A method for controlling the emergency stop of a dual-drive gantry platform under high-speed conditions with an eccentric load

Abstract

The present invention relates to the field of servo motor control technology, specifically a method for controlling an overload emergency stop of a dual-drive gantry platform in a high-speed state, comprising a Motor1 module and a Motor2 module for driving the gantry platform, wherein the Motor1 module and the Motor2 module are respectively provided with encoders, the Motor1 module is respectively connected to an MCU1 module and an FPGA1 module, the MCU1 module is respectively connected to a host computer and the FPGA1 module, and the FPGA1 module is also connected to a first RS422 interface module; the Motor2 module is respectively connected to an MCU2 module and an FPGA2 module, the MCU2 module is respectively connected to the host computer and the FPGA2 module, and the FPGA2 module is also connected to a second RS422 interface module; the first RS422 interface module is communicatively connected to the second RS422 interface module; the method comprises the following steps: (1) overload judgment (2) overload axis emergency stop control (3) empty axis emergency stop control. The method can effectively increase the rapid response of the gantry synchronization system when a certain axis is subjected to a large load disturbance, effectively improve the service life of the gantry platform, and increase the safety of work.

Description

Technical Field

[0001] The present invention relates to the technical field of servo motor control, and in particular to a method for controlling an overload emergency stop of a dual-drive gantry platform under high-speed conditions. Background Art

[0002] In the manufacturing industry, demands for increasingly high processing performance are increasing. For example, in industries such as pressing, laser cutting, and wood panel furniture processing, machine tools require long travels and high speeds, so they typically adopt a dual-drive gantry structure. Dual-drive gantry machines typically have two mechanical transmission mechanisms arranged side by side on either side of the machine frame, jointly driving the gantry axis for seamless motion. Each mechanical transmission mechanism is independently controlled by a motor.

[0003] However, in the high-speed gantry synchronization state, when one axis is subjected to a large load disturbance (i.e., hitting a rigid material), the general gantry synchronization system cannot respond quickly, causing the gantry deviation of the two axes to increase rapidly and then damage the gantry mechanical structure. Figure 1 As shown, the working situation of the press in this case is provided, because the shaft 1 is subjected to a large load disturbance, which leads to the production of abnormal bent parts.

[0004] Therefore, a new technical solution is urgently needed to solve the above technical problems. Summary of the Invention

[0005] The purpose of the present invention is to overcome the problems of the above-mentioned prior art and provide a method for controlling the overload emergency stop of a dual-drive gantry platform at high speed. FPGA is used to realize high-speed data interaction between the two axes, and the MCU determines the overload status and control method based on the interactive data. This is used to solve the problem that when one axis is subjected to a large load disturbance (i.e., colliding with a rigid material), the general gantry synchronization system cannot respond quickly, resulting in a rapid increase in the gantry deviation of the two axes and thus damaging the gantry mechanical structure.

[0006] The above objectives are achieved through the following technical solutions:

[0007] A method for controlling an overload emergency stop of a dual-drive gantry platform under high-speed conditions is characterized in that it includes a Motor1 module and a Motor2 module for driving the gantry platform, wherein the Motor1 module and the Motor2 module are respectively provided with encoders, the Motor1 module is respectively connected to the MCU1 module and the FPGA1 module, the MCU1 module is respectively connected to the host computer and the FPGA1 module, and the FPGA1 module is further connected to a first RS422 interface module; the Motor2 module is respectively connected to the MCU2 module and the FPGA2 module, the MCU2 module is respectively connected to the host computer and the FPGA2 module, and the FPGA2 module is further connected to a second RS422 interface module; the first RS422 interface module is communicatively connected to the second RS422 interface module; and the method comprises the following steps:

[0008] Step (1) bias load judgment: Calculate the estimated current of the two axes through the feedback of the two-axis encoder and the inertia value, and obtain the load data of the two axes through the difference between the estimated current of the two axes and the corresponding actual current;

[0009] Set a specific threshold value A and a specific threshold value B. When the load data of a certain axis exceeds the specific threshold value A and the difference between the load data of the two axes exceeds the specific threshold value B, it can be determined as an eccentrically loaded axis and proceed to step (2).

