Virtual main shaft control method and system of mobile platform

Abstract

The invention provides a virtual main shaft control method of a mobile platform, which is characterized in that an inter-shaft handshake constraint control algorithm is added between two or more servo motor shafts, and under the control strategy that a slave shaft follows a virtual main shaft, the synchronous control precision is further improved, and the problems that the current walking motor is asynchronous and the synchronous precision is poor are solved; the risks of clamping stagnation and damage of the machinery and even the mobile platform caused by asynchronous walking motors are reduced; hardware cost is saved, the walking motor can be selected in a low-cost and small-size mode, arrangement of sensors such as a travel switch is eliminated, installation space and construction steps are greatly saved, and another scheme of multi-shaft synchronous control is provided.

Description

Technical Field

[0001] The present invention relates to the technical field of synchronous control of mobile platforms, and in particular to a virtual spindle control method of a mobile platform. Background Art

[0002] A certain bridge is a movable working platform installed on one side of the use point. Before a certain type of special vehicle operates, a certain bridge is moved out to provide a working platform; after the operation of a certain type of special vehicle is completed, the certain bridge is retracted. The drive system adopts a rail flat car drive mode and is installed under the platform structure. The driving wheel is driven by an electric motor and walks on a preset track to drive the platform to move horizontally. The drive system assembly consists of a driving wheel group, a driven wheel group, etc. The driving wheel group consists of a servo motor, a reducer, a coupling, a transmission shaft, a roller, a roller shaft, a bearing assembly, a bearing fixing seat, a bearing cover, and a fixed connector. The driven wheel group consists of a roller, a roller shaft, a bearing assembly, a bearing fixing seat, a bearing cover, and a fixed connector.

[0003] In the prior art, multiple motors run asynchronously or with low synchronization accuracy, and there is displacement buffering; the motors are too powerful and too large, which is not conducive to installation and maintenance. Summary of the invention

[0004] In view of the problem of low current density of hydrogen evolution electrodes for alkaline water electrolysis, the present application proposes a virtual spindle control method for a mobile platform, comprising the following steps:

[0005] Establish a state machine to clarify the entire walking motor control process;

[0006] Perform path planning, set parking positions, use position control, and use intermediate states to reach the target position;

[0007] A virtual spindle is created in the controller, and the two travel servo motors are set as slave axes to follow the movement of the virtual spindle.

[0008] Furthermore, establishing a state machine specifically includes:

[0009] Treat the walking control process as a state machine, and set each action node, such as "initial position", "buffer position", "buffer position deceleration", "end position", and "end position deceleration" as a state and integrate it into the program control;

[0010] When the state machine is in a certain state position such as "initial position", it is judged to jump to the next state "buffer position deceleration". If the condition is not met, it is 0 and the state remains unchanged; if the condition is met, it is 1 and the state jumps;

[0011] At the same time, soft protection function is added.

[0012] Furthermore, the path planning is performed and the stop positions are defined with global variables, including:

[0013] When the mobile platform is retracted, the position value of the walking motor encoder is defined as zero point;

[0014] The control method adopts position control, and a multi-turn absolute encoder is selected to record the rotation position information of the travel motor.

[0015] Furthermore, each parking position has a defined position variable and an initial default value is given in the program. Combined with the user's site, the value of this variable can be adjusted to increase the match with the actual working conditions of the user's site.

[0016] Furthermore, performing path planning and setting the parking position is a preparatory step. After completion, it is not necessary to do it every time. Just set the parking position parameters.

[0017] Furthermore, the virtual spindle is established inside the controller, specifically including:

[0018] The position command is regarded as a virtual main axis, and the two travel servo motors are regarded as driven axes. The two motors follow the main axis at the same time to reduce external interference.

[0019] The input control command and the position negative feedback signal of the dual motors form the input reference signal of the synchronous controller.

[0020] Furthermore, when the virtual spindle is accelerating or decelerating, the virtual spindle uses an S acceleration curve to change speed, and it maintains a constant speed at other times.

[0021] Furthermore, the method further comprises the following steps:

[0022] The inter-axis synchronization adds a handshake signal synchronization algorithm to ensure that the synchronization control accuracy of the two walking servo motors is further enhanced.

[0023] Furthermore, the inter-axis synchronization adds a handshake signal synchronization algorithm, which specifically includes:

[0024] The speed of single axis 1 is collected in a limited period T, which are 1V1, 1V2...1Vn respectively, and the average value is Vp1;

[0025] The speed of single axis 2 is collected in a limited period T, which are 2V1, 2V2...2Vn respectively, and the average value is Vp2;

[0026] The error compensation value is △Vp=|Vp1-Vp2|, and this value is compensated into the moving axis with lower speed.

