Unmanned mine car speed control brake switching method based on hydraulic retarder

Abstract

The invention discloses an unmanned mine car speed control brake switching method based on a hydraulic retarder, which comprises the following steps: calculating the average wheel speed and the average slip rate of rear wheels of a mine car, converting the rotating speed of an output shaft of a transmission to obtain the average wheel speed of the rear wheels, and calculating the average slip rate according to the inertial navigation speed; according to the average slip rate of the rear wheels, different brake switching strategies are switched and designed based on different slip rate numerical ranges; setting an initial state of a brake switching strategy, and performing speed tracking control based on the hydraulic retarder; designing an anti-slip control strategy, designing the anti-slip strategy based on a logic threshold method, and performing mine car speed control brake switching. By designing a brake switching control strategy, the situation that slipping cannot be controlled can be avoided, after hydraulic control is switched, a logic threshold-based method is adopted for anti-slip control, and the situation that the mine car is out of control due to serious slipping can be avoided.

Description

Technical Field

[0001] The present invention relates to the technical field of automatic driving of mining vehicle engineering, and in particular to a speed control braking switching method of an unmanned mining vehicle based on a hydraulic retarder. Background Art

[0002] At present, people around the world have increasing demands for quality of life, and with it comes an increase in demand for daily necessities. Most of the items used in daily life come from various mines. As the scale of mining continues to expand, more and more equipment is needed for mining. However, the harsh working environment of mines is not acceptable to most practitioners. There will be fewer and fewer related practitioners, and unmanned mining equipment is an inevitable trend.

[0003] In addition to solving the perception, planning and control problems of general unmanned driving systems so that the mine cars can complete the set tasks, unmanned mine cars also have an important problem to solve, which is the slippage problem of mine cars. Unmanned mine cars are generally not equipped with ABS or TCS systems like passenger cars or commercial vehicles. Because mine cars are low-speed special vehicles, human drivers are fully capable of dealing with the slippage problem of mine cars and generally will not encounter dangerous situations. However, unmanned driving systems do not have the ability to predict and deal with slippage like human drivers. Therefore, how to develop a mine car anti-skid system is an important part of completing the puzzle of mine car unmanned driving systems. When a mine car goes down a long slope, a hydraulic retarder is generally used to control the speed of the mine car to keep it near the preset speed. However, the hydraulic retarder acts on the power transmission shaft. When the mine car is traveling on a slippery road, the use of a hydraulic retarder will make the vehicle difficult to control, and in severe cases, the mine car will be out of control. Therefore, experienced drivers will give up using the hydraulic retarder at this time and use hydraulic braking to control the speed. When the road is not slippery, the hydraulic retarder will be restored. How to design a set of brake switching strategies and anti-skid strategies suitable for unmanned mine cars is particularly important. Summary of the invention

[0004] The purpose of the present invention is to overcome the shortcomings of the prior art. To achieve the above purpose, a speed control braking switching method for an unmanned mining vehicle based on a hydraulic retarder is adopted to solve the problems raised in the above background technology.

[0005] A speed control braking switching method for an unmanned mining vehicle based on a hydraulic retarder comprises the following steps:

[0006] Step S1, calculating the average wheel speed and average slip rate of the rear wheels of the mining car, converting the average wheel speed of the rear wheels by the transmission output shaft speed, and then calculating the average slip rate according to the inertial navigation vehicle speed;

[0007] Step S2, according to the average slip rate of the rear wheels, different braking switching strategies are designed based on different slip rate value ranges;

[0008] Step S3, setting the initial state of the brake switching strategy, and performing speed tracking control based on the hydraulic retarder;

[0009] Step S4, designing an anti-skid control strategy, designing an anti-skid strategy based on a logic threshold method, and performing a mine car speed control braking switch.

[0010] As a further solution of the present invention: the specific steps in step S1 include:

[0011] The average wheel speed of the rear wheels is converted by the transmission output shaft speed, and the average slip rate of the rear wheels is calculated according to the inertial navigation vehicle speed. The calculation formulas for the average wheel speed and average slip rate of the rear wheels of the mine car are:

[0012]

[0013] In the formula, is the average rear wheel speed, in m / s, n tra_out is the transmission output shaft speed, in rpm, r tire is the tire radius, in meters, and v is the inertial navigation vehicle speed.

