Unmanned vehicle braking control method, braking control system and vehicle controller

Abstract

The application relates to the technical field of unmanned vehicle control, and provides an unmanned vehicle braking control method, a braking control system, a vehicle controller and an unmanned vehicle. The method comprises the following steps: acquiring target deceleration, vehicle weight, slope information and available torque capacity of electric braking and a retarder; calculating total required braking torque; determining a target gear of the retarder and controlling the retarder to output corresponding braking torque when a retarder intervention condition is met; and calculating a difference between the total required torque and the output torque of the retarder, and configuring target torques of electric braking and mechanical braking according to the difference. By using the method, the retarder can be automatically started to serve as a main force for continuous braking when the electric braking capacity is insufficient, the remaining braking demand can be accurately supplemented by electric braking and mechanical braking, a three-source collaborative composite braking architecture is formed, and the braking safety and deceleration control precision under severe working conditions such as long downhill are considered.

Description

Technical Field

[0001] This application relates to the field of autonomous vehicle control technology, and in particular to an autonomous vehicle braking control method, an autonomous vehicle braking control system, a vehicle controller, and an autonomous vehicle. Background Technology

[0002] Commercial vehicles such as mining dump trucks and heavy trucks generally have a load capacity of hundreds of tons, and their operating environment often involves harsh conditions such as long downhill slopes, unpaved roads, high and low temperatures, continuous start-stop operations, and heavy-load bumpy rides. With the upgrading of intelligence, these vehicles are gradually realizing fully automatic unmanned driving, automatic loading and unloading, and automatic obstacle avoidance operations, which places extremely high demands on the response speed, stability, and deceleration control accuracy of the braking system.

[0003] Currently, most braking solutions for autonomous vehicles still employ conventional electro-hydraulic hybrid braking strategies, which simply superimpose braking forces from each brake actuator. However, when the battery's state of charge (SOC) is high, rendering electric braking ineffective, this approach forces reliance entirely on mechanical braking. In conditions requiring continuous braking, such as long downhill slopes, this easily leads to brake pad thermal degradation, resulting in a sharp decline in braking performance or even complete failure. Furthermore, this simple superposition strategy lacks real-time perception and intelligent scheduling of the capabilities of each brake actuator, resulting in abrupt brake force distribution and an inability to guarantee high-precision deceleration control, thus severely impacting the trajectory tracking performance of autonomous vehicles. Summary of the Invention

[0004] Therefore, it is necessary to provide an unmanned vehicle braking control method, an unmanned vehicle braking control system, a vehicle controller, and an unmanned vehicle to address the aforementioned technical problems.

[0005] In a first aspect, this application provides a braking control method for an unmanned vehicle, the method comprising: In response to the detection of target deceleration, the current vehicle weight information, current slope information, current available electric braking torque capacity, and current available torque capacity of the retarder are obtained; Based on the target deceleration, the current vehicle weight information, the current slope information, and the preset vehicle longitudinal dynamics model, the total required braking torque is calculated. Based on the current available electric braking torque capacity, the current available torque capacity of the retarder, and the total required braking torque, determine whether the preset retarder intervention conditions are met. If the retarder intervention conditions are met, the target gear of the retarder is determined based on the current available electric braking torque capacity, the current available torque capacity of the retarder, and the total required braking torque. The retarder is controlled to output the braking torque corresponding to the target gear, and the difference between the total required braking torque and the braking torque corresponding to the target gear is calculated. Based on the difference between the total required braking torque and the braking torque corresponding to the target gear, the target torque for electric braking and the target torque for mechanical braking are configured.

[0006] In one embodiment, determining that the retarder intervention condition is met includes: determining that the following conditions are met simultaneously: the currently available electric braking torque capacity is lower than a preset electric braking capacity threshold; the difference between the total required braking torque and the currently available electric braking torque capacity is greater than the first-gear torque capacity of the retarder; and the currently available torque capacity of the retarder is not lower than the first-gear torque capacity.

[0007] In one embodiment, determining the target gear of the retarder based on the currently available electric braking torque capacity, the currently available torque capacity of the retarder, and the total required braking torque includes: calculating the difference between the total required braking torque and the currently available electric braking torque capacity to obtain the remaining required torque; comparing the remaining required torque with the torque capacity of each gear in descending order of the retarder gears, and simultaneously comparing the currently available torque capacity of the retarder with the torque capacity of the corresponding gear; determining the first gear that meets a preset torque condition as the target gear of the retarder; the preset torque condition includes that the remaining required torque is greater than the torque capacity of that gear, and the currently available torque capacity of the retarder is not less than the torque capacity of that gear.

[0008] In one embodiment, the method further includes: if all gears of the retarder do not meet the preset torque condition, then the target gear of the retarder is determined to be gear one.

