Motor Control Device for Electric Power Steering
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing electric power steering systems fail to perform appropriate automatic steering control when assist control is in accordance with manual steering, as the motor rotation angle includes both manual and automatic steering components, making it difficult to generate a proper following command.
Innovation Solution
A motor control device with a torque detector, steering angle detector, automatic steering controller, assist controller, integrated control amount calculator, and actual automatic steering angle calculator, which separates the automatic steering angle from the manual steering angle to enable seamless coexistence and transition between automatic and assist control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the motor rotation angle is used directly for automatic steering control, then the control system is simple, but the automatic steering control becomes inaccurate when manual steering is performed
Solution Approach 1:
The patent segments the motor rotation angle into two distinct components: an automatic steering angle component and a manual steering angle component. By separating these components, the system can accurately determine the automatic steering portion even when manual steering is being performed, thus resolving the contradiction between system simplicity and control accuracy.
Solution Approach 2:
The patent introduces an intermediary calculation process that uses the steering torque detector and assist control amount to estimate the manual steering angle, which then serves as a mediator to extract the pure automatic steering angle from the total motor rotation angle. This intermediary approach enables accurate automatic steering control without requiring a completely new control architecture.
2Device complexity
If the same control system is used for both automatic steering and assist control, then the system structure is simple, but the control performance deteriorates when both functions operate simultaneously
Solution Approach 1:
The patent implements a dynamic control architecture where the controller adaptively switches between assist control mode and automatic steering control mode based on real-time detection of steering torque and control state. This dynamic adaptation allows the system to maintain high reliability in both modes while avoiding the conflicts that arise when both functions operate simultaneously in a static system.
Solution Approach 2:
The patent creates a universal control system that can perform both assist control and automatic steering control through a unified control architecture. By using the same controller for both functions and implementing mode switching based on steering torque detection, the system achieves multi-functionality without sacrificing control performance or requiring completely separate control systems.
3Speed
If the following command is generated based on the motor rotation angle during manual steering, then the assist control responds quickly, but the automatic steering control becomes inappropriate
Solution Approach 1:
The patent performs preliminary separation of the automatic steering angle from the total motor rotation angle before generating the following command. By pre-calculating the manual steering angle component using steering torque and assist control amount, the system can extract the pure automatic steering portion in advance, ensuring both rapid response and high accuracy in the following command generation.
Data Source
Figure 1
Figure 2
Figure 3~4
AI summary
A motor controlling ECU 202 includes an automatic steering controller 42 that sets an automatic steering control amount, an assist controller 41 that sets an assist control amount, an integrated control amount calculating portion 43 that calculates an integrated control amount by adding the automatic steering control amount and the assist control amount, and an actual automatic steering angle calculating portion 46 that calculates, based on at least one of either of a steering torque and the assist control amount, an actual automatic steering angle that is a steering angle due to automatic steering control and included in an actual steering angle. The automatic steering controller 42 uses a target automatic steering angle and the actual automatic steering angle to set the automatic steering control amount.