A positioning control method of a linear displacement mechanism

Abstract

The present application relates to the technical field of industrial automation, in particular to a linear displacement mechanism positioning control method, which aims to solve the problems of poor environmental adaptability, high cost and complicated maintenance of existing laser, barcode and photoelectric positioning. The method comprises hardware deployment, setting position judgment logic, executing positioning process and post-maintenance correction. The vertical equipment is additionally provided with a drop compensation logic to dynamically solve the height difference caused by load change. The present application has high positioning accuracy, low cost and strong environmental adaptability, and is suitable for linear displacement equipment such as stacker and elevator.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of industrial automation, more particularly, it relates to a linear displacement mechanism positioning control method. BACKGROUND

[0002] In industrial automation equipment, the main actuator is motor, cylinder, etc., and the action realized by the actuator in the field is mostly linear motion, and common equipment includes elevators, hoists, stackers, and rail trolleys. The linear motion of the stacker, hoist, and rail trolley often needs to be accurately positioned. In the conventional industrial scheme, the stacker is positioned by laser ranging or bar code ranging, and the positioning accuracy is plus or minus 2 mm; the hoist usually uses slot photoelectric deceleration and positioning, and the positioning accuracy is related to the photoelectric performance; the positioning method of the rail trolley is usually to use laser ranging or photoelectric positioning.

[0003] 1. Laser ranging relies on laser ranging equipment to measure the distance between the moving equipment and the fixed reflector, thereby realizing the positioning of the moving equipment. The limitations are: strict working environment requirements, high price, and limited ranging range;

[0004] 2. Bar code ranging is to install a laser code scanner on the moving equipment, constantly scan the bar code on the path of the moving equipment, read the numerical information on the bar code, and then analyze the read bar code data to obtain the current absolute position of the equipment. The limitations are: lack of flexibility in application scenarios, poor maintainability of bar codes, cumbersome bar code replacement, and unfriendly operation for replacing bar codes to correct the position;

[0005] 3. Photoelectric positioning is to increase a set of photoelectric or mechanical baffles at each positioning position to cooperate with photoelectric in-situ detection. After the equipment runs to the corresponding position, the mechanical baffle triggers the photoelectric, thereby realizing the deceleration and parking control of the moving equipment. The limitations are: low positioning efficiency, large speed curve fluctuation, poor positioning effect, and cumbersome maintenance and use.

[0006] Based on the deficiencies in the prior art, the present application provides a linear displacement mechanism positioning control method. SUMMARY

[0007] In view of the deficiencies in the prior art, the purpose of the present application is to provide a linear displacement mechanism positioning control method.

[0008] To achieve the above purpose, the present application provides the following technical solutions:

[0009] A linear displacement mechanism positioning control method, specifically comprising the following steps:

[0010] Step 1, hardware deployment and installation.

[0011] The linear displacement mechanism is provided with sliding variable voltage sensors at each positioning position, analog output interfaces of the sliding variable voltage sensors are connected to analog input modules of a PLC in an electric control cabinet, the PLC is connected with a frequency converter, the frequency converter is connected with a driving motor of the linear displacement mechanism, the driving motor drives linear movement of the linear displacement mechanism, and an external lever fixed on the linear displacement mechanism also moves along with the linear displacement mechanism, the lever adjusts the position according to actual use conditions, and it is ensured that the lever can push the sliding contact of the sliding variable voltage sensor.

[0012] Step two, position judgment logic setting.

[0013] The position judgment logic is realized through PLC programming, when the linear displacement mechanism touches a sliding variable voltage sensor at a position, the mechanism is determined to be at the position according to the change of the voltage deviation from the extreme value of the sensor, and when the mechanism does not touch the sensor, the mechanism is determined to be between the two positions according to the opposite extreme value voltage state of the adjacent two sensors.

[0014] Step three, positioning execution process.

[0015] After the PLC receives the positioning instruction, the driving direction is determined according to the relationship between the current position and the target position, the frequency converter is controlled to drive the motor to move the mechanism, when the mechanism contacts the target position sensor and changes the voltage of the sensor, the PLC adjusts the motor speed according to the corresponding value of the real-time voltage, until the mechanism runs to the error range of the positioning target value, and the motor is stopped.