[0009] In one embodiment, controlling the retarder to output the braking torque corresponding to the target gear includes: controlling the retarder to first output braking torque at the first gear; after each preset retarder response delay, if the current gear is lower than the target gear, controlling the retarder to shift to the next adjacent gear until the target gear is reached; the retarder response delay is calibrated based on the retarder's response characteristics.

[0010] In one embodiment, configuring the electric braking target torque and the mechanical braking target torque based on the difference between the total required braking torque and the braking torque corresponding to the target gear includes: when the difference between the total required braking torque and the braking torque corresponding to the target gear is greater than zero, using the difference as the braking torque to be allocated, and determining whether the braking torque to be allocated is less than or equal to the current available electric braking torque capacity; if yes, configuring the braking torque to be allocated as the electric braking target torque and configuring the mechanical braking target torque as zero; if no, configuring the current available electric braking torque capacity as the electric braking target torque, and configuring the portion of the braking torque to be allocated that exceeds the current available electric braking torque capacity as the mechanical braking target torque; when the difference between the total required braking torque and the braking torque corresponding to the target gear is less than or equal to zero, both the electric braking target torque and the mechanical braking target torque are configured as zero.

[0011] In one embodiment, after using the difference as the braking torque to be allocated, the method further includes: obtaining a target deceleration sequence and an actual vehicle speed sequence for a preset historical duration; integrating the target deceleration sequence for the preset historical duration to obtain a target vehicle speed reduction; calculating the difference between the current vehicle speed and the initial vehicle speed before the preset historical duration to obtain an actual vehicle speed reduction; calculating the difference between the target vehicle speed reduction and the actual vehicle speed reduction, and then dividing it by the value of the preset historical duration to obtain a target compensation deceleration; inputting the target compensation deceleration into the vehicle longitudinal dynamics model for calculation to obtain a compensation braking torque; superimposing the compensation braking torque onto the braking torque to be allocated to obtain a new braking torque to be allocated; and based on the new braking torque to be allocated, returning to the step of determining whether the braking torque to be allocated is less than or equal to the current available electric braking torque capability to continue execution.

[0012] In one embodiment, the vehicle longitudinal dynamics model is: ; in, For the total required braking torque, Given the current vehicle weight, To slow down the target, It is the acceleration due to gravity. For the current slope, The rolling resistance coefficient, Main reducer transmission ratio, For mechanical transmission efficiency, This is the rolling radius of the wheel.

[0013] Secondly, this application also provides a braking control system for an unmanned vehicle, comprising: Intelligent driving controller, used to output target deceleration; A slope sensor is used to acquire current slope information; Vehicle weight sensor, used to obtain current vehicle weight information; The motor controller is used to control the target torque of the electric braking output of the motor; The retarder controller is used to control the braking torque corresponding to the target gear output of the retarder; An electronic braking system is used to control the mechanical brake to output the target mechanical braking torque. The vehicle controller is communicatively connected to the intelligent driving controller, the slope sensor, the vehicle weight sensor, the motor controller, the retarder controller, and the electronic braking system, and is configured to perform the steps of any of the methods described above.

[0014] Thirdly, embodiments of this application provide a vehicle controller, including a processor and a memory, wherein the memory stores a computer program, and the processor executes the computer program to implement the steps of any of the methods described above.

[0015] Fourthly, embodiments of this application provide an unmanned vehicle, including the aforementioned unmanned vehicle braking control system or the aforementioned vehicle controller.

[0016] One of the above technical solutions has the following advantages or beneficial effects: When insufficient electric braking capacity is detected, the retarder is automatically activated as the main force for continuous braking. At the same time, the remaining braking demand after the retarder output is distributed between electric braking and mechanical braking according to the principle of electric braking priority, thereby forming a composite braking architecture that coordinates electric braking, retarder braking, and mechanical braking. This architecture can replace mechanical braking to undertake the main continuous braking task in conditions such as long downhill when the battery charge is too high and the electric braking cannot work effectively. This fundamentally avoids the risk of thermal fade and braking failure of mechanical braking due to long-term high-intensity work. At the same time, the precise supplementation of the remaining torque by electric braking and mechanical braking ensures the tracking accuracy of the overall braking force to the target deceleration, thus taking into account both the braking safety and trajectory tracking effect of the unmanned vehicle under harsh conditions. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of the braking control system of an unmanned vehicle in one embodiment; Figure 2 This is a flowchart illustrating the braking control method for an autonomous vehicle in one embodiment; Figure 3 This is an internal structural diagram of the vehicle controller in one embodiment. Detailed Implementation

[0018] To make the objectives, technical solutions, and advantages of this application clearer, the following detailed description is provided in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the scope of this application.

