A current balance differential control method and an aerial work platform

Abstract

The present invention relates to a current balance differential control method and an aerial work platform. The control method includes the steps of: calculating a structural differential coefficient, obtaining a current differential coefficient, determining a final differential coefficient, fitting a corner relationship curve, and controlling steering differential; the control system of the aerial work platform uses the current balance differential control method to perform steering differential control. By introducing a current differential coefficient on the basis of calculating the differential coefficient of the existing structure, the present invention forms a new differential coefficient, so that the motor current during tire steering does not exceed the limited current; the relationship curve between the differential coefficient and the steering angle is fitted and output, and differential driving is performed accordingly. The differential rotation speeds of each tire are accurate, avoiding large-current tire wear during steering. The currents of the motor, electric drive, and battery are small, the heat generation is low, and the service life is long.

Description

Technical Field

[0001] The present invention relates to a current balance differential control method and an aerial work platform, belonging to the technical field of aerial work platforms. Background Art

[0002] An electric aerial work platform is a product for mobile aerial work, equipment installation, maintenance, etc. in various industries. Compared with traditional fuel-powered or hydraulic aerial work platforms, the biggest advantage of an electric aerial work platform is that both its travel and lifting are driven by motors, with low noise, no pollution, a large working range, and its traceless tires allowing it to drive freely in indoor workplaces. It is a new generation of energy-saving and environmentally friendly equipment advocated by the country at present.

[0003] When an ordinary vehicle turns, due to the different actual turning radii of the four tires, there are differences in the speeds of the respective tires, and a differential is required to achieve different rotational speeds of the respective tires during turning. Each tire of an electric aerial work platform is driven by a motor control, and a corresponding differential system is also required to control the different rotational speeds of the respective tires during turning.

[0004] In the existing differential system of an aerial platform, the ratio of the turning diameters of the respective tires at each steering angle is calculated and then converted into the differential ratio of the respective tires, and the different rotational speeds of the respective tires are driven and controlled through the differential ratio. This method approximately intersects the perpendicular lines of the wheel hubs of the respective tires at different angles at one point, and the respective tires calculate the radius with the intersection point as the turning center (as Figure 2 shown). In the actual application process, differential calculation based on the wheelbase and track of the vehicle inevitably has large deviations in the differential ratio obtained due to process errors (such as installation deviation of the steering angle sensor, welding and assembly errors of the steering mechanism, etc.) and approximate calculation errors of approximately intersecting at one point. Furthermore, during driving, the differential effect is poor, and there is a problem of large-current tire wear during driving, that is, the tire wear is accelerated, the currents of the motor, electric drive, and battery are large, and the heat generation is serious, reducing the service lives of the three major components of the motor, electric drive, and battery. Summary of the Invention

[0005] The purpose of the present invention is to overcome the above deficiencies and provide a current balance differential control method and an aerial work platform with good steering differential effect for the aerial work platform and long service lives of the three major components of the tire, motor, electric drive, and battery.

[0006] The purpose of the present invention is achieved as follows:

[0007] A current balance differential control method includes the following steps:

[0008] Step 1: Calculate the structural differential coefficient. Use the steering angle collected by the steering angle sensor to calculate the turning radius of each tire, and then calculate the structural differential coefficient Kn of each tire based on the obtained turning radius: the left front wheel K1, the left rear wheel K2, the right rear wheel K3, and the right front wheel K4;

[0009] Step 2: Obtain the current differential coefficient. Measure the battery current I during flat ground driving as the maximum differential current of each tire during flat ground differential driving;

[0010] During flat ground differential driving using the structural differential coefficient Kn obtained in Step 1, when the battery current of the driving motor of one of the tires is greater than I, the current differential coefficient Knn starts to decrease from 1 with a coefficient of 0.1, and Knn×Kn is used as the differential coefficient to control the differential of that tire until the battery current of the motor does not exceed I. The control system records the current differential coefficient Knn and the corresponding steering angle at this time;

[0011] The control system records the tire current differential coefficients Knn at each steering angle to obtain the final current differential coefficients Knn of each tire: the left front wheel K11, the left rear wheel K22, the right rear wheel K33, and the right front wheel K44;

[0012] Step 3: Determine the final differential coefficient. Take the product Knn×Kn of the current differential coefficient Knn obtained in Step 2 and the structural differential coefficient Kn obtained in Step 1 as the final differential coefficient;

[0013] Step 4: Fit the steering angle relationship curve. Perform curve fitting on the discrete data points of the final differential coefficient obtained in Step 3 and the corresponding steering angles to form the relationship curve between the driving differential coefficient of each tire and the steering angle.

