Robot load disturbance rejection method and device under torque limit conditions

Abstract

The application discloses a robot load disturbance suppression method and device under torque limiting conditions, relates to the technical field of robot servo driving, and comprises the following steps: acquiring robot joint load operation data, judging whether the robot joint load is mutated; when the robot joint load is not mutated, taking the output signal of a speed outer loop controller as a control instruction to control the stable operation of the robot joint; when the robot joint is mutated, the electromagnetic torque response of a servo motor is reconstructed under the condition that the joint torque safety is limited, so that the joint angular velocity and the output torque quickly converge to the reference value and are kept stable; and after the torque response reconstruction process is completed, the stable operation mechanism is switched back, the output signal of the speed outer loop controller is still taken as the control instruction, and the speed outer loop is recovered to normal adjustment. The application adopts the above method and device, under the premise of meeting the safety constraints, so that the joint torque and the angular velocity only need to be dynamically adjusted once to quickly converge to the reference value.

Description

Technical Field

[0001] This invention relates to the field of robot servo drive technology, and in particular to a method and apparatus for suppressing robot load disturbances under torque-limited conditions. Background Technology

[0002] Industrial robots and collaborative robots are core equipment for intelligent manufacturing and flexible production. The dynamic performance of their joints directly determines the overall operating efficiency, motion accuracy, and operational safety of the robot. Currently, high-precision robot joints generally use surface-mounted permanent magnet synchronous motors as actuators. These motors have significant advantages such as low torque ripple, high control accuracy, low rotor inertia, and high power density, which can meet the high-speed and high-precision motion control requirements of robots.

[0003] Model predictive torque control (MMC) has become the mainstream high-performance control algorithm in the field of surface-mounted permanent magnet synchronous motor (PMSM) servo drives due to its advantages such as fast dynamic response, flexible handling of multiple constraints, and intuitive control structure. However, surface-mounted PMSMs have inherent drawbacks: their electromagnetic torque is strictly limited by the peak stator current and inverter capacity, resulting in weak overload capacity. Once the torque output exceeds the peak limit, it can easily lead to stator winding overheating, irreversible demagnetization of the permanent magnets, and damage to the inverter power devices, causing serious equipment failure.

[0004] Robots inevitably encounter various load-sudden changes during actual operations, such as the end effector grasping and releasing workpieces of different weights, flexible collisions with the working environment, and sudden changes in the equivalent inertia of joints due to changes in robot posture. Existing model predictive torque control has significant shortcomings in dealing with these situations: when the load changes drastically and unexpectedly, a mismatch occurs between the system's internal predictive model and the actual physical dynamics. The optimal voltage vector selected by the controller based on the mismatched model cannot constrain the torque within the motor's peak torque limit within a single control cycle. Simultaneously, joint angular velocities often require multiple adjustment cycles to converge to the reference value and are prone to secondary oscillations. This not only reduces the robot's cycle time but also causes end effector vibration, affecting the processing quality of precision assembly and grinding processes. More seriously, torque exceeding the motor's peak torque limit may directly damage the surface-mount permanent magnet synchronous motor. Therefore, how to improve the dynamic response speed and convergence stability under load-sudden changes while strictly meeting the torque safety constraints of the surface-mount permanent magnet synchronous motor is a key technical problem that urgently needs to be solved in the field of robot servo control. Summary of the Invention

[0005] The purpose of this invention is to provide a method and apparatus for suppressing robot load disturbances under torque-constrained conditions, which overcomes the shortcomings of existing technologies where robot joint servo drive motors are difficult to simultaneously achieve strict torque constraints and rapid, oscillation-free convergence under sudden load changes.

[0006] To achieve the above objectives, the present invention provides a method for suppressing robot load disturbances under torque-constrained conditions, comprising: S0. Obtain robot joint load operation data and determine whether the robot joint load has changed abruptly. S1. When the robot joint load does not change abruptly, the output signal of the speed outer loop controller is used as a control command to control the robot joint to operate stably. S2. When a sudden load change occurs at a robot joint, under the condition that the joint torque is limited, the electromagnetic torque response of the servo motor is reconstructed so that the joint angular velocity and output torque quickly converge to the reference value and remain stable. S3. After the torque response reconstruction process in step S2 is completed, switch back to the steady-state operation mechanism in step S1, and still use the output signal of the speed outer loop controller as the control command, while the speed outer loop resumes normal regulation.