[0019] In this document, the term "embodiment" means that a particular feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of this application. The appearance of this phrase in various places throughout the specification does not necessarily refer to the same embodiment, nor is it a separate or alternative embodiment mutually exclusive with other embodiments. It will be explicitly and implicitly understood by those skilled in the art that the embodiments described herein can be combined with other embodiments.

[0020] It should be noted that all information and data involved in this application (including but not limited to data used for analysis, stored data, displayed data, vehicle operating parameters, sensor-collected data, controller feedback data, etc.) are information and data authorized by the customer or fully authorized by all parties, and the collection, use and processing of related data must comply with the relevant laws, regulations and standards of the relevant countries and regions.

[0021] The autonomous vehicle braking control method provided in this application can be applied to... Figure 1 The diagram illustrates a braking control system for an autonomous vehicle. This system includes an intelligent driving controller, a vehicle controller, a motor controller, a retarder controller, an electronic braking system (EBS), a slope sensor, and a vehicle weight sensor. The intelligent driving controller sends target deceleration commands to the vehicle controller based on perception and planning results. The slope sensor acquires real-time information about the current slope of the road where the vehicle is located. The vehicle weight sensor acquires real-time information about the vehicle's current weight. The motor controller is connected to the drive motor and controls the motor's output of electric braking torque, feeding back the available electric braking torque capability to the vehicle controller. The retarder controller is connected to the retarder and controls the retarder's output of braking torque at the corresponding gear level, feeding back the retarder's available torque capability to the vehicle controller. The electronic braking system (EBS) is connected to the mechanical brake and controls the mechanical brake's output of mechanical braking torque. The vehicle controller communicates with the aforementioned controllers and sensors via a CAN bus and is responsible for executing the braking control method provided in this application, converting the target deceleration into control commands for each braking actuator.

[0022] In one embodiment, such as Figure 2 As shown, a braking control method for an autonomous vehicle is provided, which is applied to... Figure 1 Taking the vehicle controller as an example, the explanation includes the following steps: S201, in response to detecting target deceleration, acquires current vehicle weight information, current gradient information, current available electric braking torque capacity, and current available torque capacity of the retarder.

[0023] The target deceleration is calculated and issued in real time by the intelligent driving controller based on the driving path planning and the current vehicle speed, representing the degree of deceleration expected by the autonomous driving system. Upon receiving the target deceleration, the vehicle controller immediately triggers the braking control process. Current vehicle weight information can be obtained directly through vehicle weight sensors, such as real-time detection of vehicle load status via suspension deformation sensors or axle load sensors. In other implementations, vehicle weight information can also be obtained indirectly through estimation, such as calculating the vehicle mass based on the output torque of the drive motor and the rate of change of vehicle speed. Current slope information is collected in real time by a slope sensor, which can be part of the onboard inertial measurement unit, used to obtain the longitudinal slope angle of the road. The current available electric braking torque capability is calculated and fed back by the motor controller based on factors such as the current speed of the drive motor, rotor temperature, and the state of charge of the power battery. Generally, when the state of charge of the power battery is high, the acceptable charging power of the battery is limited, and the electric braking torque capability will significantly decrease or even approach zero. The current available torque capability of the retarder is fed back by the retarder controller based on factors such as the retarder's operating temperature, fluid state, or electromagnetic coil state.

[0024] S202 calculates the total required braking torque based on the target deceleration, current vehicle weight information, current slope information, and a preset vehicle longitudinal dynamics model.

[0025] This step aims to convert the deceleration desired by the intelligent driving controller into the required braking torque on the vehicle's driveshaft. A pre-defined longitudinal dynamics model establishes the physical relationship between deceleration and braking torque. Specifically, this model, based on Newton's second law, comprehensively considers the vehicle's translational inertia, the component of gravity along the slope, and rolling resistance to convert the target deceleration into the required braking force at the wheels. Then, based on inherent vehicle parameters such as the final drive ratio, mechanical transmission efficiency, and wheel rolling radius, the total required braking torque acting on the driveshaft or drive axle input is calculated. Because the model incorporates vehicle weight and slope information, the calculated total required braking torque can adapt to different load conditions and slope conditions, laying the foundation for subsequent precise distribution of braking force.

[0026] S203, based on the current available electric braking torque capacity, the current available torque capacity of the retarder, and the total required braking torque, determines whether the preset retarder intervention conditions are met.

[0027] This step is the decision-making stage for whether the retarder should be engaged. It should be explained that the preset retarder intervention conditions can be used to identify scenarios where retarder intervention is required. For example, the retarder is only activated when the electric braking capacity is insufficient and the remaining braking demand is so great that mechanical braking alone may pose a risk of thermal fade. If the electric braking capacity is sufficient, or the remaining braking demand is very small and can be safely handled by electric braking plus mechanical braking, then there is no need to activate the retarder, so as to avoid smoothness problems caused by frequent retarder intervention.

