Steer-by-Wire Angular Rate Sensor Offset for Tire Force Compensation
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Solution Overview
Problem
Steer-by-wire systems in vehicles face challenges with non-instantaneous tire force buildup, leading to degraded handling and agility, as the driver's steering request is not executed with precise wheel response under certain operating conditions.
Innovation Solution
The implementation of an angular rate sensor in conjunction with an angle sensor to generate an angular offset output, which is fed into the control loop to modify the control signal, ensuring that both the degree and rate of steering wheel rotation are accounted for, thereby enhancing the precision of wheel response and vehicle handling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional SBW systems use only angle sensor without angular rate sensor, then device complexity is reduced, but vehicle handling and agility are degraded due to non-instantaneous tire force buildup
Solution Approach 1:
The angular rate sensor detects the rate of steering wheel rotation and generates a control signal offset in advance. This offset is added to the control signal from the angle sensor, creating a feedforward compensation that anticipates the tire force buildup delay. The preliminary action of detecting angular rate and pre-calculating the offset compensates for the inherent delay in tire force response, improving handling and agility without requiring complex mechanical modifications.
2Measurement precision
If SBW systems apply offset compensation based on angular rate, then wheel response precision is improved, but control signal processing complexity increases
Solution Approach 1:
The system implements a feedback mechanism where the angular rate sensor continuously monitors the steering wheel rotation rate and feeds this information back to the control system. The control system processes this feedback by generating a control signal offset that is added to the original control signal. This feedback loop ensures that the wheel response precision is improved by continuously adjusting for tire force buildup delays based on real-time angular rate measurements.
Solution Approach 2:
The system changes the parameter of the control signal by adding a time-dependent offset component based on angular rate. The offset is calculated as a function of the angular rate and is added to the steady-state control signal from the angle sensor. This parameter change transforms the control signal from a static angle-based command to a dynamic signal that incorporates rate information, improving wheel response precision without requiring fundamental changes to the control architecture.
Data Source
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AI summary
A steer-by-wire system (100) and method for a vehicle, including and utilizing: a steering wheel system (12) including a steering wheel, an angle sensor or mechanism (14) coupled or applied to the steering wheel and for determining an angular magnitude of the steering wheel and providing a corresponding control signal, and an angular rate sensor or mechanism (26) coupled or applied to the steering wheel and for determining an angular rate of the steering wheel and providing a corresponding control signal offset; and a steering actuator system (22) including a wheel angle actuator (24) coupled to one or more wheels (50) of the vehicle and for receiving the collective control signal and control signal offset and turning the wheels (50) in response. The steering wheel system (12) further includes an angular rate filter/tuner (30) for receiving an angular rate input (32) from the angular rate sensor or mechanism (26) and deriving an angular offset output (34) corresponding to the control signal offset.