .

[0057] Furthermore, the damping correction term Specifically: ; in, ( k () represents the discrete time value of the load-side speed setpoint; (k) represents the discrete time value of the load-side speed feedback value.

[0058] Furthermore, the target torque command is modified. Specifically: .

[0059] Furthermore, the target torque command is corrected. By applying a rate of change constraint, the torque increment Δ is obtained. T c ( k )for: ; in, T c ( k -1) indicates the original target torque command at the previous moment.

[0060] Furthermore, based on the upper limit of the reconstructed torque change rate at the current moment... Constructing the allowable torque increment after limiting : ; Based on allowable torque increment The torque reference value at the previous moment The torque reference value after rate of change constraint is obtained. : ; The final torque reference value is generated using a first-order filter. : ; in, β These represent the filter coefficients, satisfying 0 < β < 1; This represents the final torque reference value at the previous moment.

[0061] Furthermore, for surface-mounted permanent magnet synchronous motors and employing control strategies When q = 0, the q-axis current reference value satisfies: ; For embedded permanent magnet synchronous motors, the final torque reference value is used. and motor parameters , , Jointly generate d-axis reference current With q-axis reference current ; For an embedded permanent magnet synchronous motor, the d-axis reference current With q-axis reference current satisfy: .

[0062] Furthermore, a maximum torque-to-current ratio control strategy can be adopted. By looking up tables, using analytical approximation or numerical iteration, the corresponding d-axis and q-axis reference currents can be generated under the premise of meeting the target electromagnetic torque requirements, so as to reduce copper loss and improve current utilization.

[0063] S6 obtains the dual-axis voltage reference command based on the reconstructed control parameter set, dual-axis reference current, and related coupling model.

[0064] Furthermore, a dual-axis voltage reference command is obtained, specifically including: Based on the reconstructed current loop proportional coefficient, the reconstructed current loop integral coefficient, the d-axis reference current and the q-axis reference current, and combined with the stator voltage model, the d-axis voltage reference command and the q-axis voltage reference command are obtained, which together form the dual-axis voltage reference command.

[0065] Furthermore, in the current loop, the d-axis voltage reference command and q-axis voltage reference command They are respectively: ; in, and These represent the d-axis feedback current and the q-axis feedback current, respectively. T i Indicates the current loop sampling period; and These represent the d-axis reference current and the q-axis reference current at the j-th current loop sampling time, respectively. and Let represent the d-axis feedback current and the q-axis feedback current at the j-th current loop sampling time, respectively.

[0066] S7 performs rigid-flexible switching control of permanent magnet synchronous motors based on dual-axis voltage reference commands.

[0067] Furthermore, based on the dual-axis voltage reference command, the inverter switching drive signal is generated through inverse Park transform, inverse Clarke transform, and space vector pulse width modulation. Closed-loop control of the electromagnetic torque of a permanent magnet synchronous motor is achieved based on the inverter switching drive signal.

[0068] Furthermore, through the above steps, the switching factor is continuously adjusted under free-space motion conditions. When the value approaches 1, the controller exhibits high stiffness and high bandwidth control characteristics; under contact, collision, or assembly conditions, the continuously switching factor... When the resistance is close to zero, the controller exhibits low stiffness and high damping compliant control characteristics; in the transitional working conditions between the two, the controller parameters and torque reference change continuously, thereby achieving a smooth switching between stiffness and flexibility in the robot joint module.

[0069] Example 2 Based on the same inventive concept, the robot joint module in this embodiment is powered by a 48V DC bus and driven by a surface-mount permanent magnet synchronous motor, which is equipped with a harmonic reducer to form an integrated joint module. The main parameters of the permanent magnet synchronous motor are set as follows: Rated power: Rated phase current: Peak phase current: Rated speed: Polar numbers: Stator resistance: d-axis inductance: q-axis inductance: Permanent magnet flux linkage: Motor rotor inertia: ; The joint transmission mechanism uses a harmonic reducer, and its parameters are set as follows: Reduction ratio: Equivalent inertia on the load side: Motor-side viscous damping coefficient: ; Load-side viscous damping coefficient: Equivalent torsional stiffness: Equivalent torsional damping: .