[0028] S204 If the retarder intervention conditions are met, the target gear of the retarder is determined based on the current available electric braking torque capacity, the current available torque capacity of the retarder, and the total required braking torque.

[0029] After determining that retarder intervention is necessary, this step is responsible for selecting the most suitable retarder setting from its multiple discrete settings for the current operating conditions. It should be noted that the higher the retarder setting, the greater the braking torque it can provide. The core logic of setting selection is to choose a setting that can share the braking load as much as possible within the retarder's currently available torque capacity, without exceeding the total demand, thus leaving appropriate margin for subsequent fine-tuning of electric and mechanical braking.

[0030] S205 controls the retarder to output the braking torque corresponding to the target gear and calculates the difference between the total required braking torque and the braking torque corresponding to the target gear.

[0031] After determining the target gear, the vehicle controller sends the corresponding gear command to the retarder controller, and the retarder begins to output braking torque. At the same time, the vehicle controller can calculate the difference between the total required braking torque and the actual braking torque that the retarder will provide; this difference represents the remaining braking demand after the retarder outputs, which needs to be supplemented by electric braking and mechanical braking.

[0032] S206 configures the target torque for electric braking and the target torque for mechanical braking based on the difference between the total required braking torque and the braking torque corresponding to the target gear.

[0033] This step allocates the remaining braking demand to electric braking and mechanical braking according to preset principles (e.g., electric braking priority). The principle of electric braking priority means that electric braking is used first due to its fast response and precise adjustment; mechanical braking is only invoked to supplement the remaining braking demand when the electric braking capacity is fully utilized and still insufficient; when the difference is negative, meaning the braking torque output by the retarder exceeds the total demand, no further braking force is required from electric or mechanical braking. Through the configuration logic in this embodiment, the three braking actuators have clearly defined roles: the retarder bears the main continuous braking load to protect the mechanical brake from overheating, while electric and mechanical braking are responsible for precise supplementation to track the target deceleration.

[0034] In the above-described unmanned vehicle braking control method, a composite braking architecture that coordinates electric braking, retarder braking, and mechanical braking is constructed through the above steps. This architecture can automatically activate the retarder as the main force for continuous braking when the electric braking capacity is insufficient, while the electric braking and mechanical braking accurately supplement the remaining braking demand, thereby taking into account both braking safety and deceleration control accuracy under harsh conditions such as long downhill slopes.

[0035] In one embodiment, determining the retarder intervention condition in S203 may specifically include: determining that the following conditions are simultaneously met: the currently available electric braking torque capacity is lower than a preset electric braking capacity threshold; the difference between the total required braking torque and the currently available electric braking torque capacity is greater than the retarder's first-gear torque capacity; and the retarder's currently available torque capacity is not lower than its first-gear torque capacity. This embodiment aims to define three necessary conditions for retarder intervention. The first condition ensures that the electric braking is indeed in a state of insufficient capacity. This preset electric braking capacity threshold can be obtained through actual vehicle testing and calibration, for example, set as a certain low percentage of the drive motor's rated braking torque. The second condition ensures that the braking gap is large enough that it is necessary to use the retarder to share the load. If the gap is less than the retarder's first-gear torque capacity, it means that electric braking plus mechanical braking can cope with the situation, and retarder intervention is not necessary. The third condition ensures that the retarder itself has a basic output capacity. If the retarder cannot even provide first-gear torque due to reasons such as excessively high oil temperature, intervention is meaningless. By combining these three conditions, the retarder will only intervene when it is truly needed and can function, avoiding unnecessary frequent starts and stops. On the one hand, this reduces the extra temperature rise and mechanical wear of the retarder's internal oil or electromagnetic coil caused by repeated starts and stops, which helps extend the retarder's service life. On the other hand, it also avoids the fluctuation of braking force caused by the frequent intervention and withdrawal of the retarder, improving the smoothness of the vehicle's braking process and ride comfort.

[0036] In one embodiment, determining the target gear of the retarder in S204 may specifically include: calculating the difference between the total required braking torque and the currently available electric braking torque capacity to obtain the remaining required torque; comparing the remaining required torque with the torque capacity of each gear in descending order of retarder gears, and simultaneously comparing the current available torque capacity of the retarder with the torque capacity of the corresponding gear; determining the first gear that meets the preset torque condition as the target gear of the retarder; the preset torque condition includes that the remaining required torque is greater than the torque capacity of the gear, and the current available torque capacity of the retarder is not lower than the torque capacity of the gear.