[0014] As a further solution of the present invention: the specific steps in step S2 include:

[0015] Initial state setting:

[0016] When the mine car starts to go down a long slope, the initial braking mode of the longitudinal control system is set to use a hydraulic retarder for speed tracking control to keep the mine car within the preset speed range;

[0017] Slip rate monitoring and judgment:

[0018] Using the average rear wheel slip ratio calculated in real time, which is based on the average rear wheel speed converted from the transmission output shaft speed and the inertial vehicle speed;

[0019] The monitored slip rate value is used as the basis for judging the road condition and whether it is necessary to switch the braking mode.

[0020] As a further solution of the present invention: the specific steps of the braking mode switching strategy include:

[0021] Hydraulic retarder use stage:

[0022] When the monitored slip rate is not greater than 20%, the current road condition is considered to be good or slightly slippery, and the hydraulic retarder continues to be used for speed tracking control;

[0023] Switching to hydraulic braking phase:

[0024] Once the slip rate exceeds 20%, the system determines that the vehicle has entered a slippery road. At this time, the use of the hydraulic retarder may cause the rear axle wheels to slip, so the system immediately switches to hydraulic braking mode to enhance the braking effect and stability, and avoid difficulty in controlling the mine car or losing control;

[0025] Switching back to the hydraulic retarder phase:

[0026] When the slip rate drops to less than 10%, the system determines that the vehicle has left the slippery road and the road conditions have improved. At this time, in order to reduce the wear and energy consumption of the braking system, it switches back to the hydraulic retarder for speed tracking control.

[0027] As a further solution of the present invention: the specific steps of the anti-skid control strategy in step S4 include:

[0028] When the detected slip rate is greater than 20%, the hydraulic brake is applied and the value is reduced by 1 in each control cycle;

[0029] When the monitored slip rate is less than 20%, it is determined whether the monitored slip rate is greater than 15%;

[0030] If it is less than, the hydraulic brake is issued, and it is reduced by 1 in each control cycle;

[0031] If it is greater, the hydraulic brake is sent to maintain the original value calculated by PID.

[0032] Compared with the prior art, the present invention has the following technical effects:

[0033] By adopting the above technical solution,. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] The specific embodiments of the present invention are described in detail below in conjunction with the accompanying drawings:

[0035] Figure 1 A schematic diagram of the steps of the control brake switching method disclosed in the present application;

[0036] Figure 2 This is a schematic diagram of the overall control process of the embodiment disclosed in this application;

[0037] Figure 3 This is a schematic diagram of the anti-skid control strategy of the embodiment disclosed in this application. DETAILED DESCRIPTION

[0038] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0039] Please refer to Figure 1 and Figure 2 In an embodiment of the present invention, a speed control braking switching method for an unmanned mining vehicle based on a hydraulic retarder comprises the following steps:

[0040] Step S1, calculating the average wheel speed and average slip rate of the rear wheels of the mine car, converting the average wheel speed of the rear wheels by the transmission output shaft speed, and then calculating the average slip rate according to the inertial navigation vehicle speed. The specific steps include:

[0041] In this embodiment, since the mine car is a low-speed special vehicle, it is generally not equipped with a wheel speed sensor. Even if it is equipped with a wheel speed sensor, the error is relatively large due to the low wheel speed;

[0042] The average wheel speed of the rear wheels is converted by the transmission output shaft speed, and the average slip rate of the rear wheels is calculated according to the inertial navigation vehicle speed. The calculation formulas for the average wheel speed and average slip rate of the rear wheels of the mine car are:

[0043]

[0044] In the formula, is the average rear wheel speed, in m / s, n tra_out is the transmission output shaft speed, in rpm, r tire is the tire radius, in meters, and v is the inertial navigation vehicle speed.

