A mixing and walking multi-axle electric drive cooperative control method

Abstract

The application discloses a kind of stirring and walking multi-axis electric drive cooperative control method, the cross coupling control structure of servo position loop and variable frequency speed loop is proposed, high-precision position control and large torque speed control are realized, walking trajectory precision is greatly improved under the mode of side shift and rotation, and stirring speed fluctuation is strictly controlled;Special deviation coupling control strategy can simultaneously adjust walking speed and stirring speed according to proportional synchronization error, when any axis is disturbed by load, another axis can quickly respond and compensate, system synchronization stability is greatly improved, and load disturbance resistance is greatly improved;Feedforward compensation system combines extended state observer, can predict and compensate the influence of load disturbance and system dynamic characteristic difference in advance, and system response time is extremely short;The slope mode switching algorithm designed avoids current impact and mechanical jitter generated in mode switching process, prolongs the service life of equipment.

Description

Technical Field

[0001] This invention belongs to the field of electric drive control technology for industrial mixing equipment, and relates to a multi-axis electric drive coordinated control method for mixing and walking. Background Technology

[0002] Mobile mixing equipment is widely used in concrete mixing, chemical raw material mixing, sewage treatment, and mining flotation. Its core operating mode is continuous operation while moving and rotating, that is, the mixing mechanism maintains rotation and mixing while moving laterally, requiring the accuracy of the travel trajectory and the stability of the mixing speed to meet the process requirements at the same time.

[0003] Currently, the mainstream drive solutions in the industry adopt a heterogeneous electric drive combination, that is, the walking mechanism uses a servo motor to achieve high-precision position control, and the stirring mechanism uses a variable frequency geared motor to achieve high torque output. For multi-motor collaborative control, existing technologies mainly include independent control mode, master-slave control mode, cross-coupling control mode, and driver-level synchronous control.

[0004] These control methods have the following drawbacks: Existing cross-coupling technologies are all designed for homogeneous drive systems. For example, CN202223051286.5 is for the angle synchronization of four servo motors, but it does not solve the problem of heterogeneous coupling control between the servo position loop and the frequency conversion speed loop.

[0005] The mixing load is characterized by strong nonlinearity, time-varying nature, and impact. Under full-load conditions, the load fluctuation can reach 300% of the rated value. Under the existing independent control and master-slave control methods, the violent fluctuation of the mixing load will be transmitted to the walking mechanism through mechanical coupling, resulting in large deviation of the walking trajectory and seriously affecting the uniformity of mixing.

[0006] Master-slave control can only achieve unidirectional error compensation. When the walking shaft is disturbed, the stirring shaft cannot respond. Although the existing cross-coupling control can achieve bidirectional compensation, it does not take into account the differences in dynamic characteristics of heterogeneous systems, resulting in the accumulation of synchronization errors.

[0007] Existing technologies such as CN202011032995.1 employ pressure sensor feedforward compensation, but do not design a dedicated load torque feedforward for the torque characteristics of stirring loads. Existing technologies lack a dedicated mode-switching algorithm, which can easily cause current surges and mechanical vibrations when switching between pure walking, pure stirring, and simultaneous moving and rotating modes, thus affecting the equipment's lifespan. Summary of the Invention

[0008] In order to overcome the shortcomings of the prior art, the present invention provides a multi-axis electric drive coordinated control method for stirring and walking.

[0009] To achieve the above objectives, the present invention adopts the following technical solution: A method for coordinated control of stirring and walking multi-axis electric drives includes the following steps: Step 1: The motion controller performs a hardware self-test and loads preset control parameters, controls the walking mechanism to perform a return motion to determine the absolute reference position, and the frequency converter performs motor parameter self-identification and switches to vector control mode. Step 2: Receive the user's input working mode command. When the shifting and turning mode is selected, execute the ramp-type smooth switching algorithm to linearly increase the coupling gain coefficient from 0 to the set value within 500ms. Step 3: Generate walking position commands and stirring speed commands by cross-generating the high-precision motion beat generator, and initialize the fuzzy PID coupled controller; Step 4: Real-time acquisition of the actual position of the walking mechanism and the actual rotation speed of the stirring mechanism; after low-pass filtering, calculate the walking position error, stirring speed error and proportional synchronization error. Step 5: Input the proportional synchronization error and error change rate into the fuzzy PID coupled controller to generate bidirectional compensation quantity, and obtain the compensated walking speed command and stirring speed command; Step 6: Calculate the load torque feedforward compensation, speed feedforward compensation, and acceleration feedforward compensation respectively. At the same time, observe the total disturbance of the system in real time through the extended state observer and perform feedback compensation. Step 7: Send the final compensated control commands to the servo driver and the frequency converter respectively, so that the servo motor and the frequency converter can work together. Step 8: Monitor system operating parameters in real time and implement routine safety protection and synchronization error graded protection; Step 9: When the walking mechanism reaches the target position, control the walking mechanism to return to the initial position.