[0037] This embodiment aims to refine the selection logic of the retarder's target gear. The remaining required torque represents the amount of torque needed from other braking actuators after the electric brakes have exerted their maximum output. The selection is compared sequentially from high to low; for example, first checking if the fourth gear (the highest gear) meets the condition, then checking the third gear if not, and so on. In the preset torque condition, if the remaining required torque is greater than the torque capacity of that gear, it means that the braking capacity of that gear is insufficient to fully cover the remaining demand, therefore that gear needs to output its full power, leaving the final small gap to be precisely filled by the electric and mechanical brakes. Simultaneously, if the retarder's current available torque capacity is not lower than the torque capacity of that gear, it ensures that the retarder is indeed capable of outputting the braking force corresponding to that gear in the current state. When a gear meets both conditions simultaneously, it is determined as the retarder's target gear, and the gear selection logic ends. In other embodiments, the preset torque condition can be configured to include the remaining required torque being greater than or equal to the torque capacity of that gear, and the retarder's current available torque capacity not being lower than the torque capacity of that gear. In some other embodiments, the comparison can be performed in ascending order. In this case, the preset torque condition can be configured such that the torque capacity of the gear is greater than or equal to the remaining required torque, and the current available torque capacity of the retarder is not lower than the torque capacity of the gear. The first gear that meets the condition is selected as the target gear.

[0038] In one embodiment, if none of the retarder's gears meet the preset torque condition, then the target gear for the retarder is determined to be gear one. In this embodiment, when the remaining required torque is very small, so small that no gear from fourth to second has a torque capacity less than the remaining required torque, it indicates that the remaining braking demand is small. The retarder only needs to participate in braking with the lowest gear, and the rest is supplemented by electric braking and mechanical braking, which can still ensure that the overall braking force meets the demand.

[0039] In one embodiment, the control retarder outputting the braking torque corresponding to the target gear in S205 may specifically include: controlling the retarder to first output braking torque at the first gear; after each preset retarder response delay, if the current gear is lower than the target gear, controlling the retarder to move up to the next adjacent gear until the target gear is reached; the retarder response delay is calibrated based on the retarder's response characteristics.

[0040] This embodiment aims to address the issue of torque build-up delay in retarder systems. Specifically, when the retarder is a hydraulic retarder, it requires a certain amount of time to fill with oil and build up oil pressure after receiving a gear command; the torque does not reach the target value instantaneously. Eddy current retarders also have an electrical response time. If the gear jumps directly from zero to the target gear, the actual braking force during the torque ramp-up will be significantly less than required, potentially leading to a brief loss of vehicle speed control. This embodiment addresses this by progressively shifting gears, starting from the lowest gear and increasing one gear after each response delay. This results in a smooth, stepped increase in torque output, minimizing the impact of response delay on overall deceleration. It should be noted that the retarder response delay is determined based on the specific retarder model's response characteristics; the response delay of a hydraulic retarder is typically longer than that of an eddy current retarder.

[0041] In one embodiment, S206 may specifically include: when the difference between the total required braking torque and the braking torque corresponding to the target gear is greater than zero, using the difference as the braking torque to be allocated, and determining whether the braking torque to be allocated is less than or equal to the current available electric braking torque capacity; if yes, then all the braking torque to be allocated is allocated as the electric braking target torque, and the mechanical braking target torque is configured to zero; if no, then all the current available electric braking torque capacity is allocated as the electric braking target torque, and the portion of the braking torque to be allocated that exceeds the current available electric braking torque capacity is configured as the mechanical braking target torque; when the difference between the total required braking torque and the braking torque corresponding to the target gear is less than or equal to zero, both the electric braking target torque and the mechanical braking target torque are configured to zero.

[0042] This embodiment aims to refine the distribution rules of residual torque after the retarder intervenes. When the difference is positive, it indicates that there is still residual braking demand to be met after the retarder outputs its power. In this case, electric braking is prioritized because it responds quickly and can recover energy. If the electric braking capacity is insufficient, mechanical braking supplements it. Mechanical braking uses an electronic braking system to control the brake pads to output the required torque with precise pressure. When the difference is zero or negative, it indicates that the braking torque output by the retarder alone has reached or exceeded the total demand. In this case, neither electric nor mechanical braking needs to participate; both are configured to zero, and the overall braking force is provided independently by the retarder. This distribution strategy achieves seamless connection between the actuators, ensuring that the overall braking force always precisely matches the demand.

[0043] In one embodiment, after the step of using the difference as the braking torque to be allocated, the autonomous vehicle braking control method further includes: acquiring a target deceleration sequence and an actual vehicle speed sequence for a preset historical duration; integrating the target deceleration sequence for the preset historical duration to obtain a target vehicle speed reduction; calculating the difference between the current vehicle speed and the initial vehicle speed before the preset historical duration to obtain an actual vehicle speed reduction; calculating the difference between the target vehicle speed reduction and the actual vehicle speed reduction, and then dividing it by the value of the preset historical duration to obtain a target compensation deceleration; inputting the target compensation deceleration into the vehicle's longitudinal dynamics model for calculation to obtain a compensation braking torque; superimposing the compensation braking torque onto the braking torque to be allocated to obtain a new braking torque to be allocated; and based on the new braking torque to be allocated, returning to the step of determining whether the braking torque to be allocated is less than or equal to the current available electric braking torque capability to continue execution.