[0007] Preferably, the specific content of step S1 is as follows: The output signal of the speed outer loop controller is the reference torque. Based on this reference torque, the optimal option is selected from the candidate voltage vectors and applied to the joint servo motor to achieve high-precision and stable control of the robot joint.

[0008] Preferably, step S2 contains the following: S21. Electromagnetic torque response reconstruction method under torque-constrained conditions; S22. Solve for the key parameters of the electromagnetic torque response reconstruction method.

[0009] Preferably, the electromagnetic torque response reconstruction process in step S21 is as follows: S211. After a load change occurs, the magnitude of the load change is quickly estimated using a load torque observer or sensor. During this process, the electromagnetic torque of the servo motor remains constant. Because the joint output torque is less than the actual load torque, the joint angular velocity continues to decrease. S212. Apply positive ramp torque compensation to increase electromagnetic torque. At this time, the joint output torque is still less than the load torque, and the joint angular velocity continues to decrease, but the rate of decrease gradually slows down as the torque difference decreases; when the joint output torque is balanced with the load torque, the angular velocity stops decreasing. S213. Continue to apply positive ramp compensation to further increase the electromagnetic torque; the joint output torque begins to exceed the load torque, and the angular velocity changes from decreasing to increasing; this process continues until the electromagnetic torque reaches the motor peak torque limit set by the system. S214. The electromagnetic torque is maintained at the motor peak torque limit, and the joint angular velocity continues to increase with this constant value. S215. Apply negative ramp torque compensation, and the electromagnetic torque begins to decrease. During this stage, the joint output torque is still greater than the load torque, so the angular velocity continues to rise, but the rate of increase slows down as the torque difference decreases. When the electromagnetic torque decreases to the point where the joint output torque is equal to the load torque, the system stops compensation. At this point, the joint torque and the load torque are balanced, the angular velocity stabilizes at the given value, and the robot returns to a steady-state operating state.

[0010] Preferably, step S22 contains the following: The torque compensation during the electromagnetic torque response reconstruction process can be expressed as: ; in, , , , , , These are the load sudden change time, the system completion time for tracking and estimating the magnitude of the sudden change, the time when the electromagnetic torque first reaches the load torque, the end time of positive torque compensation, the end time of torque compensation hold, and the end time of negative torque compensation. , , , , , They are respectively , , , , , Electromagnetic torque compensation value at time t. and These are the positive slope compensation slope and the negative slope compensation slope, respectively. The key parameters can be solved for: ; and Furthermore: ; Solving for the results and The range of values ​​for can be represented as: .

[0011] A robot load disturbance suppression device under torque-constrained conditions includes: The load change detection module is used to quickly estimate or measure the magnitude of the load change by means of a load torque observer or sensor when a sudden change occurs in the load on the robot joint. The electromagnetic torque response reconstruction module is used to actively reconstruct the electromagnetic torque response of the servo motor under the condition of limited joint torque, so that the joint angular velocity and output torque can quickly converge to the reference value and remain stable. The torque compensation parameter solving unit is used to solve the key parameters in the electromagnetic torque response reconstruction process, including the positive slope compensation slope, the negative slope compensation slope, and each time node. The steady-state control module is used to maintain the model predictive torque control strategy by outputting control commands from the speed outer loop controller when there is no sudden change in the joint load. The mode switching module is used to switch the system back to a steady-state operation mechanism where control commands are generated by the output signal of the speed outer loop controller after the torque response reconstruction process is completed.

[0012] Therefore, the present invention adopts the above-mentioned method and device for suppressing robot load disturbances under torque-constrained conditions. By actively designing and reconstructing the dynamic response process of the electromagnetic torque of the servo motor, the torque output is strictly constrained to not exceed the safety limit throughout the entire process under the condition of sudden load change. Under the premise of meeting the system torque constraint conditions, the joint output torque and angular velocity can be quickly converged to the reference value and maintain stable operation with only one dynamic adjustment. This effectively solves the problems of multiple oscillations and slow convergence in traditional control methods under torque-constrained scenarios, and significantly improves the load disturbance suppression capability and dynamic response performance of the robot joint control system.

