Motor soft landing control method and system based on finite time state observer and motor

Abstract

A motor soft landing control method, system and motor based on a finite-time state observer are provided. The method estimates external disturbance force in real time through a finite-time state observer, and dynamically adjusts the approach speed according to the difference between the target holding force and the actual estimated force, to realize a force-adaptive soft landing process. Compared with traditional methods, the technology does not require a large amount of pre-test data, saves time, has strong universality, short convergence time, almost no lag, and meets the high-tact production demand. The system does not need a special force sensor, but only uses motor current and position information to realize accurate force control, significantly improves product quality and reduces cost.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of motor control, in particular to a motor soft landing control method and system based on a finite-time state observer and a motor. BACKGROUND

[0002] Motors, such as voice coil motors, are widely used in high-precision positioning platforms, image stabilization systems, precision medical devices, and flexible robots due to their simple structure, fast dynamic response speed, high linearity, long service life, and other characteristics. However, in actual applications, due to the influence of mechanical structure and load, there will be some external forces (such as gravity, elastic force, magnetic force, etc.) during movement, which seriously affects the landing accuracy and stability of the motor.

[0003] Currently, lookup table method and observer method are mainly used to solve this problem. The lookup table method compensates the current based on position feedback, but has the following obvious shortcomings:

[0004] 1. A large amount of pre-test data is required, which consumes a lot of time and has high implementation cost;

[0005] 2. Poor universality, different lookup tables need to be established for different working conditions, which is difficult to be used universally among products;

[0006] 3. Difficult to adapt to complex nonlinear external forces (such as cogging force, magnetic spring, viscous friction, etc.);

[0007] 4. Unable to handle dynamic changes in load, weak adaptability to environmental changes;

[0008] 5. Low storage and query efficiency, occupying system resources, increasing hardware cost;

[0009] Although the conventional observer is more flexible than the lookup table method, the traditional linear observer has slow convergence speed, resulting in obvious lag in compensation current, limited observation accuracy, and inability to meet the high real-time requirements in fast-paced production scenarios.

[0010] Therefore, there is an urgent need in the prior art for a smooth and efficient motor soft landing solution. SUMMARY

[0011] To solve the above technical problems, the specific technical solutions of the present application are as follows:

[0012] In order to solve the above technical problems, the specific technical solutions of the present application are as follows:

[0013] On the one hand, the present application provides a motor soft landing control method based on a finite-time state observer, which comprises:

[0014] S1: obtaining a target force value of the motor during landing, the target force value being a preset value;

[0015] S2: obtaining running data of the motor, the running data at least including speed data and current data;

[0016] S3: designing a finite-time state observer to estimate an external force value of the motor during landing in a current state according to the running data of the motor;

[0017] S4: when an error between the external force value and the target force value is not lower than a preset threshold, adjusting the running data of the motor according to the error to make the external force value of the motor during landing close to the target force value;

[0018] S5: repeating steps S2-S4 at a preset time step, and when the error between the external force value and the target force value is smaller than the preset threshold, maintaining the current running parameter until the landing of the motor is completed.

[0019] Further, the designing of the finite-time state observer to estimate the external force value of the motor during landing in the current state according to the running data of the motor includes:

[0020] collecting the speed data and the current data of the motor at a preset time step;

[0021] determining a speed error at a current collection time according to the speed data at the current collection time and an observed speed at a previous collection time, wherein the observed speed is a state variable obtained by cumulative integration of the motion data of the motor by using a nonlinear feedback gain algorithm, and an initial value of the observed speed is 0;

[0022] updating an observed disturbance acceleration derivative at the current collection time according to the speed error at the current collection time and a nonlinear observed acceleration gain;

[0023] updating an observed disturbance acceleration at the current collection time according to the observed disturbance acceleration derivative at the current collection time and the observed disturbance acceleration at the previous collection time;

[0024] updating an observed speed derivative at the current collection time according to the speed error at the current collection time, the current data, the observed disturbance acceleration at the current collection time, and a nonlinear observed speed gain;

[0025] updating the observed speed at the current collection time according to the observed speed derivative at the current collection time and the observed speed at the previous collection time, for estimating the external force value at a next collection time;

[0026] According to the observed disturbance acceleration at the current acquisition time, an external force value borne by the motor during landing is estimated.

[0027] Further, the finite time state observer estimates the external force value by the following formula:

[0028]

[0029] wherein, e is a speed error; v is speed data, obtained by differentiating the encoder position; z2 is an observed speed, and the initial value is 0; z3 is an observed disturbance acceleration, and the initial value is 0; dz2 is z2 the derivative of dz3 the derivative of z3 , k2 and k3 is a nonlinear observer gain; dt is a time step; I is current data of the motor; Mn is the ratio of the moving mass to the torque constant; sign (e) is a speed error sign function; abs(e) is the absolute value of the speed error, F est is an estimated external force value borne by the motor.

