Functional Safety of an Embedded Automotive System Measured by Fault Tree Birnbaum Importance – Applied for a Steering Angle Sensor with Intrinsic Redundancy

Abstract This paper investigates on sensor fault reconstruction of sensors used for steering control of autonomous vehicle for functional safety. Sensor information such as steering angle and longitudinal velocity is generally needed for the design of steering feedback control system. If there exists unexpected fault signals in sensors, fatal accident can occur during autonomous driving because controller cannot compute the accurate control input. In this study, the sliding mode observer has been designed for fault reconstruction of steering angle and velocity sensors. In order to design the observer, the bicycle model that represents dynamic relationship between steering angle and velocities such as lateral velocity and yaw rate of vehicle has been used. The stability analysis has been conducted in accordance with velocity of the vehicle. The fault signals in sensors have been reconstructed using the injection term in sliding mode observer with the sliding mode gains designed for the stability. The performance evaluation has been conducted in Matlab/Simulink environment under the curved path tracking scenario.

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Fault-Tolerant Control for Intelligent Electrified Vehicles Against Front Wheel Steering Angle Sensor Faults During Trajectory Tracking

IEEE Access ◽

10.1109/access.2021.3075325 ◽

2021 ◽

Vol 9 ◽

pp. 65174-65186

Author(s):

Lei Zhang ◽

Zihao Wang ◽

Xiaolin Ding ◽

Shaohua Li ◽

Zhenpo Wang

Keyword(s):

Trajectory Tracking ◽

Fault Tolerant ◽

Fault Tolerant Control ◽

Front Wheel ◽

Sensor Faults ◽

Steering Angle ◽

Angle Sensor ◽

Electrified Vehicles

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Development of the Noncontact Steering Angle Sensor using a Giant Magnetoresistive Element

10.4271/2007-01-0395 ◽

2007 ◽

Cited By ~ 1

Author(s):

Ichiro Tokunaga ◽

Hirofumi Okumura ◽

Yuichi Shonai ◽

Toshio Ogawa

Keyword(s):

Steering Angle ◽

Angle Sensor

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Effect of Inner and Outer Wheels Driving Force Control on Small Electric Vehicle

International Journal of Automotive and Mechanical Engineering ◽

10.15282/ijame.17.4.2020.02.0622 ◽

2020 ◽

Vol 17 (4) ◽

pp. 8246-8254

Author(s):

K. Shibazaki ◽

H. Nozaki

Keyword(s):

Control System ◽

Angular Velocity ◽

Electric Vehicle ◽

Force Constant ◽

Force Control ◽

Driving Force ◽

Vehicle Control ◽

Steering Angle ◽

Force Control System ◽

The Difference

In this study, in order to improve steering stability during turning, we devised an inner and outer wheel driving force control system that is based on the steering angle and steering angular velocity, and verified its effectiveness via running tests. In the driving force control system based on steering angle, the inner wheel driving force is weakened in proportion to the steering angle during a turn, and the difference in driving force is applied to the inner and outer wheels by strengthening the outer wheel driving force. In the driving force control (based on steering angular velocity), the value obtained by multiplying the driving force constant and the steering angular velocity, that differentiates the driver steering input during turning output as the driving force of the inner and outer wheels. By controlling the driving force of the inner and outer wheels, it reduces the maximum steering angle by 40 deg and it became possible to improve the cornering marginal performance and improve the steering stability at the J-turn. In the pylon slalom it reduces the maximum steering angle by 45 deg and it became possible to improve the responsiveness of the vehicle. Control by steering angle is effective during steady turning, while control by steering angular velocity is effective during sharp turning. The inner and outer wheel driving force control are expected to further improve steering stability.

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