Large-height overhead working truck leveling system and control method

Abstract

The invention discloses a large-height overhead working truck leveling system and a control method.The system comprises a platform leveling subsystem, a hydraulic compensation subsystem and a PLC control subsystem, and the platform leveling subsystem comprises a crank arm, a leveling oil cylinder, a first connecting rod, a second connecting rod and a platform bracket; the hydraulic compensation subsystem comprises a balance valve, a leveling proportional valve, a one-way valve, a compensation proportional valve, an overflow valve and a compensation pump. The PLC control subsystem comprises a CAN communication module, a CPLD logic control module, a PWM driving module, a digital driving module, an angle sensor and a pressure sensor. A digital driving module is used for controlling a compensation pump, a PWM driving module is used for controlling a compensation proportional valve, and pressure adjustment is carried out; a PWM driving module is used for controlling a leveling proportional valve and a leveling platform; and the PWM driving module is used for adjusting the driving current of the proportional electromagnet of the leveling proportional valve. According to the invention, the pressure loss in the leveling pipeline can be compensated in real time, the pressure in the leveling pipeline is kept constant, and the response speed of the leveling system is improved.

Description

Technical Field

[0001] The invention relates to the technical field of engineering equipment, and in particular to a leveling system and a control method for a high-altitude aerial work vehicle. Background Art

[0002] As a special vehicle for manned aerial work, aerial work vehicles are increasingly replacing the previous extremely dangerous climbing operation mode. With the development of urban construction, aerial work vehicles are not only used in large-scale infrastructure such as docks, airports, water conservancy, power stations, and gardens, but are also widely used in the installation and management of urban facilities such as street lights, communications, transportation, advertising, and photography.

[0003] As a manned equipment, the aerial work vehicle has an automatic leveling function. There are three main ways to level the existing aerial work vehicle platform: 1. Mechanical leveling. That is, the platform is automatically leveled using the principle of gravity or a parallelogram linkage mechanism, which is mostly used in folding boom aerial work vehicles. 2. Hydraulic leveling. Its adjustment principle relies on the isovolumetric triangle principle of the platform telescopic cylinder and the turntable telescopic cylinder to achieve automatic adjustment of the platform, which is mostly used in telescopic boom aerial work vehicles. 3. Electric leveling. The platform's inclination angle sensor is used to provide real-time feedback on the platform angle, and the platform leveling cylinder is adjusted through the feedback signal to ensure the leveling of the platform.

[0004] At present, due to the complex structure of aerial work vehicles with large heights and mixed arms, electric leveling can only be achieved. For aerial work vehicles with large heights and mixed arms, especially those with large heights and mixed arms above 40 meters, leveling will be delayed. Summary of the invention

[0005] The purpose of the present invention is to provide a leveling system and control method for a high-altitude aerial work vehicle, which controls the hydraulic system through PLC to compensate for the pressure loss of an overly long oil pipe, thereby achieving a rapid response of the leveling system and effectively solving the problem of leveling lag.

[0006] In order to solve the above technical problems, the present invention adopts the following technical solutions: a high-altitude aerial work vehicle leveling system, including a platform leveling subsystem, a hydraulic compensation subsystem and a PLC control subsystem.

[0007] The platform leveling subsystem includes a crank arm, a leveling cylinder, a first connecting rod, a second connecting rod and a platform bracket.

[0008] The hydraulic compensation subsystem includes a balancing valve, a leveling proportional valve, a check valve, a compensation proportional valve, a relief valve and a compensation pump.

[0009] The PLC control subsystem includes a PLC controller, an angle sensor and a pressure sensor, wherein the PLC controller includes a CAN communication module, a CPLD logic control module, a PWM drive module and a digital drive module.

[0010] The pressure sensor, the oil inlet P of the leveling proportional valve, one end of the one-way valve and the working oil port A of the compensation proportional valve constitute a leveling oil circuit.

[0011] The PLC control subsystem detects the corresponding parameters of the platform that have changed through sensors, and obtains the corresponding control strategy by comparing it with the set threshold of the parameter. The strategy is transmitted to the control hydraulic compensation subsystem to drive the leveling proportional valve, compensation proportional valve and compensation pump to perform corresponding operations, thereby enabling the platform leveling subsystem to drive the platform to rotate for leveling.