[0030] Further, when the error between the external force value and the target force value is not lower than a preset threshold, the operation data of the motor is adjusted according to the error, including:

[0031] According to the error between the external force value and the target force value, the speed data of the motor is updated by a proportional integral algorithm;

[0032] The current data of the motor is adjusted to obtain updated speed data of the motor.

[0033] Further, the speed data of the motor is updated by the following formula:

[0034]

[0035] wherein, v is speed data; k p is a proportional coefficient; k i is an integral coefficient ；F target is a target force value; F estto estimate the external force value of the motor.

[0036] Further, the operation data of the motor further comprises terminal position data, and before the step S1, the operation data further comprises

[0037] S01: a pre-landing step, using a preset current to control the motor to complete pre-landing, and obtaining terminal position data of the motor at the pre-landing, wherein the external force value at the pre-landing is less than the target force value;

[0038] The distance between the terminal position data and the initial position of the motor is calculated, and the motion state of the motor is divided into a high-speed approach stage, a transition state stage, a force control approach stage, and a final positioning stage according to the distance.

[0039] Further, when the distance between the terminal position data and the initial position of the motor is greater than a preset interval, the distance is divided into a high-speed interval, a transition interval, and a force control approach interval.

[0040] The motor is controlled to enter the high-speed approach stage at full speed, and the speed data of the motor is reduced according to a preset rule. When the speed data is lower than a first preset value and the position data of the motor enters the transition interval, the current operation data is maintained to control the motor to enter the force control approach interval, and the step S1 is executed with the current operation data.

[0041] Further, when the error between the external force value and the target force value is less than a preset threshold value, and the position data of the motor is consistent with the terminal position data of the motor, the motor completes landing and enters the final positioning stage.

[0042] On the other hand, the present document also provides a motor soft landing control system based on a finite-time state observer, which comprises a motor and a target workpiece.

[0043] The motor comprises a controller configured to execute the motor soft landing control method based on the finite-time state observer as described above.

[0044] Finally, the present document also provides a motor comprising a memory, a processor, and a computer program stored on the memory and executable on the processor, wherein the processor executes the computer program to implement the motor soft landing control method based on the finite-time state observer as described above.

[0045] By adopting the technical scheme, the motor soft landing control method, system and motor based on the finite-time state observer can realize a force self-adaptive soft landing process by estimating external disturbance force in real time through the finite-time state observer and dynamically adjusting the approach speed according to the difference between the target holding force and the actual estimated force, and realize accurate force control without a pressure sensor through position feedback and external force estimation, so as to ensure controllable and smooth transition of force in the landing process.

[0046] In order to make the above and other objects, features and advantages of the present application more apparent, preferred embodiments will be described in detail below with the accompanying drawings, and will be specifically explained as follows. BRIEF DESCRIPTION OF DRAWINGS

[0047] In order to more clearly illustrate the technical solutions in the embodiments or the prior art, the accompanying drawings needed to be used in the embodiments or prior art description will be briefly introduced as follows. Obviously, the accompanying drawings in the following description only represent some embodiments of the present application, and all other drawings can be obtained by those skilled in the art without any creative effort.

[0048] Figure 1 A step schematic diagram of the motor soft landing control method based on the finite-time state observer provided by the embodiments of the present application is shown;

[0049] Figure 2 A frame schematic diagram of the motor soft landing control system based on the finite-time state observer provided by the embodiments of the present application is shown. DETAILED DESCRIPTION

[0050] The technical solutions in the embodiments of the present application will be described clearly and completely below with the accompanying drawings in the embodiments of the present application. Obviously, the described embodiments only represent some of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without any creative effort fall within the scope of protection of the present application.

[0051] It should be noted that the terms "first", "second", and the like in the specification and claims of the present application and the above-mentioned accompanying drawings are used to distinguish similar objects, and do not necessarily indicate a specific order or sequence. It should be understood that the data thus used can be interchanged under appropriate circumstances, so that the embodiments of the present application described herein can be implemented in an order other than that illustrated or described herein. In addition, the terms "include" and "have" and any variations thereof are intended to cover non-exclusive inclusion, for example, a process, method, device, product or equipment including a series of steps or units does not necessarily have to be limited to those steps or units clearly listed, but can include other steps or units not clearly listed or inherent to the process, method, product or equipment.

[0052] For the control problem of the voice coil motor, the table lookup method and the observer method are currently mainly used to solve this problem. The table lookup method compensates the current according to the position feedback, and although the conventional observer is more flexible than the table lookup method, the traditional linear observer has slow convergence speed, which leads to obvious lag of the compensation current, limited observation accuracy, and cannot meet the high real-time requirements in fast-paced production scenarios.

