Steering Pinion Angle Estimation for Sensor Fault Validation
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Solution Overview
Problem
Steering pinion angle sensors in steer-by-wire systems are prone to failure and degradation, necessitating a strategy to compensate for sensor failures or degradation to ensure accurate and safe vehicle control.
Innovation Solution
A vehicle system estimates the steering pinion angle using a control module that generates a model of the road wheel system based on road wheel actuator command and rack force, employs a state observer to estimate the angle, and validates the measured angle using a threshold, replacing it with the estimated angle if invalid to ensure accurate vehicle control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If pinion angle sensors are used in steer-by-wire systems, then steering angle measurement is enabled, but sensor failure and degradation occur reducing reliability
Solution Approach 1:
The patent introduces an intermediary estimation system that uses readily available sensor data (steering wheel angle sensor, road wheel angle sensor, vehicle speed sensor) to calculate and validate pinion angle measurements. This intermediary calculation layer acts as a mediator between the faulty pinion angle sensor and the steering control system, providing a backup measurement path that maintains reliability when the primary sensor fails or degrades.
Solution Approach 2:
The patent implements a feedback mechanism where the estimated pinion angle is continuously compared with the measured pinion angle from the sensor. The system uses this feedback to detect sensor failures or degradation by checking if the difference exceeds a predetermined threshold, and automatically switches to using the estimated value when the sensor is determined to be faulty, thereby maintaining reliable steering control.
2Reliability
If multiple sensors are deployed for redundancy, then reliability improves, but device complexity increases
Solution Approach 1:
Instead of deploying multiple physical pinion angle sensors, the patent creates a virtual copy of the measurement function by calculating the pinion angle through estimation using data from existing sensors. This copying approach replicates the measurement capability without adding physical sensor hardware, thus improving reliability through redundancy while avoiding the complexity of installing and managing multiple physical sensors.
Solution Approach 2:
The patent makes existing sensors serve multiple functions: the steering wheel angle sensor, road wheel angle sensor, and vehicle speed sensor are not only used for their primary functions but also combined to estimate the pinion angle. This multi-functionality approach allows the system to achieve sensor redundancy and fail-safe capability without adding dedicated backup sensors, thereby reducing overall system complexity.
Data Source
AI summary
A vehicle system includes a road wheel system having a road wheel actuator and at least one pinion angle sensor, and a control module. The control module is configured to receive a road wheel actuator command and a rack force, generate a model of the road wheel system based on the road wheel actuator command and the rack force, estimate, with a state observer, a steering pinion angle based on the generated model, the road wheel actuator command and the rack force, determine a validity of a steering pinion angle measured by the at least one pinion angle sensor based on the estimated steering pinion angle and a threshold, and in response to determining that the measured steering pinion angle is invalid, control a steering function of the vehicle based on the estimated steering pinion angle.