CN111539083B - Modeling method for autonomous leveling system of aerial work platform chassis - Google Patents

Abstract

The invention discloses a modeling method for an autonomous leveling system of the chassis of an aerial work platform, which includes: based on a four-point supporting hydraulic leveling system, the angle error leveling method is used to perform corresponding leveling operations on the chassis, and electromagnetic The proportional reversing valve adjusts the flow rate of the main oil supply circuit of the hydraulic leveling system, controls the extension and retraction speed of the outriggers, and uses the switch valve to adjust the extension and retraction time of each outrigger to control the X-axis of the chassis. The accuracy of the tilt angle with the Y axis, completes the leveling work. Finally, the hydraulic leveling system and the chassis leveling process are programmed with the help of engineering simulation software GX works2. The invention greatly simplifies the modeling method of the chassis leveling program, greatly simplifies the design and modeling work of the hardware and software parts, and adds functions such as pressure alarm and angle alarm, so that the leveling process is safer and more reliable.

Description

A modeling method for the autonomous leveling system of the aerial work platform chassis

Technical Field

The invention belongs to the technical field of aerial work, and in particular relates to a modeling method for an autonomous leveling system of an aerial work platform chassis.

Background Art

Mitsubishi PLC GX Works2 is a programming software launched by Mitsubishi Electric. GX Works2 is a programmable software that combines simulation software and module setting software. It is a programming tool dedicated to PLC design, debugging and maintenance. GX WORKS2 has improved functions and operating performance and has become easier to use.

GX Works2 Features

1. GX Works2 is Mitsubishi Electric's new generation PLC software, with two programming modes: Simple Project and Structured Project.

2. Support programming languages such as ladder diagram, instruction list, SFC, ST and structured ladder diagram.

3. It can realize functions such as program editing, parameter setting, network setting, program monitoring, debugging and online change, intelligent function module setting, etc.

4. Applicable to Q, QnU, L, FX and other series of programmable controllers.

5. Compatible with GX Developer software.

6. Support iQ Works, the iQ Platform integrated management software for Mitsubishi Electric industrial control products.

7. Mitsubishi PLC GX Works2 has a system tag function that enables data sharing between PLC and HMI and motion controller.

The continuous increase in the height of the aerial work platform makes the overturning moment of the aerial work platform increase continuously. At the same time, the stability moment of the aerial work platform is mainly provided by the chassis of the whole machine. Therefore, the horizontality of the chassis of the aerial work platform is crucial to the anti-overturning ability of the whole machine.

At present, the high-altitude aerial work platforms in engineering mainly adopt methods such as increasing the chassis support torque, increasing the chassis deadweight, relative leveling of the chassis, and chassis support mechanisms to ensure the safety and stability of aerial work. However, the commonly used chassis support methods in engineering, firstly, can only achieve relative leveling of the chassis with the help of external objects, and secondly, manually adjusting the lifting height of the chassis support can only achieve a certain leveling of the chassis.

Summary of the invention

The purpose of the present invention is to overcome the deficiencies in the prior art and provide a modeling method for an autonomous leveling system of an aerial work platform chassis, thereby simplifying the complexity of modeling.

The technical solution adopted by the present invention is as follows:

A modeling method for an autonomous leveling system of an aerial work platform chassis, comprising:

Establish a hydraulic leveling system for the aerial work platform chassis; the legs of the aerial work platform chassis adopt a hydraulic support structure; the hydraulic leveling system includes four hydraulic circuits, each of which includes a switch valve, a hydraulic cylinder and a pressure sensor;

The hydraulic leveling system is leveled by using an angle error leveling method, including:

An electromagnetic proportional reversing valve is used to adjust the flow of the main oil supply circuit of the hydraulic leveling system to control the speed of extending and retracting the outriggers;

And the switch valve is used to adjust the leveling time of each leg to control the accuracy of the tilt angle of the chassis X-axis and Y-axis;

GX Works2 is used to program the hydraulic leveling system and the leveling process of the hydraulic leveling system, and the modeling of the autonomous leveling system of the aerial work platform chassis is completed.