[0010] Step (2) Emergency stop control of the eccentrically loaded axis: set the offset value C, and determine the new position command value based on the current actual encoder feedback, immediately clear the speed feedforward in the model loop, and set the torque limit in the impact direction to a smaller value; the new position command value is the current encoder feedback value - offset value C; the offset value C is a custom setting;

[0011] Step (3) Empty axis emergency stop control: Determine the first-order inertia time coefficient based on the general responsiveness of the empty axis. When the offset load logic judgment is satisfied, calculate the speed feedforward based on the encoder feedback of the offset load axis and send it to the model loop. Calculate the current feedforward based on the encoder feedback and inertia value of the offset load axis and send it to the model loop. Calculate the compensated position command based on the encoder feedback of the offset load axis and the first-order inertia time coefficient.

[0012] Furthermore, in step (1), the dual axes realize the synchronization and data interaction of the three loops of current, speed and position through the communication between the first RS422 interface module and the second RS422 interface module.

[0013] Furthermore, when the FPGA1 module or the FPGA2 module is sending communication on its own axis while also receiving communication from the other party, the start frame signal of the communication is used to determine whether there is a time difference between the communication on its own axis and the communication on the other party. If there is a difference, the advanced FPGA1 module or FPGA2 module is adjusted to complete the cycle synchronization; after the communication cycle is synchronized, the control signals of the current loop, speed loop and position loop are output using the cycle.

[0014] Furthermore, the calculation formula of the load data in step (1) is as follows: Among them, T m Indicates the load moment, T e represents the electromagnetic torque of the motor, J represents the moment of inertia, w represents the angular velocity, and t represents time.

[0015] Furthermore, the calculation formula of the first-order inertia time coefficient in step (3) is as follows: Where T represents the first-order inertia time coefficient, y represents position feedback, and x represents position command;

[0016] The approximate first-order inertia time coefficient T can be calculated based on the position command and position feedback of the normal servo operation.

[0017] Furthermore, the speed feedforward is calculated based on the encoder feedback of the eccentric load axis in step (3), and the calculation formula is as follows: Where x represents the encoder feedback and w represents the angular velocity.

[0018] Furthermore, the current feedforward is calculated according to the encoder feedback and inertia value of the eccentric load axis in step (3), and the calculation formula is as follows: Among them, T f represents current feedforward, J represents moment of inertia, and w represents angular velocity.

[0019] Furthermore, the position command after compensation is calculated based on the encoder feedback of the eccentric load axis and the first-order inertia time coefficient in step (3), and the calculation formula is as follows: Where P represents position command compensation, x represents eccentric load axis encoder feedback, w represents angular velocity, and T represents the first-order inertia time coefficient.

[0020] Beneficial effects

[0021] The present invention provides a method for controlling the emergency stop of an overload on a dual-drive gantry platform at high speed. The method uses FPGA to realize high-speed data interaction between the two axes. The MCU determines the overload status and control method based on the interactive data. This method can effectively increase the rapid response of the gantry synchronization system when a certain axis is subjected to a large load disturbance, effectively improve the service life of the gantry platform, and increase work safety. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 This is a schematic diagram of the abnormality of the lower pressing machine using traditional technology;

[0023] Figure 2 This is a system topology diagram of a method for controlling an emergency stop of an eccentric load under high-speed conditions for a dual-drive gantry platform according to the present invention;

[0024] Figure 3 This is a schematic diagram of a method for controlling an eccentric load emergency stop of a dual-drive gantry platform at high speed according to the present invention. DETAILED DESCRIPTION

[0025] The present invention will be further described in detail below with reference to the accompanying drawings and examples. The described embodiments are only some embodiments of the present invention, not all embodiments. All other embodiments derived by persons of ordinary skill in the art based on the embodiments of the present invention without inventive effort shall fall within the scope of protection of the present invention.

[0026] like Figure 2 As shown, a method for controlling an overload emergency stop of a dual-drive gantry platform in a high-speed state includes a Motor1 module and a Motor2 module for driving the gantry platform, wherein the Motor1 module and the Motor2 module are respectively provided with encoders, the Motor1 module is respectively connected to the MCU1 module and the FPGA1 module, the MCU1 module is respectively connected to the host computer and the FPGA1 module, and the FPGA1 module is also connected to the first RS422 interface module; the Motor2 module is respectively connected to the MCU2 module and the FPGA2 module, the MCU2 module is respectively connected to the host computer and the FPGA2 module, and the FPGA2 module is also connected to the second RS422 interface module; the first RS422 interface module is communicatively connected to the second RS422 interface module.