[0044] This embodiment, based on the aforementioned feedforward control, introduces a closed-loop compensation mechanism based on actual deceleration deviation. Since the slope sensor and vehicle weight sensor may have measurement errors, a deviation may exist between the calculated total required braking torque and the actual required braking torque. If only feedforward control is relied upon, the deceleration control accuracy may be affected. Simultaneously, to avoid control oscillations when compensating based on instantaneous deceleration deviation, this embodiment uses the cumulative deviation over a past period to calculate the compensation amount. Specifically, a preset historical time period is used as a calibration value. By integrating the target deceleration over the past time period, the theoretically required vehicle speed reduction is obtained. This is then compared with the actual change in vehicle speed to obtain the average deceleration deviation over this period, which is then converted into compensation braking torque. After superimposing the compensation braking torque onto the original brake torque to be allocated, the electric braking and mechanical braking allocation process is re-executed, forming a closed-loop adjustment.

[0045] It should be noted that in some embodiments, the braking force compensation control based on deceleration deviation can be executed at a lower frequency, which is a slow-loop control; while the retarder gear determination and the basic allocation of electric braking and mechanical braking can be executed at a higher frequency, which is a fast-loop control. The update frequency of the slow-loop control is lower than that of the fast-loop control, and the compensation torque only acts on the fine adjustment of electric braking and mechanical braking, without triggering the retarder to recalculate the gear, thereby avoiding control oscillations caused by instantaneous deceleration deviation and ensuring the smoothness of the braking process.

[0046] In one embodiment, the preset vehicle longitudinal dynamics model is specifically as follows: ; in, For the total required braking torque, Given the current vehicle weight, To slow down the target, It is the acceleration due to gravity. For the current slope, The rolling resistance coefficient, Main reducer transmission ratio, For mechanical transmission efficiency, This is the rolling radius of the wheel.

[0047] This model fully considers the various forces acting on a vehicle on a slope and can accurately convert the target deceleration into the required braking torque at the drive shaft end.

[0048] In conclusion, the method proposed in this application has at least the following beneficial effects: Firstly, by automatically introducing a retarder as the main force for continuous braking when the electric braking capacity is insufficient, and distributing the remaining braking demand between electric braking and mechanical braking according to the principle of electric braking priority, a three-source collaborative composite braking architecture is formed. This fundamentally solves the problem of mechanical brakes being prone to thermal fade and braking failure when continuously braking on long downhill slopes under high electric charge conditions, and significantly improves the braking safety of unmanned vehicles under harsh conditions.

[0049] Secondly, by introducing slope and vehicle weight signals into the calculation of total required braking torque, the deceleration control error under slope conditions and different load conditions is reduced, enabling braking control to adapt to different operating scenarios and effectively ensuring the trajectory tracking effect of unmanned driving.

[0050] Third, by controlling the retarder step-by-step upshift, the impact of the retarder torque build-up delay on the overall braking force response is minimized, making the retarder engagement process smoother and more controllable.

[0051] Fourth, based on feedforward control, an integral closed-loop compensation mechanism based on the deviation between the actual deceleration and the target deceleration over a period of time was designed. This improves the deceleration control accuracy while avoiding control oscillations caused by instantaneous deceleration deviations, further enhancing braking smoothness and control robustness.

[0052] The deficiencies of the above solutions and the proposed solutions are the result of the inventor's practice and careful research. Therefore, the discovery process of the above problems and the solutions proposed in this disclosure below should be considered as the inventor's contribution to this disclosure.

[0053] It should be understood that, for the foregoing method embodiments, although the steps in the flowcharts are shown sequentially as indicated by the arrows, these steps are not necessarily executed in the order indicated by the arrows. Unless explicitly stated herein, there is no strict order restriction on the execution of these steps, and they can be executed in other orders. Moreover, at least some steps in the flowcharts of the method embodiments may include multiple sub-steps or multiple stages. These sub-steps or stages are not necessarily completed at the same time, but can be executed at different times. The execution order of these sub-steps or stages is not necessarily sequential, but can be performed alternately or in turn with other steps or at least a portion of the sub-steps or stages of other steps.