[0014] Step 5: Control the steering differential. Write the differential coefficient - steering angle relationship curve obtained in Step 4 into the differential control algorithm of the control system, and the control system controls the differential driving of each tire accordingly.

[0015] Further, the value range of the current differential coefficient Knn is 0.4 to 1.

[0016] Further, the steering angle range is 0° to 90°.

[0017] Further, the tire is driven by a wheel side motor.

[0018] Further, the control system includes a PLC and a memory.

[0019] Further, the current balance differential control method is carried out during the factory commissioning stage of the product.

[0020] An aerial work platform, and the control system of the aerial work platform uses the current balance differential control method to control the steering differential.

[0021] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0022] Based on calculating the differential coefficient of the existing structure, the present invention forms a new differential coefficient by introducing a current differential coefficient during steering debugging and through repeated decreasing iterations, so that the motor current during tire steering does not exceed the specified current; the relationship curve between the differential coefficient and the steering angle is fitted and output, and differential driving is performed accordingly. The differential rotation speeds of each tire are accurate, avoiding large-current tire wear during steering. The currents of the motor, electric drive, and battery are small, the heat generation is low, and the service life is long. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 It is a current balance differential control flowchart of a current balance differential control method of the present invention.

[0024] Figure 2 It is a schematic diagram of the differential calculation structure of the existing differential control system for aerial platforms. DETAILED DESCRIPTION OF THE INVENTION

[0025] Refer to Figures 1 - 2 , a current balance differential control method involved in the present invention is carried out during the factory commissioning stage of the product, and includes the following steps:

[0026] Step 1: Calculate the structural differential coefficient. According to the existing structural differential coefficient calculation method, use the steering angle collected by the steering angle sensor and parameters such as wheelbase and track width to calculate the turning radius of each tire, and each tire is driven by a wheel-side motor; then calculate the structural differential coefficients Kn of each tire based on the obtained turning radius: the left front wheel K1, the left rear wheel K2, the right rear wheel K3, and the right front wheel K4; the steering angle range is 0° to 90°.

[0027] Step 2: Obtain the current differential coefficient. Measure the battery current I during flat-ground driving, which is 30A in this embodiment, as the maximum differential current of each tire during flat-ground differential driving.

[0028] Use the structural differential coefficient Kn obtained in Step 1 for flat-ground steering differential driving. When the battery current of the driving motor of one of the tires is greater than 30A, the current differential coefficient Knn starts to decrease by a factor of 0.1 from 1, and Knn×Kn is used as the differential coefficient to control the differential of the tire until the battery current of the motor does not exceed 30A. The control system records the current differential coefficient Knn and the corresponding steering angle at this time.

[0029] The control system records the tire current differential coefficient Knn at each steering angle to obtain the final current differential coefficient Knn of each tire: the left front wheel K11, the left rear wheel K22, the right rear wheel K33, and the right front wheel K44; the value range of the current differential coefficient Knn is 0.4 to 1; the control system includes a PLC and a memory;

[0030] Specifically, when the tire turns left at the target speed s, the speed of the right front wheel is s×K4, the speed of the left front wheel is s×K1×K11, the speed of the left rear wheel is s×K2×K22, and the speed of the right rear wheel is s×K3×K33; if the motor currents a, b, c of the left front wheel, the left rear wheel, and the right rear wheel are greater than 30, then Knn decreases by 0.1, that is, Knn = Knn - 0.1, otherwise, the decrease stops, and the final Knn value is used as the tire current differential coefficient for recording;

[0031] When the tire turns right at the target speed s, the speed of the left front wheel is s×K1, the speed of the left rear wheel is s×K2×K22, the speed of the right rear wheel is s×K3×K33, and the speed of the right front wheel is s×K4×K44; if the motor currents b, c, d of the left rear wheel, the right rear wheel, and the right front wheel are greater than 30, then Knn decreases by 0.1, that is, Knn = Knn - 0.1, otherwise, the decrease stops, and the final Knn value is used as the tire current differential coefficient for recording;