Furthermore, angle sensors are installed in the X-axis and Y-axis directions of the aerial work platform chassis to detect the inclination angles of the X-axis and Y-axis of the chassis.

Furthermore, the method of leveling the hydraulic leveling system by using an angle error leveling method further includes:

The collected signals of the angle sensor and the pressure sensor are amplified to the maximum digital quantity range of the AD module in the PLC control system through input characteristic change or amplifier, and the collected signals of the angle sensor and the pressure sensor are converted into digital signals through the AD module.

Furthermore, the method of leveling the hydraulic leveling system by using an angle error leveling method further includes:

The PLC control system determines the positive and negative tilt angles of the chassis X-axis and Y-axis, and controls the actions of various intermediate relays related to the tilt angles;

The PLC control system feeds back signals to the electromagnetic proportional reversing valve and four switch valves through the DA module according to the inclination angles of the X-axis and Y-axis of the chassis; by changing the size of the valve port of the electromagnetic proportional reversing valve, the speed of piston rod extension is different, the speed of leg extension and retraction is controlled, and the "on" and "off" states of the switch valve are controlled to control the time of leg extension and retraction, so that the inclination angles of the X-axis and Y-axis are continuously reduced until the allowable range of chassis leveling accuracy is met.

Furthermore, the method of leveling the hydraulic leveling system by using an angle error leveling method further includes:

The output of the DA module of the PLC control system is amplified through an amplifier to the measuring range of the coil voltage of the electromagnetic proportional reversing valve.

Furthermore, according to the inclination angles of the chassis X-axis and Y-axis, each leg is adjusted through the electromagnetic proportional reversing valve and the switch valve, including:

If α＞0°, β＞0°, then leg 1 is the highest point of the chassis, keep leg 1 still, and raise legs 2 and 3 at the same time to reduce the inclination angle α to 0, then raise legs 3 and 4 to reduce the inclination angle β to 0;

If α＞0, β＜0, then leg 4 is the highest point of the chassis, keep leg 4 still, and raise legs 2 and 3 at the same time to reduce the inclination angle α until it is 0, then raise legs 1 and 2 to increase the inclination angle β until it is 0;

If α＜0, β＞0, then leg 2 is the highest point of the chassis, keep leg 2 still, and raise legs 1 and 4 at the same time to increase the inclination angle α until it is 0, then raise legs 3 and 4 to reduce the inclination angle β until it is 0;

If α<0, β<0, then leg 3 is the highest point of the chassis, keep leg 3 still, and raise legs 1 and 4 at the same time to increase the inclination angle α until it is 0, then raise legs 1 and 2 to increase the inclination angle β until it is 0;

The lifting leg means that the switch valve is controlled to be turned on and the leg is extended;

Define the leg 4 as the one located in the positive direction of the X-axis and the positive direction of the Y-axis, the leg 3 as the one located in the positive direction of the X-axis and the negative direction of the Y-axis, the leg 2 as the one located in the negative direction of the X-axis and the negative direction of the Y-axis, and the leg 1 as the one located in the negative direction of the X-axis and the positive direction of the Y-axis;

α is defined as the angle between the X-axis direction of the chassis in the ideal state and the actual state, and β is defined as the angle between the Y-axis direction of the chassis in the ideal state and the actual state.

Furthermore, the method of leveling the hydraulic leveling system by using an angle error leveling method further includes:

At the beginning of leveling, all legs extend synchronously, the four legs begin to touch the ground, and the pressure oil enters the rodless chamber, causing the hydraulic support structure to extend until it touches the ground. If the rodless chamber pressure value corresponding to each leg is greater than or equal to the set pressure, the leveling state is entered.

Furthermore, the method of leveling the hydraulic leveling system by using an angle error leveling method further includes:

At the beginning of leveling, the inlet coil of the electromagnetic proportional reversing valve remains energized until the four leveling legs have completed leveling, and then the outlet coil of the electromagnetic proportional reversing valve is energized.