[0010] Furthermore, step 5 uses a 2×2 coupling gain matrix to generate bidirectional compensation quantities, including: in, This is the compensation amount for walking speed. This is the amount of compensation for stirring speed. This is the error in the walking position. 0.3 represents the stirring speed error; 0.3 and 0.7 are cross-compensation coefficients determined based on the dynamic characteristics of the heterogeneous system, allocating 70% of the synchronization error to the faster-responding stirring shaft and 30% to the traveling shaft.

[0011] Furthermore, the input variable of the fuzzy PID coupled controller in step 3 is the proportional synchronization error. and error change rate The output variables are the proportional correction ΔKp, the integral correction ΔKi, and the differential correction ΔKd; the fuzzy language variable set is {NB,NM,NS,Z,PS,PM,PB}, and the membership function is a trigonometric function.

[0012] Furthermore, the compensation method in step 6 specifically includes: Load torque feedforward compensation: The stirring load torque T_L(t) is estimated using the inverter current feedback signal, and the compensation amount is generated. ; Speed ​​feedforward compensation: This refers to the speed command of the travel axis. Feedforward to the stirring shaft velocity loop to generate velocity feedforward compensation: ,in This is the process ratio coefficient; Acceleration feedforward compensation: This refers to the acceleration command of the travel axis. Feedforward to servo position loop to generate compensation amount .

[0013] Furthermore, the extended state observer described in step 6 is a second-order discrete extended state observer, whose equation is: in, These are the observations of the walking position. For the total disturbance observations, For system output, To control the input, Input gain to the system , For observer gain, The sampling period is defined as the total observed disturbance value, which is then fed back to the control input to achieve active suppression.

[0014] Furthermore, the formula for the ramp-type smooth switching algorithm described in step 2 is: ,in Set the coupling gain value; when switching from the side-shifting mode to other modes, perform a reverse ramp switch, linearly reduce the coupling gain from the set value to 0 within 500ms, and then turn off the feedforward compensation function.

[0015] Furthermore, the synchronization error graded protection described in step 8 specifically refers to: when the proportional synchronization error | When the error exceeds 0.5mm, the system automatically reduces the operating speed by 50% and issues a yellow warning; when the proportional synchronization error is greater than 0.5mm, the system automatically reduces the operating speed by 50% and issues a yellow warning. When the error exceeds 1mm, the system immediately cuts off the output of the servo and inverter, performs an emergency stop, and issues a red alarm.

[0016] In summary, the advantages of this invention are: This invention proposes a cross-coupled control structure of servo position loop and variable frequency speed loop, which realizes the combination of high-precision position control and high-torque speed control. The accuracy of the walking trajectory is greatly improved in the moving and rotating mode, and the fluctuation of stirring speed is strictly controlled.

[0017] The dedicated deviation coupling control strategy can simultaneously adjust the walking speed and stirring speed according to the proportional synchronization error. When either axis is subjected to load disturbance, the other axis can respond quickly and compensate, greatly improving the system's synchronization stability and resistance to load disturbance.

[0018] The feedforward compensation system, combined with the extended state observer, can predict and compensate for the effects of load disturbances and differences in system dynamic characteristics in advance, resulting in an extremely short system response time.

[0019] The designed ramp-type mode switching algorithm avoids current surges and mechanical vibrations during mode switching, thus extending the equipment's service life. Attached Figure Description

[0020] Figure 1 This is a structural block diagram of the multi-axis electric drive coordinated control method for stirring and walking according to the present invention. Detailed Implementation

[0021] The following specific examples illustrate the implementation of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and various details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention. It should be noted that, unless otherwise specified, the following embodiments and features described therein can be combined with each other.

[0022] This invention provides a multi-axis electric drive coordinated control method for stirring and walking, comprising the following steps: Step 1: System power-on initialization and reference point calibration.

