Steered Wheel Angle Control Under Steering Actuator Power 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, load, and target steering angle displacement, and modifies conditions such as vertical load or displacement rate to prevent exceeding the steering actuator capacity threshold, thereby reducing the risk of power peaks and ensuring stable steering operations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the steering actuator operates at high force to achieve target steering angle displacement at zero or low speeds, then the steering function is maintained, but power peaks occur that may cause shut-down or instability of the electric power system
Solution Approach 1:
The system dynamically adjusts the steering angle displacement rate based on vehicle speed. At low speeds, the displacement rate is reduced to prevent excessive power demands, while at higher speeds, normal displacement rates are permitted. This dynamic adaptation allows the steering system to maintain reliability across different operating conditions without causing power peaks that could destabilize the electric power system.
Solution Approach 2:
The control system modifies the steering angle displacement rate parameter as a function of vehicle speed. When the vehicle is stationary or moving at low speed, the system imposes a reduced displacement rate limit on the steering actuator. This parameter change prevents the actuator from demanding excessive power, thereby avoiding power peaks while still providing functional steering control through adjusted motion characteristics.
2Ease of operation
If the steering actuator capacity threshold is increased to handle demanding steering situations, then steering performance at low speeds improves, but the risk of power peaks and electric power system instability increases
Solution Approach 1:
Rather than increasing the steering actuator capacity threshold, the system dynamically adapts the steering angle displacement rate to match vehicle speed conditions. This dynamic approach maintains ease of operation at low speeds by providing sufficient steering control through adjusted displacement rates, while simultaneously preventing power peaks by avoiding demands that would exceed the actuator's safe operating capacity.
Solution Approach 2:
The system continuously monitors vehicle speed and uses this feedback to adjust the steering angle displacement rate in real-time. This feedback mechanism ensures that the steering actuator operates within safe power limits by reducing displacement rate demands when vehicle speed indicates low-power availability, thereby preventing power peaks while maintaining adequate steering performance across all operating conditions.
3Speed
If the target steering angle displacement rate is maintained at high levels during low-speed operation, then steering responsiveness is improved, but the steering actuator capacity threshold is exceeded
Solution Approach 1:
The system implements dynamic adjustment of the steering angle displacement rate based on real-time vehicle speed measurements. During low-speed operation, the displacement rate is automatically reduced to levels that the steering actuator can safely deliver without exceeding its capacity threshold. This dynamic adaptation maintains steering functionality and reliability by matching actuator demands to available power capacity, preventing operation failures while still providing responsive steering control appropriate to the operating conditions.
Data Source
AI summary
A computer-implemented method for changing a steering angle of a steered wheel of a vehicle, the steered wheel being connected to a steering actuator adapted to change the steering angle of the steered wheel, the steering actuator having a steering actuator capacity threshold, the method comprising:modifying, by the processor device, a condition of the vehicle relevant for the target steering angle displacement. The disclosure further relates to a computer system, a vehicle, a computer program, a control system and a non-transitory computer readable storage medium.