Furthermore, the accuracy of the inclination angles of the chassis X-axis and Y-axis is:

-0.1°<α<0.1° and -0.1°<β<0.1.

Furthermore, the hydraulic leveling system also includes a protection valve;

During the leveling process, the protection valve is always energized. When the switch valves of the four legs are in the disconnected state, the protection valve is de-energized.

Compared with the prior art, the present invention has the following beneficial effects:

(1) The modeling method provided by the present invention uses the internal function of the AD sensor to change the input characteristics in the processing of physical quantities, namely pressure values and angle values, so that the input voltage changes from 0.5V to 5V to 0V to 10V, which indirectly expands the input range of the digital quantity and makes the numerical values of the pressure and angle sensors more accurate.

(2) The modeling method provided by the present invention first completes the leveling of the X-axis in the functional program segment, and then completes the leveling of the Y-axis, and adds pressure alarm, angle alarm and interlocking function settings for each leg in the functional program, which simplifies the complexity of modeling, so that the model can accurately determine the action time of each leg, the action sequence of the legs and the action accuracy of the legs;

(3) The modeling method provided by the present invention controls each valve group through a DA converter for the output program segment, and adds a corresponding amplifier so that the output voltage can match the actuator.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG1 is a three-dimensional diagram of the chassis of the present invention;

FIG2 is a simplified structural diagram of the chassis legs in the present invention;

FIG3 is a schematic diagram of a hydraulic leveling system in the present invention;

FIG4 is a schematic diagram of the configuration of the angle sensor in the hydraulic leveling system of the present invention;

FIG5 is a hardware configuration diagram of the hydraulic leveling system of the present invention;

FIG6 is a schematic diagram of the leveling control principle of the hydraulic leveling system of the present invention;

FIG7 is a diagram showing the working principle of the AD module in the present invention;

FIG8 is a flow chart of detecting a virtual leg in the present invention;

FIG9 is a schematic diagram of the leg adjustment in the present invention;

FIG10 is a graph showing input characteristic changes in the present invention;

Figure 11 is an input characteristic modification procedure;

Figure 12 shows the average procedure of the FX3u-4AD;

Figure 13 is a leg 1 action indication program;

Figure 14 is a leg 2 action indication program;

Figure 15 is a leg 3 action indication program;

Figure 16 is a leg 4 action instruction program;

Figure 17 is the energizing procedure of the electromagnetic proportional directional valve coil;

Figure 18 is a solenoid proportional reversing valve coil retraction action indication program;

Figure 19 is a protection valve indicating the action procedure;

Figure 20 is a virtual leg judgment procedure;

Figure 21 is the touchdown indicator light procedure;

Figure 22 is a pressure warning light program;

Figure 23 is a procedure for determining whether the inclination angle meets the range requirements;

Fig. 24 is a procedure for determining the positive and negative leveling angles;

Figure 25 is a procedure for determining the highest support point;

Figure 26 is a procedure for determining whether the inclination angle meets the accuracy requirements;

Figure 27 shows the output procedure.

DETAILED DESCRIPTION

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.

The invention provides a modeling method for a chassis leveling program of an aerial work platform. Based on a four-point support hydraulic leveling system, an angle error leveling method is adopted to perform corresponding leveling operations on the chassis to support the chassis of the aerial work platform.

Referring to Figures 1 and 2, the aerial work platform chassis consists of a chassis and four legs supporting the chassis. In Figure 2, XYZ is the ideal horizontal coordinate system of the chassis, X ₀ Y ₀ Z ₀ is the coordinate system of the initial state of the chassis, α is the angle between the X axis and the X0 axis, indicating the inclination angle of the chassis in the X-axis direction, and β is the angle between the Y axis and the Y0 axis, indicating the inclination angle of the chassis in the Y-axis direction. The legs adopt a hydraulic support structure, and each leg is equipped with a pressure sensor.

