Control method for smooth lifting of proportional valve hydraulic lifting platform system

Abstract

The present application belongs to the technical field of hydraulic lifting platform, and particularly relates to a control method for stable lifting of a proportional valve hydraulic lifting platform system, comprising: determining and recording optimal control parameters in a debugging mode; entering a normal lifting mode and obtaining a lifting command and a target height; determining a proportional valve opening direction; adjusting the proportional valve opening corresponding to each oil cylinder in real time; stopping lifting upon receiving a stop command or reaching the target height. The present application obtains the extension amount of each hydraulic oil cylinder of the lifting platform through a linear displacement sensor placed in the hydraulic oil cylinder, controls the opening of the proportional valve corresponding to each hydraulic oil cylinder through a stable lifting control algorithm, thereby realizing fast and stable lifting of the lifting platform and avoiding the phenomenon of tilting of the platform leading to dropping of the lifted workpiece.

Description

Technical Field

[0001] This invention belongs to the field of hydraulic lifting platform technology, specifically relating to a control method for the smooth lifting of a proportional valve hydraulic lifting platform system. Background Technology

[0002] With increasing automation in industrial production processes, the transportation and installation of workpieces are becoming increasingly unmanned. This has led to the emergence of various intelligent unmanned transport platforms. These platforms need to be able to lift and lower themselves to access workpieces, raise the platform to lift them, and automatically transport them to their target location along a pre-set route. After the workpiece lands smoothly on the lowered platform, the platform moves away from under the workpiece and continues to transport it automatically. However, due to the misalignment of the center of mass and geometric center of the transport platform and the cargo, coupled with inconsistent pipeline lengths leading to varying flow losses, fluids will initially flow to areas of lower pressure. This causes significant tilting of the transport platform during lifting and lowering, which is detrimental to safe transport. To overcome this problem, a control method for the smooth lifting and lowering of a proportional valve hydraulic lifting platform system is needed. This method effectively ensures the stability of the platform during lifting and lowering, improving the safety of transport. Summary of the Invention

[0003] (a) Technical problems to be solved The technical problem to be solved by this invention is: how to maintain the stable lifting and lowering of a hydraulic lifting platform during the lifting and lowering process.

[0004] (II) Technical Solution To solve the above technical problems, the present invention provides a control method for the smooth lifting of a proportional valve hydraulic lifting platform system, the method comprising the following steps: Step S1: In the lifting and lowering debugging mode, obtain the lifting and lowering command; Step S2: Determine the opening direction of the proportional valve according to the lifting command; Step S3: Set the opening degree of all proportional valves to the same fixed value; Step S4: Repeat steps S1 to S3 to determine and record the reference target cylinder during the lifting and lowering process; Step S5: During the lifting process, calculate in real time the difference between the extension of each hydraulic cylinder and the extension of the reference target hydraulic cylinder; Step S6: Calculate the proportional valve opening degree corresponding to each cylinder based on the differences. Step S7: Repeat steps S5 to S6 to adjust the control parameters so that the extension of each cylinder during the platform lifting process is less than the set value. Step S8: Determine and record the optimal control parameters; Step S9: Exit the lifting and debugging mode, enter the normal lifting and hoisting mode, and obtain the lifting and hoisting command and target height; Step S10: Determine the opening direction of the proportional valve according to the lifting command and the actual extension of each cylinder; Step S11: Adjust the opening degree of the proportional valve corresponding to each oil cylinder in real time; Step S12: Stop ascent / descend upon receiving a stop command or upon reaching the target altitude.

[0005] In step S1, firstly, in the lifting and debugging mode, the lifting command from the host computer or operation panel is obtained through the CAN bus. The action required by the hydraulic lifting platform is parsed according to the lifting command. The hydraulic lifting platform action in the lifting command is divided into rising, lowering and stopping actions.

[0006] In step S2, the action required by the hydraulic lifting platform obtained in step S1 is as follows: if it is a stop action, the proportional valve is closed; if it is a lifting action, the opening direction of the proportional valve is set to the lifting direction; if it is a lowering action, the opening direction of the proportional valve is set to the lowering direction.

[0007] In step S3, after determining the opening direction of the proportional valve, all proportional valve openings are set to fixed values, so that each hydraulic cylinder of the hydraulic lifting platform simultaneously performs oil filling and discharging actions with the same proportional valve opening.