[0027] Among them, the MCU1 module communicates with the FPGA1 module through the SPI protocol, the FPGA1 module communicates with the Motor1 module through the 485 communication protocol, and the MCU1 module communicates with the Motor1 module through the PWM communication protocol;

[0028] The MCU2 module communicates with the FPGA2 module via the SPI protocol, the FPGA2 module communicates with the Motor2 module via the 485 communication protocol, and the MCU2 module communicates with the Motor2 module via the PWM communication protocol.

[0029] like Figure 3 As shown, this method includes the following steps:

[0030] Step (1) bias load judgment: Calculate the estimated current of the two axes through the feedback of the two-axis encoder and the inertia value, and obtain the load data of the two axes through the difference between the estimated current of the two axes and the corresponding actual current;

[0031] Set a specific threshold value A and a specific threshold value B. When the load data of a certain axis exceeds the specific threshold value A and the difference in the load data of the two axes exceeds the specific threshold value B, it can be determined as an unbalanced load axis, and continue with step (2). The specific threshold value A and the specific threshold value B can be customized.

[0032] Step (2) Emergency stop control of the eccentrically loaded axis: set the offset value C, and determine the new position command value based on the current actual encoder feedback, immediately clear the speed feedforward in the model loop, and set the torque limit in the impact direction to a smaller value; the new position command value is the current encoder feedback value - offset value C; the offset value C is a custom setting;

[0033] Step (3) Empty axis emergency stop control: Determine the first-order inertia time coefficient based on the general responsiveness of the empty axis. When the offset load logic judgment is satisfied, calculate the speed feedforward based on the encoder feedback of the offset load axis and send it to the model loop. Calculate the current feedforward based on the encoder feedback and inertia value of the offset load axis and send it to the model loop. Calculate the compensated position command based on the encoder feedback of the offset load axis and the first-order inertia time coefficient.

[0034] Wherein, in said step (1), the dual axes realize the synchronization and data interaction of the three loops of current, speed and position through the communication between the first RS422 interface module and the second RS422 interface module.

[0035] Due to differences in the dual-axis crystal oscillators, synchronization of the current, velocity, and position loops is required. The two FPGAs sample the same cycle to send communication data. While the FPGA is sending its own axis's communication, it is also receiving communication from the other. The communication start frame signal is used to determine if there is a time difference between the current and the other axis's communication. If a difference is found, the leading FPGA is adjusted to achieve cycle synchronization. That is, when either FPGA1 or FPGA2 is sending its own axis's communication while also receiving communication from the other, the communication start frame signal can be used to determine if there is a time difference between the current and the other axis's communication. If a difference is found, the leading FPGA1 or FPGA2 is adjusted to achieve cycle synchronization. After the communication cycle is synchronized, the control signals for the three loops (i.e., current, velocity, and position loops) are output using this cycle.

[0036] The calculation formula of the load data in step (1) of this method is as follows: Among them, T m Indicates the load moment, T e represents the electromagnetic torque of the motor, J represents the moment of inertia, w represents the angular velocity, and t represents time.

[0037] Since there is a lag between the servo command and feedback, assuming that the servo system is a first-order inertia link, the calculation formula of the first-order inertia time coefficient in step (3) of this method is as follows: Where T represents the first-order inertia time coefficient, y represents position feedback, and x represents position command;

[0038] The approximate first-order inertia time coefficient T can be calculated based on the position command and position feedback of the normal servo operation.

[0039] In step (3) of this method, the speed feedforward is calculated based on the encoder feedback of the eccentric load axis. The calculation formula is as follows: Where x represents the encoder feedback and w represents the angular velocity.

[0040] In step (3) of this method, the current feedforward is calculated based on the encoder feedback and inertia value of the offset axis. The calculation formula is as follows: Among them, T f represents current feedforward, J represents moment of inertia, and w represents angular velocity.

[0041] In step (3) of this method, the position command after compensation is calculated based on the encoder feedback of the eccentric load axis and the first-order inertia time coefficient. The calculation formula is as follows: Where P represents position command compensation, x represents eccentric load axis encoder feedback, w represents angular velocity, and T represents the first-order inertia time coefficient.