[0054] In one embodiment, a vehicle controller is provided, the internal structure diagram of which can be as follows: Figure 3 As shown. The vehicle controller includes a processor, memory, input / output interfaces, and a communication interface. The processor, memory, and input / output interfaces are connected via a system bus, and the communication interface is also connected to the system bus via the input / output interfaces. The processor of the vehicle controller provides computing and control capabilities. The memory of the vehicle controller includes non-volatile storage media and internal memory. The non-volatile storage media stores the operating system and computer programs. The internal memory provides an environment for the operation of the operating system and computer programs in the non-volatile storage media. The input / output interfaces of the vehicle controller are used for exchanging information between the processor and external devices. The communication interface of the vehicle controller is used for wired or wireless communication with external terminals; wireless communication can be achieved through Wi-Fi, mobile cellular networks, NFC, or other technologies. When the computer program is executed by the processor, it implements the steps of any of the aforementioned autonomous vehicle braking control methods.

[0055] Those skilled in the art will understand that Figure 3 The structure shown is merely a block diagram of a portion of the structure related to the present application and does not constitute a limitation on the vehicle controller to which the present application is applied. A specific vehicle controller may include more or fewer components than those shown in the figure, or combine certain components, or have different component arrangements.

[0056] In one embodiment, an autonomous vehicle is provided, which, by being equipped with the aforementioned vehicle controller or the aforementioned autonomous vehicle braking control system, also possesses all the aforementioned technical effects. Specifically, the autonomous vehicle includes, but is not limited to, autonomous mining dump trucks or autonomous heavy trucks, which can automatically coordinate and schedule three braking modes—electric braking, retarder braking, and mechanical braking—according to the target deceleration command issued by the intelligent driving system under harsh working conditions such as long downhill slopes, heavy loads, and unpaved roads. When the battery charge is too high and electric braking is limited, the retarder intervenes in time to take over the main continuous braking task, avoiding thermal fade of mechanical braking due to continuous high-intensity work. At the same time, through slope and vehicle weight adaptive torque calculation and closed-loop compensation based on historical deviation, the target deceleration is accurately tracked, ensuring the safety and smoothness of autonomous driving trajectory tracking.

[0057] Those skilled in the art will understand that all or part of the processes in the above embodiments can be implemented by a computer program instructing related hardware. The computer program can be stored in a non-volatile computer-readable storage medium. When executed, the computer program can include the processes of the embodiments described above. Any references to memory, databases, or other media used in the embodiments provided in this application can include at least one of non-volatile and volatile memory. Non-volatile memory can include read-only memory (ROM), magnetic tape, floppy disk, flash memory, optical memory, high-density embedded non-volatile memory, resistive random access memory (ReRAM), magnetic random access memory (MRAM), ferroelectric random access memory (FRAM), phase change memory (PCM), graphene memory, etc. Volatile memory can include random access memory (RAM) or external cache memory, etc. By way of illustration and not limitation, RAM can take many forms, such as Static Random Access Memory (SRAM) or Dynamic Random Access Memory (DRAM). The databases involved in the embodiments provided in this application may include at least one type of relational database and non-relational database. Non-relational databases may include, but are not limited to, blockchain-based distributed databases. The processors involved in the embodiments provided in this application may be general-purpose processors, central processing units, graphics processing units, digital signal processors, programmable logic devices, quantum computing-based data processing logic devices, etc., and are not limited to these.

[0058] It should be noted that in the embodiments of this application, certain existing solutions in the industry, such as software, components, and models, may be mentioned. These should be considered as exemplary, intended only to illustrate the feasibility of implementing the technical solution of this application, and do not imply that the applicant has already used or necessarily used such solutions. The methods described in this application are all independently developed executable software algorithms, all implemented using general-purpose high-level languages, and do not involve software licensing or other intellectual property issues.

[0059] The technical features of the above embodiments can be combined arbitrarily. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as the combination of these technical features does not contradict each other, it should be considered within the scope of this specification. In the above embodiments, the descriptions of each embodiment have their own emphasis. For parts not described in detail in a certain embodiment, please refer to the relevant descriptions of other embodiments.

[0060] The terms “comprising” and “having”, and any variations thereof, in the embodiments herein are intended to cover non-exclusive inclusion. For example, a process, method, system, product, or apparatus that includes a series of steps or (module) units is not limited to the steps or units listed, but may optionally include steps or units not listed, or may optionally include other steps or units inherent to such process, method, product, or apparatus.

[0061] The embodiments described above are merely illustrative of several implementation methods of this application, and while the descriptions are specific and detailed, they should not be construed as limiting the scope of protection of this application. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this application, and these modifications and improvements all fall within the scope of protection of this application.

Claims

1. A braking control method for an unmanned vehicle, characterized in that, include: In response to the detection of target deceleration, the current vehicle weight information, current slope information, current available electric braking torque capacity, and current available torque capacity of the retarder are obtained; Based on the target deceleration, the current vehicle weight information, the current slope information, and the preset vehicle longitudinal dynamics model, the total required braking torque is calculated. Based on the current available electric braking torque capacity, the current available torque capacity of the retarder, and the total required braking torque, determine whether the preset retarder intervention conditions are met. If the retarder intervention conditions are met, the target gear of the retarder is determined based on the current available electric braking torque capacity, the current available torque capacity of the retarder, and the total required braking torque. The retarder is controlled to output the braking torque corresponding to the target gear, and the difference between the total required braking torque and the braking torque corresponding to the target gear is calculated. Based on the difference between the total required braking torque and the braking torque corresponding to the target gear, the target torque for electric braking and the target torque for mechanical braking are configured.

