Steering Control System with Offset Torque Compensation
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Solution Overview
Problem
Conventional steering systems for autonomous vehicles using a redundant steering actuator at one wheel face challenges in achieving independence between redundant parts, leading to suboptimal steering performance and increased risk of counteractive failures.
Innovation Solution
A method and system where both steerable wheels are mechanically connected, with each wheel having a separate steering actuator, determining and applying steering torques based on the difference between the requested and current steering angles, including an offset steering angle to account for mechanical offset and play, ensuring improved redundancy and path-following capability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a redundant steering actuator is used at one wheel, then redundancy is achieved, but independency of the redundant parts is difficult to achieve
Solution Approach 1:
The steering system is segmented by providing separate steering actuators at each steerable wheel rather than using a single redundant actuator. This segmentation allows each wheel to be controlled independently, achieving both redundancy and independency simultaneously.
Solution Approach 2:
Each steerable wheel is equipped with its own steering actuator, providing local control capability. This local quality approach ensures that each wheel can be controlled independently while maintaining overall system redundancy.
2Device complexity
If a redundant steering actuator at one wheel is used, then system simplicity is maintained, but steering operation may not follow the desired steering path
Solution Approach 1:
By segmenting the steering control into separate actuators for each wheel, the system achieves precise control over individual wheel angles. This enables accurate following of desired steering paths while maintaining reasonable system complexity through modular design.
Solution Approach 2:
The control system incorporates feedback mechanisms that monitor the actual steering angles of both wheels and adjust the steering torques accordingly. This feedback ensures that the vehicle follows the desired steering path accurately by compensating for deviations in real-time.
3Reliability
If separate steering actuators are used at each steerable wheel, then independency and redundancy are improved, but mechanical offset and play between wheels must be compensated
Solution Approach 1:
The control system continuously monitors the steering angles of both wheels and calculates the offset between them. This feedback mechanism detects and measures the mechanical offset and play, then compensates for these deviations by adjusting the steering torques applied to each wheel.
Solution Approach 2:
The control system dynamically adjusts the steering torque parameters based on the detected offset between wheels. By changing the torque parameters in real-time, the system compensates for mechanical offset and play, ensuring accurate steering performance despite physical imperfections in the mechanical connection.
Data Source
AI summary
A method of controlling a steering operation of a vehicle comprising a first steerable wheel and a second steerable wheel mechanically connected to each other. Is provided. The method includes determining a steering angle for operating the vehicle during a turning maneuver, determining, during the turning maneuver, a first current steering angle indicative of a current steering angle of the first steerable wheel, and a second current steering angle indicative of a current steering angle of the second steerable wheel, determining an offset steering angle, the offset steering angle being a difference between the first current steering angle and the second current steering angle, applying a first steering torque on the first steerable wheel, the first steering torque being based on a difference between the requested steering angle and the first current steering angle, and applying a second steering torque on the second steerable wheel, the second steering torque being based on the offset steering angle and a difference between the requested steering angle and the second current steering angle.