A new energy commercial passenger car downhill adaptive speed limiting control method

Abstract

This invention discloses an adaptive speed limit control method for downhill driving of new energy commercial buses, relating to the field of passenger vehicle safety control technology. The method includes the following steps: First, the road gradient corresponding to the vehicle's pitch angle is calculated in real time, and historical downhill control data is queried from a cloud platform based on the current location. Simultaneously, driver control signals are monitored to identify the driver's intention. Then, based on the historical average vehicle speed and the current gradient, a first correction is made, followed by a second correction based on the driver's intention, thereby dynamically setting the final downhill target speed limit. The system continuously compares the actual vehicle speed with the target speed limit: if the speed is exceeded, the required total braking torque is calculated and electric braking is prioritized; if the speed is not exceeded, the driver's driving request is arbitrated based on the driver's intention and the current operating conditions to determine whether and how to respond. This invention achieves safe, adaptive, smooth, and intelligent downhill speed control.

Description

Technical Field

[0001] This invention relates to the field of passenger vehicle safety control technology, specifically to a downhill adaptive speed limit control method for new energy commercial buses. Background Technology

[0002] Speed ​​control for new energy commercial buses on downhill sections, especially long and steep slopes, is a critical issue affecting driving safety and operational efficiency. Existing downhill speed control schemes typically rely on a vehicle controller to manage the vehicle's longitudinal motion. These schemes generally estimate the road gradient indirectly using internal vehicle signals such as longitudinal acceleration sensors and drive motor torque, using this as the basis for calculating the required braking force. In terms of control logic, a fixed target speed is often set, prioritizing regenerative braking from the drive motor to maintain speed; when electric braking force is insufficient, the traditional pneumatic braking system is called in to supplement it. However, this mainstream approach has gradually revealed several limitations in practical applications. First, its core gradient perception relies on indirect estimation and fusion of vehicle dynamic signals, which inherently involves recognition delays and accumulated errors, making it difficult to achieve high-precision, real-time gradient information acquisition. This results in insufficient accuracy in the feedforward stage of the control system, affecting the timeliness of the initial speed control response and the smoothness of the entire control process. Secondly, most control strategies are based on preset fixed parameters and simple rules, lacking the ability to effectively identify and integrate decision-making in complex and ever-changing downhill scenarios (such as gradient changes and curve combinations) and the driver's real-time operating intentions, resulting in a relatively rigid system interaction mode. Furthermore, in terms of the actual distribution and coordination of braking force, electric braking and air braking often exhibit a simple sequential complementary relationship, lacking a dynamic coordination mechanism based on total demand and system state, which can easily trigger mode switching shocks and affect driving comfort. Summary of the Invention

[0003] To ensure timely and smooth speed response during downhill driving and to guarantee driving comfort, this invention proposes an adaptive speed limit control method for new energy commercial buses during downhill driving, comprising the following steps executed cyclically: S1: Real-time acquisition of vehicle pitch angle and calculation of current road slope based on pitch angle; S2: Obtain the vehicle's current location information and query the historical downhill control data corresponding to that location in the cloud platform; S3: Real-time monitoring of driver control signals and identification of the driver's current driving intention based on the control signals; S4: Based on the historical average vehicle speed in the historical downhill control data, the historical average vehicle speed is first corrected according to the current road gradient to obtain the preliminary target vehicle speed, and the preliminary target vehicle speed is second corrected based on the identified driver intention, thereby dynamically setting the downhill target speed limit. S5: Compare the current actual vehicle speed with the downhill target speed limit. If the current actual vehicle speed exceeds the downhill target speed limit, proceed to step S6; otherwise, proceed to step S7. S6: Calculate the required total braking torque based on the current road slope, vehicle mass and wind resistance parameters, execute electric braking through the motor controller according to the total braking torque and return to step S1; S7: Respond to the driver's drive request based on the driver's intention and the current operating conditions, and return to step S1.

[0004] This invention integrates real-time slope perception, cloud data learning, and driver intent recognition to dynamically set and maintain the target speed limit for downhill driving, achieving safe, adaptive, smooth, and intelligent downhill speed control. It effectively overcomes the problems of lagging slope recognition, abrupt braking mode switching, and poor human-machine collaboration in traditional solutions.