2. The method according to claim 1, characterized in that, Determining that the retarder intervention conditions are met includes: Ensure that the following conditions are met simultaneously: The currently available electric braking torque capacity is lower than a preset electric braking capacity threshold. The difference between the total required braking torque and the currently available electric braking torque capacity is greater than the retarder's first-gear torque capacity. The retarder's current available torque capacity is not less than the first gear torque capacity.

3. The method according to claim 1, characterized in that, Determining the target gear of the retarder based on the currently available electric braking torque capacity, the currently available torque capacity of the retarder, and the total required braking torque includes: The remaining required torque is obtained by calculating the difference between the total required braking torque and the currently available electric braking torque capacity. According to the retarder gears from high to low, the remaining required torque is compared with the torque capacity of each gear, and the current available torque capacity of the retarder is compared with the torque capacity of the corresponding gear. The first gear that meets the preset torque condition is determined as the target gear of the retarder; the preset torque condition includes that the remaining required torque is greater than the torque capacity of the gear, and the current available torque capacity of the retarder is not lower than the torque capacity of the gear.

4. The method according to claim 3, characterized in that, Also includes: If none of the gears of the retarder meet the preset torque condition, then the target gear of the retarder is determined to be gear one.

5. The method according to claim 1, characterized in that, The control of the retarder to output the braking torque corresponding to the target gear includes: The retarder is controlled to output braking torque at the first gear. After a preset retarder response delay, if the current gear is lower than the target gear, the retarder is controlled to move up to the next adjacent gear until the target gear is reached. The retarder response delay duration is determined based on the retarder's response characteristics.

6. The method according to any one of claims 1 to 5, characterized in that, The configuration of the electric braking target torque and the mechanical braking target torque based on the difference between the total required braking torque and the braking torque corresponding to the target gear includes: When the difference between the total required braking torque and the braking torque corresponding to the target gear is greater than zero, the difference is taken as the braking torque to be allocated. It is then determined whether the braking torque to be allocated is less than or equal to the current available electric braking torque capacity. If so, the braking torque to be allocated is configured as the electric braking target torque, and the mechanical braking target torque is configured as zero. If not, the current available electric braking torque capacity is configured as the electric braking target torque, and the portion of the braking torque to be allocated that exceeds the current available electric braking torque capacity is configured as the mechanical braking target torque. When the difference between the total required braking torque and the braking torque corresponding to the target gear is less than or equal to zero, both the electric braking target torque and the mechanical braking target torque are configured to be zero.

7. The method according to claim 6, characterized in that, After using the difference as the braking torque to be allocated, the method further includes: Obtain the target deceleration sequence and actual vehicle speed sequence for a preset historical duration; Integrating the target deceleration sequence over the preset historical duration yields the target vehicle speed reduction. Calculate the difference between the current vehicle speed and the starting vehicle speed before the preset historical time period to obtain the actual vehicle speed reduction; Calculate the difference between the target vehicle speed reduction and the actual vehicle speed reduction, and then divide it by the preset historical time to obtain the target compensation deceleration. The target compensated deceleration is input into the vehicle longitudinal dynamics model for calculation to obtain the compensated braking torque; The compensated braking torque is superimposed on the braking torque to be allocated to obtain a new braking torque to be allocated. Based on the new braking torque to be allocated, return to the step of determining whether the braking torque to be allocated is less than or equal to the current available electric braking torque capacity and continue execution.

8. A braking control system for an unmanned vehicle, characterized in that, include: Intelligent driving controller, used to output target deceleration; A slope sensor is used to acquire current slope information; Vehicle weight sensor, used to obtain current vehicle weight information; The motor controller is used to control the target torque of the electric braking output of the motor; The retarder controller is used to control the braking torque corresponding to the target gear output of the retarder; An electronic braking system is used to control the mechanical brake to output the target mechanical braking torque. The vehicle controller is communicatively connected to the intelligent driving controller, the slope sensor, the vehicle weight sensor, the motor controller, the retarder controller, and the electronic braking system, and is configured to perform the steps of the method as described in any one of claims 1 to 7.

9. A vehicle controller, characterized in that, It includes a processor and a memory, wherein the memory stores a computer program, and the processor executes the computer program to implement the steps of the method as described in any one of claims 1 to 7.

10. An unmanned vehicle, characterized in that, This includes the autonomous vehicle braking control system as described in claim 8 or the vehicle controller as described in claim 9.

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