Motor-Driven Power Steering Mode Change Controller
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Solution Overview
Problem
Conventional motor-driven power steering (MDPS) systems face limitations in rapidly switching from autonomous driving mode to manual driving mode due to unconditional time requirements and reduced control stability, leading to potential accidents and abnormal vehicle behavior.
Innovation Solution
An apparatus and method that include an MDPS-basic logic unit, an autonomous driving steering controller, and a mode change controller, which determine a driver's steering intervention using a variable reference time based on column torque, allowing for rapid mode changes and optimizing auxiliary command currents to ensure smooth transitions between driving modes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If a given time is unconditionally maintained for determining driver steering intervention, then the autonomous driving mode can be released, but rapid mode change is impossible and control stability is reduced
Solution Approach 1:
The patent applies dynamics by making the reference time variable rather than fixed. The mode change controller adjusts the reference time based on the magnitude of column torque detected during autonomous driving. When column torque exceeds a threshold, the reference time is reduced, enabling faster mode changes. This dynamic adjustment resolves the contradiction by allowing rapid mode transition when necessary while maintaining stability during normal operation.
Solution Approach 2:
The patent changes the parameter of reference time from a constant value to a variable value that depends on column torque magnitude. When the driver applies significant torque indicating urgent intervention, the reference time parameter is reduced, enabling rapid mode switching. This parameter change allows the system to adapt between fast response and stable operation based on driving conditions.
2Loss of time
If the mode change time is reduced for rapid response, then sudden steering can be responded quickly, but control stability and steering smoothness deteriorate
Solution Approach 1:
The patent uses dynamic adjustment of mode change time based on real-time column torque detection. Rather than using a fixed short time that causes vibrations, the system calculates an appropriate mode change time based on the magnitude of driver input torque. This dynamic approach allows rapid response to urgent steering needs while preventing excessively fast transitions that would cause steering vibrations and abnormal vehicle behavior.
Solution Approach 2:
The patent applies preliminary anti-action by detecting column torque in advance and using it to predict the need for rapid mode change. The mode change controller monitors torque magnitude and prepares for mode transition by adjusting the reference time before the actual mode change occurs. This preliminary detection and preparation prevents the harmful effects of sudden, unprepared mode switches while enabling rapid response when truly needed.
3Productivity
If a fixed reference time is used for mode change, then the control logic is simple, but rapid response to sudden steering is impossible
Solution Approach 1:
The patent changes the reference time parameter from fixed to variable based on column torque magnitude. The mode change controller detects the torque applied to the steering column and adjusts the reference time accordingly. When torque exceeds a threshold, the reference time is reduced for faster response. This parameter change approach maintains relatively simple control logic while dramatically improving response efficiency to sudden steering inputs.
Data Source
AI summary
An apparatus for controlling an MDPS system may include an MDPS-basic logic unit determining a first auxiliary command current for driving an MDPS motor in a manual driving mode, based on column torque applied to a steering column of a vehicle and a vehicle speed, an autonomous driving steering controller determining a second auxiliary command current for driving the MDPS motor in an autonomous driving mode, and a mode change controller determining a driver's steering intervention using a variable reference time variably determined based on the column torque in the manual driving mode, determining a mode change time from the autonomous driving mode to the manual driving mode based on the column torque, and determining a final auxiliary command current for driving the MDPS motor upon mode change, by applying, to the first and second auxiliary command currents, a weight into which the mode change time is incorporated.