Hill Rollback Speed Control via Dynamic Brake Pressure
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Solution Overview
Problem
Existing vehicle control systems, particularly those with advanced transmissions, lack effective mechanisms for controlling rollback speed on hills, which can lead to unintended vehicle movement when the brake pedal is released on inclines.
Innovation Solution
A system comprising a driving direction arbitration module, a start/stop arbitration module, a vehicle speed limit module, and a vehicle brake control module, which utilize wheel direction signals, terrain grade angle sensors, and transmission temperature sensors to maintain a target rollback speed by adjusting brake pressure based on terrain grade and transmission temperature.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If hill hold control is implemented using traditional mechanisms, then the vehicle can be prevented from rolling backward on hills, but the control system becomes insufficient for advanced transmissions and cannot effectively control rollback speed
Solution Approach 1:
The system dynamically adjusts the target rollback speed based on transmission temperature conditions. When transmission temperature is below a threshold, the target rollback speed is set to a first value; when above the threshold, it is set to a second value. This dynamic adaptation ensures effective hill hold control across different transmission states and temperatures, resolving the contradiction between reliability and adaptability to advanced transmission systems.
2Ease of operation
If the brake pedal is released on an incline, then the vehicle can move forward, but the vehicle may roll backward unintentionally
Solution Approach 1:
The system applies preliminary anti-action by establishing a target rollback speed that prevents unintended backward movement. The brake control module receives the target rollback speed and controls the brakes to maintain this speed, counteracting the gravitational force that causes rollback before the vehicle can move forward. This preliminary control action eliminates the harmful rollback effect while preserving ease of operation.
Solution Approach 2:
The system uses feedback by continuously monitoring actual vehicle speed and comparing it to the target rollback speed. The brake control module adjusts brake application based on the difference between actual and target speeds, ensuring the vehicle maintains the desired rollback speed and preventing unintended movement. This closed-loop feedback control resolves the contradiction between ease of operation and prevention of harmful rollback.
3Stability of the object's composition
If brake pressure is increased to prevent rollback, then vehicle stability is improved, but transmission temperature may increase
Solution Approach 1:
The system changes the parameter of target rollback speed based on transmission temperature. When transmission temperature is below the threshold, a higher target rollback speed (first value) is permitted, allowing greater brake application for enhanced stability. When transmission temperature exceeds the threshold, the target rollback speed is reduced to a second value, limiting brake application to prevent overheating. This parameter change strategy resolves the contradiction between stability and temperature control.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The system effectively controls the rollback speed of a vehicle on hills, ensuring stability and preventing unintended movement by dynamically adjusting brake pressure according to terrain grade and transmission conditions, enhancing safety and control.
Implementation Method 1
A terrain grade angle sensor ascertains a grade angle of the terrain
Implementation Method 2
transmission temperature sensors to maintain a target rollback speed
Implementation Method 3
The system effectively controls the rollback speed of a vehicle on hills, ensuring stability and preventing unintended movement by dynamically adjusting brake pressure
Data Source
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AI summary
A hill rollback control system and method for controlling a rollback speed of a motor vehicle with wheel brakes. Upon ascertaining that the vehicle is rolling back, the system and method determine, based on a grade angle of the terrain that the vehicle is traveling on and a temperature of a transmission, a target rollback speed for the vehicle. The target rollback speed is lower when the grade of the terrain is above a threshold value. Also, the target rollback speed is lower when the temperature of the transmission is above a threshold value. The actual rollback speed of the vehicle is set and maintained at the target rollback speed by applying the vehicle's wheel brakes.