[0016] Step four, later maintenance correction.

[0017] When there is an error in positioning, the positioning value in the PLC is adjusted through software to realize fine tuning of the positioning position, without adjusting the hardware.

[0018] Further, in step one, the sliding variable voltage sensor selects a type with a preset voltage output range, has a preset effective sliding stroke, and sets the minimum value of the voltage output range corresponding to one end of the sensor and the maximum value of the voltage output range corresponding to the other end.

[0019] Further, in step one, the analog input module of the PLC is a module with a bit number suitable for the voltage output range of the sliding variable voltage sensor, and the voltage output range of the sensor corresponds to a preset value range of the internal variable of the PLC.

[0020] Further, in step two, the extreme value voltage is a stable extreme value voltage when the sliding variable voltage sensor is not touched, specifically the minimum value or the maximum value of the voltage output range thereof, and the opposite extreme value voltage state of the adjacent two sensors is that one sensor outputs the minimum value of the voltage output range and the other outputs the maximum value of the voltage output range.

[0021] Further, in step four, the software adjusts the calculation method of the positioning value as follows:

[0022] The adjustment value is calculated by the formula , wherein, represents the distance that needs to be adjusted, represents the preset effective sliding stroke of the sliding variable pressure sensor, represents the preset maximum value of the PLC internal variable; the original positioning value is added to to obtain a new positioning value.

[0023] Further, when the linear displacement mechanism is a vertical linear motion device, the step two further includes a drop compensation logic setting: the PLC calculates the current height position of the device in real time through the voltage value fed back by the sensor and records the reference value of each positioning position, and sets a preset position change threshold value, when the position deviation caused by the load change exceeds the threshold value, the dynamic compensation logic is triggered.

[0024] Further, the positioning execution flow of the vertical linear motion device further includes: when the device sinks due to load increase, the PLC controls the motor to drive the device to fine-tune upward; when the device rises due to load reduction, the PLC controls the motor to drive the device to fine-tune downward, so that the device position is maintained within the preset range corresponding to the reference value.

[0025] Compared with the prior art, the present application has the following beneficial effects:

[0026] 1. The sliding variable pressure sensor is used to replace the optical sensor for position positioning, breaking the industry tradition, laying a solid foundation for the use of linear motion devices in special environments, and improving the compatibility of the device to the scene;

[0027] 2. The sliding variable pressure sensor with low price, mature and stable technology is used to replace the laser ranging and photoelectric positioning method, which meets the standard positioning requirements, reduces the equipment cost, and improves the operation stability;

[0028] 3. In special use scenarios, using the sliding variable pressure sensor positioning can solve the sensor adaptability problem caused by high temperature and high pressure;

[0029] 4. By applying the positioning method, the problem of high and low drop in the positioning process is solved, which is convenient for later maintenance and adjustment, and saves labor. BRIEF DESCRIPTION OF DRAWINGS

[0030] Figure 1 A flowchart of a linear displacement mechanism positioning control method;

[0031] Figure 2 A schematic diagram of the positioning position of the trolley of the present application;

[0032] Figure 3 Hardware installation diagram for the present application;

[0033] Figure 4 Positioning execution flow diagram for the present application from position 3 to position 4. DETAILED DESCRIPTION

[0034] Embodiment one, with reference to Figure 1 The present embodiment is a linear displacement mechanism positioning control method, taking a horizontal translation cart requiring positioning at 6 positions as an example, to illustrate the positioning control steps based on sliding variable pressure sensors, specifically including the following steps:

[0035] Step one, hardware deployment and installation.