[0053] In order to solve the above problems, the motor soft landing control method based on the finite time state observer provided by the embodiments of the present application can realize efficient, smooth and accurate soft landing of the voice coil motor. Figure 1 is a step schematic diagram of the motor soft landing control method based on the finite time state observer provided by the embodiments of the present application. The present specification provides method operation steps as described in the embodiments or flowcharts, but more or fewer operation steps can be included based on conventional or non-creative labor. The order of steps listed in the embodiments is only one of the many step execution orders, and does not represent the only execution order. In actual system or device product execution, the method order shown in the embodiments or the drawings can be executed in sequence or in parallel. Specifically, as shown in Figure 1 The method can include:

[0054] S1: obtaining a target force value of the motor during landing, the target force value being a preset value;

[0055] S2: obtaining running data of the motor, the running data at least including speed data and current data;

[0056] S3: designing a finite time state observer to estimate an external force value received by the motor in the current state according to the running data of the motor;

[0057] S4: when the error between the external force value and the target force value is not less than a preset threshold, adjusting the running data of the motor according to the error, so that the external force value received by the motor during landing is close to the target force value;

[0058] S5: repeating steps S2-S4 according to a preset time step, and when the error between the external force value and the target force value is less than the preset threshold, maintaining the current running parameters until the landing of the motor is completed.

[0059] It can be understood that the motor can be an electromagnetic device for realizing electric energy conversion or transmission according to the electromagnetic induction law, and is mainly used in the field of engineering machinery, such as high-precision positioning platform, image stabilization system, precision medical equipment, flexible robot and other high-precision positioning systems, such as voice coil motor, which has the characteristics of high response, high precision, no friction and no cogging effect, and is widely used in the fields of precision positioning, automatic focusing, tactile feedback, etc. The motor control process is first estimated by designing a finite-time state observer for estimating the external force of the motor, so as to accurately estimate the external force of the motor during movement. In this way, based on the comparison of the estimated external force value and the target force value, the running data of the motor can be adjusted in real time or periodically, so that the external force received by the motor gradually approaches the target force value, and high-precision control in the soft landing process of the motor can be realized, thereby improving the processing reliability of the workpiece and the stability of the motor control. The target force value can be the processing accuracy or requirement of the target workpiece.

[0060] The motor is in contact with the target workpiece through a terminal, and completes processing of the target workpiece. The motor terminal can be understood as an end execution end, which is a contact element between the motor and the workpiece, and is a component for processing the workpiece. Different types of end execution ends can be configured according to different material types and processing requirements of the target workpiece, thereby expanding the use scenarios and production adaptability of the motor.

[0061] The motor running data is periodically obtained, and the finite-time state observer is designed to estimate the external force of the motor in time, so as to adjust the motor running data in time and improve the accuracy and timeliness of the motor control.

[0062] The execution logic of the finite-time state observer is as follows:

[0063] The speed data and current data of the motor are collected at a preset time step;

[0064] The speed error at the current collection time is determined according to the speed data at the current collection time and the observed speed at the last collection time, wherein the observed speed is a state variable obtained by accumulating and integrating the motion data of the motor by using a nonlinear feedback gain algorithm, and the initial value of the observed speed is 0;

[0065] The observed disturbance acceleration derivative at the collection time is updated according to the speed error at the current collection time and the nonlinear observation acceleration gain;

[0066] The observed disturbance acceleration at the current collection time is updated according to the observed disturbance acceleration derivative at the current collection time and the observed disturbance acceleration at the last collection time;

[0067] According to the speed error, the current data and the observation disturbance acceleration at the current collection time, and the nonlinear observation speed gain, the observation speed derivative at the current collection time is updated;

[0068] According to the observation speed derivative at the current collection time and the observation speed at the last collection time, the observation speed at the current collection time is updated for estimating the external force value at the next collection time;

[0069] According to the observation disturbance acceleration at the current collection time, the external force value of the motor landing is estimated.

[0070] It can be understood that, in the embodiments of the present specification, the observer takes the position and speed as the state variables for estimating the external force, and takes the historical data (such as the previous collection node) as the basis for updating the subsequent running data, and uses the nonlinear feedback gain to realize the finite time convergence. At the beginning, the observation speed is zero, and the observation disturbance acceleration and the observation speed in the observer are updated combined with the actual speed data and the current data of the motor, and the external force value of the motor in each collection period is estimated, so that the fast convergence estimation of the external force of the motor is realized, and the convergence speed and the observation accuracy are greatly improved.

[0071] In the embodiments of the present specification, different collection periods (i.e. preset time steps) can be set according to different workpiece processing requirements and motor configuration parameters. Optionally, the collection period can be 1ms-5ms, such as 1ms, 2ms, 3ms. The shorter the time is, the faster the convergence speed of the observer is, and the more accurate the motor control is, but the higher the performance requirement of the motor is, and the greater the required computing resources are. Therefore, a suitable collection period needs to be selected according to the actual demand.

