A mine car emergency braking anti-lock control method based on a logic threshold

Abstract

The application discloses a mine car emergency braking anti-lock control method based on a logic threshold, which performs real-time calculation on wheel speed of the mine car, and calculates wheel angular acceleration and wheel slip rate according to inertial navigation vehicle speed and the wheel speed in real time, and performs hydraulic braking control in the emergency braking process based on a logic threshold strategy by using two sets of parallel hydraulic braking systems of the mine car, so that the emergency braking anti-lock is achieved. The application has the advantages of saving the cost of adding an anti-lock braking control suite and improving the safety of mine car driving.

Description

Technical Field

[0001] This invention relates to the field of unmanned mining truck technology, and in particular to a method for emergency braking anti-lock braking control of mining trucks based on logic thresholds. Background Technology

[0002] Mining operations are typically in harsh environments. To reduce driver workload and improve efficiency, autonomous driving technology is playing an increasingly important role in the mining sector. However, mine roads are often unstructured and in poor condition. Rain, snow, or even water spraying for dust control can make the roads muddy and severely degrade road adhesion. Mining environments are prone to unforeseen events, and mine trucks must brake suddenly if they encounter falling rocks or other emergencies. Because mine trucks are specialized vehicles with low speeds and heavy loads, installing anti-lock braking systems (ABS) is not only costly, but skilled drivers can also use intermittent braking at normal operating speeds to prevent wheel lock-up and skidding, thus minimizing the risk of accidents. Therefore, mine trucks generally do not have ABS. However, under autonomous driving conditions, the system cannot determine wheel lock-up or apply intermittent braking, making wheel lock-up a serious possibility and posing a danger. In such cases, ABS is essential for mine trucks. Summary of the Invention

[0003] The technical problem to be solved by the present invention is to provide a logic threshold-based emergency braking anti-lock braking control method for mine cars to improve the driving safety of mine cars.

[0004] To address the aforementioned technical problems, this invention provides a logic threshold-based emergency braking anti-lock braking control method for mine cars. The method calculates the wheel speed of the mine car in real time, and calculates the wheel angular acceleration and wheel slip ratio based on the inertial navigation vehicle speed and wheel speed. Based on a logic threshold strategy, it utilizes the two parallel hydraulic braking systems on the mine car to control the hydraulic braking during emergency braking, achieving anti-lock braking. The method includes the following steps:

[0005] Step S1: Install wheel speed sensors on the four wheels of the mining truck;

[0006] Step S2: Calculate wheel speed in real time;

[0007] Step S3: Calculate the average angular acceleration of the front and rear wheels and the average wheel slip ratio in real time based on the vehicle speed information provided by the vehicle inertial navigation system and the wheel speed information calculated above;

[0008] Step S4: Based on the calculated values ​​of angular acceleration and slip ratio, and according to the calibrated parameter table, use a logic threshold strategy to control the front and rear hydraulic braking values ​​of the mine car to perform emergency braking and anti-lock braking.

[0009] The wheel speed sensor toothed ring has n teeth, the tire diameter is r (in meters), and the wheel speed calculation period is p (in seconds). Within one calculation period, the wheel speed sensor's sensing probe detects n1 teeth of the toothed ring rotating. Therefore, the wheel speed ω is... t (Unit: rad / s) and converted wheel speed v t (Unit: m / s) Real-time calculation is as follows:

[0010]

[0011] The wheel speed in the previous anti-lock braking system calculation cycle was ω. t1 The vehicle-road speed in the current calculation period is ω. t2 If the calculation period is p1, then the angular acceleration α is calculated as follows:

[0012]

[0013] If the vehicle speed provided by the vehicle's inertial navigation system is v (in m / s), then the wheel slip ratio is calculated as follows:

[0014]

[0015] The mine car is equipped with two parallel hydraulic braking systems: an emergency braking system and a general braking system. These two systems correspond to the front and rear axles, respectively, with different maximum hydraulic pressure values ​​for the front and rear axles. The left and right wheels of both the front and rear axles have the same hydraulic pressure value. The maximum braking hydraulic pressure is the same for both emergency and general braking. Emergency braking responds much faster than general braking. The emergency braking system can only accept a 0 or 1 command, meaning no hydraulic pressure or maximum hydraulic pressure. The general braking system accepts hydraulic pressure commands of any percentage between 0% and 100%, correspondingly generating any hydraulic pressure value between 0% and 100% of the maximum hydraulic pressure.