[0070] The controller is implemented using a DSP, with the PWM carrier frequency set to 20kHz and the current loop sampling period set to: The velocity loop sampling period is set to: The location loop sampling period is set to: The current loop bandwidth is designed to be approximately 1.2 kHz, and the speed loop bandwidth is designed to be approximately 80 Hz.

[0071] (I) Constructing a permanent magnet synchronous motor coupling model for robot joint modules For the robot joint module in this embodiment, the permanent magnet synchronous motor satisfies the following in the rotating coordinate system: ; ; Substituting the parameters into this embodiment, we get: ; .

[0072] This embodiment uses a surface-mount permanent magnet synchronous motor, which meets the requirements. Therefore, under rated operating conditions, the following is adopted: ; The expression for electromagnetic torque simplifies to: ; Substitution Later: ; Right now q Each increase in shaft current The electromagnetic torque increases by approximately .

[0073] Assuming a reduction ratio of 100, the ideal torque at the joint output end would be approximately: ; The efficiency of the harmonic reducer is taken as Therefore, for every 1A increase q The shaft current and the theoretical torque at the joint output end increase by approximately: This provides a basis for setting subsequent torque limit slope and contact buffer parameters.

[0074] The dual-inertia model adopts: ; in The value is based on the torsional stiffness calibration results of the harmonic reducer in the rated output torque range of this embodiment; This is obtained by fitting the joint free decay test.

[0075] (ii) Extracting rigidity and flexibility features of joint modules In this embodiment, the controller collects the following signals in real time: Load side position Load-side speed Motor side position Motor side speed q-axis reference current q-axis feedback current .

[0076] Therefore, the following calculation is performed: ; ; ; ; To facilitate uniform threshold setting, this embodiment normalizes each state variable, setting the position error reference value as follows: Speed ​​error reference value: Torsion angle difference reference value: ;Disturbance change rate benchmark value: Current error reference value: .

[0077] The normalized state variables are: ; The selection of the torsional angle difference reference value of 0.003 rad is based on the following: In this embodiment, when the contact torque at the joint output end reaches about 5.4 N·m, the transmission elastic angle deformation is about 0.003 rad. This value can be used as an effective boundary reference before and after contact establishment.

[0078] Disturbance torque estimation uses output-side dynamic estimation: ; In this embodiment, the following is taken: ; The rate of change of the disturbance is expressed using discrete difference: ; Here, a velocity loop sampling period of 0.5ms is used for calculation to ensure the sensitivity of disturbance change detection.

[0079] (III) Constructing the rigid-flexible state discrimination function and dividing the working conditions. To ensure that state variables with different dimensions can be weighted uniformly, this embodiment uses a normalized discriminant function: ; In this embodiment, the weighting coefficient is set as follows: ; The above weight settings are based on the following: Torsional angle difference is most sensitive to contact establishment and elastic transmission deformation, so it is given a large weight of 0.30; position error and disturbance change rate reflect trajectory deviation and contact impact, respectively, so they are given a medium weight of 0.20; velocity error and current error are used to help characterize dynamic changes, so they are each given a weight of 0.15.

[0080] In this embodiment, the rigid threshold and the flexible threshold are set as follows: ; Right now: ; To prevent repeated switching near the threshold, this embodiment sets the hysteresis interval as follows: ; ; ; It is stipulated that the state switch is confirmed only if the judgment result is maintained for 5 consecutive velocity loop sampling cycles, i.e., 2.5ms. This setting is based on the fact that robot contact establishment usually lasts longer than 1ms, and using 5 sampling cycles for confirmation can balance anti-interference and response speed.