[0013] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. Attached Figure Description

[0014] Figure 1 This is a flowchart of an embodiment of the robot load disturbance suppression method under torque-limited conditions according to the present invention; Figure 2 This is a schematic diagram of the electromagnetic torque response reconstruction process according to an embodiment of the present invention; Figure 3 This is a control block diagram of an embodiment of the robot load disturbance suppression method under torque-limited conditions of the present invention; Figure 4 This is a schematic diagram of the structure of an electronic device provided in an embodiment of the present invention. Detailed Implementation

[0015] The technical solution of the present invention will be further described below with reference to the accompanying drawings and embodiments.

[0016] Unless otherwise defined, the technical or scientific terms used in this invention shall have the ordinary meaning understood by one of ordinary skill in the art to which this invention pertains. The terms "first," "second," and similar terms used in this invention do not indicate any order, quantity, or importance, but are merely used to distinguish different components. Terms such as "comprising" or "including" mean that the element or object preceding the word encompasses the elements or objects listed following the word and their equivalents, without excluding other elements or objects. Terms such as "connected" or "linked" are not limited to physical or mechanical connections, but can include electrical connections, whether direct or indirect. Terms such as "upper," "lower," "left," and "right" are used only to indicate relative positional relationships; when the absolute position of the described object changes, the relative positional relationship may also change accordingly.

[0017] Example Please see Figures 1-3 This invention provides a method for suppressing robot load disturbances under torque-constrained conditions, comprising: S0. Obtain robot joint load operation data and determine whether the robot joint load has changed abruptly.

[0018] S1. When the robot joint load does not change abruptly, the output signal of the speed outer loop controller is used as a control command to control the stable operation of the robot joint. The output signal of the speed outer loop controller is a reference torque. Based on this reference torque, the optimal option is selected from the candidate voltage vectors and applied to the joint servo motor to achieve high-precision and stable control of the robot joint.

[0019] S2. When a sudden load change occurs at a robot joint, under the condition that the joint torque is limited, the electromagnetic torque response of the servo motor is reconstructed so that the joint angular velocity and output torque quickly converge to the reference value and remain stable.

[0020] S21. Electromagnetic torque response reconstruction method under torque-constrained conditions.

[0021] The specific details of the electromagnetic torque response reconstruction process are as follows: S211. After a load change occurs, the magnitude of the load change is quickly estimated using a load torque observer or sensor. During this process, the electromagnetic torque of the servo motor remains constant. Because the joint output torque is less than the actual load torque, the joint angular velocity continues to decrease. S212. Apply positive ramp torque compensation to increase electromagnetic torque. At this time, the joint output torque is still less than the load torque, and the joint angular velocity continues to decrease, but the rate of decrease gradually slows down as the torque difference decreases; when the joint output torque is balanced with the load torque, the angular velocity stops decreasing. S213. Continue to apply positive ramp compensation to further increase the electromagnetic torque; the joint output torque begins to exceed the load torque, and the angular velocity changes from decreasing to increasing; this process continues until the electromagnetic torque reaches the motor peak torque limit set by the system. S214. The electromagnetic torque is maintained at the motor peak torque limit, and the joint angular velocity continues to increase with this constant value. S215. Apply negative ramp torque compensation, and the electromagnetic torque begins to decrease. During this stage, the joint output torque is still greater than the load torque, so the angular velocity continues to rise, but the rate of increase slows down as the torque difference decreases. When the electromagnetic torque decreases to the point where the joint output torque is equal to the load torque, the system stops compensation. At this point, the joint torque and the load torque are balanced, the angular velocity stabilizes at the given value, and the robot returns to a steady-state operating state.

[0022] S22. Solve for the key parameters of the electromagnetic torque response reconstruction method.

[0023] The torque compensation during the electromagnetic torque response reconstruction process can be expressed as: ; in: , , , , , These are the load sudden change time, the system completion time for tracking and estimating the magnitude of the sudden change, the time when the electromagnetic torque first reaches the load torque, the end time of positive torque compensation, the end time of torque compensation hold, and the end time of negative torque compensation. , , , , , They are respectively , , , , , Electromagnetic torque compensation value at time t. and These are the positive slope compensation slope and the negative slope compensation slope, respectively.