The hydraulic leveling system designed by the present invention is used for leveling the chassis. Referring to FIG3 , the hydraulic leveling system includes an oil tank 1, a filter 2, a pump 3, a throttle valve 6, an electromagnetic proportional reversing valve 7 and a balance valve 8, and four hydraulic circuits connected in sequence. Each hydraulic circuit is composed of a switch valve, a hydraulic cylinder and a pressure sensor. Referring to FIG3 , the first switch valve 9-1, the first hydraulic cylinder 11-1 and the first pressure sensor 10-1 constitute the first hydraulic circuit, the second switch valve 9-2, the second hydraulic cylinder 11-2 and the second pressure sensor 10-2 constitute the second hydraulic circuit, the third switch valve 9-3, the third hydraulic cylinder 11-3 and the third pressure sensor 10-3 constitute the third hydraulic circuit, and the fourth switch valve 9-4, the fourth hydraulic cylinder 11-4 and the fourth pressure sensor 10-4 constitute the fourth hydraulic circuit.

The balance valve 8 and the protection valve 12 are both located on the main oil supply line.

The pump 3 is driven by the motor 4. In addition, a relief valve 5 is provided, which mainly plays a role of safety protection in the system and is connected in parallel with the main oil supply line. When the oil line pressure is too large, the relief valve opens the overflow unloading function.

Refer to Figure 5. The electromagnetic proportional reversing valve is used to adjust the flow rate of the main oil supply circuit, thereby controlling the extension and retraction speed of the leveling legs. The pressure sensor is used to detect the pressure of the hydraulic cylinder to fill each leg. By controlling the power-on time of the switch valve, the leveling time of the leveling legs is controlled. By controlling the leveling time, the inclination angles of the X-axis and Y-axis of the chassis can meet the leveling accuracy.

Referring to Figures 4 and 5, angle sensors are installed on the X-axis and Y-axis directions of the aerial work platform chassis. The angle sensors are used to detect whether the leveling accuracy meets the working conditions and ensure the leveling accuracy of the chassis. The inclination angles of the X-axis and Y-axis are ≤0.1 degrees.

The present invention uses GX Works2 to write the leveling program according to the hydraulic system schematic diagram and the leveling method. The program of the chassis self-leveling system is mainly divided into input program writing, function program writing and output program writing. The overall program is mainly written in the form of a body diagram.

1. Writing the input program

Input programming consists of two parts: changes to input characteristics and averaging procedures.

The input program needs to collect signals from four pressure sensors and two angle sensors and convert the analog quantities into voltage quantities.

The number of AD modules selected depends on the number of AD conversion channels, pressure sensors, and angle sensors.

The AD module in the present invention has 4 channels, so two AD modules are used to convert the collected analog quantity. The working principle of the AD module is shown in Figure 7. The FX3u-4AD PLC of Mitsubishi Corporation is used as the control system. Since the output voltage of the pressure sensor and the angle sensor are both 0.5 to 4.5V, and the input voltage of FX3u-4AD is -10V to +10V, in order to improve the resolution of the signal, the voltage input mode of the AD module is specified as 0 mode, that is, the range of the digital quantity is -32000 to +32000.

Therefore, in order to improve the resolution of the sensor's collected signal, the sensor's output voltage needs to be proportionally increased to the maximum digital range, that is, -32000 to +32000.

The input program needs to change the input characteristics or add an amplifier so that the input voltage of the pressure sensor and angle sensor matches the input voltage of the PLC control system. The output program can also change the input characteristics or add a corresponding amplifier so that the output voltage of the PLC controller matches the voltage of the switch valve.

Use digital value 0 to 32000 to output DC0.5 to 4.5V, output mode 0, that is, the output characteristics at the factory.

Bias data: The analog input value when the digital value is 0 (bias reference value), that is, 0.5v = 500mv;

Gain data: The input value of the analog quantity when the digital value becomes the gain value, that is, 2.5v=2500mv.