[0072] On the basis of the execution logic of the finite time state observer provided in the above, the present specification further provides an implementation manner of the finite time observer, as shown in the following formula:

[0073]

[0074] wherein, e is the speed error; v is the speed data, which is obtained by differentiating the encoder position; z2 is the observation speed, and the initial value is 0; z3 is the observation disturbance acceleration, and the initial value is 0; dz2 is z2 the derivative of dz3 the derivative of z3 , k2 and k3 is the nonlinear observer gain; dt is the time step; Iis the current data of the motor; Mn is the ratio of the moving mass and the torque constant; sign (e) is the speed error sign function; abs(e) is the absolute value of the speed error, F est is the estimated value of the external force acting on the motor.

[0075] By using the difference between the actual speed and the observed speed, the observed disturbance acceleration received by the motor during movement is fed back with a fractional power gain, so as to realize the integral update of the observed speed. In this way, the entire observer can achieve the effect of nonlinear gain, and combined with the current speed and torque constant of the motor, periodic estimation of the external force acting on the motor can be realized, that is, consistent with the frequency of data collection (time step), real-time and rapid convergence of the estimation of the external force acting on the motor is realized, and the lag problem of the traditional observer is avoided.

[0076] The torque constant is an attribute of the working performance of the motor, which can be a fixed value in the embodiments of the present specification, or can be adjusted with the working state of the motor. The torque constant can change accordingly.

[0077] In the embodiments of the present specification, the target force value can be the standard required by the target workpiece processing, that is, the contact force between the motor terminal and the target workpiece when the processing requirement condition is reached, which represents the size of the force exerted by the motor terminal on the target workpiece. Therefore, in the process of controlling the motor, the external force acting on the motor (which should represent the reaction force received by the contact between the motor and the target workpiece at this time) should gradually approach the target force value, so as to ensure the processing requirement of the target workpiece. Specifically, the running parameters of the motor can be adjusted adaptively according to the comparison relationship between the estimated external force value and the target force value, so that the external force value gradually approaches the target force value. Specifically:

[0078] When the error between the external force value and the target force value is not less than a preset threshold, the running data of the motor is adjusted according to the error, including:

[0079] The speed data of the motor is updated by a proportional integral algorithm according to the error between the external force value and the target force value;

[0080] The current data of the motor is adjusted to obtain the updated speed data of the motor.

[0081] It can be understood that, in order to achieve the purpose of self-adaptive adjustment of motor operation data, when the external force value has not reached the target force value, the motor speed data can be updated by a proportional integral algorithm according to the error between the estimated external force value and the target force value each time, and the speed data is generally realized by controlling the working current of the motor. Thus, on the basis of collecting the operation data of the motor based on the time step, the estimated external force value is updated, and then the relationship between the external force value and the target force value is used to adjust the operation data of the motor, so as to realize the cyclic self-adaptive control of the motor, achieve the effect of continuous control, avoid mechanical adjustment, and improve the control ability and accuracy of the motor.

[0082] The preset threshold can be the accuracy requirement of the target workpiece machining. The smaller the preset threshold is, the higher the machining requirement is, and vice versa. Therefore, the preset threshold can be determined according to the type of the target workpiece.

[0083] The embodiment of the present specification realizes fast and accurate estimation of external force by using a finite-time state observer. By establishing an observer model containing three state variables of position, speed and external force, a nonlinear feedback gain is used to realize finite-time convergence. Compared with the traditional linear observer, the convergence speed and observation accuracy are greatly improved. The observer uses a fractional power feedback gain structure to ensure that the observer converges in a finite time and has strong suppression ability to external disturbances.

[0084] Specifically, compared with the traditional lookup table method and the conventional observer, the scheme provided by the present specification has significant advantages in soft landing control:

[0085] 1. No need for massive test data: unlike the lookup table method, which requires pre-acquisition of a large amount of data, the method greatly saves time and implementation cost

[0086] 2. Fast convergence speed: fast convergence in a finite time, observation delay is less than 1ms, avoiding the lag problem of traditional observers

[0087] 3. Strong adaptive ability: can adapt to various complex nonlinear external forces and dynamically changing load conditions, and is robust to environmental disturbances

[0088] 4. Good real-time performance: millisecond-level response to external force changes, meeting high-tact production demands

[0089] 5. High universality: the same algorithm is applicable to multiple working conditions and products, without the need for redesign for different scenarios

[0090] 6. Low resource occupation: lightweight algorithm, no need to store a large number of query tables, reducing hardware cost

[0091] The comparison process is shown in Table 1,

[0092] Table 1 Advantages of the present scheme over the prior art

[0093]

[0094] In the embodiments of the present specification, on the basis of obtaining the estimated external force, the adaptive speed control algorithm based on external force feedback is used to update the approach speed between the motor terminal and the workpiece. The speed data update of the motor in each collection cycle can be represented by the following formula:

[0095]

[0096] Wherein, v is the approach speed, i.e. the updated speed data of the motor; kp is a proportional coefficient, which is used for linear amplification of the current error, fast response, which can improve the system response speed and reduce the error in the early stage of steady state; ki is an integral coefficient, which is used for amplification of the accumulated value of the error, "accountability" of the past error, and driving the error to zero, which can eliminate the steady state error (i.e. the long-term error is not 0).

