MDPS Mode Switching Control for Steering Stability
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Solution Overview
Problem
The transition from autonomous driving mode to manual driving mode in motor-driven power steering (MDPS) systems can cause a reduction in momentary control stability and result in abnormal vehicle behavior or steering vibrations due to differences in output between the two modes.
Innovation Solution
An apparatus and method that include a column torque sensor, vehicle velocity sensor, MDPS basic logic unit, autonomous driving control unit, and mode switching control unit to determine a final assist command current by reflecting the driver's steering intention, blending the assist command currents from both modes, and adjusting weights based on sensed column torque and vehicle velocity to ensure smooth mode switching.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Extent of automation
If the autonomous driving modules continuously perform position control of the MDPS system, then the autonomous driving function is maintained, but the driver's steering input cannot be properly recognized and control stability is degraded
Solution Approach 1:
The system dynamically adjusts the control mode based on real-time detection of driver steering input. When driver steering is detected during autonomous driving, the system transitions from autonomous position control to manual torque-based control, allowing the control strategy to adapt to changing operational conditions and maintain stability
Solution Approach 2:
The system continuously monitors steering torque and steering angle to detect driver input. This feedback mechanism allows the system to recognize when a driver intends to take control, enabling a timely transition from autonomous to manual control mode and preventing control instability
2Ease of operation
If the MDPS system switches from autonomous driving mode to manual driving mode, then the driver can directly control the vehicle, but momentary control stability is reduced and steering vibrations occur
Solution Approach 1:
The system detects driver steering input in advance during autonomous driving mode and prepares for mode transition. By recognizing the driver's intention before the actual mode switch, the system can smoothly transition control modes and avoid sudden changes that would cause steering vibrations
Solution Approach 2:
The control system dynamically adjusts between autonomous and manual control modes based on detected driver input. The transition is managed smoothly by detecting steering torque and angle changes, ensuring continuous and stable control without abrupt switches that would cause vibrations
3Measurement precision
If the motor control current is significantly changed to recognize driver steering, then the driver's steering intention is detected, but the driver feels a sense of steering difference
Solution Approach 1:
The system changes control parameters (from position control to torque control) based on the detected operational mode. During autonomous driving, position control parameters are used, while during manual driving, torque control parameters are applied, optimizing both detection accuracy and steering feel for each mode
Data Source
AI summary
An apparatus for controlling an MDPS system may include: a column torque sensor configured to sense column torque applied to a steering column of a vehicle; a vehicle velocity sensor configured to sense vehicle velocity of the vehicle; an MDPS basic logic unit configured to decide a first assist command current for driving an MDPS motor in a manual driving mode of a driver; an autonomous driving control unit configured to decide a second assist command current for driving the MDPS motor in an autonomous driving mode of the vehicle; and a mode switching control unit configured to decide a weight into which the driver's steering intention is reflected, and apply the decided weight to the first and second assist command currents to decide a final assist command current for driving the MDPS motor when the vehicle is switched from the autonomous driving mode to the manual driving mode.