[0012] Furthermore, in the platform leveling subsystem, one end of the leveling cylinder is placed on the crank arm, one end of the crank arm is connected to the platform bracket, one end of the first connecting rod is connected to the end of the crank arm, one end of the second connecting rod is connected to the platform bracket, and the other end of the first connecting rod and the other end of the second connecting rod are connected to the other end of the leveling cylinder.

[0013] Furthermore, the cylinder barrel of the leveling cylinder is placed on the crank arm through a pin shaft, one end of the crank arm is hinged to the platform bracket, one end of the first connecting rod is hinged to the end of the crank arm, one end of the second connecting rod is hinged to the platform bracket, and the other end of the first connecting rod and the other end of the second connecting rod are hinged to the piston rod of the leveling cylinder.

[0014] Furthermore, in the hydraulic compensation subsystem, the working oil port A of the balancing valve is connected to the large chamber of the leveling cylinder, the working oil port B of the balancing valve is connected to the small chamber of the leveling cylinder, the oil inlet P of the balancing valve is connected to the working oil port A of the leveling proportional valve, the oil return port T of the balancing valve is connected to the working oil port B of the leveling proportional valve, the oil inlet P of the leveling proportional valve and one end of the one-way valve are connected to the working oil port A of the compensation proportional valve, the other end of the one-way valve is connected to the oil inlet P of the main oil circuit, the oil return port T of the leveling proportional valve is connected to the oil return port T of the main oil circuit, the working oil port B of the compensation proportional valve is blocked, the oil inlet P of the compensation proportional valve and the output oil port of the compensation pump are connected to the oil inlet of the overflow valve, the oil return port T of the compensation proportional valve and the oil return port of the overflow valve are connected to the oil return port T of the compensation oil circuit, and the oil input port of the compensation pump is connected to the oil inlet P of the compensation oil circuit.

[0015] Furthermore, in the PLC control subsystem, the angle sensor is arranged on the platform bracket, the CAN communication module is connected to the angle sensor and the pressure sensor, one end of the CPLD logic control module is connected to the CAN communication module, the other end of the CPLD logic control module is connected to the PWM drive module and the digital drive module, the PWM drive module is connected to the leveling proportional valve and the compensation proportional valve, the digital drive module is connected to the compensation pump, and the pressure sensor is connected to the oil inlet P of the leveling proportional valve, one end of the one-way valve, and the working oil port A of the compensation proportional valve.

[0016] Furthermore, the angle sensor is connected to the platform bracket through bolts, and the CAN communication module is connected to the angle sensor and the pressure sensor through a CAN bus.

[0017] Furthermore, the present invention also proposes a control method for a high-altitude aerial work vehicle leveling system, comprising: Step 1: The CAN communication module detects the pressure P of the leveling oil circuit in real time and sets the allowable pressure range of the leveling oil circuit to P min ~P max , the data of the CAN communication module is transmitted to the PWM drive module and the digital drive module respectively through the CPLD logic control module. <P min When P>P max When the digital drive module drives the compensation pump to stop running, the PWM drive module drives the proportional solenoid on the left side of the compensation proportional valve to be energized; when P min ≤P≤P max When the digital drive module drives the compensation pump to stop running, the PWM drive module drives the compensation proportional valve to lose power, and the compensation proportional valve returns to the middle position.

[0018] Step 2: The angle sensor detects the tilt angle of the platform in real time , set the maximum allowable tilt angle of the platform to ,when and When it is positive, the PWM drive module drives the left coil of the leveling proportional valve to be energized, and the hydraulic oil enters the small chamber of the leveling cylinder through the left position of the leveling proportional valve, driving the platform bracket to move counterclockwise around the hinge point, and then drives the angle sensor to rotate around the hinge point, and the platform is leveled counterclockwise; when and When it is negative, the PWM drive module drives the right coil of the leveling proportional valve to be energized, and the hydraulic oil enters the large chamber of the leveling cylinder through the right position of the leveling proportional valve, driving the platform bracket to move clockwise around the hinge point, and then drives the angle sensor to rotate around the hinge point, and the platform is leveled clockwise; when the platform's tilt angle When the PWM drive module closes the output of the leveling proportional valve, cuts off the oil circuit of the leveling cylinder, and the platform is not leveled.