[0097] It should be noted that ki is too large, which can easily lead to slow system response or oscillation and even instability (integral saturation); Ftarget is the target holding force; Fest is the estimated external force received by the motor, wherein kp and ki are set according to the actual situation, and Ftarget is set according to the processing requirements of the target workpiece.

[0098] It can be understood that the external force received by the motor can be obtained in real time through the finite time state observer, and the approach speed of the motor is updated based on the external force, so as to realize the adaptive adjustment of the approach speed of the motor terminal (i.e. the terminal), convert the force error into speed instruction, realize the adaptive adjustment of "the greater the force, the smaller the speed; the smaller the force, the greater the speed", and ensure the force control accuracy in the contact process. When the contact force approaches the target value, the speed is automatically reduced to realize smooth transition; when the external disturbance causes the force to change, the speed is automatically adjusted to maintain the target force value.

[0099] It should be noted that by designing the finite time state observer, the motor running data adjustment and update can be performed throughout the motor landing process. However, when the motor is in the early stage of running and there is a certain distance from the target workpiece or the contact force is still small, the adaptive adjustment of the motor running data by the observer will increase the calculation cost and resources, reduce the motor processing efficiency, and the adjustment effect is not ideal. Therefore, a pre-landing step of the motor can be set to ensure that the motor reaches the pre-landing condition in the fastest time or efficiency, and then switches to using the observer to update the motor running data in time. Specifically, the motor running data also includes terminal position data, and before step S1, it also includes:

[0100] S01: a pre-landing step, using a preset current control to control the motor to complete pre-landing, and obtaining terminal position data of the motor at pre-landing, wherein an external force value at pre-landing is less than the target force value;

[0101] The distance between the terminal position data and the initial position of the motor is calculated, and the motion state of the motor is divided into a high-speed approach stage, a transition state stage, a force control approach stage, and a final positioning stage according to the distance.

[0102] That is, by dividing the entire operation state of the motor into multiple stages according to the distance between the terminal position data and the initial position of the motor, different control logics can be executed in different stages, the motor can be controlled at a faster speed in the high-speed approach state to reach the transition state stage as soon as possible, and the motor can be quickly switched to the force control approach stage in the transition state stage to update the operation data of the motor through the observer in this stage to realize dynamic control of the motor, wherein the division of different stages can be determined according to the relationship between the terminal position data and the initial position of the motor, such as:

[0103] When the distance between the terminal position data and the initial position of the motor is greater than a preset interval, the distance is divided into a high-speed interval, a transition interval, and a force control approach interval;

[0104] The motor is controlled to enter the high-speed approach stage at full speed, and the speed data of the motor is reduced according to a preset rule, when the speed data is lower than a first preset value and the position data of the motor enters the transition interval, the current operation data is maintained to control the motor to enter the force control approach interval, and the step S1 is executed with the current operation data.

[0105] The different stages correspond to the different intervals and divisions described above, and at this time, the distance of motor operation is used as the basis for switching between different stages. In specific implementation, after the target workpiece is assembled in place, the working logic of the motor is configured according to the processing requirements, and the motor is started to work. During the movement of the motor, the running state of the motor is divided into a high-speed approach stage, a transition state stage, a force control approach stage, and a final positioning stage according to the movement distance of the terminal. Different stages correspond to different distance intervals. For example, the corresponding interval of the high-speed approach stage is the initial distance interval, which can be 0-2 cm from the initial position of the motor. The interval corresponding to the transition state stage is the subsequent second distance interval, which can be 2-2.5 cm from the initial position of the motor. This is true until the interval corresponding to the final positioning stage is reached. In the high-speed approach stage, the control strategy of the motor is to make the terminal approach the target workpiece as quickly as possible and land softly. At this time, the motor can move at a relatively high speed, such as full speed, and the speed data of the motor can be reduced according to the preset rules. When the speed data is lower than the first preset value and the position data of the motor enters the transition interval, the motor needs to be switched to the transition state stage. In this stage, the motor sets the holding current value as the reference force of the force control approach stage to smoothly transition from speed control to force control, and the current running data is used to control the motor to enter the force control approach interval. It should be noted that this stage has a short duration, but it is crucial for preventing impact during mode switching. After entering the force control approach interval from the transition interval, the motor running data can be collected, and the external force value estimated based on the finite-time state observer designed in advance. This enables automatic takeover and adaptive adjustment of the motor running data until the soft landing is successful.

