EPS Torque Compensation for Steering Angle Deviation
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Solution Overview
Problem
In autonomous vehicles, the actual steering angle often deviates from the expected angle due to various vehicle conditions, leading to inefficiencies in steering control, particularly at different speeds and under varying environmental conditions.
Innovation Solution
A planning circuit onboard the vehicle determines a compensatory torque signal to adjust the actual steering angle, using a feedforward approach to proactively modify the base torque signal applied to the EPS system, ensuring the steering wheel aligns with the expected angle by anticipating and compensating for deviations in real-time.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a base torque signal is applied to the EPS system without compensation, then the steering control is simple, but the actual steering angle deviates from the expected angle under varying vehicle conditions
Solution Approach 1:
The system performs preliminary action by calculating and applying compensatory torque before the steering operation. The planning circuit determines the compensatory torque signal based on expected vehicle conditions and steering maneuvers, then applies this compensation in advance through the control circuit to the EPS system, preventing steering angle deviation before it occurs rather than correcting it afterward
Solution Approach 2:
The system implements feedback by continuously monitoring actual steering angle and vehicle conditions, then using this information to adjust the compensatory torque signal. The control circuit receives feedback from sensors about actual steering performance and modifies the base torque signal accordingly to maintain alignment between expected and actual steering angles under varying conditions
2Reliability
If compensatory torque signal is calculated and applied, then the steering angle precision is improved, but the control system complexity increases
Solution Approach 1:
The control circuit is designed with multi-functionality to handle both base torque signal processing and compensatory torque calculation within a single integrated system. The planning circuit serves multiple functions by determining both the desired steering angle and the necessary compensatory torque based on the same sensor inputs and vehicle condition data, reducing overall system complexity despite the enhanced control capabilities
Solution Approach 2:
The system merges the base torque control and compensatory torque adjustment into a unified control signal that is applied to the EPS system. The planning circuit combines multiple control objectives (steering angle tracking, torque compensation, condition-based adjustment) into a single integrated torque signal, simplifying the control architecture while maintaining high reliability
3Measurement precision
If the base torque signal is modified with compensatory torque, then the steering accuracy under dynamic conditions is enhanced, but the energy consumption increases
Solution Approach 1:
The system applies partial compensation by calculating compensatory torque only when and where needed based on actual vehicle conditions and steering maneuvers. Rather than continuously applying maximum compensation, the planning circuit determines the minimal necessary compensatory torque signal to achieve acceptable steering accuracy under current conditions, reducing unnecessary energy consumption while maintaining precision when required
Data Source
AI summary
Among other things, we describe techniques for electric power steering torque compensation. Techniques are provided for a method implemented by a computer, e.g., a computer onboard an autonomous vehicle. A planning circuit onboard the vehicle and connected to an EPS of the vehicle determines a compensatory torque signal to modify an actual steering angle of a steering wheel of the vehicle to match an expected steering angle of the steering wheel. The planning circuit transmits the compensatory torque signal to a control circuit that controls the steering angle of the steering wheel. The EPS modifies the actual steering angle based on the compensatory torque signal resulting in a modified steering angle. The control circuit operates the vehicle based on the modified steering angle.