[0008] In step S4, after setting all proportional valve openings to a fixed opening, the lifting and lowering actions are repeatedly performed. Due to the different friction losses along the hydraulic lines, the lifting and lowering speeds of each hydraulic cylinder are also different. Although the proportional valve openings are the same, the hydraulic lifting platform will tilt because there is no control action involved. The lowest angle and the cylinder with the slowest lifting speed during the lifting process are recorded, as well as the highest angle and the cylinder with the slowest descent during the descent process. The cylinder with the slowest lifting speed during the lifting process is set as the reference target cylinder for the lifting process, and the cylinder with the slowest descent speed during the descent process is set as the reference target cylinder for the descent process.

[0009] In step S5, the proportional valve openings corresponding to the rising reference target cylinder and the falling reference target cylinder are set to fixed openings. During the rising process, the extension amount of each cylinder is collected in real time and compared with the extension amount of the rising reference target cylinder. The difference is calculated and recorded. During the falling process, the extension amount of each cylinder is collected in real time and compared with the extension amount of the falling reference target cylinder. The difference is calculated and recorded.

[0010] In step S6, the difference between the extension amount of each cylinder and the extension amount of the rising reference target cylinder and the extension amount of the falling reference target cylinder is input into the control algorithm. The control algorithm uses an incremental PID adjustment algorithm to calculate the change in the opening of the proportional valve corresponding to the cylinder through the input difference, and outputs the change to the opening of each proportional valve to adjust the lifting and lowering speed of each cylinder.

[0011] In step S7, the lifting and lowering speed of the hydraulic cylinders is controlled by adjusting the opening of each proportional valve through a control algorithm. In order to achieve rapid and stable lifting and lowering, the lifting and lowering speed adjustment of the hydraulic cylinders also needs to respond quickly. By repeatedly executing the lifting and lowering actions, the PID control parameters of each hydraulic cylinder are adjusted so that the lifting and lowering speed adjustment response of each hydraulic cylinder meets the requirements.

[0012] In step S8, after adjusting the PID control parameters in step S7, the lifting of the hydraulic lifting platform meets the requirements of rapid and stable lifting. The final PID control parameters of each cylinder are recorded and saved as the optimal control parameters. Subsequent lifting actions of the hydraulic lifting platform will be controlled and calculated using the recorded optimal control parameters.

[0013] In step S9, after the debugging in steps S1 to S8, the control process of the hydraulic lifting platform is debugged, the optimal control parameters are obtained and determined, the control performance meets the requirements, and the lifting debugging mode is exited, and the normal lifting mode is entered. The lifting command and target height are then obtained through the CAN bus.

[0014] In step S10, if the control command obtained by the bus is an upward command, the opening direction of the proportional valve is set to the upward direction; if the control command obtained is a downward command, the opening direction of the proportional valve is set to the downward direction. Alternatively, based on the target height in the control command, the extension amount of all cylinders is compared with the target height. If the extension amount of all cylinders is less than the target height, the opening direction of the proportional valve is set to the upward direction; if the extension amount of all cylinders is greater than the target height, the opening direction of the proportional valve is set to the downward direction.

[0015] In step S11, after determining the opening direction of the proportional valve, the extension amount of each cylinder is collected in real time and the difference between the extension amount and the target height is calculated. The opening adjustment amount of the proportional valve of each cylinder is calculated so that the lifting speed of each cylinder is consistent and the lifting platform can lift smoothly.

[0016] In step S12, when a stop command is received from the bus or the platform has reached the target height, the proportional valve is closed to stop the platform's lifting and lowering action.

[0017] (III) Beneficial Effects Compared with existing technologies, this invention uses a proportional valve hydraulic system as the control system for a hydraulic lifting platform. During the lifting process, the platform can remain stable, reducing the height and center of gravity limitations of the transported goods, increasing the safety of the lifting process, and allowing the lifting platform to transport more goods. This improves the economic value of the lifting platform and reduces the pumping costs of transporting goods. Attached Figure Description

[0018] Figure 1 This is a flowchart of the method of the present invention. Detailed Implementation

[0019] To make the objectives, contents, and advantages of the present invention clearer, the specific embodiments of the present invention will be described in further detail below with reference to the accompanying drawings and examples.