[0042] The above description is only for explaining the embodiments of the present invention and is not intended to limit the present invention. For those skilled in the art, any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A method for controlling an overload emergency stop of a dual-drive gantry platform at high speed, characterized in that: The invention comprises a Motor1 module and a Motor2 module for driving a gantry platform, wherein the Motor1 module and the Motor2 module are respectively provided with an encoder, the Motor1 module is respectively connected to the MCU1 module and the FPGA1 module, the MCU1 module is respectively connected to the host computer and the FPGA1 module, and the FPGA1 module is further connected to a first RS422 interface module; the Motor2 module is respectively connected to the MCU2 module and the FPGA2 module, the MCU2 module is respectively connected to the host computer and the FPGA2 module, and the FPGA2 module is further connected to a second RS422 interface module; the first RS422 interface module is communicatively connected to the second RS422 interface module; and the invention comprises the following steps: Step (1) bias load judgment: Calculate the estimated current of the two axes through the feedback of the two-axis encoder and the inertia value, and obtain the load data of the two axes through the difference between the estimated current of the two axes and the corresponding actual current; Set a specific threshold value A and a specific threshold value B. When the load data of a certain axis exceeds the specific threshold value A and the difference between the load data of the two axes exceeds the specific threshold value B, it can be determined as an eccentrically loaded axis and proceed to step (2). Step (2) Emergency stop control of the eccentrically loaded axis: set the offset value C, and determine the new position command value based on the current actual encoder feedback, immediately clear the speed feedforward in the model loop, and set the torque limit in the impact direction to a smaller value; the new position command value is the current encoder feedback value - offset value C; the offset value C is a custom setting; Step (3) Empty axis emergency stop control: Determine the first-order inertia time coefficient based on the general responsiveness of the empty axis. When the offset load logic judgment is satisfied, calculate the speed feedforward based on the encoder feedback of the offset load axis and send it to the model loop. Calculate the current feedforward based on the encoder feedback and inertia value of the offset load axis and send it to the model loop. Calculate the compensated position command based on the encoder feedback of the offset load axis and the first-order inertia time coefficient.

2. The method for controlling an overload emergency stop of a dual-drive gantry platform under high-speed conditions according to claim 1, characterized in that: In step (1), the dual axes realize the synchronization and data interaction of the three loops of current, speed and position through the communication between the first RS422 interface module and the second RS422 interface module.

3. The method for controlling an overload emergency stop of a dual-drive gantry platform under high-speed conditions according to claim 2, characterized in that: When FPGA1 or FPGA2 is sending communication from its own axis while also receiving communication from the other axis, the start frame signal of the communication is used to determine whether there is a time difference between the communication of the own axis and the other axis. If there is a difference, the leading FPGA1 or FPGA2 module is adjusted to complete cycle synchronization. After the communication cycle is synchronized, the cycle is used to output the control signals of the current loop, speed loop, and position loop.

4. The method for controlling an overload emergency stop of a dual-drive gantry platform under high-speed conditions according to claim 1, characterized in that: The calculation formula for the load data in step (1) is as follows: Among them, T m Indicates the load moment, T e represents the electromagnetic torque of the motor, J represents the moment of inertia, ω represents the angular velocity, and t represents time.

5. The method for controlling an overload emergency stop of a dual-drive gantry platform at high speed according to claim 1, characterized in that: The calculation formula of the first-order inertia time coefficient in step (3) is as follows: Where T represents the first-order inertia time coefficient, y represents position feedback, and x represents position command; The approximate first-order inertia time coefficient T can be calculated based on the position command and position feedback of the normal servo operation.

6. The method for controlling an overload emergency stop of a dual-drive gantry platform at high speed according to claim 1, characterized in that: The speed feedforward is calculated based on the encoder feedback of the eccentric load axis as described in step (3). The calculation formula is as follows: Where x represents the encoder feedback and ω represents the angular velocity.

7. The method for controlling an overload emergency stop of a dual-drive gantry platform at high speed according to claim 1, characterized in that: In step (3), the current feedforward is calculated based on the encoder feedback and inertia value of the offset axis. The calculation formula is as follows: Among them, T f represents current feedforward, J represents moment of inertia, and ω represents angular velocity.

8. The method for controlling an overload emergency stop of a dual-drive gantry platform at high speed according to claim 1, characterized in that: In step (3), the position command after compensation is calculated based on the encoder feedback of the offset axis and the first-order inertia time coefficient. The calculation formula is as follows: Where P represents position command compensation, x represents eccentric load axis encoder feedback, ω represents angular velocity, and T represents the first-order inertia time coefficient.

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