[0019] Step 3: The pressure sensor detects the pressure of the leveling oil circuit in real time. The CAN communication module converts the electrical signals of the pressure sensor and the angle sensor into measurement signals and transmits them to the CPLD logic control module. The CPLD logic control module records the platform tilt angle of the current sampling period in real time. and the platform tilt angle of the previous sampling cycle , and the rate of change of the platform inclination angle is obtained as ,in n Indicates the sampling period of the current CPLD logic control module; sets the maximum allowable change rate of the platform to ,when and When is positive, the PWM drive module increases the proportional solenoid drive current of the leveling proportional valve, so that the valve core opening of the leveling proportional valve is increased and the extension and retraction speed of the leveling cylinder is increased; when and When it is negative, the PWM drive module reduces the proportional solenoid drive current of the leveling proportional valve, which reduces the valve core opening of the leveling proportional valve and reduces the extension and retraction speed of the leveling cylinder; when When the leveling cylinder is in the state of tension and tension, the PWM drive module keeps the proportional solenoid drive current of the leveling proportional valve unchanged, so that the valve opening of the leveling proportional valve remains unchanged, ensuring that the extension and retraction speed of the leveling cylinder is constant.

[0020] Furthermore, when the main oil circuit is not working, the one-way valve is used to lock the pressure in the leveling oil circuit, and at the same time prevent the compensating pressure from overflowing from the main oil circuit P port when compensating the leveling oil circuit pressure.

[0021] When the opening of the compensating proportional valve is less than the set threshold, the excess pressure returns to the tank from the relief valve.

[0022] Furthermore, in step 3, the calculation formula of the change in the proportional electromagnet drive current is: ; in, Indicates the change in the proportional solenoid drive current. represents the proportional gain, Indicates the angular velocity change rate of the current sampling period, Indicates the rate of change of angular velocity in the previous sampling period, represents the integral gain, represents the differential gain, Indicates the rate of change of angular velocity during the previous two sampling periods.

[0023] Compared with the prior art, the present invention adopts the above technical solution and has the following technical effects: The present invention reduces the pressure loss of the pipeline by adding a hydraulic compensation system, can compensate the pressure loss in the leveling pipeline in real time, keep the pressure in the leveling pipeline constant, and solve the leveling lag problem caused by the excessively long leveling pipeline and large pressure loss.

[0024] In addition, the present invention improves the response speed of the leveling system through the cascade PID speed control system. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 It is the overall structural diagram of the present invention.

[0026] Figure 2 It is a structural schematic diagram of the platform leveling subsystem of the present invention.

[0027] Figure 3 It is a schematic diagram of the structure of the hydraulic compensation subsystem of the present invention.

[0028] Figure 4 It is a schematic diagram of the principle of the PLC control subsystem of the present invention.

[0029] Figure numbers: 1-platform leveling subsystem, 2-hydraulic compensation subsystem, 3-PLC control subsystem, 4-crank arm, 5-leveling cylinder, 6-first connecting rod, 7-second connecting rod, 8-platform bracket, 9-angle sensor, 10-platform, 11-balancing valve, 12-leveling proportional valve, 13-pressure sensor, 14-check valve, 15-compensation proportional valve, -16 overflow valve, 17-compensation pump, 18-PLC controller. DETAILED DESCRIPTION

[0030] The present invention will be further described below in conjunction with the accompanying drawings. The following embodiments are only used to more clearly illustrate the technical solution of the present invention, and cannot be used to limit the protection scope of the present invention.

[0031] To achieve the above object, the present invention proposes a high altitude aerial work vehicle leveling system, such as Figure 1 As shown, it includes a platform leveling subsystem 1, a hydraulic compensation subsystem 2 and a PLC control subsystem 3.

