Electric Power Steering Controller Position Feedback Torque
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Solution Overview
Problem
Conventional electric power steering systems fail to provide a consistent steering feeling across varying vehicle conditions such as loading capacity and tire specifications, leading to an unpredictable steering experience for drivers.
Innovation Solution
An electric power steering apparatus with a controller that acquires the steering wheel position, sets a target steering reaction torque, and performs feedback control of the motor to maintain a consistent steering assist mechanism position, ensuring a constant steering feeling by adjusting the steering reaction torque based on vehicle and environmental conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If torque control is performed based on steering torque input by a driver, then the steering assist mechanism can provide basic steering assistance, but the steering feeling becomes inconsistent across different vehicle conditions such as loading capacity and tire specifications
Solution Approach 1:
The control method changes from pure torque control to position control with torque feedback. The controller determines a position command value based on the steering operation amount and steering torque, then controls the motor to output torque corresponding to the steering reaction force based on the position command value. This parameter transformation enables consistent steering feeling across different vehicle conditions.
Solution Approach 2:
The system implements feedback control by using the steering reaction torque sensor to detect the steering reaction torque and feed it back to the controller. The controller then adjusts the motor output torque based on this feedback to maintain the steering reaction torque within the target range, ensuring consistent steering feeling regardless of vehicle conditions.
2Reliability
If the steering assist mechanism adapts to different vehicle conditions, then the steering feeling can be optimized for each condition, but the system complexity increases
Solution Approach 1:
The position command value serves as an intermediary that bridges the steering operation amount and the motor output torque. The controller determines the position command value based on the steering operation amount and steering torque, then uses this intermediate parameter to control the motor, simplifying the control logic while achieving consistent steering feeling across different vehicle conditions.
Solution Approach 2:
The feedback mechanism using the steering reaction torque sensor allows the system to automatically adapt to different vehicle conditions without increasing structural complexity. The controller adjusts the motor output based on the detected steering reaction torque, enabling the system to maintain consistent steering feeling across various vehicle configurations using the same hardware setup.
3Speed
If torque control is used in the steering assist mechanism, then the motor can respond to driver input, but the driver cannot obtain a constant steering feeling when vehicle conditions change
Solution Approach 1:
The system transforms the control parameter from direct torque control to position control with torque feedback. The controller determines a position command value that responds quickly to steering operation changes, then controls the motor to output torque based on this position command, achieving both fast response and consistent steering feeling.
Solution Approach 2:
The steering reaction torque feedback enables the system to maintain consistent steering feeling while responding quickly to driver input. The controller continuously adjusts the motor output torque based on the detected steering reaction torque, ensuring that the steering feeling remains constant even as vehicle conditions change, while still providing rapid response to steering operations.
Data Source
AI summary
The electric power steering apparatus according to the present disclosure includes a steering assist mechanism and a controller. The steering assist mechanism is driven by a motor and assists operation of a steering wheel by a driver. The controller acquires the position of the steering wheel and sets a target value of a steering reaction torque acting on the steering wheel. Then, the controller calculates a position target of the steering assist mechanism based on the position of the steering wheel and the target value of the steering reaction torque, and controls the motor of the steering assist mechanism according to the position target of the steering assist mechanism.