[0020] To solve the above technical problems, the present invention provides a control method for the smooth lifting of a proportional valve hydraulic lifting platform system, the method comprising the following steps: Step S1: In the lifting and lowering debugging mode, obtain the lifting and lowering command; Step S2: Determine the opening direction of the proportional valve according to the lifting command; Step S3: Set the opening degree of all proportional valves to the same fixed value; Step S4: Repeat steps S1 to S3 to determine and record the reference target cylinder during the lifting and lowering process; Step S5: During the lifting process, calculate in real time the difference between the extension of each hydraulic cylinder and the extension of the reference target hydraulic cylinder; Step S6: Calculate the proportional valve opening degree corresponding to each cylinder based on the differences. Step S7: Repeat steps S5 to S6 to adjust the control parameters so that the extension of each cylinder during the platform lifting process is less than the set value. Step S8: Determine and record the optimal control parameters; Step S9: Exit the lifting and debugging mode, enter the normal lifting and hoisting mode, and obtain the lifting and hoisting command and target height; Step S10: Determine the opening direction of the proportional valve according to the lifting command and the actual extension of each cylinder; Step S11: Adjust the opening degree of the proportional valve corresponding to each oil cylinder in real time; Step S12: Stop ascent / descend upon receiving a stop command or upon reaching the target altitude.

[0021] In step S1, firstly, in the lifting and debugging mode, the lifting command from the host computer or operation panel is obtained through the CAN bus. The action required by the hydraulic lifting platform is parsed according to the lifting command. The hydraulic lifting platform action in the lifting command is divided into rising, lowering and stopping actions.

[0022] In step S2, the action required by the hydraulic lifting platform obtained in step S1 is as follows: if it is a stop action, the proportional valve is closed; if it is a lifting action, the opening direction of the proportional valve is set to the lifting direction; if it is a lowering action, the opening direction of the proportional valve is set to the lowering direction.

[0023] In step S3, after determining the opening direction of the proportional valve, all proportional valve openings are set to fixed values, so that each hydraulic cylinder of the hydraulic lifting platform simultaneously performs oil filling and discharging actions with the same proportional valve opening.

[0024] In step S4, after setting all proportional valve openings to a fixed opening, the lifting and lowering actions are repeatedly performed. Due to the different friction losses along the hydraulic lines, the lifting and lowering speeds of each hydraulic cylinder are also different. Although the proportional valve openings are the same, the hydraulic lifting platform will tilt because there is no control action involved. The lowest angle and the cylinder with the slowest lifting speed during the lifting process are recorded, as well as the highest angle and the cylinder with the slowest descent during the descent process. The cylinder with the slowest lifting speed during the lifting process is set as the reference target cylinder for the lifting process, and the cylinder with the slowest descent speed during the descent process is set as the reference target cylinder for the descent process.

[0025] In step S5, the proportional valve openings corresponding to the rising reference target cylinder and the falling reference target cylinder are set to fixed openings. During the rising process, the extension amount of each cylinder is collected in real time and compared with the extension amount of the rising reference target cylinder. The difference is calculated and recorded. During the falling process, the extension amount of each cylinder is collected in real time and compared with the extension amount of the falling reference target cylinder. The difference is calculated and recorded.

[0026] In step S6, the difference between the extension amount of each cylinder and the extension amount of the rising reference target cylinder and the extension amount of the falling reference target cylinder is input into the control algorithm. The control algorithm uses an incremental PID adjustment algorithm to calculate the change in the opening of the proportional valve corresponding to the cylinder through the input difference, and outputs the change to the opening of each proportional valve to adjust the lifting and lowering speed of each cylinder.

[0027] In step S7, the lifting and lowering speed of the hydraulic cylinders is controlled by adjusting the opening of each proportional valve through a control algorithm. In order to achieve rapid and stable lifting and lowering, the lifting and lowering speed adjustment of the hydraulic cylinders also needs to respond quickly. By repeatedly executing the lifting and lowering actions, the PID control parameters of each hydraulic cylinder are adjusted so that the lifting and lowering speed adjustment response of each hydraulic cylinder meets the requirements.

[0028] In step S8, after adjusting the PID control parameters in step S7, the lifting of the hydraulic lifting platform meets the requirements of rapid and stable lifting. The final PID control parameters of each cylinder are recorded and saved as the optimal control parameters. Subsequent lifting actions of the hydraulic lifting platform will be controlled and calculated using the recorded optimal control parameters.

[0029] In step S9, after the debugging in steps S1 to S8, the control process of the hydraulic lifting platform is debugged, the optimal control parameters are obtained and determined, the control performance meets the requirements, and the lifting debugging mode is exited, and the normal lifting mode is entered. The lifting command and target height are then obtained through the CAN bus.