[0036] Sensor selection and installation: as shown in Figure 2 and Figure 3 , install sliding variable pressure sensors at the 6 positioning positions of the horizontal translation cart, select 0~10V voltage output type, set the leftmost position of each sensor to correspond to 0V, the rightmost position to correspond to 10V, and the effective sliding stroke to be 800mm. Ensure that the alignment error between the cart and each positioning position is controlled within ±20mm during installation;

[0037] Hardware connection: connect the analog output interface of the 6 sliding variable pressure sensors to the analog input module of the PLC in the electrical control cabinet (use Siemens 12-bit module, 0~10V corresponding to PLC internal variable 0~27648); connect the PLC with the frequency converter, and connect the frequency converter with the drive motor of the cart to form a control loop;

[0038] Adjust the position of the external lever on the translation cart, including the horizontal and vertical directions, to ensure that the lever can smoothly push the sliding contact of each position sensor when the cart moves, and to ensure that the voltage changes linearly during the sliding process of the contact;

[0039] Step two, position judgment logic setting.

[0040] Position detection: achieve position judgment logic through PLC programming, when the cart touches a sensor at a position, the lever pushes the contact to slide, the sensor voltage deviates from the extreme value (0V or 10V), and the PLC directly determines that the cart is at that position according to the voltage change;

[0041] Interval position detection: when the cart does not touch any sensor, the voltage of each sensor is at the extreme value state (0V or 10V). If the voltages of the sensors at two adjacent positions are opposite extreme values (one maximum and one minimum), the PLC determines that the cart is between these two positions;

[0042] Step three, positioning execution flow (as shown in Figure 4 , taking the example of from position 3 to position 4).

[0043] Instruction receiving and direction determination: after receiving the positioning instruction, the PLC determines that the trolley is currently located at position 3, the target position 4 is on the right side, and the driving motor is determined to move to the right.

[0044] Movement process control: the PLC sends a signal to the frequency converter to drive the motor to move the trolley to the right. The trolley gradually moves away from position 3, and the position 3 sensor contact resets to a stable state of 10V; at this time, the position 4 sensor remains at a 0V extreme state.

[0045] Positioning range entry and speed adjustment: after the trolley contacts the position 4 sensor, the lever pushes the contact to slide, and the sensor voltage starts to rise from 0V. The PLC detects the voltage change and determines that the trolley has entered the position 4 positioning range. The frequency converter adjusts the motor speed according to the real-time voltage value (0~27648) to achieve smooth deceleration.

[0046] Precise parking: when the trolley runs to the positioning target value 13824 (corresponding to a position of 400mm, with an error of ±1mm), the PLC controls the frequency converter to stop the motor operation, completing the positioning.

[0047] Step four, late maintenance correction.

[0048] If there is an error in positioning (e.g., a 5mm fine adjustment to the right is required), calculate the adjustment value In the PLC, modify the original positioning value 13824 to 13824+173=13997, without the need to adjust the hardware position.

[0049] Example two, this example is a positioning control method of a linear displacement mechanism. Taking an elevator car carrying an AGV trolley as an example, the positioning control steps of vertical equipment are explained as follows:

[0050] Step one, hardware deployment and installation.

[0051] Sensor installation: install a sliding variable voltage sensor at each positioning position of the elevator car on each stop floor. Choose a 0~10V voltage output type, with an effective sliding stroke of 800mm. Set the sensor contact to slide linearly with the car (e.g., when the car rises, the voltage rises from 0V to 10V).

[0052] Hardware connection: connect the sensor analog output to the PLC analog input module, connect the PLC to the frequency converter of the elevator traction motor to realize motor speed regulation and operation control; install an external lever on the car to ensure precise contact with the sensor contact;

[0053] Step two, position monitoring and gap compensation logic setting.

[0054] Real-time position monitoring: PLC calculates the current height position of the car (0~800mm corresponds to 0~27648 values) in real time through the voltage value feedback by the sensor, and records the reference positioning values of each floor (such as floor 1 corresponds to value X1, floor 2 corresponds to value X2).

[0055] Drop compensation trigger condition: Set the position change threshold, when the position deviation caused by load change (AGV entering / leaving) exceeds the threshold (such as ±3mm), trigger the dynamic compensation logic;

[0056] Step three, positioning and drop compensation process.