[0032] Step three: Determine the final differential coefficient, and use the product Knn×Kn of the current differential coefficient Knn obtained in step two and the structural differential coefficient Kn obtained in step one as the final differential coefficient;

[0033] Step four: Fit the corner relationship curve, and perform curve fitting on the discrete data points of the final differential coefficient obtained in step three and the corresponding steering angles to form the relationship curve between the traveling differential coefficients of each tire and the steering angles. Use the cftool toolbox in the MATLAB software to perform curve fitting on the discrete data points.

[0034] Step five: Control the steering differential, write the differential coefficient - steering angle relationship curve obtained in step four into the differential control algorithm of the control system, and the control system controls the differential driving of each tire accordingly.

[0035] An aerial work platform based on the above current balance differential control method, the control system of the aerial work platform adopts the current balance differential control method, forms the relationship curve between the traveling differential coefficients of each tire and the steering angles that matches its own specific parameters during the factory commissioning of the aerial work platform, and performs differential steering driving based on this, making the differential steering of each tire accurate, avoiding excessive wear of the tires, having a small steering motor current, small heat generation of the motor, electric drive, and battery, and a long service life.

[0036] The present invention determines the current balance differential coefficient fitting for each aerial work platform one by one. The differential coefficient-steering angle relationship curve of each aerial work platform is matched with itself. Therefore, the differential control system of the mass-produced aerial work platforms is stable and reliable, and the differential consistency is good.

[0037] In addition, it should be noted that the above specific implementation manner is only an optimized solution of this patent. Any modification or improvement made by those skilled in the art according to the above conceptions shall fall within the protection scope of this patent.

Claims

1. A current balance differential control method, characterized in that: it includes the following steps: Step 1: Calculate the structural differential coefficient. Use the steering angle collected by the steering angle sensor to calculate the turning radius of each tire, and then calculate the structural differential coefficient Kn of each tire based on the obtained turning radius: the left front wheel K1, the left rear wheel K2, the right rear wheel K3, and the right front wheel K4; Step 2: Obtain the current differential coefficient. Measure the battery current I during flat ground driving as the maximum differential current of each tire during flat ground differential driving; Use the structural differential coefficient Kn obtained in Step 1 for differential driving on flat ground. When the battery current of the driving motor of one of the tires is greater than I, the current differential coefficient Knn starts to decrease by a factor of 0.1 from 1, and use Knn×Kn as the differential coefficient to control the differential of that tire until the battery current of the motor does not exceed I. The control system records the current differential coefficient Knn and the corresponding steering angle at this time; The control system records the tire current differential coefficients Knn at each steering angle to obtain the final current differential coefficients Knn of each tire: the left front wheel K11, the left rear wheel K22, the right rear wheel K33, and the right front wheel K44; Step 3: Determine the final differential coefficient. Use the product Knn×Kn of the current differential coefficient Knn obtained in Step 2 and the structural differential coefficient Kn obtained in Step 1 as the final differential coefficient; Step 4: Fit the steering angle relationship curve. Fit the discrete points of the data of the final differential coefficient obtained in Step 3 and the corresponding steering angle to form a relationship curve between the differential coefficient of each tire's driving and the steering angle; Step 5: Control the steering differential. Write the differential coefficient - steering angle relationship curve obtained in Step 4 into the differential control algorithm of the control system, and the control system controls each tire to perform differential driving accordingly.

2. The current balance differential control method according to claim 1, characterized in that: the value range of the current differential coefficient Knn is 0.4 to 1.

3. The current balance differential control method according to claim 1, characterized in that: the steering angle range is 0° to 90°.

4. The current balance differential control method according to claim 1, characterized in that: the tire is driven by a wheel motor.

5. The current balance differential control method according to claim 1, characterized in that: the control system includes a PLC and a memory.

6. The current balance differential control method according to claim 1, characterized in that: the current balance differential control method is carried out during the factory commissioning stage of the product.

7. An aerial work platform based on the current balance differential control method according to claim 1, characterized in that: the control system of the aerial work platform uses the current balance differential control method for steering differential control.

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