Dual-Controller EPS Steering Torque Failover for Full Motor Output
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Solution Overview
Problem
Existing vehicle steering control systems using electric power steering (EPS) face challenges in achieving 100% motor output when there are abnormalities in the torque message, particularly at low vehicle speeds or when stopped, due to limitations in the master ECU's ability to control steering.
Innovation Solution
The system employs a dual-controller setup where the first controller and second controller exchange roles when an abnormality in the torque message is detected, allowing each to calculate and supply motor torque independently, ensuring 100% output by monitoring operating states and communicating through a communication interface.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the master ECU controls steering alone when torque message abnormality occurs, then the system can maintain basic steering function, but the motor output is limited to 50% and insufficient at low speeds or when stopped
Solution Approach 1:
The patent divides the control function into two separate ECUs (master ECU and slave ECU), each capable of independently calculating motor torque. When torque message abnormality occurs, the slave ECU takes over control, ensuring that the motor can output 100% power rather than being limited to 50%, thus resolving the contradiction between reliability and power output.
Solution Approach 2:
The system performs preliminary setup by equipping both master and slave ECUs with the capability to calculate motor torque independently. This preliminary action ensures that when abnormality occurs, the slave ECU can immediately take over without loss of power output, maintaining both reliability and full motor power capability.
2Reliability
If a dual-controller setup is implemented to enable 100% motor output, then the system can provide redundant safety mechanism, but the device complexity increases
Solution Approach 1:
Both master and slave ECUs are designed with universal functionality to independently calculate motor torque and control the motor. This multi-functionality allows either ECU to take over when the other fails, providing redundant safety mechanism while managing device complexity through functional equivalence rather than adding entirely separate systems.
Solution Approach 2:
The system changes the operational parameter from single-controller to dual-controller mode based on detected abnormalities. When torque message abnormality is detected, the control parameter switches from master ECU to slave ECU, enabling redundant safety mechanism while managing complexity through parameter-based switching rather than permanent complex architecture.
3Speed
If the slave ECU controls steering with 50% output at high speeds, then the system can operate safely, but the output is insufficient when vehicle speed is below certain speed or when stopped
Solution Approach 1:
The slave ECU is pre-configured with the capability to independently calculate motor torque, similar to the master ECU. This preliminary action ensures that when the slave ECU takes over due to torque message abnormality, it can provide 100% motor output regardless of vehicle speed, resolving the issue of insufficient power at low speeds or when stopped.
Data Source
AI summary
The present disclosure provides an apparatus for controlling the steering, including a first controller for controlling a torque sensor for detecting a steering torque, and a motor which calculates a motor torque based on the steering torque, and supplies at least a part of the motor torque; and a second controller for controlling the motor which receives a torque message corresponding to the remaining part of the motor torque from the first controller through a communication interface, and supplies the remaining part of the motor torque based on the torque message, wherein the second controller determines whether there is an abnormality in the torque message, and the first controller and the second controller exchange roles when there is an abnormality in the torque message.