Therefore, the program will specify the input mode of the corresponding AD module, use the sequence program to write the offset data (BFM#41~#44) and gain data (BFM#51~#54), and write them to the corresponding position of each channel of the input characteristic writing (BFM#21) to turn on, thereby changing the input characteristics. Figure 10 is a graph of the input characteristic change.

In addition, a timer needs to be added to the input mode. The timing period is 5 seconds, which is used to change the input mode (BFM#0). After the input mode is changed, the writing of each setting will be executed after about 5 seconds or more.

Figure 11 shows the corresponding change procedure.

The present invention adopts the average program of FX3u-4AD for data acquisition. The main purpose of the average program is to make the digital quantity acquisition more accurate and enhance the anti-interference ability of the system. First, the channel mode needs to be specified, then the sampling average and the filter function settings are set, and finally the data in the channel is read out into the data memory.

Changed the input characteristics of two AD modules (M0/M1).

Figure 12 is the corresponding average program, setting the sampling average and digital filter of two AD modules. From the above program, it can be seen that the analog input voltage used by the first AD module is -10V~+10V, the corresponding digital quantity is -32000~+32000, and the digital quantity used is 0~+32000. The analog quantity of the pressure sensor is written into D0~D3 of the first AD module, and the analog quantity of the angle sensor is written into D4~D5 of the second AD module.

2. Writing of Functional Programs

The functional program segment is mainly divided into three stages. The first stage is the free extension stage of the piston rod of the hydraulic cylinder, the second stage is the chassis leveling stage, and the third stage is the retraction stage of the piston rod of the hydraulic cylinder.

It mainly includes functional program segments such as setting the action time of each leg, setting the leveling accuracy, setting the pressure alarm, setting the angle alarm, setting the interlocking alarm, etc.

Table 1 shows the contacts, data storage and coils of the program. Since the range of the pressure sensor is 0-200 bar, the corresponding output voltage is 0.5-4.5 V, which is converted into the corresponding digital value 0-32000. The digital value corresponding to 10 bar is 1600, and the digital value corresponding to 100 bar is 16000. The range of the angle sensor is -15° to +15°, and the corresponding output voltage is 0.5-4.5 V. Therefore, 30° corresponds to 32000, and the digital value corresponding to the leveling accuracy of 0.1° is about 107.

Table 1 is the correspondence table between contacts and coils

Table 2 is the distribution table of intermediate relays

The whole outrigger leveling process is:

All legs extend synchronously, the four legs begin to touch the ground, and the pressure oil enters the rodless chamber, causing the hydraulic support structure to extend until it touches the ground. The pressure oil is continuously input into the rodless chamber to enable the hydraulic support structure to overcome the virtual legs and compact the ground, and the leveling system begins.

If the rodless chamber pressure value of the hydraulic cylinder corresponding to each leg is greater than or equal to the set pressure, the leveling state is entered, the leg at the highest point is kept stationary, and the other three legs chase the highest point to shorten their respective leveling displacement differences. First, the X-axis angle is leveled, and then the Y-axis angle is leveled. After completion, the chassis is leveled.

The leveling process is shown in Figure 6. The inclination angles α and β of the X-axis and the Y-axis are detected by the angle sensor, and the detected angles α and β are fed back to the PLC control system through the A/D converter. The PLC control system determines the positive and negative of the inclination angles α and β through the corresponding program, determines the action of each intermediate relay, and first adjusts the inclination angle of the X-axis, and then adjusts the inclination angle of the Y-axis to complete the leveling of the chassis.

The control system provides feedback signals to the electromagnetic proportional reversing valve and four switch valves. By changing the size of the valve port of the electromagnetic proportional reversing valve, the extension and retraction of the outriggers are controlled. The switch valve has only two states, "on" and "off". The length of the on-off time is controlled, so that the inclination angles α and β of the platform are continuously reduced until the allowable range of the chassis leveling accuracy is met.