[0005] Furthermore, in step S3, the driver control signals include the accelerator pedal opening change rate, the brake pedal opening change rate, and the steering angle rate.

[0006] Furthermore, in step S3, identifying the driver's current driving intention based on the control signals specifically includes: If the rate of change of accelerator pedal opening continuously exceeds the positive threshold, it is identified as an intention to actively accelerate. If the rate of change of brake pedal opening continuously exceeds the positive threshold and / or the steering angle rate exceeds the set threshold, it is identified as an emergency avoidance. Otherwise, it is identified as a routine patrol intention.

[0007] Furthermore, in step S4, the specific method for making the first correction to the historical average vehicle speed based on the current road gradient is as follows: Based on a pre-established gradient speed correction coefficient mapping table, the corresponding correction coefficient is queried according to the current road gradient, and the historical average speed is multiplied by the correction coefficient to obtain the preliminary target speed.

[0008] Furthermore, in step S4, the specific method for making a second correction to the initial target vehicle speed based on the identified driver's intention is as follows: If the driver's intention is identified as actively accelerating, a preset tolerance value is added to the initial target speed to obtain the downhill target speed limit. If the driver's intention is identified as normal cruising, then maintain the initial target speed as the downhill target speed limit. If the driver's intention is identified as an emergency evasive maneuver, a preset redundancy value is subtracted from the initial target speed to obtain the downhill target speed limit.

[0009] Furthermore, in step S7, determining whether and how to respond to the driver's driving request based on the driver's intention and the current operating conditions specifically includes: Obtain the drive torque requested corresponding to the current driver's accelerator pedal opening; If the driver's intention is to accelerate actively and the current actual vehicle speed is lower than the downhill target speed limit value - a set threshold, then respond with all or part of the drive request torque. If the driver's intention is identified as normal cruising, the drive torque request will be limited to the range of drive force required to maintain the current vehicle speed. If the driver's intention is identified as an emergency evasive maneuver, the output of the requested drive torque is cut off.

[0010] Furthermore, step S6 also includes the step of: S61: Real-time determination of whether the electric braking torque meets the total braking torque requirement. If it does, return to step S1; otherwise, proceed to step S62. S62: Send a braking pressure request to the electronic braking system and coordinate the execution of air braking until the actual vehicle speed recovers to no more than the downhill target speed limit and return to step S1.

[0011] Furthermore, sending a braking pressure request to the electronic braking system specifically involves: Based on the difference between the total braking torque and the current maximum electric braking torque, the target braking chamber pressure is calculated using a PI control algorithm, and then sent to the electronic braking system.

[0012] Furthermore, during the execution of air braking, the process also includes using the regenerative braking energy generated during electric braking to drive the vehicle's air compressor to store braking air pressure for the air braking system.

[0013] Compared with the prior art, the present invention has at least the following beneficial effects: (1) The present invention proposes a new energy commercial bus downhill adaptive speed limit control method, which obtains real-time slope information through attitude perception and uses it as the basic input, and then combines cloud-based historical data learning with real-time driver intention recognition, so that the downhill target speed limit value is no longer a fixed or static value based solely on the slope, but a dynamic variable that can integrate historical experience, real-time road conditions and driver subjective intentions, significantly improving the tacit understanding and driving smoothness of human-machine co-driving under the premise of ensuring safety. (2) A composite braking strategy of prioritizing electric braking and coordinating with air braking is adopted, and a seamless and smooth switching between the two braking modes is achieved based on feedforward and feedback control. This solves the problem of vehicle vibration caused by frequent alternation of driving, coasting and braking modes in traditional downhill speed limits, and improves driving comfort and safety. Attached Figure Description

[0014] Figure 1 A flowchart illustrating the steps of an adaptive speed limit control method for downhill driving of a new energy commercial bus; Figure 2 A schematic diagram illustrating the implementation of basic modular functions. Detailed Implementation

[0015] The following are specific embodiments of the present invention, which are described in conjunction with the accompanying drawings. However, the present invention is not limited to these embodiments.