[0032] like Figure 2 As shown, the platform leveling subsystem 1 includes a crank arm 4, a leveling cylinder 5, a first connecting rod 6, a second connecting rod 7 and a platform bracket 8. The cylinder barrel of the leveling cylinder 5 is hinged to the crank arm 4 through a pin, one end of the crank arm 4 is hinged to the platform bracket 8 at a hinge point C, one end of the first connecting rod 6 is hinged to the end of the crank arm 4 at a hinge point F, one end of the second connecting rod 7 is hinged to the platform bracket 8 at a hinge point E, and the other end of the first connecting rod 6 and the other end of the second connecting rod 7 are hinged to the piston rod of the leveling cylinder 5 at a hinge point D.

[0033] like Figure 3 As shown, the hydraulic compensation subsystem 2 includes a balancing valve 11, a leveling proportional valve 12, a one-way valve 14, a compensation proportional valve 15, a relief valve 16 and a compensation pump 17. The working oil port A of the balancing valve 11 is connected to the large chamber of the leveling cylinder 5, the working oil port B of the balancing valve 11 is connected to the small chamber of the leveling cylinder 5, the oil inlet P of the balancing valve 11 is connected to the working oil port A of the leveling proportional valve 12, and the oil return port T of the balancing valve 11 is connected to the working oil port B of the leveling proportional valve 12. The oil inlet P of the leveling proportional valve 12 and one end of the one-way valve 14 are connected to the working oil port A of the compensating proportional valve 15, the other end of the one-way valve 14 is connected to the oil inlet P of the main oil circuit, the oil return port T of the leveling proportional valve 12 is connected to the oil return port T of the main oil circuit, the working oil port B of the compensating proportional valve 15 is blocked, the oil inlet P of the compensating proportional valve 15 and the oil output port of the compensating pump 17 are connected to the oil inlet of the relief valve 16, the oil return port T of the compensating proportional valve 15 and the oil return port of the relief valve 16 are connected to the oil return port T of the compensation oil circuit, and the oil input port of the compensation pump 17 is connected to the oil inlet P of the compensation oil circuit.

[0034] like Figure 4 As shown, the PLC control subsystem 3 includes a PLC controller 18, an angle sensor 9 and a pressure sensor 13, wherein the PLC controller 18 includes a CAN communication module, a CPLD logic control module, a PWM drive module and a digital drive module. The angle sensor 9 is connected to the platform bracket 8 by bolts, the CAN communication module is connected to the angle sensor 9 and the pressure sensor 13 through the CAN bus, the PWM drive module is connected to the leveling proportional valve 12 and the compensation proportional valve 15, the digital drive module is connected to the compensation pump 17, and the pressure sensor 13 is connected to the oil inlet P of the leveling proportional valve 12, one end of the one-way valve 14, and the working oil port A of the compensation proportional valve 15.

[0035] The pressure sensor 13, the oil inlet P of the leveling proportional valve 12, one end of the one-way valve 14 and the working oil port A of the compensation proportional valve 15 constitute a leveling oil circuit.

[0036] The PLC control subsystem 3 detects the corresponding parameters of the platform 10 that have changed through sensors, and obtains the corresponding control strategy by comparing it with the set threshold value of the parameter. The strategy is transmitted to the control hydraulic compensation subsystem 2 to drive the leveling proportional valve 12, the compensation proportional valve 15 and the compensation pump 17 to perform corresponding operations, thereby enabling the platform leveling subsystem 1 to drive the platform 10 to rotate for leveling.

[0037] A control method principle of a high-altitude aerial work vehicle leveling system is as follows: Step 1: The hydraulic compensation subsystem ensures that the pressure at the oil inlet of the leveling proportional valve is constant, thereby ensuring that the flow rate will not change due to load or environmental factors. Specifically, the CAN communication module detects the pressure P of the leveling oil circuit in real time and sets the allowable pressure range of the leveling oil circuit to Pmin ~P max , the data of the CAN communication module is transmitted to the PWM drive module and the digital drive module respectively through the CPLD logic control module. <P min When , it indicates that the pressure of the leveling oil circuit is too low and needs to be compensated. The digital drive module drives the compensation pump to supply oil to the compensation oil circuit. The PWM drive module drives the proportional solenoid on the right end of the compensation proportional valve to be energized. The compensation oil circuit flows into the leveling oil circuit through the right position of the compensation proportional valve, thereby increasing the pressure of the leveling oil circuit. When P>P max When P is on, it indicates that the pressure in the leveling oil circuit is too high and needs to be reduced. The digital drive module drives the compensation pump to stop running and stop supplying oil to the compensation oil circuit. The PWM drive module drives the proportional solenoid on the left side of the compensation proportional valve to be energized, and the leveling oil circuit overflows through the left position of the compensation proportional valve, thereby reducing the pressure in the leveling oil circuit. min ≤P≤P max , indicating that the pressure of the leveling oil circuit is normal, the digital drive module drives the compensation pump to stop running, the PWM drive module controls the compensation proportional valve to lose power, the compensation proportional valve returns to the middle position, and the compensation oil circuit is switched.