[0027] A system required for realizing a virtual spindle control method of a mobile platform includes a signal acquisition module, a data processing module, a display and control terminal, and an actuator:

[0028] The information acquisition module is a multi-turn absolute encoder, which can measure the position and direction of the rotating shaft by assigning different binary codes to the position of the rotating shaft, and then reading these codes through a reader to determine the position of the travel motor 1 and the travel motor 2;

[0029] The data processing module is a PLC, which can exchange data with the travel servo driver through Modbus communication, obtain the travel motor position information, and use it as the input variable of position control to control the travel motor;

[0030] The display and control terminal is an operation box and an LCD screen. Through CAN communication, the operation box receives data signals from the PLC, generates an operation state machine operation diagram, and displays the current mobile platform action status in real time; the operation box is arranged with switches and control handles to execute action instructions such as walking motors, and sends operation instructions to the PLC through the bus to realize the functional actions of the mobile platform;

[0031] The actuator is a servo motor, which is connected to a corresponding servo driver to form a servo drive system. According to the state machine control logic, the PLC sends a control instruction to the servo driver, and the servo motor drives the walking wheel to move, thereby completing the movement and retraction of the mobile platform.

[0032] The virtual spindle control method of the mobile platform provided by the present invention has the following beneficial effects compared with the prior art:

[0033] The present invention solves the current problems of asynchronous travel motors and poor synchronization accuracy; reduces the risk of machinery or even mobile platforms being stuck or damaged due to asynchronous travel motors; saves hardware costs, and the travel motors can be selected to be low-cost and small-volume, eliminating the arrangement of sensors such as travel switches, greatly saving installation space and construction steps; the multi-point parking positions of the travel motors are integrated into the "state machine", the path is planned in advance, and the parking position parameters can be set, thereby improving the adaptability to the user's on-site working conditions; the synchronous control of the two travel motors adopts a control method of following the virtual main axis and handshake constraints between the slave axes, and a dual strategy is used to ensure and improve the synchronization accuracy, while reducing external interference. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 It is the walking control process state machine of the present invention;

[0035] Figure 2 This is a flow chart of the inter-axis handshake link of the present invention. DETAILED DESCRIPTION

[0036] In order to enable those skilled in the art to better understand the technical solution of the present invention, the present invention is further described below in conjunction with the accompanying drawings and specific implementation methods.

[0037] This application proposes a virtual spindle control method for a mobile platform. The system required to implement this method consists of a signal acquisition module, a data processing module, a display and control terminal, and an actuator:

[0038] The information acquisition module is a multi-turn absolute encoder, which can measure the position and direction of the rotating shaft. It encodes the position of the rotating shaft by assigning different binary codes to the position of the rotating shaft, and then reads these codes through the reader to determine the position of the travel motor 1 and the travel motor 2;

[0039] The data processing module is a PLC, which can exchange data with the travel servo driver through Modbus communication, obtain the travel motor position information, and use it as the input variable of position control to control the travel motor;

[0040] The display and control terminal is an LCD screen of the operation box. Through CAN communication, the operation box receives data signals from the PLC, generates an operation state machine operation diagram, and displays the current mobile platform action status in real time. The operation box is equipped with switches and control handles to execute action instructions such as the travel motor, and sends operation instructions to the PLC through the bus to realize the functional action of the mobile platform.

[0041] The actuator is a servo motor, which is connected to the corresponding servo driver to form a servo drive system. According to the state machine control logic, the PLC sends control instructions to the servo driver, and the servo motor drives the walking wheels to move, thereby completing the movement and retraction of the mobile platform.

[0042] The process steps required by the present invention include: establishing a state machine, performing path planning to set a parking position, establishing a virtual main axis in a controller, and adding a handshake signal synchronization algorithm between axes.

[0043] (1) Establish a state machine

[0044] Treat the walking control process as a state machine, and set each action node, such as "initial position", "buffer position", "buffer position deceleration", "end position", and "end position deceleration" as a state, and integrate it into the program control. When the state machine is in a certain state position such as "initial position", it is judged to jump to the next state "buffer position deceleration". If the condition is not met, it is 0 and the state remains unchanged; if the condition is met, it is 1 and the state jumps. At the same time, soft protection function is added.

[0045] (2) Perform path planning and define global variables for the stop positions

[0046] When the mobile platform is retracted, the position value of the walking motor encoder is defined as zero. The control method adopts position control, and a multi-turn absolute encoder is selected to record the rotation position information of the walking motor. Figure 1The parking positions involved are defined as position variables, and an initial default value is given in the program. Combined with the user's site, the value of this variable can be adjusted to increase the match with the actual working conditions of the user's site.

[0047] (3) Establishing a virtual spindle inside the controller

[0048] The position command is regarded as a virtual main axis, and the two walking servo motors are regarded as slave axes. The two motors follow the main axis at the same time to reduce external interference. The input control command and the position negative feedback signal of the dual motors form the input reference signal of the synchronous controller.

[0049] When the virtual spindle is accelerating or decelerating, the virtual spindle uses the S acceleration curve to change speed, and it maintains a constant speed at other times.

[0050] (4) Inter-axis synchronization, adding handshake signal synchronization algorithm

[0051] The speed of single axis 1 is collected within a limited period T, which are 1V1, 1V2...1Vn respectively, and the average value is Vp1; the speed of single axis 2 is collected within a limited period T, which are 2V1, 2V2...2Vn respectively, and the average value is Vp2; the error compensation value is △Vp=|Vp1-Vp2|, and this value is compensated into the moving axis with lower speed, so as to further improve the speed synchronization between the two motors.