[0023] 1.1 When the system is powered on, the PLC executes a hardware self-test program, sequentially checking the communication status of the servo driver, frequency converter, encoder, limit switch and touch screen. If a hardware fault is detected, the fault code is immediately displayed on the touch screen and startup is prohibited. 1.2 Load preset control parameters from the PLC data block, including servo three-loop parameters, frequency converter speed loop parameters, coupling gain coefficient, feedforward compensation coefficient, synchronization error protection threshold, and process proportional coefficient μ; 1.3 Control the walking mechanism to perform the origin return action: that is, move towards the origin at low speed, trigger the origin limit switch and move in the opposite direction. When the zero pulse of the absolute encoder of the servo motor is detected, stop immediately and set the position as the absolute reference point of the system to eliminate accumulated error; If the positive / negative limit switch is triggered during the origin return process, the system will stop immediately and trigger an alarm. 1.4 The frequency converter performs static motor parameter self-identification, identifies parameters such as motor stator resistance, rotor resistance, and leakage inductance, and switches to sensorless vector control mode to ensure low-speed, high-torque output characteristics.

[0024] Step 2: Working mode recognition and smooth switching control.

[0025] The system receives user input via touchscreen commands regarding operating modes. It supports three operating modes: pure walking mode, pure stirring mode, and simultaneous moving and rotating mode. If the pure walking mode is selected, the system disables cross-coupling control and feedforward compensation functions, and only starts independent control of the servo position loop to perform point-to-point motion according to the input walking distance and speed; If the pure stirring mode is selected, the system disables cross-coupling control and feedforward compensation functions, and only starts the independent control of the variable frequency speed loop to perform rotary stirring according to the input stirring speed and time; If the shift-while-rotate mode is selected, the system executes a ramp-style smooth switching algorithm: The coupling gain coefficient increases linearly with time. ; The coupling gain is increased from 0 to the set value within 500ms; at the same time, the feedforward compensation function is gradually introduced to avoid current surges and mechanical jitter during mode switching; if a fault occurs during the switching process, all enable signals are immediately cut off. If switching from the edge-shifting and rotating mode to another mode, perform a reverse ramp switch: Within 500ms, the coupling gain is linearly reduced from the set value to 0, and then the feedforward compensation function is turned off.

[0026] Step 3: Synchronous Motion Command Generation and Cross-Coupling Architecture Startup 3.1 The PLC has a built-in 1ms high-precision motion beat generator, implemented through the cyclic interrupt organization block OB1, which generates instructions in the following order: 1ms: Generate walking position command ; 2ms: Generate stirring speed command ,in This is a walking speed command; This process is repeated continuously to ensure that the time synchronization error between the two commands is less than 1ms. 3.2. Start the dual-input dual-output cross-coupling control of position and speed, and couple the output of the servo position loop with the input of the frequency converter speed loop in a closed loop; 3.3 Initialize the fuzzy PID coupled controller: Input variables include: proportional synchronization error The universe of discourse is [-3,3] mm; the rate of change of error is... The domain of discourse is [-10, 10] mm / s. The output variables are defined as follows: proportional correction ΔKp, universe of discourse [-10, 10]; integral correction ΔKi, universe of discourse [-2, 2]; differential correction ΔKd, universe of discourse [-1, 1]; The fuzzy linguistic variable set is {NB, NM, NS, Z, PS, PM, PB}; Membership functions are trigonometric functions; Step 4: Acquisition of fully closed-loop feedback signal and error calculation 4.1 The servo motor's built-in 17-bit absolute encoder acquires the motor shaft rotation angle in real time and sends it to the PLC via the PROFINET bus, converting it into the actual position of the traveling mechanism. Sampling frequency 1kHz; 4.2 An incremental encoder installed on the output shaft of the variable frequency geared motor is connected to the PLC via a high-speed counter module to collect the actual rotational speed of the stirring mechanism in real time. Sampling frequency 1kHz; 4.3 Perform first-order digital low-pass filtering on the acquired position and rotation speed signals: Filtering formula: By setting the cutoff frequency to 50Hz, high-frequency electromagnetic interference and mechanical vibration noise are filtered out. 4.4 Calculate systematic errors, including: Walking position error: ; Stirring speed error: ; Proportional synchronization error: This reflects the coordinated deviation between the walking position and the stirring speed.

[0027] Step 5: Deviation Coupling Control and Two-Way Error Compensation 5.1. Adjust proportional synchronization error and error change rate Input fuzzy PID coupled controller; 5.2. The PID parameter corrections ΔKp, ΔKi, and ΔKd are calculated using Mamdani fuzzy inference and centroid defuzzification. 5.3 Update the PID parameters of the coupled controller, including: Kp = Kp0 + ΔKp, where Kp0 = 10; Ki=Ki0+ΔKi, where Ki0=2; Kd = Kd0 + ΔKd, where Kd0 = 0.5; 5.4 The coupling controller generates bidirectional compensation quantities based on the error calculation results using a 2×2 coupling gain matrix: in, This is the compensation amount for walking speed. This is the amount of compensation for stirring speed. This is the error in the walking position. 0.3 represents the stirring speed error; 0.3 and 0.7 are cross-compensation coefficients determined based on the dynamic characteristics of the heterogeneous system, allocating 70% of the synchronization error to the faster-responding stirring shaft and 30% to the traveling shaft.