[0081] (iv) Generate rigid-flexible switching factor and reconstruct control parameters online. Constructing a continuous switching factor: ; This embodiment pre-sets a rigid parameter group. P r and flexible parameter group P f : .

[0082] The specific settings are as follows: (1) Velocity loop parameters The speed loop control law in this embodiment is: ; Based on the target velocity loop closed-loop bandwidth of approximately 80Hz, and considering the equivalent inertia and electromagnetic torque coefficient, the rigid mode parameters are taken as follows: ; In flexible mode, to reduce contact stiffness and decrease the intensity of response, the following values ​​are taken: .

[0083] (2) Current loop parameters In this embodiment, the current loop employs discrete PI control, with a target closed-loop bandwidth of approximately 1.2kHz. Based on the L / R time constant and discretization design, the rigid parameter set is selected as follows: ; In flexible mode, to reduce the abrupt current change during rapid contact, the current loop stiffness is appropriately reduced, and the following value is taken: ; (3) Damping compensation coefficient The damping correction term is: ; In rigid mode, to ensure fast speed tracking, the damping compensation should not be too large, and should be: ; In flexible mode, to enhance contact buffering and energy dissipation, the following is taken: .

[0084] (4) Upper limit of torque change rate Since each 1A of q-axis current output in this embodiment corresponds to approximately 13.8 N·m of output torque, considering contact safety and the dynamic capability of the driver, the following settings are made: ; ; in: S r It has a faster torque build-up capability in rigid mode; S f The slower torque change rate corresponds to the flexible mode, in order to reduce contact impact.

[0085] The final parameters are continuously interpolated according to the following formula: ;Right now: .

[0086] (v) Damping correction and smoothing of the target torque command. Obtain the final torque reference value The process is the same as the corresponding content in Embodiment 1 above, and will not be described in detail here.

[0087] In this embodiment, the filter coefficients are set as follows: The equivalent filtering time constant corresponding to this value is approximately 2.6 times the sampling period of the velocity loop, which can effectively suppress sudden changes without significantly reducing the control response.

[0088] Because this embodiment uses a surface-mount permanent magnet synchronous motor and ,but: ; Simultaneously, the q-axis current reference value is limited: Here, the upper limit is set to 15A, slightly lower than the driver's maximum allowable peak value of 18A, in order to provide current protection margin for collisions and disturbances.

[0089] (vi) Implementing rigid-flexible switching control for permanent magnet synchronous motors In this embodiment, the d-axis reference current is fixed as follows: ; The current loop control law is: ; Considering the 48V bus voltage limitation, the voltage vector limit in this embodiment is: This value is determined based on the maximum output voltage of SVPWM in the linear modulation region: Therefore, the limiting value is set to 27.5V to allow for modulation margin.

[0090] Under free motion conditions, the following typically apply: At this point, the system uses a rigid parameter set, exhibiting high stiffness and high bandwidth control; under contact establishment and assembly conditions, as the torsional angle difference and disturbance rate of change increase, the following typically occurs: ,at this time The control parameters change continuously between 0 and 1, and are smoothly adjusted synchronously with the torque reference, gradually transitioning the system to compliant control. Under collision or significant contact conditions, if: If the system enters a flexible control state, it reduces output stiffness and increases damping, thereby achieving impact suppression and safety buffering.

[0091] According to prototype testing, during the transition from free motion to rigid contact at the joint output end, compared to fixed rigid parameter control, this embodiment can reduce the peak q-axis current at the moment of contact by about 28% and reduce the maximum impact torque at the joint output end by about 24%. After the free motion is restored, the steady-state position error remains within 0.015 rad, indicating that the rigid-flexible switching control method can effectively balance accuracy and compliance.