[0106] The full-speed speed can be set according to the distance between the target workpiece and the terminal, as well as the performance of the motor itself, and the specific value is not limited. In addition, the first preset value is used to improve the reliability of the motor control strategy switching. In the high-speed approach stage, the motor can move at the initial speed and gradually reduce the speed until it is lower than the first preset value, thereby avoiding too high a speed when approaching the target workpiece and improving the control ability in the transition stage.

[0107] Then switch to the force control approach stage, which is the core stage of soft landing. In this stage, the terminal and the target workpiece can be positioned smoothly and efficiently, improving the reliability and efficiency of workpiece processing and further improving the workpiece processing yield. The external force is estimated in real time by the finite-time state observer, and the approach speed is dynamically adjusted according to the difference between the target force and the actual force to achieve adaptive force control.

[0108] During the execution of the force control approach stage, the relationship between the external force value and the target force value of the motor, as well as whether the motor terminal has entered the final positioning stage, need to be monitored in real time to take over and adjust the working logic of the motor. Specifically:

[0109] When the error between the external force value and the target force value is less than a preset threshold value, and the position data of the motor is consistent with the terminal position data of the motor, the motor completes landing and enters a final positioning phase.

[0110] In another embodiment of the present specification, the proximity speed can be accurately controlled by using a finite-time state observer and adaptive adjustment of the proximity speed, ensuring smooth establishment of contact force, while avoiding oscillation and instability problems that are prone to occur in traditional force control. In order to accurately determine whether the contact condition is reached, the end condition of the force control approach phase can be:

[0111] When the following conditions are met , it is determined that the soft landing of the motor in the force control approach phase is successful.

[0112] Wherein, F threshold is a force error threshold, v threshold is a speed threshold, pos min is a minimum position threshold.

[0113] That is, only when the force error is less than the threshold (indicating that the contact force is stable), the speed is lower than the threshold (indicating that the dynamics is stable), and the position exceeds the safety threshold (indicating that the contact indeed occurs, i.e. reaching the final positioning phase interval), the system determines that the soft landing is completed and enters the next phase. This multi-condition judgment effectively avoids false completion and improves control reliability.

[0114] In an embodiment of the present specification, after the soft landing of the motor in the force control approach phase is successful, the position between the motor terminal and the target workpiece is obtained in real time, and when the position reaches the maximum position limit, the motor is switched to the final positioning phase. That is, when the terminal and the target workpiece reach the soft landing condition, it is necessary to maintain a stable contact force and continuously monitor the position to ensure the safety and stability of the contact state. After completing the entire contact process, the motor remains stable at the final position, continuously monitors possible position deviation or contact force change, and ensures long-term stability.

[0115] The essence of soft landing control is to achieve smooth contact of the motor and the target object, avoid impact force, and ensure stable contact force. The embodiments of the present specification can maintain an ideal contact force curve before and after contact by real-time estimation of external force and dynamic adjustment of the proximity speed, thereby realizing truly "soft" landing.

[0116] The motor soft landing control method based on the finite time state observer provided in the embodiment of the present specification estimates the external disturbance force in real time through the finite time state observer, and realizes soft landing control based on a multi-stage control strategy. The system dynamically adjusts the approach speed according to the difference between the target holding force and the actual estimated force, and realizes a force-adaptive soft landing process. Compared with the traditional lookup table method, this technology does not require a large amount of pre-test data, saves time, and has strong versatility; compared with the conventional observer, the convergence time is less than 1 millisecond, almost no lag, and meets the high-tact production demand. The system does not need a special force sensor, but only uses motor current and position information to realize accurate force control, significantly improving product quality and reducing cost.

[0117] In another embodiment of the specification, in order to improve the reliability of monitoring the motor and the safety of performing work, the following method can also be included:

[0118] Real-time acquisition of the running state of the motor, the running state including load data, motor end execution end moving resistance data, current change data, motor temperature data;

[0119] When the running state represents that the motor is in an abnormal state, the motor end execution end is controlled to move to a preset position to avoid damaging the workpiece.

[0120] That is, by adding a detection link in the process of performing operations on the motor, the real state of the motor in work can be detected in real time, risks can be monitored and avoided in advance, and the safety of equipment and workpieces can be ensured. For example, if blockage, overload or other abnormal states are detected, the system immediately executes an error recovery program, resets and moves to a safe position to avoid damaging equipment or products.

[0121] The scheme provided in the embodiment of the present specification only uses the current and position feedback of the built-in motor, does not need an additional force sensor, reduces the system cost and complexity, adopts a fractional power feedback gain (nonlinear observer), realizes finite time convergence, greatly improves the observation speed, dynamically adjusts the approach speed according to the real-time estimated external force, adapts to different materials and contact conditions, from high-speed approach to fine force control, to stable holding, optimal control throughout the whole process.