[0030] In step S10, if the control command obtained by the bus is an upward command, the opening direction of the proportional valve is set to the upward direction; if the control command obtained is a downward command, the opening direction of the proportional valve is set to the downward direction. Alternatively, based on the target height in the control command, the extension amount of all cylinders is compared with the target height. If the extension amount of all cylinders is less than the target height, the opening direction of the proportional valve is set to the upward direction; if the extension amount of all cylinders is greater than the target height, the opening direction of the proportional valve is set to the downward direction.

[0031] In step S11, after determining the opening direction of the proportional valve, the extension amount of each cylinder is collected in real time and the difference between the extension amount and the target height is calculated. The opening adjustment amount of the proportional valve of each cylinder is calculated so that the lifting speed of each cylinder is consistent and the lifting platform can lift smoothly.

[0032] In step S12, when a stop command is received from the bus or the platform has reached the target height, the proportional valve is closed to stop the platform's lifting and lowering action.

[0033] This invention uses linear displacement sensors placed inside hydraulic cylinders to obtain the extension amount of each hydraulic cylinder of the lifting platform. Through a smooth lifting control algorithm, it controls the opening degree of the proportional valve corresponding to each hydraulic cylinder, thereby enabling the lifting platform to rise quickly and smoothly, and avoiding the phenomenon of the lifting workpiece falling due to platform tilting.

[0034] Example 1 This embodiment provides a control method for the smooth lifting of a proportional valve hydraulic lifting platform system, which includes the following steps: Step S1: Obtain the lifting command; Step S2: Determine the opening direction of the proportional valve according to the command; Step S3: Set the opening degree of all proportional valves to the same fixed value; Step S4: Repeat steps S1 to S3 to determine and record the reference hydraulic cylinder during the lifting process; Step S5: During the lifting process, calculate the difference between the extension of each hydraulic cylinder and the extension of the reference hydraulic cylinder in real time; Step S6: Input each difference value into the control algorithm to calculate the proportional valve opening degree corresponding to each oil cylinder; Step S7: Repeat steps S5 to S6 to adjust the control parameters so that the extension of each cylinder during the platform lifting process is less than the set value. Step S8: Determine and record the optimal control parameters; Step S9: The system enters normal mode and obtains the lifting command and target height; Step S10: Determine the opening direction of the proportional valve according to the command and the actual extension of each cylinder; Step S11: Adjust the opening degree of the proportional valve corresponding to each oil cylinder in real time through the control algorithm; Step S12: Stop ascent / descend upon receiving a stop command or upon reaching the target altitude.

[0035] In step S1, the lifting command is obtained through the CAN bus.

[0036] In step S2, the opening direction of the proportional valve is determined by the lifting command obtained in step S1.

[0037] In step S3, after determining the opening direction of the proportional valve in step S2, the opening of the proportional valve is set to a fixed opening.

[0038] In step S4, the lifting and lowering action is repeatedly performed by the proportional valve opening set in step S3 to determine and record the lifting and lowering reference target cylinder. In step S5, the elongation of each cylinder is collected and calculated in real time using the lifting reference target cylinder determined and recorded in step S4, and compared with the reference target cylinder to calculate the difference.

[0039] In step S6, the elongation difference calculated in step S5 is used to input each difference into the control algorithm to calculate the adjustment amount of each proportional valve opening and adjust the opening of each proportional valve.

[0040] In step S7, after adjusting the opening of the proportional valve in step S6, in order for the platform to achieve rapid and stable lifting and lowering, the PID control parameters of each cylinder are adjusted by repeatedly executing the lifting and lowering actions, so that the lifting speed adjustment response of each cylinder meets the requirements.

[0041] In step S8, after repeatedly debugging in step S7 to obtain the optimal control parameters, the optimal parameters are recorded and written into the control system.

[0042] In step S9, after the final parameters are determined in step S8, the control system adjustment parameters are determined, the control system enters normal mode, and receives lifting commands and target heights via the CAN bus.

[0043] In step S10, after obtaining the action command in step S9, the required opening direction of the proportional valve is parsed to determine the reference target cylinder. By substituting the difference between the real-time calculation and the target cylinder into the control system, the opening change of each proportional valve is calculated. The change is combined with the current opening to calculate the target scale, and the target opening is output to the corresponding proportional valve.

[0044] In step S11, after obtaining the reference cylinder in step S10, the difference between the real-time calculation and the target cylinder is substituted into the control system to calculate the opening change of each proportional valve. The change is combined with the current opening to calculate the target scale, and the target opening is output to the corresponding proportional valve.

