Steer-By-Wire Steering with Redundant Drive Force Switching
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Solution Overview
Problem
Steering devices with steer-by-wire systems face challenges in ensuring reliable wheel turning and continuous steering wheel operation without mechanical connection, often resulting in increased device size due to the need for multiple drive systems.
Innovation Solution
A steering device with three or more drive systems, each configured to output a driving force for electric motors, where the total maximum driving force exceeds the required force to turn the wheels, allowing for reliable operation even if one system fails, with a control unit managing the switching of driving forces to maintain functionality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If multiple drive systems are provided to ensure fail-safe operation, then reliability is improved, but device size increases
Solution Approach 1:
The patent applies dynamics by making the drive system configuration adaptable rather than fixed. The control unit dynamically switches between different drive systems based on operational status, allowing the system to maintain reliability with fewer physical components. The three or more drive systems share the load during normal operation, and the system dynamically reconfigures when a failure occurs, resolving the contradiction between reliability and device size.
Solution Approach 2:
Each drive system is designed to be universal and interchangeable, capable of performing the same steering function. Any of the three or more drive systems can take over when another fails, eliminating the need for dedicated backup systems. This multi-functionality allows the patent to achieve fail-safe operation with a more compact configuration compared to having separate primary and backup drive systems.
2Volume of moving object
If three or more drive systems are used with reduced individual capacity, then device size is reduced, but complexity of control increases
Solution Approach 1:
The control unit implements feedback by continuously monitoring the operational status of each drive system and automatically adjusting the distribution of driving forces. When a failure is detected, the system receives feedback and reconfigures the remaining drive systems to compensate. This automated feedback mechanism manages the complexity of controlling multiple drive systems, making the system more compact while maintaining ease of control.
3Reliability
If drive systems operate at reduced capacity during normal conditions, then reliability is improved through load distribution, but power utilization efficiency decreases
Solution Approach 1:
The system dynamically adjusts power utilization based on operational conditions. During normal operation, the driving forces are distributed among three or more drive systems at reduced individual capacity, improving reliability. When a failure occurs, the system dynamically shifts to using fewer drive systems at higher capacity to maintain required steering performance. This dynamic power management resolves the contradiction between reliability through load distribution and power utilization efficiency.
Data Source
AI summary
A steering device includes: a plurality of electric motors 10 configured to be driven to turn wheels of a vehicle; and three or more drive systems 20 each configured to output a driving force for driving a corresponding one of the electric motors 10 to the corresponding one of the electric motors 10. A total of maximum driving forces each of which is a maximum value of a driving force of each drive system 20 of the steering device is set larger than a required driving force required to turn the wheels with the vehicle stationary, and in an event of a failure occurring in one of the three or more drive systems 20, a total of the maximum driving forces of other properly working drive systems 20 out of the three or more drive systems 20 amounts to the required driving force.