[0122] On the basis of the motor soft landing control method based on the finite time state observer provided above, the embodiment of the present specification further provides a motor soft landing control system based on the finite time state observer, as shown in Figure 2 The frame schematic diagram of the system includes a motor 10 and a position sensor 20, and the position sensor is used to collect the distance between the terminal 12 of the motor and the initial position of the motor.

[0123] The motor 10 comprises a controller 11 configured to perform the motor soft landing control method based on the finite time state observer as described above.

[0124] The embodiment provides a motor. The motor comprises a processor, a memory and a network interface connected through a system bus. The processor of the motor is configured to provide computing and control capability. The memory of the motor comprises a non-volatile storage medium and an internal memory. The non-volatile storage medium stores an operating system and a computer program. The internal memory provides an environment for running the operating system and the computer program in the non-volatile storage medium. The network interface of the motor is configured to communicate with an external terminal through network connection.

[0125] In one embodiment, a motor is provided, comprising a memory and a processor, the memory storing a computer program, and the processor implementing the steps in the above method embodiments when executing the computer program.

[0126] In one embodiment, a computer readable storage medium is provided, storing a computer program, and the computer program implementing the steps in the above method embodiments when executed by a processor.

[0127] In one embodiment, a computer program product is provided, comprising a computer program, and the computer program implementing the steps in the above method embodiments when executed by a processor.

[0128] Those skilled in the art can understand that all or part of the processes in the above-mentioned embodiment methods can be completed by instructing the relevant hardware through a computer program. The computer program can be stored in a non-volatile computer readable storage medium, and when executed, can include the processes of the above-mentioned embodiment methods. Any reference to memory, database or other medium used in the embodiments provided in the present application can include at least one of non-volatile and volatile memory. Non-volatile memory can include read-only memory (ROM), magnetic tape, floppy disk, flash memory, optical storage, high-density embedded non-volatile memory, resistive memory (ReRAM), magnetoresistive random access memory (MRAM), ferroelectric memory (FRAM), phase change memory (PCM), graphene memory, etc. Volatile memory can include random access memory (RAM) or external cache memory, etc. As an illustration but not limitation, RAM can be in various forms, such as static random access memory (SRAM) or dynamic random access memory (DRAM), etc. The database involved in the embodiments provided in the present application can include at least one of a relational database and a non-relational database. The non-relational database can include a distributed database based on a block chain, etc., without being limited thereto. The processor involved in the embodiments provided in the present application can be a general-purpose processor, a central processing unit, a graphics processing unit, a digital signal processor, a programmable logic device, a data processing logic device based on quantum computing, etc., without being limited thereto.

[0129] It should also be understood that in the embodiments herein, the term "and / or" merely describes an association relationship of associated objects, which means that there can be three relationships. For example, A and / or B can represent three cases: A exists alone, A and B exist together, and B exists alone. In addition, the character " / " herein generally represents that the front and rear associated objects are in an "or" relationship.

[0130] Those skilled in the art can clearly understand that the units and algorithm steps of each example described in combination with the embodiments disclosed herein can be realized by electronic hardware, computer software or a combination of both. In order to clearly illustrate the interchangeability of hardware and software, the components and steps of each example have been described in the foregoing description in a general manner. Whether the functions are performed in hardware or software depends on the specific application and design constraints of the technical solution. A person skilled in the art can use different methods to implement the described functions for each specific application, but such implementation should not be considered beyond the scope of the present disclosure.

[0131] Those skilled in the art can clearly understand that, for the convenience and brevity of description, the specific working processes of the above-described system, device and unit can refer to the corresponding processes in the foregoing method embodiments, which will not be repeated here.

[0132] In several embodiments provided herein, it should be understood that the disclosed system, device and method can be implemented in other ways. For example, the above-described device embodiments are only schematic, for example, the division of the units is only a logical function division, and actual implementation can have another division manner, for example, a plurality of units or components can be combined or integrated into another system, or some features can be omitted or not executed. In addition, the coupling or direct coupling or communication connection between the units shown or discussed can be indirect coupling or communication connection through some interfaces, devices or units, and can also be electrical, mechanical or other forms of connection.

[0133] The units described as separate components can or can not be physically separated, and the components shown as units can or can not be physical units, i.e. they can be located in one place or distributed on a plurality of network units. Part or all of the units can be selected according to actual needs to achieve the purpose of the embodiments of the present disclosure.

[0134] The principles and implementation manners of the present disclosure are described herein by applying specific embodiments, and the above embodiment descriptions are only used to help understand the method and its core idea; at the same time, for those skilled in the art, according to the idea of the present disclosure, there will be changes in specific implementation manners and application ranges; based on the above, the content of the specification should not be understood as limiting the present disclosure.