[0038] When the main oil circuit is not working, the one-way valve is used to lock the pressure in the leveling oil circuit, and at the same time prevent the compensating pressure from overflowing from the P port of the main oil circuit when compensating the leveling oil circuit pressure.

[0039] When the opening of the compensation proportional valve is less than 30%, the excess pressure returns to the oil tank from the relief valve to ensure the safety of the hydraulic compensation subsystem.

[0040] Step 2: Set the maximum allowable tilt angle of the platform to , the angle sensor detects the tilt angle of the platform in real time ,when and When the PWM drive module drives the left coil of the leveling proportional valve to be energized, and the hydraulic oil enters the small chamber of the leveling cylinder through the left position of the leveling proportional valve, pushing the piston rod of the leveling cylinder to retract, and then pulling back the first connecting rod and the second connecting rod. The second connecting rod drives the platform bracket to move counterclockwise around the hinge point C. When the platform bracket rotates, it drives the angle sensor to rotate around the hinge point C, and the platform is leveled counterclockwise. and When it is negative, the PWM drive module drives the right coil of the leveling proportional valve to be energized, and the hydraulic oil enters the large chamber of the leveling cylinder through the right position of the leveling proportional valve, pushing the leveling cylinder to extend, and then pushing the first connecting rod and the second connecting rod. The second connecting rod drives the platform bracket to move clockwise around the hinge point C. When the platform bracket rotates, it drives the angle sensor to rotate around the hinge point C, and the platform is leveled clockwise. When the platform's tilt angle When the leveling proportional valve is turned off, the PWM drive module turns off the output of the leveling proportional valve, returns the leveling proportional valve to the middle position, cuts off the oil circuit of the leveling cylinder, and the platform is not leveled.

[0041] Step 3: The pressure sensor detects the pressure of the leveling oil circuit in real time. The CAN communication module converts the electrical signals of the pressure sensor and the angle sensor into measurement signals and transmits them to the CPLD logic control module. The CPLD logic control module records the platform tilt angle of the current sampling period in real time. and the platform tilt angle of the previous sampling cycle , and the rate of change of the platform inclination angle is obtained as ,in n Indicates the sampling period of the current CPLD logic control module; sets the maximum allowable change rate of the platform to ,when and When it is positive, it means that the platform leveling speed is slower than the platform tilting speed, the leveling hysteresis increases, and the PWM drive module increases the proportional solenoid drive current of the leveling proportional valve, so that the valve core opening of the leveling proportional valve is increased, the extension and retraction speed of the leveling oil cylinder is increased, the response speed of the leveling system is increased, and the hysteresis is reduced. and When it is negative, it means that the platform leveling speed is greater than the platform tilting speed, the leveling overshoot increases, and the PWM drive module reduces the proportional solenoid drive current of the leveling proportional valve, which reduces the valve core opening of the leveling proportional valve, reduces the extension and retraction speed of the leveling cylinder, reduces the response speed of the leveling system, and reduces overshoot. When , it means that the speed of platform leveling is equal to the speed of platform tilting. The PWM drive module keeps the proportional solenoid drive current of the leveling proportional valve unchanged, so that the valve opening of the leveling proportional valve remains unchanged, ensuring that the extension and retraction speed of the leveling cylinder is constant.

[0042] The calculation formula for the change in proportional solenoid drive current is: ; in, Indicates the change in the proportional solenoid drive current. represents the proportional gain, Indicates the angular velocity change rate of the current sampling period, Indicates the rate of change of angular velocity in the previous sampling period, represents the integral gain, represents the differential gain, Indicates the rate of change of angular velocity during the previous two sampling periods.