[0045] Step S2: According to the average slip rate of the rear wheels, different braking switching strategies are designed based on different slip rate value ranges. The specific steps include:

[0046] Initial state setting:

[0047] When the mine car starts to go down a long slope, the initial braking mode of the longitudinal control system is set to use a hydraulic retarder for speed tracking control to keep the mine car within the preset speed range;

[0048] Slip rate monitoring and judgment:

[0049] Using the average rear wheel slip ratio calculated in real time, which is based on the average rear wheel speed converted from the transmission output shaft speed and the inertial vehicle speed;

[0050] The monitored slip rate value is used as the basis for judging the road condition and whether it is necessary to switch the braking mode.

[0051] The specific steps of the braking mode switching strategy include:

[0052] Hydraulic retarder use stage:

[0053] When the monitored slip rate is not greater than 20%, the current road condition is considered to be good or slightly slippery, and the hydraulic retarder continues to be used for speed tracking control;

[0054] Switching to hydraulic braking phase:

[0055] Once the slip rate exceeds 20%, the system determines that the vehicle has entered a slippery road. At this time, the use of the hydraulic retarder may cause the rear axle wheels to slip, so the system immediately switches to hydraulic braking mode to enhance the braking effect and stability, and avoid difficulty in controlling the mine car or losing control;

[0056] Switching back to the hydraulic retarder phase:

[0057] When the slip rate drops to less than 10%, the system determines that the vehicle has left the slippery road and the road conditions have improved. At this time, in order to reduce the wear and energy consumption of the braking system, it switches back to the hydraulic retarder for speed tracking control.

[0058] In a specific implementation, the braking switching strategy is designed based on the slip ratio.

[0059] The longitudinal control system of the mine car includes a speed tracking control algorithm designed according to PID. It can use a hydraulic retarder or a hydraulic brake to track the speed of the mine car so that the mine car maintains a preset speed. The system is not described here, and only the brake switching strategy is designed.

[0060] According to the experience of skilled drivers, the driver can feel the mine car slipping and then adjust the control strategy, switching from the hydraulic retarder to the hydraulic brake, so as to avoid the mine car being difficult to control or even out of control. Since the hydraulic retarder acts on the drive shaft, that is, on the rear axle (rear-wheel drive) wheels, it will cause the rear axle wheels to slip. The brake switching strategy is designed based on the average rear wheel slip rate calculated by formulas (1)-(2).

[0061] When starting to go down a long slope, the hydraulic retarder is used by default in the initial state. When the slip rate is not more than 20%, the hydraulic retarder is still used for speed tracking control. When the slip rate exceeds 20%, it is considered that the vehicle has entered a slippery road, and the hydraulic brake is switched to speed tracking control. When the slip rate is less than 10%, it is considered that the vehicle has left the slippery road, and the hydraulic retarder control is switched back to control.

[0062] Step S3, setting the initial state of the brake switching strategy, and performing speed tracking control based on the hydraulic retarder;

[0063] Step S4, designing an anti-skid control strategy, designing an anti-skid strategy based on a logic threshold method, and performing a mine car speed control braking switch.

[0064] In this embodiment, through the above switching strategy, the mine car can be controlled on slippery roads without the characteristics of the hydraulic retarder. However, the anti-skid problem after switching cannot be solved. Under hydraulic braking, the mine car may still slip. At this time, an anti-skid control strategy needs to be designed, such as Figure 3 As shown, the figure is a schematic diagram of the anti-skid control strategy;

[0065] Among them, the specific steps of the anti-slip control strategy include:

[0066] When the detected slip rate is greater than 20%, the hydraulic brake is applied and the value is reduced by 1 in each control cycle;

[0067] When the monitored slip rate is less than 20%, it is determined whether the monitored slip rate is greater than 15%;

[0068] If it is less than, the hydraulic brake is issued, and it is reduced by 1 in each control cycle;

[0069] If it is greater, the hydraulic brake is sent to maintain the original value calculated by PID.

