Steering Control Torque Signal Correction for ADAS Interference
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Solution Overview
Problem
Electric power steering systems (EPS) face reduced follow-up accuracy when driver assistance systems interfere with the steering torque generated by the driver, due to the viscosity and inertia of the steering wheel, affecting the accuracy of steering angle control.
Innovation Solution
A steering control system that includes a first calculation circuit for the basic assist force, a second calculation circuit for compensation, a command value generation adder, and a torque signal correction circuit to isolate the driver's steering torque, reducing the influence of driver assistance on follow-up accuracy by adjusting the torque signal based on environmental information.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If driver assistance control is implemented based on environmental information, then advanced driver assistance is achieved, but follow-up accuracy of steering angle is reduced due to interference with driver's steering torque
Solution Approach 1:
The patent segments the assist force calculation into two independent components: a basic component based on driver's steering torque and a compensation component based on ADAS control. This segmentation allows each component to be calculated separately using different torque signals, preventing interference between driver assistance and follow-up control while maintaining both functionalities.
Solution Approach 2:
The patent introduces a torque signal correction circuit as an intermediary that processes the torque signal before it reaches the assist force calculation. This intermediary corrects the torque signal by removing the influence of ADAS-induced steering torque variations, allowing the basic component calculation to remain accurate despite the presence of driver assistance control.
2Measurement precision
If torque signal from torsion bar is used directly for assist force calculation, then driver's steering torque is detected, but torque signal contains interference from driver assistance causing calculation inaccuracy
Solution Approach 1:
The patent extracts and removes the harmful ADAS-induced torque component from the total torque signal before it is used for calculating the basic assist force component. The torque signal correction circuit specifically targets and eliminates the interference portion while preserving the genuine driver's steering torque information.
Solution Approach 2:
The patent converts the harmful effect of ADAS-induced torque variations into a beneficial correction mechanism. By identifying the specific torque variations caused by ADAS control and systematically correcting for them, the system transforms what would be interfering noise into an opportunity for more accurate driver intent detection.
Data Source
AI summary
A steering control system with which a steering angle accurately follows a steering angle command value is provided. An assist command value calculation circuit calculates a first assist component based on a value obtained by adding a basic assist controlled variable with a system stabilization controlled variable. The assist command value calculation circuit includes a pinion angle feedback control circuit that calculates a second assist component by executing angle feedback control based on a deviation between a pinion angle and a final pinion angle command value that is the sum of a pinion angle command value and an ADAS command angle. The assist command value calculation circuit outputs an assist command value based on the first assist component and the second assist component. The assist command value calculation circuit receives a steering torque obtained after the influence of viscosity and inertia is reduced by a steering torque compensation circuit.