[0043] In this embodiment, .

[0044] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the technical principles of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A high altitude aerial work vehicle leveling system, characterized in that: It includes a platform leveling subsystem (1), a hydraulic compensation subsystem (2) and a PLC control subsystem (3); The platform leveling subsystem (1) comprises a crank arm (4), a leveling cylinder (5), a first connecting rod (6), a second connecting rod (7) and a platform bracket (8); The hydraulic compensation subsystem (2) includes a balancing valve (11), a leveling proportional valve (12), a check valve (14), a compensation proportional valve (15), a relief valve (16) and a compensation pump (17); The PLC control subsystem (3) comprises a PLC controller (18), an angle sensor (9) and a pressure sensor (13), wherein the PLC controller (18) comprises a CAN communication module, a CPLD logic control module, a PWM drive module and a digital drive module.

2. The high altitude aerial work vehicle leveling system according to claim 1, characterized in that: In the platform leveling subsystem (1), one end of the leveling cylinder (5) is placed on the crank arm (4), one end of the crank arm (4) is connected to the platform bracket (8), one end of the first connecting rod (6) is connected to the end of the crank arm (4), one end of the second connecting rod (7) is connected to the platform bracket (8), and the other end of the first connecting rod (6) and the other end of the second connecting rod (7) are connected to the other end of the leveling cylinder (5).

3. The high altitude aerial work vehicle leveling system according to claim 2, characterized in that: The cylinder barrel of the leveling oil cylinder (5) is placed on the crank arm (4) via a pin shaft, one end of the crank arm (4) is hinged to the platform bracket (8), one end of the first connecting rod (6) is hinged to the end of the crank arm (4), one end of the second connecting rod (7) is hinged to the platform bracket (8), and the other end of the first connecting rod (6) and the other end of the second connecting rod (7) are hinged to the piston rod of the leveling oil cylinder (5).

4. The high altitude aerial work vehicle leveling system according to claim 1, characterized in that: In the hydraulic compensation subsystem (2), the working oil port A of the balancing valve (11) is connected to the large chamber of the leveling cylinder (5), the working oil port B of the balancing valve (11) is connected to the small chamber of the leveling cylinder (5), the oil inlet P of the balancing valve (11) is connected to the working oil port A of the leveling proportional valve (12), the oil return port T of the balancing valve (11) is connected to the working oil port B of the leveling proportional valve (12), the oil inlet P of the leveling proportional valve (12) and one end of the check valve (14) are connected to the working oil port of the compensation proportional valve (15). A is connected to the check valve (14), the other end of the check valve (14) is connected to the main oil circuit oil inlet P, the oil return port T of the leveling proportional valve (12) is connected to the main oil circuit oil return port T, the working oil port B of the compensating proportional valve (15) is blocked, the oil inlet P of the compensating proportional valve (15) and the oil output port of the compensating pump (17) are connected to the oil inlet of the relief valve (16), the oil return port T of the compensating proportional valve (15) and the oil return port of the relief valve (16) are connected to the oil return port T of the compensation oil circuit, and the oil input port of the compensation pump (17) is connected to the oil inlet P of the compensation oil circuit.

5. The high altitude aerial work vehicle leveling system according to claim 1, characterized in that: In the PLC control subsystem (3), the angle sensor (9) is arranged on the platform bracket (8), the CAN communication module is connected to the angle sensor (9) and the pressure sensor (13), one end of the CPLD logic control module is connected to the CAN communication module, the other end of the CPLD logic control module is connected to the PWM drive module and the digital drive module, the PWM drive module is connected to the leveling proportional valve (12) and the compensation proportional valve (15), the digital drive module is connected to the compensation pump (17), and the pressure sensor (13) is connected to the oil inlet P of the leveling proportional valve (12), one end of the one-way valve (14), and the working oil port A of the compensation proportional valve (15).

6. The high altitude aerial work vehicle leveling system according to claim 5, characterized in that: The angle sensor (9) is connected to the platform bracket (8) via bolts, and the CAN communication module is connected to the angle sensor (9) and the pressure sensor (13) via a CAN bus.