[0052] The flow chart of the handshake between axes.

[0053] This application integrates the multi-point parking positions of the walking motor into the "state machine", the path is planned in advance, and the parking position parameters can be set, which improves the adaptability to the user's on-site working conditions; the synchronous control of the two walking motors adopts a control method of following the virtual main axis and handshake constraints between the slave axes, and a dual strategy is used to ensure and improve the synchronization accuracy while reducing external interference.

[0054] A control algorithm with handshake constraints between axes is added between two or more servo motor axes. At the same time, under the control strategy of slave axis following virtual master axis, the synchronization control accuracy is further improved, solving the current problems of asynchronous travel motors and poor synchronization accuracy. The risk of mechanical or even mobile platform jamming and damage due to asynchronous travel motors is reduced. Hardware costs are saved, and the travel motors can be selected with low cost and small size, eliminating the arrangement of sensors such as travel switches, greatly saving installation space and construction steps, and providing another solution for multi-axis synchronous control.

[0055] In summary, the above are only preferred embodiments of the present invention, and the protection scope of the present invention is not limited thereto. All equivalent changes and modifications made according to the patent scope of the present invention and the contents of the specification are within the scope covered by the patent of the present invention.

Claims

1. A virtual spindle control method for a mobile platform, characterized in that: The following steps are involved: Establish a state machine to clarify the entire walking motor control process; Perform path planning, set parking positions, use position control, and use intermediate states to reach the target position; A virtual spindle is created in the controller, and the two travel servo motors are set as slave axes to follow the movement of the virtual spindle.

2. The method according to claim 1, characterized in that Establishing a state machine specifically includes: Treat the walking control process as a state machine. Each action node, such as "initial position", "buffer position", "buffer position deceleration", "end position", and "end position deceleration", is set as a state and integrated into the program control. When the state machine is in a certain state such as "initial position", it is judged to jump to the next state "buffer position deceleration". If the condition is not met, it is 0 and the state remains unchanged; if the condition is met, it is 1 and the state jumps; At the same time, soft protection function is added.

3. The method according to claim 1, characterized in that Perform path planning and define global variables for the stop positions, including: When the mobile platform is retracted, the position value of the walking motor encoder is defined as zero point; The control method adopts position control, and a multi-turn absolute encoder is selected to record the rotation position information of the travel motor.

4. The method according to claim 3, characterized in that: Position variables are defined for each parking position, and an initial default value is given in the program. Combined with the user's site, the value of this variable can be adjusted to increase the match with the actual working conditions of the user's site.

5. The method according to claim 4, characterized in that: Performing route planning and setting the parking position is a preparatory step. Once completed, you do not need to do it every time. Just set the parking position parameters.

6. The method according to claim 1, characterized in that The virtual spindle established inside the controller includes: The position command is regarded as a virtual main axis, and the two travel servo motors are regarded as driven axes. The two motors follow the main axis at the same time to reduce external interference. The input control command and the position negative feedback signal of the dual motors form the input reference signal of the synchronous controller.

7. The method according to claim 6, characterized in that: When the virtual spindle is accelerating or decelerating, the virtual spindle uses the S acceleration curve to change speed, and it maintains a constant speed at other times.

8. The method according to claim 1, characterized in that The following steps are also included: The inter-axis synchronization adds a handshake signal synchronization algorithm to ensure that the synchronization control accuracy of the two walking servo motors is further enhanced.

9. The method according to claim 8, characterized in that The synchronization algorithm of adding handshake signal to the axis synchronization specifically includes: The speed of single axis 1 is collected in a limited period T, which are 1V1, 1V2...1Vn respectively, and the average value is Vp1; The speed of single axis 2 is collected in a limited period T, which are 2V1, 2V2...2Vn respectively, and the average value is Vp2; The error compensation value is △Vp=|Vp1-Vp2|, and this value is compensated into the moving axis with lower speed.

10. A system for implementing a virtual spindle control method of a mobile platform, comprising a signal acquisition module, a data processing module, a display and control terminal, and an actuator, characterized in that: The information acquisition module is a multi-turn absolute encoder, which can measure the position and direction of the rotating shaft by assigning different binary codes to the position of the rotating shaft, and then reading these codes through a reader to determine the position of the travel motor 1 and the travel motor 2; The data processing module is a PLC, which can exchange data with the travel servo driver through Modbus communication, obtain the travel motor position information, and use it as the input variable of position control to control the travel motor; The display and control terminal is an operation box and an LCD screen. Through CAN communication, the operation box receives data signals from the PLC, generates an operation state machine operation diagram, and displays the current mobile platform action status in real time; the operation box is arranged with switches and control handles to execute action instructions such as walking motors, and sends operation instructions to the PLC through the bus to realize the functional actions of the mobile platform; The actuator is a servo motor, which is connected to a corresponding servo driver to form a servo drive system. According to the state machine control logic, the PLC sends a control instruction to the servo driver, and the servo motor drives the walking wheel to move, thereby completing the movement and retraction of the mobile platform.

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