Figure 13 shows the action indication of outrigger 1, which is divided into 3 stages. The first stage is the normally closed contact Y010. The action executed in the first stage is that the outriggers are freely extended. When all four outriggers touch the ground, the second stage is the normally open contact Y010. The action executed in the second stage is that the outriggers start to level. After the chassis is leveled, the third stage Y005 is executed. The action of the third stage is that after pressing X003, the outriggers are fully retracted.

Similarly, FIG. 14 , FIG. 15 , and FIG. 16 are respectively the outrigger 2 action indication program, the outrigger 3 action indication program, and the outrigger 4 action indication program.

According to the inclination angles α and β of the X-axis and the Y-axis, the outriggers are adjusted as shown in Figure 9. The process is as follows:

If α＞0°, β＞0°, then fulcrum 1 is the highest point of the chassis. Keep outrigger 1 still, and raise points 2 and 3 at the same time to reduce the inclination angle α to 0. Then raise points 3 and 4 to reduce the inclination angle β to 0. At this time, α and β are both 0, the system stops working, and the chassis is in a horizontal state. Table 3 shows the leveling process in this case:

Table 3 α＞0°, β＞0° leveling process

If α＞0, β＜0, then fulcrum 4 is the highest point of the chassis, keep outrigger 4 still, and simultaneously raise points 2 and 3 to reduce the inclination angle α until it is 0, and then raise points 1 and 2 to increase the inclination angle β until it is 0. At this time, α and β are both 0, the system stops working, and the chassis is in a horizontal state. Table 4 shows the leveling process in this case:

Table 4 Leveling process of α＞0°, β＜0°

If α＜0, β＞0, then fulcrum 2 is the highest point of the chassis, keep leg 2 still, and simultaneously raise points 1 and 4 to increase the inclination angle α until it is 0, and then raise points 3 and 4 to reduce the inclination angle β until it is 0. At this time, α and β are both 0, the system stops working, and the chassis is in a horizontal state. Table 5 shows the leveling process in this case:

Table 5 Leveling process of α＜0°, β＞0°

If α＜0, β＜0, then fulcrum 3 is the highest point of the chassis, keep leg 3 still, and simultaneously raise points 1 and 4 to increase the inclination angle α until it is 0, and then raise points 1 and 2 to increase the inclination angle β until it is 0. At this time, α and β are both 0, the system stops working, and the chassis is in a horizontal state. Table 6 shows the leveling process in this case:

Table 6 α＜0°, β＜0° leveling process

In addition, if |α|＞|β|, adjust the inclination angle α first, and then adjust the inclination angle β. When leveling with this method, keep the highest point still, and only need to extend the legs to achieve the corresponding chassis level.

The energizing procedure of the electromagnetic proportional directional valve inlet coil is shown in Figure 17. After pressing X001, the electromagnetic proportional directional valve inlet coil will be self-retaining and the coil will always be energized. Only when the four leveling legs have completed leveling, that is, Y000, Y001, Y002, and Y003 have all lost power, the electromagnetic proportional reversing valve coil will lose power.

The electromagnetic proportional reversing valve retraction coil action instruction procedure is shown in Figure 18. Press X003 and the electromagnetic proportional reversing valve retraction coil will be energized.

The protective valve indication action procedure is shown in Figure 19. Generally, the Y006 protective valve is always energized. Only when all four legs are not energized, that is, the switch valve is in the disconnected state, the protective valve Y006 is de-energized.

Determine the pressure value of the rodless cavity of the four legs and compare it with the set pressure value to determine whether a virtual leg or overload phenomenon occurs as shown in Figure 8. See Figure 20 for the procedure.

The touchdown indicator light procedure and the pressure warning light procedure are shown in Figures 21 and 22.

The whole leveling process is as follows:

Use the ZCP instruction in the PLC program to compare whether the inclination angles α and β meet the range requirements, see Figure 23.