7. The control method for the leveling system of a high-altitude aerial work vehicle according to claim 1 is characterized in that: include: The PLC control subsystem (3) detects the corresponding parameter of the platform (10) that has changed through a sensor, and obtains a corresponding control strategy by comparing it with a set threshold value of the parameter, and transmits the strategy to the control hydraulic compensation subsystem (2), thereby driving the leveling proportional valve (12), the compensation proportional valve (15) and the compensation pump (17) to perform corresponding operations, thereby causing the platform leveling subsystem (1) to drive the platform (10) to rotate and perform leveling; Step 1: The CAN communication module detects the pressure P of the leveling oil circuit in real time and sets the allowable pressure range of the leveling oil circuit to P min ~P max , the data of the CAN communication module is transmitted to the PWM drive module and the digital drive module respectively through the CPLD logic control module. <P min When P>P max When the digital drive module drives the compensation pump to stop running, the PWM drive module drives the proportional solenoid on the left side of the compensation proportional valve to be energized; when P min ≤P≤P max When the digital drive module drives the compensation pump to stop running, the PWM drive module drives the compensation proportional valve to lose power, and the compensation proportional valve returns to the middle position; Step 2: The angle sensor detects the tilt angle of the platform in real time , set the maximum allowable tilt angle of the platform to ,when and When it is positive, the PWM drive module drives the left coil of the leveling proportional valve to be energized, and the hydraulic oil enters the small chamber of the leveling cylinder through the left position of the leveling proportional valve, driving the platform bracket to move counterclockwise around the hinge point, and then drives the angle sensor to rotate around the hinge point, and the platform is leveled counterclockwise; when and When it is negative, the PWM drive module drives the right coil of the leveling proportional valve to be energized, and the hydraulic oil enters the large chamber of the leveling cylinder through the right position of the leveling proportional valve, driving the platform bracket to move clockwise around the hinge point, and then drives the angle sensor to rotate around the hinge point, and the platform is leveled clockwise; when the platform's tilt angle When the PWM drive module closes the output of the leveling proportional valve, cuts off the oil circuit of the leveling cylinder, and the platform is not leveled; Step 3: The pressure sensor detects the pressure of the leveling oil circuit in real time. The CAN communication module converts the electrical signals of the pressure sensor and the angle sensor into measurement signals and transmits them to the CPLD logic control module. The CPLD logic control module records the platform tilt angle of the current sampling period in real time. and the platform tilt angle of the previous sampling cycle , and the rate of change of the platform inclination angle is obtained as ,in n Indicates the sampling period of the current CPLD logic control module; sets the maximum allowable change rate of the platform to ,when and When is positive, the PWM drive module increases the proportional solenoid drive current of the leveling proportional valve, so that the valve core opening of the leveling proportional valve is increased and the extension and retraction speed of the leveling cylinder is increased; when and When it is negative, the PWM drive module reduces the proportional solenoid drive current of the leveling proportional valve, which reduces the valve core opening of the leveling proportional valve and reduces the extension and retraction speed of the leveling cylinder; when When the leveling cylinder is in the state of tension and tension, the PWM drive module keeps the proportional solenoid drive current of the leveling proportional valve unchanged, so that the valve opening of the leveling proportional valve remains unchanged, ensuring that the extension and retraction speed of the leveling cylinder is constant.

8. The control method of the high-altitude aerial work vehicle leveling system according to claim 7, characterized in that: When the main oil circuit is not working, the one-way valve is used to lock the pressure in the leveling oil circuit, and at the same time prevent the compensated pressure from overflowing from the P port of the main oil circuit when compensating the pressure of the leveling oil circuit; When the opening of the compensating proportional valve is less than the set threshold, the excess pressure returns to the tank from the relief valve.

9. The control method of the high altitude aerial work vehicle leveling system according to claim 7, characterized in that: In step 3, the calculation formula for the change in the proportional solenoid drive current is: ； in, Indicates the change in the proportional solenoid drive current. represents the proportional gain, Indicates the angular velocity change rate of the current sampling period, Indicates the rate of change of angular velocity in the previous sampling period, represents the integral gain, represents the differential gain, Indicates the rate of change of angular velocity during the previous two sampling periods.

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