[0028] 5.5 Generate compensated control commands: Walking speed command after compensation: ; Compensated stirring speed command: ; 5.6 Achieve bidirectional error compensation: When the stirring shaft is disturbed by the load, causing the speed to drop, the system automatically reduces the travel speed; when the traveling shaft is resisted, causing the position to lag, the system automatically increases the stirring speed to ensure that the proportional synchronization error is always within the allowable range.

[0029] Step 6: Multi-dimensional feedforward compensation and active disturbance suppression 6.1 Load torque feedforward compensation: The stirring load torque is estimated in real time using the current feedback signal I(t) from the frequency converter: T_L (t) = 9550・P_N・I(t) / (n_N・I_N), where P_N is the rated power of the motor, n_N is the rated speed of the motor, and I_N is the rated current of the motor. Generate torque feedforward compensation: ; Pre-compensation for the impact of load fluctuations on stirring speed; 6.2 Velocity feedforward compensation: Speed ​​command of the travel axis Feedforward to the stirring shaft velocity loop to generate velocity feedforward compensation: Improve the system's dynamic response speed; 6.3 Acceleration feedforward compensation: Differentiating the walking speed command yields the acceleration command: Generate acceleration feedforward compensation: This reduces position tracking errors; 6.4 Extended State Observer Perturbation Suppression: Start the second-order extended state observer to observe the total system disturbance in real time: in, These are the observations of the walking position. For the total disturbance observations, For system output, To control the input, Input gain to the system , For observer gain, The sampling period; The observed total disturbance value is fed back to the control input: It enables active suppression of load disturbances, parameter perturbations, and external interference.

[0030] Step 7: Control command output and heterogeneous driver coordinated execution 7.1. Send the final compensated walking speed command Converted into PROFINET bus commands recognizable by the servo drive and sent to the servo drive; 7.2 The servo driver performs closed-loop control of the internal position loop, speed loop, and current loop, driving the servo motor to move the walking mechanism along the track; 7.3 The servo driver feeds back the motor current, voltage, temperature, position and other status information to the PLC in real time; 7.4. The final compensated stirring speed command Converted into a 0-10V analog signal and sent to the frequency converter; 7.5 The frequency converter performs closed-loop control of the internal speed loop and current loop, driving the K-series geared motor to rotate the stirring mechanism; 7.6 The frequency converter feeds back the motor current, voltage, speed, torque and other status information to the PLC in real time; 7.7 The servo system and the frequency converter system achieve information interaction and collaborative control through PLC to ensure that the walking position and stirring speed operate synchronously in strict accordance with the preset ratio.

[0031] Step 8: Real-time monitoring and safety protection of operational status, including: Real-time monitoring of system operating parameters, among which, Servo system parameters include: current, voltage, temperature, position, and speed; The parameters of a frequency converter system include: current, voltage, temperature, speed, and torque; System status parameters include: proportional synchronization error, communication status, and fault codes; Implement routine security protection, among which, Overcurrent protection: The machine will stop when the servo current exceeds 5A or the frequency converter current exceeds 50A. Overvoltage protection: Shuts down when DC bus voltage exceeds 800V; Overload protection: The machine will stop if the load torque exceeds 120% of the rated value for 10 seconds. Overheat protection: The machine will stop when the motor temperature exceeds 80℃; Furthermore, implement hierarchical protection for synchronization errors: When | When the error exceeds 0.5mm, the system automatically reduces the running speed by 50% and displays a yellow warning on the touchscreen; When | When the error exceeds 1mm, the system immediately cuts off the servo and inverter outputs, performs an emergency stop, and displays a red alarm. Real-time recording of operating data, including: position curve, speed curve, synchronization error curve; load torque curve, current curve; fault occurrence time, fault code, operating parameters at the time of fault, etc. Step 9: Job Completion and System Reset 9.1 When the traveling mechanism reaches the preset target position, the system stops outputting the stirring speed command; executes the reverse ramp switching algorithm to linearly reduce the coupling gain to 0 within 500ms; and disables the feedforward compensation function. 9.2 Control the walking mechanism to return to the initial position at a speed of 5m / min, and stop after triggering the origin limit switch; 9.3. Turn off the enable signals of the servo drive and frequency converter, and the system enters standby mode; 9.4 Generate this work report, including: start and end times of the work; total walking distance and average walking speed; average stirring speed and maximum stirring speed fluctuation; maximum synchronization error and average synchronization error; average load torque and maximum load torque.