[0070] In this embodiment, the characteristic of the hydraulic retarder acting on the drive shaft is utilized. Using the hydraulic retarder for speed control on a slippery road surface may cause the vehicle to be difficult to control. Therefore, a brake switching strategy is designed. When going down a long slope, the hydraulic retarder is used for speed tracking control by default, and the average wheel speed of the rear wheels is calculated according to the transmission output shaft speed, and the average slip rate of the rear wheels is calculated according to the inertial navigation vehicle speed. The brake switching is performed according to the slip rate. If the slip rate exceeds the set threshold, it switches to hydraulic braking. If the slip rate is less than the set threshold, it returns to the hydraulic retarder control. After switching to hydraulic control, a method based on a logic threshold is used for anti-skid control.

[0071] Although the embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention. The scope of the present invention is defined by the appended claims and their equivalents, and all should be included within the scope of protection of the present invention.

Claims

1. A speed control braking switching method for an unmanned mining vehicle based on a hydraulic retarder, characterized in that: The following steps are involved: Step S1, calculating the average wheel speed and average slip rate of the rear wheels of the mining car, converting the average wheel speed of the rear wheels by the transmission output shaft speed, and then calculating the average slip rate according to the inertial navigation vehicle speed; Step S2, according to the average slip rate of the rear wheels, different braking switching strategies are designed based on different slip rate value ranges; Step S3, setting the initial state of the brake switching strategy, and performing speed tracking control based on the hydraulic retarder; Step S4, designing an anti-skid control strategy, designing an anti-skid strategy based on a logic threshold method, and performing a mine car speed control braking switch.

2. According to claim 1, a speed control braking switching method for an unmanned mining vehicle based on a hydraulic retarder is characterized in that: The specific steps in step S1 include: The average wheel speed of the rear wheels is converted by the transmission output shaft speed, and the average slip rate of the rear wheels is calculated according to the inertial navigation vehicle speed. The calculation formulas for the average wheel speed and average slip rate of the rear wheels of the mine car are: In the formula, is the average rear wheel speed, in m / s, n tra_out is the transmission output shaft speed, in rpm, r tire is the tire radius, in meters, and v is the inertial navigation vehicle speed.

3. According to claim 1, a speed control braking switching method for an unmanned mining vehicle based on a hydraulic retarder is characterized in that: The specific steps in step S2 include: Initial state setting: When the mine car starts to go down a long slope, the initial braking mode of the longitudinal control system is set to use a hydraulic retarder for speed tracking control to keep the mine car within the preset speed range; Slip rate monitoring and judgment: Using the average rear wheel slip ratio calculated in real time, which is based on the average rear wheel speed converted from the transmission output shaft speed and the inertial vehicle speed; The monitored slip rate value is used as the basis for judging the road condition and whether it is necessary to switch the braking mode.

4. According to claim 3, a speed control braking switching method for an unmanned mining vehicle based on a hydraulic retarder is characterized in that: The specific steps of the braking mode switching strategy include: Hydraulic retarder use stage: When the monitored slip rate is not greater than 20%, the current road condition is considered to be good or slightly slippery, and the hydraulic retarder continues to be used for speed tracking control; Switching to hydraulic braking phase: Once the slip rate exceeds 20%, the system determines that the vehicle has entered a slippery road. At this time, the use of the hydraulic retarder may cause the rear axle wheels to slip, so the system immediately switches to hydraulic braking mode to enhance the braking effect and stability, and avoid difficulty in controlling the mine car or losing control; Switching back to the hydraulic retarder phase: When the slip rate drops to less than 10%, the system determines that the vehicle has left the slippery road and the road conditions have improved. At this time, in order to reduce the wear and energy consumption of the braking system, it switches back to the hydraulic retarder for speed tracking control.

5. According to claim 1, a speed control braking switching method for an unmanned mining vehicle based on a hydraulic retarder is characterized in that: The specific steps of the anti-skid control strategy in step S4 include: When the detected slip rate is greater than 20%, the hydraulic brake is applied and the value is reduced by 1 in each control cycle; When the monitored slip rate is less than 20%, it is determined whether the monitored slip rate is greater than 15%; If it is less than, the hydraulic brake is issued, and it is reduced by 1 in each control cycle; If it is greater, the hydraulic brake is sent to maintain the original value calculated by PID.

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