[0057] Parking positioning control: After the elevator receives the parking instruction, PLC controls the motor to drive the car to rise or fall according to the difference between the current position and the target floor reference value; when the car approaches the target floor, the sensor voltage approaches the reference value, PLC controls the motor to slow down until the voltage value enters the ±1mm error range, stops the motor operation, and completes the parking positioning;

[0058] Drop compensation when AGV enters: During the process of AGV entering the car, the car sinks due to the increase of load, and the value corresponding to the sensor voltage decreases (height decreases). PLC monitors the value change trend in real time, calculates the sinking amount, controls the motor to drive the car to fine-tune upward (reverse operation), so that the voltage value is maintained within the reference positioning range, and the height difference is eliminated;

[0059] Drop compensation when AGV leaves: After AGV leaves the car, the car rises due to the decrease of load, and the value corresponding to the sensor voltage increases (height increases). After PLC detects the change, it controls the motor to drive the car to fine-tune downward, so that the voltage value returns to the reference positioning range, ensuring that the car is flush with the floor platform;

[0060] Step four, later maintenance correction.

[0061] If there is a deviation in the parking position of the floor (such as a certain floor needs to be adjusted by 2mm), calculate the adjustment value Increase the floor reference value by 69 in PLC to achieve precise fine-tuning, without the need to adjust the sensor installation position.

[0062] Through the detailed introduction of the above embodiment, the positioning control method of the linear displacement mechanism can realize a new positioning mode of the linear operation device by installing a set of sliding variable voltage sensor at each positioning position to feed back the current position of the linear movement device. Through this scheme, high-precision positioning and real-time position detection and calculation of the linear movement device can be realized at low cost, and the late maintenance and adjustment is simple, and the positioning position can be fine-tuned by setting parameters on the software; the current position of the movement device within the effective stroke range of the sensor can be monitored in real time, which is used for position closed-loop control, realizes accurate positioning, and also solves the problem of the height difference between the lifting device car and the ground platform in the above embodiment.

[0063] The above formulas are all dimensionless numerical calculations, and the preset parameters in the formulas are set by a person skilled in the art according to the actual situation.

[0064] The above embodiments can be realized wholly or partially by software, hardware, firmware or any other combination. When realized by software, the above embodiments can be realized wholly or partially in the form of a computer program product. The computer program product includes one or more computer instructions or computer programs. When the computer instructions or computer programs are loaded or executed on a computer, the processes or functions described in the embodiments of the present application are wholly or partially generated. The computer can be a general-purpose computer, a special-purpose computer, a computer network or other programmable devices. The computer instructions can be stored in a computer readable storage medium or transmitted from one computer readable storage medium to another, for example, the computer instructions can be transmitted from one website, computer, server or data center to another website, computer, server or data center through wired or wireless (such as infrared, wireless, microwave, etc.) mode. The computer readable storage medium can be any available medium that can be accessed by a computer or a data storage device such as a server, data center and the like containing one or more available medium sets. The available medium can be a magnetic medium (such as a floppy disk, a hard disk, a magnetic tape), an optical medium (such as a DVD) or a semiconductor medium. The semiconductor medium can be a solid state disk.

[0065] It should be understood that in various embodiments of the present application, the size of the sequence number of each process does not mean the order of execution, and the execution order of each process should be determined by its function and inherent logic, and should not constitute any limitation on the implementation process of the embodiments of the present application.

[0066] 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 or a combination of computer software and electronic hardware. Whether the functions are performed in hardware or software depends on the specific application and design constraints of the technical solution. Those 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 application.

[0067] Those skilled in the art can clearly understand that, for the convenience and brevity of the 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.

[0068] In several embodiments provided in the present application, 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 ignored 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 interface, device or unit, and can be electrical, mechanical or other forms.

[0069] If the functions are realized in the form of software function units and sold or used as independent products, they can be stored in a computer readable storage medium. Based on such understanding, the technical solutions of the present application essentially or the parts that make contributions to the prior art or parts of the technical solutions can be embodied in the form of a software product. The computer software product is stored in a storage medium and includes a plurality of instructions for causing a computer device (which can be a personal computer, a server, or a network device, etc.) to execute all or part of the steps of the methods described in the various embodiments of the present application. The foregoing storage medium includes: a U disk, a mobile hard disk, a read-only memory (ROM), a random access memory (RAM), a magnetic disk or an optical disk, and various media that can store program codes.