[0016] The logic threshold strategy is used to control the front and rear hydraulic braking values ​​of the mine car for emergency braking and anti-lock braking, including the following steps:

[0017] Step S41: Determine if the vehicle speed is less than the threshold.

[0018] Yes, proceed to step S44;

[0019] No, issue an activation command to the emergency braking system and an initial hydraulic braking percentage to the general braking system;

[0020] Step S42: Determine if the wheel angular acceleration is less than the threshold.

[0021] Yes, issue a shutdown command to the emergency braking system and issue a corresponding hydraulic braking percentage to the general braking system; proceed to step S43;

[0022] No, hold the previous instruction; proceed to step S43;

[0023] Step S43: Determine whether the wheel slip ratio is greater than the threshold.

[0024] Yes, issue a corresponding hydraulic braking percentage to the general braking system; proceed to step S41;

[0025] No, hold the previous instruction; proceed to step S41;

[0026] Step S44: When the vehicle speed is below the threshold, issue an activation command to the emergency braking system and a 100% command to the general braking system until the mine car stops.

[0027] The superior advantages of this invention are: it saves the cost of installing an anti-lock braking control kit, eliminates the high equipment and manpower costs associated with modifying the original brake lines, and avoids the more difficult maintenance issues caused by modifying mining trucks. The function can be achieved simply by adding wheel speed sensors. Currently, mining trucks generally do not have anti-lock braking control functions. This function can effectively prevent problems such as wheel lock-up and skidding during emergency braking and vehicle fishtailing during the autonomous driving process of mining trucks, improve the driving safety of mining trucks, and provide assistance for the implementation of autonomous driving of mining trucks. Attached Figure Description

[0028] The accompanying drawings, which form part of this application, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an undue limitation of the invention. In the drawings:

[0029] Figure 1 This is a flowchart of the logic threshold control in an embodiment of the present invention. Detailed Implementation

[0030] The following is combined Figure 1 The embodiments of the present invention will be described in detail.

[0031] This invention provides a logic threshold-based emergency braking anti-lock braking control method for mining cars. It calculates the wheel speed of the mining car in real time, and calculates the wheel angular acceleration and wheel slip ratio in real time based on the inertial navigation vehicle speed and wheel speed. Based on a logic threshold strategy, it utilizes the two parallel hydraulic braking systems on the mining car to control the hydraulic braking during emergency braking, achieving anti-lock braking. The method includes the following steps:

[0032] Step S1: Install wheel speed sensors on the four wheels of the mining truck;

[0033] The wheel speed sensor gear ring is mounted on the end of the hub of each wheel.

[0034] Step S2: Calculate wheel speed in real time;

[0035] The wheel speed sensor toothed ring has n teeth, the tire diameter is r (in meters), and the wheel speed calculation period is p (in seconds). Within one calculation period, the wheel speed sensor's sensing probe detects n1 teeth of the toothed ring rotating. Therefore, the wheel speed ω is... t (Unit: rad / s) and converted wheel speed v t (Unit: m / s) Real-time calculation is as follows:

[0036]

[0037] Step S3: Calculate the average angular acceleration of the front and rear wheels and the average wheel slip ratio in real time based on the vehicle speed information provided by the vehicle inertial navigation system and the wheel speed information calculated above;

[0038] The wheel speed in the previous anti-lock braking system calculation cycle was ω. t1 The vehicle-road speed in the current calculation period is ω. t2 If the calculation period is p1, then the angular acceleration α is calculated as follows:

[0039]

[0040] If the vehicle speed provided by the vehicle's inertial navigation system is v (in m / s), then the wheel slip ratio is calculated as follows:

[0041]

[0042] Step S4: Based on the calculated values ​​of angular acceleration and slip ratio, and according to the calibrated parameter table, use a logic threshold strategy to control the front and rear hydraulic braking values ​​of the mine car to perform emergency braking and anti-lock braking.