[0092] Example 3 like Figure 3 As shown, based on the same inventive concept, this embodiment of the invention also provides a rigid-flexible switching control system for a permanent magnet synchronous motor of a robot joint module, including: a coupling model construction module, a state feature acquisition module, a rigid-flexible state discrimination module, a control parameter reconstruction module, a reference current acquisition module, and a rigid-flexible state switching module; The coupling model construction module is used to construct relevant coupling models based on the permanent magnet synchronous motors of the target robot joint module. The state feature acquisition module is used to acquire the state feature quantities of the joint module based on the relevant coupling model. The rigid-flexible state discrimination module is used to construct a rigid-flexible state discrimination function based on state feature quantities and generate a continuous switching factor. The control parameter reconstructing module is used to reconstruct the rigid and flexible control parameter set of the permanent magnet synchronous motor based on the continuous switching factor, so as to obtain the reconstructed control parameter set. The reference current acquisition module is used to perform damping correction and smoothing shaping on the target torque based on the reconstructed control parameter set to obtain a biaxial reference current. The rigid-flexible switching module is used to obtain the dual-axis voltage reference command based on the reconstructed control parameter group, dual-axis reference current and related coupling model; and to perform rigid-flexible switching control on the permanent magnet synchronous motor based on the dual-axis voltage reference command.

[0093] Furthermore, in this embodiment, the functional implementation methods of each functional module correspond one-to-one with the methods described above, and will not be repeated here.

[0094] Example 4 Based on the same inventive concept, the present invention also provides an electronic device, which includes a processor and a memory, wherein the memory stores instructions, characterized in that the instructions are loaded and executed by the processor to implement the rigid-flexible switching control method of the permanent magnet synchronous motor of the robot joint module as in Embodiment 1.

[0095] Based on the same inventive concept, the present invention also provides a computer device, including a processor, a communication interface, a memory, and a communication bus, wherein the processor, the communication interface, and the memory communicate with each other through the communication bus; Memory, used to store computer programs; When the processor executes the program stored in the memory, it can implement the rigid-flexible switching control method for the permanent magnet synchronous motor of the robot joint module as shown in Example 1.

[0096] The electronic device may include a processor, a communications interface, a memory, and a communication bus, wherein the processor, communications interface, and memory communicate with each other via the communication bus. The processor can call logical instructions in the memory to execute the rigid-flexible switching control method of the permanent magnet synchronous motor of the robot joint module in Embodiment 1.

[0097] Furthermore, the logical instructions in the aforementioned memory can be implemented as software functional units and sold or used as independent products, and can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of the present invention, or the part that contributes to the prior art, or a part of the technical solution, can be embodied in the form of a software product. This computer software product is stored in a storage medium and includes several instructions to cause a computer device (which may be a personal computer, server, or network device, etc.) to execute all or part of the steps of the methods of the various embodiments of the present invention. The aforementioned storage medium includes various media capable of storing program code, such as USB flash drives, portable hard drives, read-only memory (ROM), random access memory (RAM), magnetic disks, or optical disks.

[0098] The various embodiments in this specification are described in a progressive manner, with each embodiment focusing on its differences from other embodiments. Similar or identical parts between embodiments can be referred to interchangeably. For the apparatus disclosed in the embodiments, since they correspond to the methods disclosed in the embodiments, the description is relatively simple; relevant parts can be referred to the method section.

[0099] The above description of the disclosed embodiments enables those skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for rigid-flexible switching control of a permanent magnet synchronous motor in a robot joint module, characterized in that, include: A relevant coupling model is constructed based on the permanent magnet synchronous motor of the target robot joint module; The state feature quantities of the joint module are obtained based on the aforementioned related coupling model; Based on the state feature quantities, a rigid-flexible state discrimination function is constructed and a continuous switching factor is generated; Based on the continuous switching factor, the rigid-flexible control parameter set of the permanent magnet synchronous motor is reconstructed to obtain the reconstructed control parameter set. Based on the reconstructed control parameter set, the original target torque is damped and smoothed to obtain a biaxial reference current. Based on the reconstructed control parameter set, the dual-axis reference current, and the related coupling model, the dual-axis voltage reference command is obtained; The permanent magnet synchronous motor is subjected to rigid-flexible switching control based on the dual-axis voltage reference command.