[0016] This invention relates to a downhill adaptive speed limit control method for new energy commercial buses. The method uses the vehicle controller as the core of the system, comprehensively processing signals from high-precision attitude sensors, cloud platforms, driver operating interfaces, and various vehicle bus signals. It also coordinates the motor controller, electronic braking system, battery management system, and multiple auxiliary actuators to achieve intelligent, smooth, and highly safe autonomous speed management during downhill driving. Figure 1 As shown, the control method includes the following steps: S1: Real-time acquisition of vehicle pitch angle and calculation of current road slope based on pitch angle; S2: Obtain the vehicle's current location information and query the historical downhill control data corresponding to that location in the cloud platform; S3: Real-time monitoring of driver control signals and identification of the driver's current driving intention based on the control signals; S4: Based on the historical average vehicle speed in the historical downhill control data, the historical average vehicle speed is first corrected according to the current road gradient to obtain the preliminary target vehicle speed, and the preliminary target vehicle speed is second corrected based on the identified driver intention, thereby dynamically setting the downhill target speed limit. S5: Compare the current actual vehicle speed with the downhill target speed limit. If the current actual vehicle speed exceeds the downhill target speed limit, proceed to step S6; otherwise, proceed to step S7. S6: Calculates the required total braking torque based on the current road slope, vehicle weight, and wind resistance parameters, and executes electric braking through the motor controller according to the total braking torque; S61: Real-time determination of whether the electric braking torque meets the total braking torque requirement. If it does, return to step S1; otherwise, proceed to step S62. S62: Send a braking pressure request to the electronic braking system and coordinate the execution of air braking until the actual vehicle speed is restored to no more than the downhill target speed limit and return to step S1; S7: Respond to the driver's drive request based on the driver's intention and the current operating conditions, and return to step S1.

[0017] The basis for implementing the technical solution of this invention includes (such as)Figure 2 (As shown): An inertial measurement unit (IMU) is installed at the vehicle's center of gravity or, after position compensation calculation, can equivalently reflect the vehicle's pitch attitude. This unit is used to collect vehicle pitch angle data in real time. The vehicle controller, as the core processing unit, communicates with the motor controller, electronic braking system controller, battery management system, transmission controller, and other power domain and chassis domain controllers via the vehicle controller LAN bus. At the same time, the vehicle controller also receives analog or digital signals from the accelerator pedal position sensor, brake pedal position sensor, and steering angle sensor. In addition, the system also includes an onboard remote communication module connected to the vehicle controller for data exchange with the cloud server. And multiple actuators controlled by the vehicle controller, such as a voice alarm device, seat belt electric pretensioner, high-power electrical equipment that can be directly driven by a high-voltage power supply, an electric air compressor that supplies air to the pneumatic braking system, and a water-cooled compressor and circulation pump for the battery thermal management system.

[0018] When the vehicle starts and the vehicle controller completes its self-test, the downhill adaptive speed limit control program enters a standby loop. The initial step of the control process is to acquire and calculate the current road gradient in real time. The vehicle controller reads the raw pitch angle data output by the inertial measurement unit at a fixed frequency via the local area network bus. To eliminate high-frequency noise interference caused by vehicle vibration and road bumps, the raw pitch angle data needs to be filtered, for example, using a first-order low-pass filter or a moving average filter algorithm, to obtain a stable pitch angle estimate. Subsequently, based on the pitch angle zero-point reference calibrated when the vehicle is stationary or traveling at a constant speed on a level road, the filtered pitch angle value is converted into a road gradient angle. In a preferred embodiment, the gradient calculation is also dynamically compensated by combining the vehicle's longitudinal acceleration sensor signal to distinguish the inertial component caused by the vehicle's own acceleration and deceleration, but the core gradient information mainly comes from the directly measured pitch angle.