[0043] The mine car is equipped with two parallel hydraulic braking systems: an emergency braking system and a general braking system. These two systems correspond to the front and rear axles, respectively, with different maximum hydraulic pressure values ​​for the front and rear axles. The left and right wheels of both the front and rear axles have the same hydraulic pressure value. The maximum braking hydraulic pressure is the same for both emergency and general braking. Emergency braking responds much faster than general braking. The emergency braking system can only accept a 0 or 1 command, meaning no hydraulic pressure or maximum hydraulic pressure. The general braking system accepts hydraulic pressure commands of any percentage between 0% and 100%, correspondingly generating any hydraulic pressure value between 0% and 100% of the maximum hydraulic pressure.

[0044] like Figure 1As shown, this invention uses a logic threshold strategy to control the front and rear hydraulic braking values ​​of the mine car for emergency braking and anti-lock braking, including the following steps:

[0045] Step S41: Determine if the vehicle speed is less than the threshold.

[0046] Yes, proceed to step S44;

[0047] No, issue an activation command to the emergency braking system and an initial hydraulic braking percentage to the general braking system;

[0048] Step S42: Determine if the wheel angular acceleration is less than the threshold.

[0049] Yes, issue a shutdown command to the emergency braking system and issue a corresponding hydraulic braking percentage to the general braking system; proceed to step S43;

[0050] No, hold the previous instruction; proceed to step S43;

[0051] Step S43: Determine whether the wheel slip ratio is greater than the threshold.

[0052] Yes, issue a corresponding hydraulic braking percentage to the general braking system; proceed to step S41;

[0053] No, hold the previous instruction; proceed to step S41;

[0054] Step S44: When the vehicle speed is below the threshold, issue an activation command to the emergency braking system and a 100% command to the general braking system until the mine car stops.

[0055] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for preventing lock-up during emergency braking of a mining car based on logic thresholds, characterized in that: The wheel speed of the mine car is calculated in real time, and the wheel angular acceleration and wheel slip ratio are calculated in real time based on the inertial navigation vehicle speed and wheel speed. Based on a logic threshold strategy, the two parallel hydraulic braking systems on the mine car are used to control the hydraulic braking during emergency braking to achieve anti-lock braking. The steps include the following: Step S1: Install wheel speed sensors on the four wheels of the mining truck; Step S2: Calculate wheel speed in real time; The wheel speed sensor gear ring has a total number of teeth. One; tire diameter is The unit is The calculation period for wheel speed is... The unit is Within one calculation cycle, the wheel speed sensor's sensing probe detects the rotation of the gear ring. Each tooth determines the wheel speed. The unit is and conversion wheel speed The unit is The real-time calculation is as follows: ； Step S3: Calculate the average angular acceleration of the front and rear wheels and the average wheel slip ratio in real time based on the vehicle speed information provided by the vehicle inertial navigation system and the wheel speed information calculated above; The wheel speed in the previous anti-lock braking system calculation cycle was The vehicle-road speed in the current calculation period is The calculation period is Then angular acceleration The calculation method is as follows: ； The vehicle speed provided by the vehicle's inertial navigation system is The unit is The wheel slip ratio is calculated as follows: ； Step S4: Based on the calculated values ​​of angular acceleration and slip ratio, and according to the calibrated parameter table, use a logic threshold strategy to control the front and rear hydraulic braking values ​​of the mine car to perform emergency braking and anti-lock braking. Step S4 includes the following steps: Step S41: Determine if the vehicle speed is less than the threshold; Yes, proceed to step S44; No, issue an activation command to the emergency braking system and an initial hydraulic braking percentage to the general braking system; Step S42: Determine whether the wheel angular acceleration is less than the threshold; Yes, issue a shutdown command to the emergency braking system and issue a corresponding hydraulic braking percentage to the general braking system; Proceed to step S43; No, keep the previous instruction; Proceed to step S43; Step S43: Determine whether the wheel slip ratio is greater than the threshold; Yes, issue a corresponding hydraulic braking percentage to the general braking system; Proceed to step S41; No, keep the previous instruction; Proceed to step S41; Step S44: When the vehicle speed is below the threshold, issue an activation command to the emergency braking system and a 100% command to the general braking system until the mine car stops.

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