Steering Controller Torque Compensation for Driver Feel
Solution Overview
Problem
The existing steering systems that combine electric power steering devices with toe angle changers for rear wheels can cause discomfort to drivers due to differences in responsive feeling compared to vehicles with only front wheel steering, and may not detect abnormal states of the toe angle changer effectively.
Innovation Solution
A steering system that includes an electric power steering device, toe angle changers for rear wheels, and a steering controller with an auxiliary torque calculating unit to compensate for self-aligning torques and detect anomalies, ensuring a consistent responsive feeling with vehicles having only front wheel steering, and adjusting the auxiliary torque to enhance the feeling when an abnormal state is detected.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If toe angle changers are added to control rear wheel operation based on steering wheel angle and vehicle speed, then vehicle maneuverability and stability are improved, but the responsive feeling from steering torque becomes different from conventional front-wheel-only steering vehicles, causing driver discomfort
Solution Approach 1:
The patent calculates and compensates for the difference in self-aligning torque between the all-wheel steering system and conventional front-wheel steering systems. By dynamically adjusting the auxiliary torque parameter based on the calculated torque difference, the system maintains a responsive feeling that is familiar to drivers while enabling rear wheel steering functionality.
2Reliability
If the toe angle changer is in an abnormal state (e.g., rear wheel toe angle locked) or if front wheel steering is assisted by electric power steering, then the steering system continues to operate, but the driver cannot detect the abnormal state through responsive feeling changes
Solution Approach 1:
The patent employs feedback by continuously monitoring the actual auxiliary torque and comparing it with the calculated target auxiliary torque. When an abnormal state is detected (such as toe angle changer failure or electric power steering activation), the system generates feedback signals that can trigger warnings or adjustments, enabling the driver to detect abnormal conditions through the steering system's response.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The system provides a responsive feeling similar to that of a vehicle with only front wheel steering, while also allowing easy detection of abnormal states, thereby improving driver comfort and vehicle stability.
Implementation Method 1
an electric motor configured to generate an auxiliary torque in accordance with at least a steering torque, and configured to transmit the auxiliary torque to the steering unit
Implementation Method 2
a difference between a first self-aligning torque generated at the front wheels and a second self-aligning torque generated at front wheels of a hypothetical vehicle having only a front wheel steering function is compensated
Data Source
AI summary
A steering controller for an electric power steering device 110 includes a base signal computing part 51 for computing a base signal DT in accordance with at least the steering torque; a damper compensation signal computing part 52 for computing a damper compensation signal in accordance with an angular velocity of an electric motor 4 or a speed of steering wheel turn; and an inertia compensation signal computing part 53 for compensating inertia and viscosity in the steering unit. The electric motor is driven by a target signal IM1 obtained by compensating the base signal with a damper compensation signal and an inertia compensation signal, to provide a steering auxiliary force. The target signal of the auxiliary torque is compensated so that a difference between a reference self-aligning torque of front wheel in a front wheel steering vehicle and a self-aligning torque of front wheel in an all-wheel steering vehicle is provided to a driver as a responsive feeling from the steering torque.