Road Wheel Angle Estimation Using Kingpin Torque And Roll Steer
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Solution Overview
Problem
Conventional methods for estimating road wheel angles in vehicles often lead to significant discrepancies between estimated and actual angles during dynamic maneuvers due to the reliance on a simple kinematic ratio relationship between steering wheel angle and road wheel angle, failing to account for factors like compliance steer and roll steer.
Innovation Solution
The vehicle system utilizes multiple sensors to detect parameters such as steering rack load, wheel-to-body displacement, vertical and longitudinal acceleration, and tire torque to calculate kingpin torque and roll steer angle, applying filters and look-up tables to generate an accurate road wheel angle estimation by considering suspension and steering conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a simple kinematic ratio relationship between steering wheel angle and road wheel angle is used, then the device complexity is reduced, but the measurement precision of road wheel angle deteriorates during dynamic maneuvers
Solution Approach 1:
The system changes from using a single kinematic parameter (steering wheel angle) to multiple dynamic parameters including steering rack load, wheel-to-body displacement, vertical acceleration, longitudinal acceleration, and tire torque. These parameter changes enable accurate calculation of kingpin torque and roll steer angle, resolving the measurement precision issue while maintaining reasonable system complexity through sensor integration.
2Measurement precision
If multiple sensors and complex calculations are used to account for compliance steer and roll steer, then the measurement precision of road wheel angle is improved, but the device complexity increases
Solution Approach 1:
The control module serves multiple functions: it processes data from multiple sensors, calculates kingpin torque, determines roll steer angle, and generates the final road wheel angle estimation. This multi-functional approach consolidates complexity into a single processing unit rather than requiring separate dedicated systems for each function, making the increased complexity more manageable.
Solution Approach 2:
The patent introduces intermediate calculation parameters (kingpin torque, roll steer angle, compliance steer) that mediate between the raw sensor data and the final road wheel angle estimation. These intermediaries break down the complex estimation problem into manageable computational steps, allowing accurate results without requiring an overly complex direct measurement system.
3Ease of operation
If conventional kinematic estimation is used, then the ease of operation is maintained, but the reliability of vehicle control systems deteriorates
Solution Approach 1:
The system incorporates feedback by continuously monitoring multiple dynamic parameters (steering rack load, wheel-to-body displacement, accelerations, tire torque) and using this feedback to dynamically adjust the road wheel angle estimation. This feedback mechanism ensures reliable control during dynamic maneuvers while maintaining ease of operation through automated processing in the control module.
Data Source
AI summary
A vehicle system for determining a road wheel angle of a vehicle includes sensors configured to detect vehicle parameters including at least a steering rack load on a steering rack of the vehicle, and a control module in communication with the sensors. The control module is configured to calculate a kingpin torque based on the sensed steering rack load and a wheel-to-body displacement of the vehicle, determine a roll steer angle based on the wheel-to-body displacement of the vehicle, determine a road wheel angle of the vehicle based on the roll steer angle and the kingpin torque, and generate a signal indicative of the road wheel angle to control at least one vehicle control system. Other example vehicle systems and methods for determining a road wheel angle of a vehicle are also disclosed.