Steered Wheel Angle Control Under Steering Actuator Limits
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Solution Overview
Problem
Heavy-duty vehicles face challenges in achieving cost-effective, reliable, and robust steering functions, particularly at zero or low speeds, due to the risk of exceeding steering actuator capacity thresholds, which can lead to power peaks and instability in electric power systems.
Innovation Solution
A computer system that determines the vehicle's speed and load values to assess whether the steering actuator can achieve a target steering angle displacement without exceeding its capacity threshold, and modifies relevant conditions such as reducing vertical load or displacement rate to prevent capacity threshold exceedance, thereby ensuring stable operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the steering actuator operates at high capacity to achieve target steering angle displacement at zero or low speeds, then the steering function is effective, but power peaks occur and electric power system instability arises
Solution Approach 1:
The patent applies dynamics by making the steering angle displacement rate adaptive rather than fixed. The control system dynamically adjusts the maximum allowable steering angle displacement rate based on real-time vehicle speed conditions. At zero or low speeds, the system permits higher displacement rates to maintain steering effectiveness, while at higher speeds, it reduces the displacement rate to prevent capacity threshold exceedance. This dynamic adaptation resolves the contradiction between maintaining reliable steering function and avoiding power peaks that cause electric power system instability.
Solution Approach 2:
The patent implements parameter changes by modifying the steering angle displacement rate parameter according to vehicle speed conditions. The system determines a maximum allowable steering angle displacement rate as a function of vehicle speed, thereby changing the operational parameters of the steering actuator. This parameter adjustment ensures that the steering actuator operates within its capacity threshold across different driving conditions, preventing power peaks while maintaining steering effectiveness when needed.
2Object-affected harmful factors
If the steering actuator capacity threshold is reduced to avoid power peaks, then electric power system stability is maintained, but steering effectiveness at zero or low speeds deteriorates
Solution Approach 1:
The system dynamically adjusts the maximum steering angle displacement rate based on vehicle speed, allowing the steering actuator to operate at higher capacity when the vehicle is stationary or moving slowly, while maintaining electric power system stability at higher speeds. This dynamic approach ensures steering effectiveness is preserved when most needed (at low speeds) without causing power peaks that would destabilize the electric power system.
Solution Approach 2:
The control system changes the operational parameter (maximum steering angle displacement rate) based on vehicle speed conditions. By determining this parameter as a function of vehicle speed, the system allows higher displacement rates at zero or low speeds to maintain steering effectiveness, while reducing the rate at higher speeds to prevent capacity threshold exceedance and maintain electric power system stability.
3Reliability
If a robust steering system with high capacity actuator is used, then steering function is reliable across all conditions, but cost and system complexity increase
Solution Approach 1:
The steering control system performs self-service by automatically determining the maximum allowable steering angle displacement rate based on real-time vehicle speed measurements. The system monitors its own operating conditions and autonomously adjusts the steering actuator parameters without external intervention. This self-regulating capability maintains reliable steering function across all driving conditions while avoiding the need for more complex hardware solutions such as multiple actuators or sophisticated mechanical systems.
Solution Approach 2:
The system achieves reliable steering function across all conditions by dynamically changing the steering angle displacement rate parameter based on vehicle speed. This software-based parameter adjustment provides a cost-effective and complexity-minimizing solution compared to hardware upgrades, while still ensuring the steering actuator operates within its capacity threshold and maintains effectiveness in all operating conditions.
Data Source
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AI summary
A computer-implemented method for changing a steering angle (α) of a steered wheel (10, 12) of a vehicle (1), the steered wheel (10, 12) being connected to a steering actuator (20) adapted to change the steering angle (α) of the steered wheel (10, 12), the steering actuator (20) having a steering actuator capacity threshold, the method comprising: - modifying (S6), by the processor device (602), a condition of the vehicle (1) relevant for the target steering angle displacement (α). The disclosure further relates to a computer system (600), a vehicle (1), a computer program, a control system and a non-transitory computer readable storage medium.