[0019] While acquiring real-time gradient data, the vehicle controller also obtains the vehicle's coordinate data through the onboard remote communication module and uploads an information packet containing a timestamp, vehicle identification number, and current location to the cloud server. The cloud server stores a dynamically updated road segment database containing a large amount of historical vehicle driving data, extracted using geographic location as an index. For downhill control scenarios, the cloud database aggregates key historical statistical information for specific road segments or locations, such as average passing speed, average braking intensity, and common gradient ranges recorded multiple times at that point. After the vehicle controller initiates a query request, the cloud server matches the current vehicle location against the electronic map database to find the current driving segment or the segment it will soon enter. If a match is successful, the historical downhill control data for that segment is sent to the vehicle controller. This data serves as prior knowledge, providing a reference for the vehicle's current decision-making. If the current road segment is a completely new route lacking historical data, the cloud can return a null value or provide a default reference value based on road grade and topographic map information. In this case, the system will rely entirely on real-time sensor data for control, ensuring baseline functionality availability.

[0020] In addition to the data acquisition mentioned above, the vehicle controller continuously collects and analyzes a series of signals characterizing driver operation behavior, mainly including the accelerator pedal opening change rate, brake pedal opening change rate, and steering angle rate. The opening change rates of the accelerator and brake pedals are obtained by differentiating the pedal position signals and then filtering them appropriately to eliminate operational jitter. The steering angle rate can be obtained directly from the steering column sensor or through differential steering angle signals. The recognition logic makes judgments based on preset thresholds and state durations.

[0021] Specifically, if the control system detects that the rate of change of accelerator pedal opening exceeds a set positive sensitivity threshold for several consecutive control cycles, it infers that the driver has a clear intention to actively accelerate, possibly to overtake the vehicle in front or to quickly pass a slope. If the rate of change of brake pedal opening rapidly exceeds its set threshold, it indicates that the driver may be performing anticipatory braking or emergency braking; or, if the steering angle rate increases sharply in a short period of time and exceeds the threshold, it indicates that the driver may be performing an emergency avoidance maneuver. Both of these situations can be classified as emergency avoidance intentions. If none of the above signals reach the trigger threshold and the pedal operation is smooth, the system determines that the driver is in a normal cruise intention state.

[0022] After integrating real-time gradient data, historical cloud data, and driver intent information, the control system dynamically sets the target speed limit for downhill driving. This setting process is divided into two logical levels, which are performed sequentially.

[0023] The first level is slope correction based on physical safety. The vehicle controller stores or loads a pre-defined "slope-speed correction coefficient mapping table" internally. This table defines recommended speed adjustment coefficients for different slope ranges, from gentle to steep. Generally, the steeper the slope, the lower the required speed limit to ensure safety; therefore, the corresponding correction coefficient is less than or equal to 1. The control system queries this mapping table based on the calculated current road slope to obtain a specific correction coefficient. Next, it multiplies this correction coefficient by the historical average speed of the current road segment obtained from the cloud to obtain a preliminary target speed. This step essentially standardizes and adjusts the historical average speed according to the current specific slope conditions, making it more suitable for current safety requirements.

[0024] The second level is a human-centered adjustment based on driver intent. This step aims to respond to the driver's reasonable operational intentions within a limited flexibility, thereby improving the driving experience. If the currently identified driver intent is active acceleration, a preset tolerance value is added to the initial target speed. This value can be calibrated as a fixed value or a variable value related to the gradient, depending on the vehicle model and strategy, thus forming the final downhill target speed limit. If the driver intent is normal cruising, the initial target speed is directly adopted as the final downhill target speed limit without additional adjustments. If an emergency evasive intent is identified, prioritizing maximum safety, a preset redundancy value is subtracted from the initial target speed to set a more conservative speed limit with a greater safety margin, allowing more reaction time and vehicle control stability for emergency maneuvers. Through these two adjustments, objective road conditions, historical driving experience, and subjective driving intent are integrated to obtain the target speed limit.

[0025] The target speed limit for downhill driving is compared with the actual vehicle speed obtained by the vehicle control system from the bus.

[0026] When the current actual vehicle speed exceeds the downhill target speed limit, the overspeed braking control process is triggered. The primary task in this process is to calculate the total braking force required to maintain the target speed. The vehicle controller performs this calculation based on the vehicle dynamics model, with input parameters including the current road gradient, the vehicle's curb weight and estimated load weight, the vehicle's drag coefficient and frontal area, and tire rolling resistance coefficient. By calculating the vehicle's gravity component in the downhill direction and subtracting the air resistance and rolling resistance at the current speed, the braking force required to counteract the additional acceleration force can be obtained, which is then converted into the total braking torque required for the drive axle or all wheels. After obtaining the total braking torque requirement, the control strategy follows the principle of prioritizing electric braking. The vehicle controller sends a torque command to the motor controller, requesting it to apply reverse torque, i.e., regenerative braking. The motor controller responds to the command, controlling the motor to enter generator mode, converting kinetic energy into electrical energy while generating braking torque.