[0045] In step S12, after adjusting the opening of the proportional valve in step S11, the platform rises and falls smoothly and rapidly under the control of the control system until it reaches the target height or stops moving after receiving a stop command from the CAN bus.

[0046] Example 2 This embodiment provides a control method for the smooth lifting and lowering of a proportional valve hydraulic lifting platform system. By adopting this control method, the stability of the lifting platform during the lifting and lowering of goods can be effectively guaranteed.

[0047] Specific implementation methods include: Step 1: After the proportional valve hydraulic lifting system is installed on the lifting platform, check whether the data from the built-in displacement sensors in each cylinder is normal, test whether the power unit of the hydraulic lifting system is normal, and test whether the proportional valve operates normally.

[0048] Step 2: Set all switching valve openings to a uniform fixed opening. Send rise and fall commands via CAN bus. After multiple rises and falls, identify the cylinders with the slowest rise and fall, and designate them as the target reference cylinders. Set the proportional valve of the target reference cylinder to a fixed opening, and the other cylinders as follower cylinders. Calculate the displacement difference between the follower cylinders and the target reference cylinder in real time, and input this difference into the control algorithm. The control algorithm uses an incremental PID control algorithm to calculate the change in the proportional valve opening of the corresponding cylinder based on the input error, and outputs this change to the opening of each proportional valve to adjust the rise and fall speed of each cylinder. This ensures that the position of the follower cylinders always remains consistent with the target reference cylinder.

[0049] Step 3: Repeatedly raise and lower the platform, adjust the PID parameters of each follower cylinder, so that the lifting speed adjustment of the cylinder can respond quickly, and the position of the follower cylinder always remains consistent with the target reference cylinder during the lifting process. After the displacement of each cylinder is consistent, the platform remains stable without tilting or shaking. Write the optimal control parameters into the control system.

[0050] Step 4: After completing the parameter debugging, the lifting platform enters the normal mode. It analyzes the lifting action of the hydraulic cylinder according to the command received from the CAN bus, and controls the platform to lift smoothly and safely transport goods through the control system.

[0051] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the technical principles of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A control method for smooth lifting of a proportional valve hydraulic lifting platform system, characterized in that, The method includes the following steps: Step S1: In the lifting and lowering debugging mode, obtain the lifting and lowering command; Step S2: Determine the opening direction of the proportional valve according to the lifting command; Step S3: Set the opening degree of all proportional valves to the same fixed value; Step S4: Repeat steps S1 to S3 to determine and record the reference target cylinder during the lifting and lowering process; Step S5: During the lifting process, calculate in real time the difference between the extension of each hydraulic cylinder and the extension of the reference target hydraulic cylinder; Step S6: Calculate the proportional valve opening degree corresponding to each cylinder based on the differences. Step S7: Repeat steps S5 to S6 to adjust the control parameters so that the extension of each cylinder during the platform lifting process is less than the set value. Step S8: Determine and record the optimal control parameters; Step S9: Exit the lifting and debugging mode, enter the normal lifting and hoisting mode, and obtain the lifting and hoisting command and target height; Step S10: Determine the opening direction of the proportional valve according to the lifting command and the actual extension of each cylinder; Step S11: Adjust the opening degree of the proportional valve corresponding to each oil cylinder in real time; Step S12: Stop ascent / descend upon receiving a stop command or upon reaching the target altitude.

2. The control method for smooth lifting of a proportional valve hydraulic lifting platform system as described in claim 1, characterized in that, In step S1, firstly, in the lifting and debugging mode, the lifting command from the host computer or operation panel is obtained through the CAN bus. The action required by the hydraulic lifting platform is parsed according to the lifting command. The hydraulic lifting platform action in the lifting command is divided into rising, lowering and stopping actions.

3. The control method for smooth lifting of a proportional valve hydraulic lifting platform system as described in claim 2, characterized in that, In step S2, the action required by the hydraulic lifting platform obtained in step S1 is as follows: if it is a stop action, the proportional valve is closed; if it is a lifting action, the opening direction of the proportional valve is set to the lifting direction; if it is a lowering action, the opening direction of the proportional valve is set to the lowering direction.

4. The control method for smooth lifting of a proportional valve hydraulic lifting platform system as described in claim 3, characterized in that, In step S3, after determining the opening direction of the proportional valve, all proportional valve openings are set to fixed values, so that each hydraulic cylinder of the hydraulic lifting platform simultaneously performs oil filling and discharging actions with the same proportional valve opening.