2. The rigid-flexible switching control method for the permanent magnet synchronous motor of the robot joint module as described in claim 1, characterized in that, Constructing a relevant coupling model specifically includes: Based on the permanent magnet synchronous motor, the d-axis stator voltage model and the q-axis stator voltage model are constructed in the dq rotating coordinate system, which together form the stator voltage model; Based on the flexible transmission characteristics of the robot joint module, and combined with the output electromagnetic torque, transmission elastic torque and load torque of the permanent magnet synchronous motor, the corresponding motor-side dynamic model and load-side dynamic model are constructed. The motor-side dynamics model and the load-side dynamics model together form a dual-inertia coupling model between the motor side and the load side. The stator voltage model and the dual-inertia coupling model together serve as the relevant coupling model.

3. The rigid-flexible switching control method for the permanent magnet synchronous motor of the robot joint module as described in claim 2, characterized in that, The method for obtaining state feature quantities is as follows: Based on the dual inertia coupling model, the operating status information of the robot joint module is obtained in real time, and the position error, velocity error, equivalent torsional angle difference between the motor side and the load side and q-axis current error, which characterize the operating status of the system are constructed. Based on the load-side dynamic model, and combined with electromagnetic torque, load-side angular velocity, load-side angular acceleration, equivalent inertia of the joint output side, and equivalent damping parameters of the joint output side, the estimated value of the disturbance torque is obtained. The rate of change of disturbance is obtained based on the estimated value of the disturbance torque; The position error, the speed error, the equivalent torsional angle difference between the motor side and the load side, the q-axis current error, and the disturbance change rate together constitute the state characteristic quantity.

4. The rigid-flexible switching control method for the permanent magnet synchronous motor of the robot joint module as described in claim 3, characterized in that, Constructing a rigid-flexible state discrimination function specifically includes: After normalizing the position error, speed error, equivalent torsional angle difference between the motor side and the load side, q-axis current error, and disturbance rate of change, the stiffness-flexibility state discrimination function is obtained by weighting and summing them together with the corresponding weighting coefficients.

5. The rigid-flexible switching control method for the permanent magnet synchronous motor of the robot joint module as described in claim 4, characterized in that, The method for obtaining the continuous switching factor is as follows: Set rigid thresholds and flexible thresholds; The discriminant function value is obtained based on the rigid-flexible state discriminant function; Determine whether the value of the discrimination function is greater than or equal to the flexible threshold; If so, the current operating condition is determined to be a flexible control state, and the continuous switching factor is set to 0; Otherwise, determine whether the value of the discrimination function is greater than the rigid threshold; If so, the current operating condition is determined to be a rigid-flexible transition state, and the continuous switching factor is obtained based on the discrimination function value, the rigid threshold, and the flexible threshold; Otherwise, the current operating condition is determined to be a rigid control state, and the continuous switching factor is set to 1.

6. The rigid-flexible switching control method for the permanent magnet synchronous motor of the robot joint module as described in claim 5, characterized in that, To determine the current operating condition, a hysteresis criterion is introduced: Set rigid entry threshold, rigid exit threshold, flexible entry threshold, and flexible exit threshold; When the previous moment was in a rigid control state, if the value of the discrimination function is greater than or equal to the rigid exit threshold for a preset duration, a switch from the rigid control state to the rigid-flexible transition state is triggered. When the previous moment was in a flexible control state, if the value of the discrimination function is less than or equal to the flexible exit threshold for a preset duration, a switch from the flexible control state to the rigid-flexible transition state is triggered. When the system is in a transitional state, it switches to a rigid control state after the discrimination function value is less than or equal to the rigid entry threshold for a preset duration; and switches to a flexible control state after the discrimination function value is greater than or equal to the flexible entry threshold for a preset duration.

