Dual-Motor Steering Control Device Fail-Switching Logic
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Solution Overview
Problem
Existing steering control systems with multiple motors face challenges in ensuring fail-safe operation, as a malfunctioning motor renders the other motor unusable, limiting the utilization of dual motor advantages and compromising layout flexibility and operational reliability.
Innovation Solution
A steering control device with a clutch and two motors, where control modes switch based on motor and controller functionality, allowing one motor to take over if the other fails, ensuring continuous operation and maintaining steering-by-wire and electric power steering functions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If one motor is used for steering, then the motor size increases to obtain sufficient power, but the degree of freedom of layout is reduced
Solution Approach 1:
The steering system is divided into two independent motor units (first motor and second motor), each capable of providing steering power independently. This segmentation allows the use of smaller motors while maintaining sufficient total steering power, thereby improving layout flexibility without sacrificing power capability
2Device complexity
If two motors are used for turning wheels, then layout characteristics are improved, but fail-safe capability is compromised as the other motor becomes unusable when one malfunctions
Solution Approach 1:
The control system dynamically switches between two-motor turning control and one-motor turning control based on the operational status of the motors. When one motor malfunctions, the system automatically transitions to using the other motor for turning control, maintaining fail-safe capability while preserving the layout advantages of the two-motor configuration
Solution Approach 2:
Each motor unit is designed to be universally capable of performing both turning control and assist control functions. The first motor can perform turning control while the second performs assist control, and vice versa. This multi-functionality ensures that when one motor fails, the other can take over both functions, maintaining system reliability
3Reliability
If backup clutch is connected when motor malfunctions, then mechanical coupling is achieved, but the other non-malfunctioning motor becomes unusable
Solution Approach 1:
The clutch is dynamically controlled to connect or disconnect based on the operational status of the motors and the desired control mode. The system can operate with the clutch disconnected while using only one motor for both turning and assist control, allowing full utilization of the non-malfunctioning motor without requiring mechanical coupling through the clutch
Data Source
AI summary
To achieve a fail-safe fully utilizing the advantage of plural motors, a second controller performs a one-motor SBW mode when at least one of a first turning controller, a first turning motor and a torque sensor malfunctions in a state where the first turning controller and the second turning controller perform a two-motor SBW mode. Furthermore, the first controller performs a one-motor EPS mode when at least one of the second turning controller and the second turning motor malfunctions in the state where the first turning controller and the second turning controller perform a two-motor SBW mode.