[0070] The above is only a specific implementation of the present application, but the protection scope of the present application is not limited thereto. Any person skilled in the art can easily think of changes or replacements within the technical scope disclosed in the present application, which should be covered within the protection scope of the present application. Therefore, the protection scope of the present application should be subject to the protection scope of the claims.

Claims

1. A positioning control method of a linear displacement mechanism, characterized by, The method comprises the following steps: Step one, hardware deployment and installation: install the sliding voltage sensor at each positioning position of the linear displacement mechanism, connect the analog output interface of the sliding voltage sensor to the analog input module of the PLC in the electric control cabinet, connect the PLC with the frequency converter, connect the frequency converter with the driving motor of the linear displacement mechanism, drive the linear displacement mechanism to move linearly, and the external lever fixed on the linear displacement mechanism also moves with the linear displacement mechanism, the lever adjusts the position according to the actual use condition, and it is ensured that the lever can push the sliding contact of the sliding voltage sensor; Step two, position judgment logic setting: realize the position judgment logic through PLC programming, when the linear displacement mechanism touches the sliding voltage sensor at a certain position, determine that the mechanism is at the position according to the change of the voltage deviation from the extreme value of the sensor; when the mechanism does not touch the sensor, determine that the mechanism is between the two positions according to the opposite extreme value voltage state of the adjacent two sensors; Step three, positioning execution process: after the PLC receives the positioning instruction, determine the driving direction according to the relationship between the current position and the target position, control the frequency converter to drive the motor to move the mechanism, when the mechanism contacts the target position sensor and changes the voltage of the sensor, the PLC adjusts the motor speed according to the corresponding value of the real-time voltage, until the mechanism runs to the error range of the positioning target value, and the motor stops; Step four, later maintenance correction: when there is an error in positioning, adjust the positioning value in the PLC through software to realize fine tuning of the positioning position, without adjusting the hardware.

2. The positioning control method of a linear displacement mechanism according to claim 1, wherein In step one, the sliding voltage sensor selects a type with a preset voltage output range, has a preset effective sliding stroke, and sets the minimum value of the voltage output range corresponding to one end of the sensor and the maximum value of the voltage output range corresponding to the other end.

3. The positioning control method of a linear displacement mechanism according to claim 1, wherein In step one, the analog input module of the PLC is a module with a bit number suitable for the voltage output range of the sliding voltage sensor, and the voltage output range of the sensor corresponds to a preset value range of the internal variable of the PLC.

4. The positioning control method of a linear displacement mechanism according to claim 1, wherein In step two, the extreme value voltage is the stable extreme value voltage when the sliding voltage sensor is not touched, specifically the minimum value or the maximum value of the voltage output range; the opposite extreme value voltage state of the adjacent two sensors is that one sensor outputs the minimum value of the voltage output range and the other outputs the maximum value of the voltage output range.

5. The positioning control method of a linear displacement mechanism according to claim 1, wherein In step four, the calculation method of adjusting the positioning value in the PLC through software is as follows: The adjustment value is calculated by the formula wherein, represents the distance to be adjusted, represents the preset effective sliding stroke of the sliding variable transformer sensor, represents the preset maximum value of the PLC internal variable; and the original positioning value is added to to obtain the new positioning value.

6. The positioning control method of a linear displacement mechanism according to claim 1, wherein When the linear displacement mechanism is a vertical linear motion device, step two further comprises fall compensation logic setting: the PLC calculates the current height position of the device in real time through the voltage value fed back by the sensor and records the reference value of each positioning position, sets a preset position change threshold, and triggers the dynamic compensation logic when the position deviation caused by the load change of the device exceeds the threshold.

7. The positioning control method of a linear displacement mechanism according to claim 6, wherein The positioning execution process of the vertical linear motion device further comprises: when the device sinks due to the increase of the load, the PLC controls the motor to drive the device to fine tune upward; when the device rises due to the decrease of the load, the PLC controls the motor to drive the device to fine tune downward, so that the position of the device is maintained within the preset range corresponding to the reference value.

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