[0027] At the moment or before initiating electric braking, the system executes several key auxiliary management and safety preparation strategies in parallel. First, the vehicle controller queries the real-time state of charge (SOC) of the power battery provided by the battery management system. If the SOC exceeds a set high threshold, it indicates limited battery storage capacity, and high-power energy recovery may cause battery overvoltage or trigger protection, limiting braking power. Therefore, the system proactively controls one or more high-power onboard electrical devices to start. For example, it can independently control the electric compressor of the bus air conditioner to operate in full-power mode, or turn on a high-power PTC heater, thereby actively consuming battery power, reducing the SOC, and making room for continuous and effective energy recovery, ensuring the availability and stability of electric braking torque. Second, anticipating downhill braking, especially the potential for large currents during energy recovery, the vehicle controller sends a command to the battery thermal management system in advance to activate the battery pack liquid cooling circulation system. The water-cooled unit starts working to cool the battery coolant, thus creating good heat dissipation conditions for the battery in advance, preventing the battery from triggering overheat protection or affecting its lifespan and safety due to excessive temperature rise during regenerative braking.

[0028] Due to the physical limitations of the motor and its controller, there is an upper limit to the maximum regenerative braking torque it can provide. Under steep inclines and heavy vehicle loads, the required total braking torque may exceed the currently available maximum electric braking torque. Therefore, during electric braking, the vehicle controller also receives the actual electric braking torque feedback signal from the motor controller and compares it with the calculated total braking torque demand. When the system determines that the electric braking torque is insufficient to meet the total demand, it immediately initiates air braking coordination. The vehicle controller calculates the difference between the total required torque and the current actual maximum electric braking torque; this difference represents the braking force that needs to be supplemented by the mechanical braking system. Subsequently, a closed-loop control algorithm, such as a proportional-integral controller, converts this torque difference into a target brake chamber pressure request for the electronic braking system. This control algorithm uses the deviation between the actual vehicle speed and the target speed limit as the main feedback variable for adjustment, thereby ensuring that the vehicle speed smoothly and stably returns to below the target speed limit.

[0029] As for the regenerative electrical energy generated by electric braking, in addition to supplying power to onboard electrical appliances and charging the battery, a portion of the electrical energy is specifically allocated to drive the electric air compressor that supplies air to the pneumatic braking system. Traditional vehicle air compressors are usually driven by the engine and may not operate under pure electric conditions or downhill driving conditions. This invention actively utilizes regenerative electrical energy to drive the air compressor continuously or intermittently to refill the air tank. This approach proactively consumes excess regenerative energy, especially when the battery is highly charged, acting as an energy release mechanism to help maintain electric braking capability. Furthermore, it ensures that the air pressure in the air tank remains at a high level, providing sufficient pressure for the frequent or continuous air braking required on long downhill sections, effectively avoiding the risk of braking force attenuation due to pressure drop. Finally, it reduces the energy consumed by the drive motor or battery for refilling air, improving overall energy efficiency.

[0030] The entire braking control process, whether pure electric braking or electro-pneumatic combined braking, is a continuous process until the vehicle controller detects that the vehicle's actual speed has decreased and stabilized within the downhill target speed limit. Simultaneously with triggering active braking, the system also activates the occupant safety alert function. The vehicle controller drives the voice synthesis module in the driver's cab to play a preset alert message, such as "Downhill speed too fast, automatic deceleration in progress," to inform the driver of the current system status. To further enhance safety, in a preferred embodiment, the controller can also send a short-duration trigger signal to the seatbelt pretensioner, causing the seatbelt to tighten slightly and rapidly. This tactile warning further reminds the driver to pay attention to the vehicle's dynamics.