[0032] Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort should fall within the scope of protection of the present invention.

Claims

1. A multi-axis electric drive coordinated control method for stirring and walking, characterized in that, Includes the following steps: Step 1: The motion controller performs a hardware self-test and loads preset control parameters, controls the walking mechanism to perform a return motion to determine the absolute reference position, and the frequency converter performs self-identification of motor parameters and switches to vector control mode. Step 2: Receive the user's input working mode command. When the shifting and turning mode is selected, execute the ramp-type smooth switching algorithm to linearly increase the coupling gain coefficient from 0 to the set value within 500ms. Step 3: Generate walking position commands and stirring speed commands by cross-generating the high-precision motion beat generator, and initialize the fuzzy PID coupled controller; Step 4: Real-time acquisition of the actual position of the walking mechanism and the actual rotation speed of the stirring mechanism; after low-pass filtering, calculate the walking position error, stirring speed error and proportional synchronization error. Step 5: Input the proportional synchronization error and error change rate into the fuzzy PID coupled controller to generate bidirectional compensation quantity, and obtain the compensated walking speed command and stirring speed command; Step 6: Calculate the load torque feedforward compensation, speed feedforward compensation, and acceleration feedforward compensation respectively. At the same time, observe the total disturbance of the system in real time through the extended state observer and perform feedback compensation. Step 7: Send the final compensated control commands to the servo driver and the frequency converter respectively, so that the servo motor and the frequency converter can work together. Step 8: Monitor system operating parameters in real time and implement routine safety protection and synchronization error graded protection; Step 9: When the walking mechanism reaches the target position, control the walking mechanism to return to the initial position.

2. The multi-axis electric drive coordinated control method for stirring and walking according to claim 1, characterized in that, Step 5 uses a 2×2 coupling gain matrix to generate bidirectional compensation quantities, including: in, This is the compensation amount for walking speed. This is the amount of compensation for stirring speed. This is the error in the walking position. 0.3 represents the stirring speed error; 0.3 and 0.7 are cross-compensation coefficients determined based on the dynamic characteristics of the heterogeneous system, allocating 70% of the synchronization error to the faster-responding stirring shaft and 30% to the traveling shaft.

3. The multi-axis electric drive coordinated control method for stirring and walking according to claim 1, characterized in that, The input variable of the fuzzy PID coupled controller in step 3 is the proportional synchronization error. and error change rate The output variables are the proportional correction ΔKp, the integral correction ΔKi, and the differential correction ΔKd; the fuzzy language variable set is {NB,NM,NS,Z,PS,PM,PB}, and the membership function is a trigonometric function.

4. The multi-axis electric drive coordinated control method for stirring and walking according to claim 1, characterized in that, The compensation methods in step 6 specifically include: Load torque feedforward compensation: The stirring load torque T_L(t) is estimated using the inverter current feedback signal, and the compensation amount is generated. ; Speed ​​feedforward compensation: This refers to the speed command of the travel axis. Feedforward to the stirring shaft velocity loop to generate velocity feedforward compensation: ,in This is the process ratio coefficient; Acceleration feedforward compensation: This refers to the acceleration command of the travel axis. Feedforward to the servo position loop to generate compensation amount .

5. The multi-axis electric drive coordinated control method for stirring and walking according to claim 4, characterized in that, The extended state observer mentioned in step 6 is a second-order discrete extended state observer, and its equation is: in, These are the observations of the walking position. For the total disturbance observations, For system output, To control the input, Input gain to the system , For observer gain, The sampling period is defined as the total observed disturbance value, which is then fed back to the control input to achieve active suppression.

6. The multi-axis electric drive coordinated control method for stirring and walking according to claim 1, characterized in that, The formula for the ramp-type smooth switching algorithm described in step 2 is: ,in Set the coupling gain value; when switching from the side-shifting mode to other modes, perform a reverse ramp switch, linearly reduce the coupling gain from the set value to 0 within 500ms, and then turn off the feedforward compensation function.

7. The multi-axis electric drive coordinated control method for stirring and walking according to claim 1, characterized in that, The synchronization error graded protection mentioned in step 8 specifically refers to: when the proportional synchronization error | When the error exceeds 0.5mm, the system automatically reduces the operating speed by 50% and issues a yellow warning; when the proportional synchronization error is greater than 0.5mm, the system automatically reduces the operating speed by 50% and issues a yellow warning. When the error exceeds 1mm, the system immediately cuts off the output of the servo and inverter, performs an emergency stop, and issues a red alarm.

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