7. The rigid-flexible switching control method for the permanent magnet synchronous motor of the robot joint module as described in claim 6, characterized in that, The reconstructed control parameter set is obtained, specifically including: Based on the motor parameters, reduction ratio, load inertia, transmission stiffness, driver bandwidth and target operating conditions of the permanent magnet synchronous motor, a rigid parameter set and a flexible parameter set are pre-tuned and used together as the rigid-flexible control parameter set. The rigid-flexible control parameter set is reconstructed based on the continuous switching factor to obtain the reconstructed control parameter set. The reconfiguration control parameter set includes: reconfiguration speed loop proportional coefficient, reconfiguration speed loop integral coefficient, reconfiguration current loop proportional coefficient, reconfiguration current loop integral coefficient, reconfiguration damping compensation coefficient, and upper limit of reconfiguration torque change rate.

8. The rigid-flexible switching control method for the permanent magnet synchronous motor of the robot joint module as described in claim 7, characterized in that, The biaxial reference current is obtained, specifically including: Based on the reconstructed speed loop proportional coefficient, the reconstructed speed loop integral coefficient, and the speed error at the previous moment, the basic torque command output by the speed loop is obtained as the original target torque. Based on the reconstructed damping compensation coefficient, a damping correction term is obtained, and the original target torque command is damped to obtain a corrected target torque command. Based on the modified target torque command, the rate of change is constrained to obtain the torque increment; Based on the upper limit of the reconstructed torque change rate and the torque increment, construct the allowable torque increment after limiting; Based on the allowable torque increment and the torque reference value at the previous moment, the torque reference value after the rate of change constraint is obtained. The final torque reference value is generated by first-order filtering based on the torque reference value. Based on the final torque reference value and relevant motor parameters, the d-axis reference current and q-axis reference current corresponding to the permanent magnet synchronous motor are obtained, which together form the dual-axis reference current.

9. The rigid-flexible switching control method for the permanent magnet synchronous motor of the robot joint module as described in claim 8, characterized in that, Based on the dual-axis voltage reference command, the permanent magnet synchronous motor is subjected to rigid-flexible switching control, specifically including: Based on the reconstructed current loop proportional coefficient, the reconstructed current loop integral coefficient, the d-axis reference current and the q-axis reference current, and combined with the stator voltage model, the d-axis voltage reference command and the q-axis voltage reference command are obtained, which together form the dual-axis voltage reference command. Based on the dual-axis voltage reference command, an inverter switching drive signal is generated through inverse Park transform, inverse Clarke transform, and space vector pulse width modulation. Closed-loop control of the electromagnetic torque of the permanent magnet synchronous motor is achieved based on the inverter switching drive signal.

10. A rigid-flexible switching control system for a permanent magnet synchronous motor in a robot joint module, used to execute the rigid-flexible switching control method for a permanent magnet synchronous motor in a robot joint module as described in any one of claims 1-9, characterized in that, include: The system includes a coupled model construction module, a state feature acquisition module, a rigid-flexible state discrimination module, a control parameter reconstruction module, a reference current acquisition module, and a rigid-flexible state switching module. The coupling model construction module is used to construct a relevant coupling model based on the permanent magnet synchronous motor of the target robot joint module. The state feature acquisition module is used to acquire the state feature quantities of the joint module based on the relevant coupling model; The rigid-flexible state discrimination module is used to construct a rigid-flexible state discrimination function based on the state feature quantity and generate a continuous switching factor. The control parameter reconstruction module is used to reconstruct the rigid-flexible control parameter set of the permanent magnet synchronous motor based on the continuous switching factor to obtain the reconstructed control parameter set. The reference current acquisition module is used to perform damping correction and smoothing shaping on the target torque based on the reconstructed control parameter group to obtain a biaxial reference current. The rigid-flexible state switching module is used to obtain a dual-axis voltage reference command based on the reconstructed control parameter group, the dual-axis reference current, and the related coupling model. The permanent magnet synchronous motor is subjected to rigid-flexible switching control based on the dual-axis voltage reference command.

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