Make sure the leveling accuracy of the X-axis and Y-axis is 0.1 degree, and determine the positive and negative leveling angles as shown in Figure 24.

According to the positive or negative value of the leveling angle, the highest support point is determined, so that each leveling leg can selectively determine the size of the extended leveling amount, thereby completing the chassis leveling as shown in Figure 25.

When the leveling accuracy meets the leveling requirements of -0.1°＜α＜0.1° and -0.1°＜β＜0.1, the leveling completion indicator light is as shown in Figure 26.

3. Writing the output program

Since the output voltage of the FX3u-4DA module is -10V~+10V, and the coil voltage of the electromagnetic proportional directional valve is 24V, if the electromagnetic proportional directional valve is to be fully opened, an amplifier needs to be added to proportionally amplify the output voltage.

Secondly, it is necessary to transmit HFF00 to BFM#0 (channel 1~4 output mode) of the DA module. Channels 3 and 4 have no signal input, and the output mode of channel 1 and 2 voltage output (-10V~+10V) is 0.

Furthermore, the conditions for writing data to channels 1 and 2 are different. When Y004 is turned on and Y010 is not turned on, the pressure oil flows into the rodless chamber. In the stage of free extension of the piston rod, the PLC writes K32000, i.e. +10V voltage, to the memory of the DA module. When Y004 is turned on and Y010 is turned on, in the stage of leveling the piston rod touching the ground, the PLC writes K16000, i.e. +5V voltage, to the memory of the DA module. The amplifier amplifies the output voltage of the DA module, so that the proportional reversing valve inlet coil is energized. The piston rod adjusts the corresponding opening of the proportional reversing valve according to the different coil energization, so that the speed of the piston rod extension is different. When Y005 is turned on, that is, the hydraulic cylinder has oil inlet, the PLC writes K32000, i.e. +10V voltage, to the memory of the DA module, so that the proportional reversing valve retracting coil is energized and the piston rod retracts, as shown in Figure 27.

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 (8)

1. A modeling method for an autonomous leveling system of a chassis of an aerial work platform is characterized by comprising the following steps:

establishing a hydraulic leveling system of the aerial work platform chassis; the support legs of the aerial work platform chassis adopt hydraulic support structures; the hydraulic leveling system comprises four hydraulic circuits, wherein each hydraulic circuit comprises a switch valve, a hydraulic cylinder and a pressure sensor;

leveling the hydraulic leveling system by adopting an angle error type leveling method, comprising the following steps of:

the PLC control system judges whether the inclination angles of the X axis and the Y axis of the chassis are positive or negative and controls the action of each intermediate relay related to the inclination angles;

the PLC control system feeds back signals to the electromagnetic proportional reversing valve and the four switch valves through the DA module according to the inclination angles of the X axis and the Y axis of the chassis; through the size that changes the electromagnetic proportional directional valve port for the speed that the piston rod stretches out is different, and the speed that the control landing leg stretches out and retracts to and control switch valve "switch on" and "disconnection" state, the time that the control landing leg stretches out and retracts makes the inclination of X axle and Y axle constantly reduce, and the permission scope of leveling precision until satisfying the chassis includes:

if alpha is more than 0 degree and beta is more than 0 degree, the supporting leg 1 is the highest point of the chassis, the supporting leg 1 is kept still, meanwhile, the supporting leg 2 and the supporting leg 3 are lifted to reduce the inclination angle alpha to 0, and then the supporting leg 3 and the supporting leg 4 are lifted to reduce the inclination angle beta to 0;

if alpha is more than 0 and beta is less than 0, the supporting leg 4 is the highest point of the chassis, the supporting leg 4 is kept still, meanwhile, the supporting leg 2 and the supporting leg 3 are lifted to reduce the inclination angle alpha to 0, and then the supporting leg 1 and the supporting leg 2 are lifted to increase the inclination angle beta to 0;