5. The control method for smooth lifting of a proportional valve hydraulic lifting platform system as described in claim 4, characterized in that, In step S4, after setting all proportional valve openings to a fixed opening, the lifting and lowering actions are repeatedly performed. Due to the different friction losses along the hydraulic lines, the lifting and lowering speeds of each hydraulic cylinder are also different. Although the proportional valve openings are the same, the hydraulic lifting platform will tilt because there is no control action involved. The lowest angle and the cylinder with the slowest lifting speed during the lifting process are recorded, as well as the highest angle and the cylinder with the slowest descent speed during the descent process. The cylinder with the slowest lifting speed during the lifting process is set as the reference target cylinder for the lifting process, and the cylinder with the slowest descent speed during the descent process is set as the reference target cylinder for the descent process.

6. The control method for smooth lifting of a proportional valve hydraulic lifting platform system as described in claim 5, characterized in that, In step S5, the proportional valve openings corresponding to the rising reference target cylinder and the falling reference target cylinder are set to fixed openings. During the rising process, the extension amount of each cylinder is collected in real time and compared with the extension amount of the rising reference target cylinder. The difference is calculated and recorded. During the descent, the extension amount of each hydraulic cylinder is collected in real time and compared with the extension amount of the reference target hydraulic cylinder. The difference is calculated and recorded.

7. The control method for smooth lifting of a proportional valve hydraulic lifting platform system as described in claim 6, characterized in that, In step S6, the difference between the extension amount of each cylinder and the extension amount of the rising reference target cylinder and the extension amount of the falling reference target cylinder is input into the control algorithm. The control algorithm uses an incremental PID adjustment algorithm to calculate the change in the opening of the proportional valve corresponding to the cylinder through the input difference, and outputs the change to the opening of each proportional valve to adjust the lifting and lowering speed of each cylinder.

8. The control method for smooth lifting of a proportional valve hydraulic lifting platform system as described in claim 7, characterized in that, In step S7, the lifting and lowering speed of the hydraulic cylinders is controlled by adjusting the opening of each proportional valve through the control algorithm. In order to achieve rapid and stable lifting and lowering, the lifting and lowering speed adjustment of the hydraulic cylinders also needs to respond quickly. By repeatedly executing the lifting and lowering actions, the PID control parameters of each hydraulic cylinder are adjusted so that the lifting and lowering speed adjustment response of each hydraulic cylinder meets the requirements.

9. The control method for smooth lifting of a proportional valve hydraulic lifting platform system as described in claim 8, characterized in that, In step S8, after adjusting the PID control parameters in step S7, the lifting of the hydraulic lifting platform meets the requirements of rapid and stable lifting. The final PID control parameters of each cylinder are recorded and saved as the optimal control parameters. Subsequent lifting actions of the hydraulic lifting platform will be controlled and calculated using the recorded optimal control parameters.

10. The control method for smooth lifting of a proportional valve hydraulic lifting platform system as described in claim 9, characterized in that, In step S9, after the debugging in steps S1 to S8, the control process of the hydraulic lifting platform is debugged, the optimal control parameters are obtained and determined, the control performance meets the requirements, and it leaves the lifting debugging mode and enters the normal lifting mode, continuing to obtain lifting commands and target heights through the CAN bus.

11. The control method for smooth lifting of a proportional valve hydraulic lifting platform system as described in claim 10, characterized in that, In step S10, if the control command obtained by the bus is an upward command, the opening direction of the proportional valve is set to the upward direction; if the control command obtained is a downward command, the opening direction of the proportional valve is set to the downward direction. Alternatively, based on the target height in the control command, the extension amount of all cylinders is compared with the target height. If the extension amount of all cylinders is less than the target height, the opening direction of the proportional valve is set to the upward direction; if the extension amount of all cylinders is greater than the target height, the opening direction of the proportional valve is set to the downward direction.

12. The control method for smooth lifting of a proportional valve hydraulic lifting platform system as described in claim 11, characterized in that, In step S11, after determining the opening direction of the proportional valve, the extension amount of each cylinder is collected in real time and the difference between the extension amount and the target height is calculated. The opening adjustment amount of the proportional valve of each cylinder is calculated so that the lifting speed of each cylinder is consistent and the lifting platform can lift smoothly.

13. The control method for smooth lifting of a proportional valve hydraulic lifting platform system as described in claim 12, characterized in that, In step S12, when the control command received from the bus is a stop command or the platform has reached the target height, the proportional valve is closed to stop the platform's lifting and lowering action.

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