[0031] On the other hand, if the vehicle speed monitoring comparison finds that the current actual vehicle speed does not exceed the downhill target speed limit, the system enters the drive request analysis step. In this step, the core task of the system is not to apply braking, but to intelligently manage the driver's acceleration requests to prevent the vehicle from speeding due to improper throttle operation.

[0032] The vehicle controller first reads the current accelerator pedal opening signal and converts it into the driver's requested drive torque through a lookup table or function calculation. Next, it analyzes the drive request based on the identified driver intent and the current vehicle state. The specific analysis logic is as follows: If the identified driver intent is active acceleration, and the current actual vehicle speed is lower than a set positive buffer threshold below the downhill target speed limit, the system considers there to be reasonable acceleration space. In this case, the controller can selectively respond to the driver's requested drive torque in full or in part, allowing the vehicle to accelerate smoothly, gradually approaching but not exceeding the target speed limit. If the driver intent is normal cruising, the controller will limit the driver's requested drive torque within a safe range. The upper limit of this range is usually set as the theoretical drive force required to maintain a constant speed at the current gradient and vehicle speed. Thus, even if the driver unconsciously presses the accelerator pedal deeply, the system will limit the final output drive torque, effectively preventing accidental acceleration and speeding. If the identified intent is emergency avoidance, for absolute safety priority, the vehicle controller will temporarily ignore or completely cut off the drive torque requested from the accelerator pedal, so no drive force is generated even if the driver presses the accelerator. This ensures that the vehicle will not become uncontrollable due to sudden power intervention when the driver may perform emergency steering or braking operations, giving complete control of the vehicle's state to the driver's hazard avoidance maneuvers. This respects the driver's normal operating habits, avoiding the jerky feeling and unpleasant experience caused by abrupt system intervention, while also possessing the ability to take over in critical moments, thus guaranteeing driving safety.

[0033] In summary, the new invention proposes an adaptive speed limit control method for downhill driving of new energy commercial buses. By acquiring real-time slope information through attitude perception and using it as the basic input, the method combines cloud-based historical data learning with real-time driver intention recognition. This makes the downhill target speed limit no longer a fixed or static value based solely on the slope, but a dynamic variable that integrates historical experience, real-time road conditions, and the driver's subjective intentions. Under the premise of ensuring safety, this significantly improves the tacit understanding and driving smoothness of human-machine co-driving.

[0034] It adopts a composite braking strategy that prioritizes electric braking and coordinates with air braking, and achieves seamless and smooth switching between the two braking modes based on feedforward and feedback control. This solves the problem of vehicle vibration caused by frequent alternation of driving, coasting and braking modes in traditional downhill speed limits, and improves driving comfort and safety.

[0035] It should be noted that all directional indications (such as up, down, left, right, front, back, etc.) in the embodiments of the present invention are only used to explain the relative positional relationship and movement of each component in a certain specific posture (as shown in the figure). If the specific posture changes, the directional indication will also change accordingly.

[0036] Furthermore, in this invention, descriptions involving terms such as "first," "second," and "a" are for descriptive purposes only and should not be construed as indicating or implying their relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this invention, "a plurality of" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0037] In this invention, unless otherwise explicitly specified and limited, the terms "connection," "fixed," etc., should be interpreted broadly. For example, "fixed" can mean a fixed connection, a detachable connection, or an integral part; it can mean a mechanical connection or an electrical connection; it can mean a direct connection or an indirect connection through an intermediate medium; it can mean the internal communication of two components or the interaction between two components, unless otherwise explicitly limited. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0038] Furthermore, the technical solutions of the various embodiments of the present invention can be combined with each other, but only if they are feasible for those skilled in the art. If the combination of technical solutions is contradictory or cannot be implemented, it should be considered that such combination of technical solutions does not exist and is not within the scope of protection claimed by the present invention.