if alpha is less than 0 and beta is more than 0, the supporting leg 2 is the highest point of the chassis, the supporting leg 2 is kept still, meanwhile, the supporting leg 1 and the supporting leg 4 are lifted, so that the inclination angle alpha is increased until the inclination angle alpha is 0, and then the supporting leg 3 and the supporting leg 4 are lifted, so that the inclination angle beta is reduced until the inclination angle beta is 0;

if alpha is less than 0 and beta is less than 0, the supporting leg 3 is the highest point of the chassis, the supporting leg 3 is kept still, meanwhile, the supporting leg 1 and the supporting leg 4 are lifted, so that the inclination angle alpha is increased until the inclination angle alpha is 0, and then the supporting leg 1 and the supporting leg 2 are lifted, so that the inclination angle beta is increased until the inclination angle beta is 0;

the lifting support legs are used for controlling the switch valve to be conducted, and the support legs extend out;

defining a supporting leg 4 positioned in the positive direction of an X axis, a supporting leg 3 positioned in the positive direction of the X axis and the negative direction of the Y axis, a supporting leg 2 positioned in the negative direction of the X axis and a supporting leg 1 positioned in the positive direction of the X axis;

defining alpha as an included angle between the ideal state of the chassis and the X-axis direction in the actual state, and defining beta as an included angle between the ideal state of the chassis and the Y-axis direction in the actual state;

and programming the leveling processes of the hydraulic leveling system and the hydraulic leveling system by adopting GX Works2 to complete the modeling of the aerial work platform chassis autonomous leveling system.

2. The modeling method of the autonomous leveling system of the aerial work platform chassis according to claim 1, wherein angle sensors are installed in the X-axis and Y-axis directions of the aerial work platform chassis and used for detecting the inclination angles of the X-axis and Y-axis of the chassis.

3. The modeling method of the autonomous leveling system of the aerial work platform chassis according to claim 2, wherein the leveling of the hydraulic leveling system is performed by an angular error leveling method, further comprising:

collected signals of the angle sensor and the pressure sensor are amplified to the maximum digital quantity range of an AD module in the PLC control system through input characteristic change or an amplifier, and the collected signals of the angle sensor and the pressure sensor are converted into digital signals through the AD module.

4. The modeling method of the autonomous leveling system of the aerial work platform chassis according to claim 1, wherein the leveling of the hydraulic leveling system is performed by an angular error leveling method, further comprising:

and amplifying the output of the DA module of the PLC control system to a range of the coil voltage of the electromagnetic proportional reversing valve through an amplifier.

5. The modeling method of the autonomous leveling system of the aerial work platform chassis according to claim 1, wherein the leveling of the hydraulic leveling system is performed by an angular error leveling method, further comprising:

when the leveling is started, all the supporting legs synchronously extend out, the four supporting legs start to touch the ground, pressure oil enters the rodless cavity, the hydraulic supporting structure extends out until the hydraulic supporting structure contacts the ground, and if the pressure value of the rodless cavity corresponding to each supporting leg is larger than or equal to the set pressure, the hydraulic supporting structure enters a leveling state.

6. The modeling method of the autonomous leveling system of the aerial work platform chassis according to claim 1, wherein the leveling of the hydraulic leveling system is performed by an angular error leveling method, further comprising:

when the leveling is started, the wire inlet coil of the electromagnetic proportional directional valve is always electrified until the four leveling supporting legs are leveled, and the wire outlet coil of the electromagnetic proportional directional valve is electrified.

7. The modeling method for the autonomous leveling system of the chassis of the aerial work platform according to claim 1, wherein the precision of the inclination angle of the X-axis and the Y-axis of the chassis is as follows:

alpha is more than minus 0.1 degree and less than 0.1 degree, and beta is more than minus 0.1 degree and less than 0.1 degree.

8. The modeling method for the autonomous leveling system of the aerial work platform chassis according to claim 1, wherein the hydraulic leveling system further comprises a protection valve;

in the leveling process, the protection valve is always powered on, and when the switch valves of the four supporting legs are all in a disconnected state, the protection valve is powered off.

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