Hill Descent Control Using Gradient-Aware PID Integration
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Solution Overview
Problem
Existing Hill Descent Control (HDC) systems for motor vehicles struggle with precise speed control on variable gradients, leading to control oscillations, sudden brake influences, and uneven vehicle speed, especially when transitioning between sections with different gradients.
Innovation Solution
A method and device that determine actual and target speed signals, calculate a differential signal influenced by an inclination signal, and convert this into braking signals to manage the vehicle's speed effectively, utilizing PID control and wheel-specific brake signals to distribute braking forces optimally, incorporating anti-lock braking system (ABS) and electronic stability program (ESP) functions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional HDC systems determine brake pressure only from speed difference or gradient, then the control system is simple, but control oscillations and sudden brake influences occur on variable gradients
Solution Approach 1:
The system performs preliminary determination of the gradient signal before calculating brake pressure. By obtaining the gradient information in advance and using it to influence the actuating signal calculation, the system proactively compensates for gradient changes before they cause control oscillations or instability, thereby improving reliability without excessive complexity
Solution Approach 2:
The system uses feedback by continuously determining the actual speed signal and comparing it with the target speed to generate a differential signal. This feedback loop, enhanced by the gradient signal influence, allows the system to adjust brake pressure dynamically based on actual performance, reducing control oscillations and improving stability
2Speed
If service brake is applied for long descents, then vehicle speed can be controlled, but fuel consumption increases and engine wear increases due to part-load operation
Solution Approach 1:
The gradient signal acts as an intermediary that influences the actuating signal calculation. By incorporating gradient information into the control algorithm, the system can optimize brake application timing and intensity, enabling effective speed control while allowing the engine to operate more efficiently rather than in continuous part-load condition
Solution Approach 2:
The system changes the control parameters by incorporating the gradient signal into the actuating signal determination. This parameter modification allows the control system to adapt brake pressure based on actual gradient conditions, achieving effective speed control with reduced unnecessary brake application and improved fuel efficiency
3Speed
If service brake is used to reduce descent speed, then speed control is achieved, but control oscillations and uneven vehicle speed occur on variable gradients
Solution Approach 1:
The gradient signal is determined in advance and used to influence the actuating signal before brake application. This preliminary action allows the system to anticipate gradient changes and adjust brake pressure accordingly, preventing control oscillations and maintaining uniform vehicle speed on variable gradients
Solution Approach 2:
The system continuously monitors actual speed and compares it with target speed to generate a differential signal. This feedback mechanism, combined with gradient signal influence, enables real-time adjustment of brake pressure to maintain smooth and uniform speed control, eliminating oscillations caused by variable gradients
Data Source
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AI summary
Described are a method and a device for regulating the speed of a motor vehicle in particular when travelling on an incline. In a PID regulator which acts on the brake system of the motor vehicle, the change in the vehicle inclination is fed into the I-branch of the regulator, thereby providing adaptive speed regulation.