[0024] Neglecting the viscous friction coefficient and Coulomb friction torque of the robot joint system, the motion equation of the permanent magnet synchronous motor can be expressed as: ; in: For electromagnetic torque, For load torque, For rotational inertia, For extreme logarithms, It represents the electrical angular velocity.

[0025] For the above formula in the time interval Integrating within the inner quadrant yields: ; in: and They are respectively and The electrical angular velocity at a given moment.

[0026] To restore the motor to a stable operating state, and They should be equal. The above equation can be further transformed into the torque impulse balance condition: ; remember , , , , Each region , , , , The area of ​​the region can be represented as: ; and It can be represented as: ; according to Figure 2 ,have: ; The torque impulse equilibrium condition can be transformed into a relationship of equal areas, that is: ; Solving the above equation, we get: ; To ensure the existence of (2), there must be Furthermore: ; Solving the above equation yields... and The range of values ​​for can be represented as: .

[0027] S3. After the torque response reconstruction process in step S2 is completed, switch back to the steady-state operation mechanism in step S1. The output signal of the speed outer loop controller is still used as the control command. At the same time, the speed outer loop resumes normal adjustment to ensure the trajectory tracking accuracy and positioning accuracy of the robot end effector.

[0028] It also provides a robot load disturbance suppression device under torque-constrained conditions, including: The load change detection module is used to quickly estimate or measure the magnitude of the load change by means of a load torque observer or sensor when a sudden change occurs in the load on a robot joint.

[0029] The electromagnetic torque response reconstruction module is used to actively reconstruct the electromagnetic torque response of the servo motor under conditions of limited joint torque, so that the joint angular velocity and output torque can quickly converge to the reference value and remain stable.

[0030] The torque compensation parameter solving unit is used to solve the key parameters in the electromagnetic torque response reconstruction process, including the positive slope compensation slope, the negative slope compensation slope, and each time node. The steady-state control module is used to maintain the model predictive torque control strategy by outputting control commands from the speed outer loop controller when there is no sudden change in the joint load.

[0031] The mode switching module is used to switch the system back to a steady-state operation mechanism where control commands are generated by the output signal of the speed outer loop controller after the torque response reconstruction process is completed.

[0032] Figure 3 This is a control block diagram of an embodiment of the robot load disturbance suppression method under torque-constrained conditions provided by this invention. Wherein, is... Given an electrical angular velocity, This is the actual electrical angular velocity. For motor angular velocity tracking error, For load torque observations, For a given stator flux linkage, for Stator flux linkage at time, for Stator current at time t, for Stator flux linkage at time, for Electromagnetic torque at time t, for Stator voltage at time t, , , Inverter switching state. This is the bus voltage.

[0033] Figure 4 This is a schematic diagram of the structure of an electronic device provided in an embodiment of the present invention. The electronic device may vary considerably due to different configurations or performance. It may include one or more processors (central processing units, CPUs) and one or more memories. The memory stores at least one instruction, which is loaded and executed by the processor to implement the above-mentioned method for suppressing robot load disturbance under torque-limited conditions.

[0034] A computer-readable storage medium is also provided, such as a memory including instructions that can be executed by a processor in a terminal to perform the above-described method for suppressing robot load disturbances under torque-constrained conditions. For example, the computer-readable storage medium may be a ROM, random access memory (RAM), CD-ROM, magnetic tape, floppy disk, or optical data storage device.

[0035] Therefore, the present invention adopts the above-mentioned method and device for suppressing robot load disturbances under torque-constrained conditions. By actively designing and reconstructing the dynamic response process of the electromagnetic torque of the servo motor, the torque output is strictly constrained to not exceed the safety limit throughout the entire process under the condition of sudden load change. Under the premise of meeting the system torque constraint conditions, the joint output torque and angular velocity can be quickly converged to the reference value and maintain stable operation with only one dynamic adjustment. This effectively solves the problems of multiple oscillations and slow convergence in traditional control methods under torque-constrained scenarios, and significantly improves the load disturbance suppression capability and dynamic response performance of the robot joint control system.

[0036] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit them. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can still be made to the technical solutions of the present invention, and these modifications or equivalent substitutions cannot cause the modified technical solutions to deviate from the spirit and scope of the technical solutions of the present invention.