Claims

1. A method for adaptive speed limit control of a new energy commercial bus on a downhill slope, characterized in that, The following steps are executed in a loop: S1: Real-time acquisition of vehicle pitch angle and calculation of current road slope based on pitch angle; S2: Obtain the vehicle's current location information and query the historical downhill control data corresponding to that location in the cloud platform; S3: Real-time monitoring of driver control signals and identification of the driver's current driving intention based on the control signals; S4: Based on the historical average vehicle speed in the historical downhill control data, the historical average vehicle speed is first corrected according to the current road gradient to obtain the preliminary target vehicle speed, and the preliminary target vehicle speed is second corrected based on the identified driver intention, thereby dynamically setting the downhill target speed limit. S5: Compare the current actual vehicle speed with the downhill target speed limit. If the current actual vehicle speed exceeds the downhill target speed limit, proceed to step S6; otherwise, proceed to step S7. S6: Calculate the required total braking torque based on the current road slope, vehicle mass and wind resistance parameters, execute electric braking through the motor controller according to the total braking torque and return to step S1; S7: Respond to the driver's drive request based on the driver's intention and the current operating conditions, and return to step S1.

2. The adaptive speed limit control method for downhill driving of a new energy commercial bus as described in claim 1, characterized in that, In step S3, the driver control signals include the accelerator pedal opening change rate, the brake pedal opening change rate, and the steering angle rate.

3. The adaptive speed limit control method for downhill driving of a new energy commercial bus as described in claim 2, characterized in that, In step S3, identifying the driver's current driving intention based on the control signals specifically includes: If the rate of change of accelerator pedal opening continuously exceeds the positive threshold, it is identified as an intention to actively accelerate. If the rate of change of brake pedal opening continuously exceeds the positive threshold and / or the steering angle rate exceeds the set threshold, it is identified as an emergency avoidance. Otherwise, it is identified as a routine patrol intention.

4. The adaptive speed limit control method for downhill driving of a new energy commercial bus as described in claim 3, characterized in that, In step S4, the specific method for making the first correction to the historical average vehicle speed based on the current road gradient is as follows: Based on a pre-established gradient speed correction coefficient mapping table, the corresponding correction coefficient is queried according to the current road gradient, and the historical average speed is multiplied by the correction coefficient to obtain the preliminary target speed.

5. The adaptive speed limit control method for downhill driving of a new energy commercial bus as described in claim 4, characterized in that, In step S4, the specific method for making a second correction to the initial target vehicle speed based on the identified driver intention is as follows: If the driver's intention is identified as actively accelerating, a preset tolerance value is added to the initial target speed to obtain the downhill target speed limit. If the driver's intention is identified as normal cruising, then maintain the initial target speed as the downhill target speed limit. If the driver's intention is identified as an emergency evasive maneuver, a preset redundancy value is subtracted from the initial target speed to obtain the downhill target speed limit.

6. The adaptive speed limit control method for downhill driving of a new energy commercial bus as described in claim 3, characterized in that, In step S7, responding to the driver's driving request based on the driver's intention and the current operating conditions specifically includes: Obtain the drive torque requested corresponding to the current driver's accelerator pedal opening; If the driver's intention is to accelerate actively and the current actual vehicle speed is lower than the downhill target speed limit value - a set threshold, then respond with all or part of the drive request torque. If the driver's intention is identified as normal cruising, the drive torque request will be limited to the range of drive force required to maintain the current vehicle speed. If the driver's intention is identified as an emergency evasive maneuver, the output of the requested drive torque is cut off.

7. The adaptive speed limit control method for downhill driving of a new energy commercial bus as described in claim 1, characterized in that, Step S6 further includes the following step: S61: Real-time determination of whether the electric braking torque meets the total braking torque requirement. If it does, return to step S1; otherwise, proceed to step S62. S62: Send a braking pressure request to the electronic braking system and coordinate the execution of air braking until the actual vehicle speed recovers to no more than the downhill target speed limit and return to step S1.

8. The adaptive speed limit control method for downhill driving of a new energy commercial bus as described in claim 7, characterized in that, Sending a braking pressure request to the electronic braking system specifically involves: Based on the difference between the total braking torque and the current maximum electric braking torque, the target braking chamber pressure is calculated using a PI control algorithm, and then sent to the electronic braking system.

9. The adaptive speed limit control method for downhill driving of a new energy commercial bus as described in claim 7, characterized in that, The process of performing air braking also includes using the regenerative braking energy generated during electric braking to drive the vehicle's air compressor to store braking air pressure for the air braking system.

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