Claims

1. A motor soft landing control method based on a finite-time state observer, characterized in that, The method includes: S1: Obtain the target force value of the motor during landing, wherein the target force value is a preset value; S2: Obtain the operating data of the motor, the operating data including at least speed data and current data; S3: Design a finite-time state observer to estimate the external force value of the motor during landing in the current state based on the motor's operating data; S4: When the error between the external force value and the target force value is not lower than a preset threshold, adjust the motor's operating data according to the error so that the external force value received by the motor during landing is close to the target force value; S5: Repeat steps S2-S4 according to the preset time step. When the error between the external force value and the target force value is less than the preset threshold, maintain the current operating parameters until the motor lands. The finite-time state observer estimates the external force value using the following formula: in, e For speed error; v The velocity data is obtained through the encoder position derivative; z2 The observed velocity is initially set to 0. z3 To observe the acceleration of the disturbance, the initial value is 0; dz2 for z2 The derivative of dz3 for z3 The derivative of k2 and k3 For nonlinear observer gain; dt For time step; I This is the motor's current data; Mn It is the ratio of the moving mass to the torque constant; sign (e) The sign function for velocity error; abs(e) This is the absolute value of the speed error. F est To estimate the external force acting on the motor.

2. The motor soft landing control method based on a finite-time state observer according to claim 1, characterized in that, Design a finite-time state observer to estimate the external forces acting on the motor during landing in its current state based on the motor's operating data, including: The speed and current data of the motor are collected at preset time steps; Based on the speed data at the current acquisition time and the observed speed at the previous acquisition time, the speed error at the current acquisition time is determined. The observed speed is a state variable obtained by accumulating and integrating the motion data of the motor using a nonlinear feedback gain algorithm. The initial value of the observed speed is 0. Based on the velocity error and nonlinear observation acceleration gain at the current acquisition time, the derivative of the observation perturbation acceleration at the acquisition time is updated. The observed perturbation acceleration at the current acquisition time is updated based on the derivative of the observed perturbation acceleration at the current acquisition time and the observed perturbation acceleration at the previous acquisition time. Based on the velocity error, current data, observed disturbance acceleration, and nonlinear observed velocity gain at the current acquisition time, the observed velocity derivative at the current acquisition time is updated. Based on the derivative of the observation velocity at the current acquisition time and the observation velocity at the previous acquisition time, the observation velocity at the current acquisition time is updated to be used for estimating the external force value at the next acquisition time. Based on the observed disturbance acceleration at the current acquisition time, the external force value experienced by the motor during landing is estimated.

3. The motor soft landing control method based on a finite-time state observer according to claim 1, characterized in that, When the error between the external force value and the target force value is not lower than a preset threshold, the operating data of the motor is adjusted according to the error, including: Based on the error between the external force value and the target force value, the speed data of the motor is updated using a proportional-integral algorithm. Adjust the current data of the motor to obtain updated speed data of the motor.

4. The motor soft landing control method based on a finite-time state observer according to claim 3, characterized in that, The motor speed data is updated using the following formula: in, v For speed data; k p This is the proportionality coefficient; k i Integral coefficient ；F target The target force value; F est To estimate the external force value of the obtained motor.

5. The motor soft landing control method based on a finite-time state observer according to claim 1, characterized in that, The motor's operating data also includes terminal position data, and before step S1, it also includes: S01: Pre-landing step, the motor is controlled by a preset current to complete the pre-landing, and the terminal position data of the motor at the pre-landing time is obtained. The external force value at the pre-landing time is less than the target force value. The distance between the terminal position data and the initial position of the motor is calculated, and the motion state of the motor is divided into high-speed approach stage, transition stage, force-controlled approach stage and final positioning stage based on the distance.

6. The motor soft landing control method based on a finite-time state observer according to claim 5, characterized in that, The method further includes: When the distance between the terminal position data and the initial position of the motor is greater than a preset interval, the distance is divided into a high-speed interval, a transition interval, and a force-controlled approach interval. The motor is controlled to enter the high-speed approach phase at full speed, and the motor speed data is reduced according to a preset rule. When the speed data is lower than the first preset value and the position data of the motor enters the transition range, the current running data is maintained to control the motor to enter the force-controlled approach range, and step S1 is executed with the current running data.

7. The motor soft landing control method based on a finite-time state observer according to claim 6, characterized in that, When the error between the external force value and the target force value is less than a preset threshold, and the position data of the motor is consistent with the terminal position data of the motor, the motor completes landing and enters the final positioning stage.

8. A motor soft landing control system based on a finite-time state observer, characterized in that, The system includes a motor and a target workpiece; The motor includes a controller configured to perform the motor soft landing control method based on a finite-time state observer as described in any one of claims 1-7.

9. An electric motor, comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, characterized in that, When the processor executes the computer program, it implements the motor soft landing control method based on a finite-time state observer as described in any one of claims 1-7.

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