Claims

1. A method for suppressing robot load disturbance under torque-constrained conditions, characterized in that, include: S0. Obtain robot joint load operation data and determine whether the robot joint load has changed abruptly. S1. When the robot joint load does not change abruptly, the output signal of the speed outer loop controller is used as a control command to control the robot joint to operate stably. S2. When a sudden load change occurs at a robot joint, under the condition of limited joint torque safety, the electromagnetic torque response of the servo motor is reconstructed to quickly converge the joint angular velocity and output torque to the reference value and maintain stability; the details are as follows: S21. Electromagnetic torque response reconstruction method under torque-constrained conditions; details are as follows: S211. After a load change occurs, the magnitude of the load change is quickly estimated using a load torque observer or sensor. During this process, the electromagnetic torque of the servo motor remains constant. Because the joint output torque is less than the actual load torque, the joint angular velocity continues to decrease. S212. Apply positive ramp torque compensation to increase electromagnetic torque. At this time, the joint output torque is still less than the load torque, and the joint angular velocity continues to decrease, but the rate of decrease gradually slows down as the torque difference decreases. When the joint output torque is balanced with the load torque, the angular velocity stops decreasing. S213. Continue to apply positive ramp compensation to further increase the electromagnetic torque; the joint output torque begins to exceed the load torque, and the angular velocity changes from decreasing to increasing; this process continues until the electromagnetic torque reaches the preset motor peak torque limit. S214. The electromagnetic torque is maintained at the motor peak torque limit, and the joint angular velocity continues to increase with this constant value. S215. Apply negative ramp torque compensation. The electromagnetic torque begins to decrease. During this stage, the joint output torque is still greater than the load torque, so the angular velocity continues to rise, but the rate of increase slows down as the torque difference decreases. When the electromagnetic torque decreases to the point where the joint output torque is equal to the load torque, compensation stops. At this point, the joint torque and the load torque are balanced, the angular velocity stabilizes at the given value, and the robot returns to a steady-state operating state. S22. Solve for the key parameters of the electromagnetic torque response reconstruction method; S3. After the torque response reconstruction process in step S2 is completed, switch back to the steady-state operation mechanism in step S1, and still use the output signal of the speed outer loop controller as the control command, while the speed outer loop resumes normal regulation.

2. The method for suppressing robot load disturbance under torque-constrained conditions according to claim 1, characterized in that, The specific content of step S1 is as follows: The output signal of the speed outer loop controller is the reference torque. Based on this reference torque, the optimal option is selected from the candidate voltage vectors and applied to the joint servo motor to achieve high-precision and stable control of the robot joint.

3. The method for suppressing robot load disturbance under torque-constrained conditions according to claim 1, characterized in that, The content of step S22 is as follows: The torque compensation during the electromagnetic torque response reconstruction process can be expressed as: ； in, , , , , , These are the load sudden change time, the system completion time for tracking and estimating the magnitude of the sudden change, the time when the electromagnetic torque first reaches the load torque, the end time of positive torque compensation, the end time of torque compensation hold, and the end time of negative torque compensation. , , , , , They are respectively , , , , , Electromagnetic torque compensation value at time t. and These are the positive slope compensation slope and the negative slope compensation slope, respectively. The key parameters were obtained by solving: ； and Furthermore: ； Solving for the results and The range of values ​​for can be represented as: 。 4. A robot load disturbance suppression device under torque-limited conditions, employing the robot load disturbance suppression method under torque-limited conditions as described in any one of claims 1-3, characterized in that, include: The load change detection module is used to quickly estimate or measure the magnitude of the load change by means of a load torque observer or sensor when a sudden change occurs in the load on the robot joint. The electromagnetic torque response reconstruction module is used to actively reconstruct the electromagnetic torque response of the servo motor under the condition of limited joint torque, so that the joint angular velocity and output torque can quickly converge to the reference value and remain stable. The torque compensation parameter solving unit is used to solve the key parameters in the electromagnetic torque response reconstruction process, including the positive slope compensation slope, the negative slope compensation slope, and each time node. The steady-state control module is used to maintain the model predictive torque control strategy by outputting control commands from the speed outer loop controller when there is no sudden change in the joint load. The mode switching module is used to switch the system back to a steady-state operation mechanism where control commands are generated by the output signal of the speed outer loop controller after the torque response reconstruction process is completed.

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