Motor Driven Power Steering Friction Compensation via Torque Averaging
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Solution Overview
Problem
Conventional Motor Driven Power Steering (MDPS) systems experience decreased mechanical friction due to aging, leading to altered steering feelings for drivers, which are different from those experienced when the vehicle was new.
Innovation Solution
A device and method that include a sensing unit to monitor steering angle, angular speed, and vehicle speed, a storage unit to store steering torques, and a control unit to calculate and apply a friction-compensating torque by comparing average steering torques with reference values, ensuring consistent steering feelings by compensating for friction changes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional MDPS system operates over time, then mechanical friction decreases due to aging, but steering feelings become altered and different from when the vehicle was new
Solution Approach 1:
The system continuously monitors steering torque through a torque sensor and compares it with reference values stored in memory. Based on this feedback, the control unit calculates friction compensation values and adjusts the motor output torque to maintain consistent steering feelings throughout the vehicle's service life.
Solution Approach 2:
The system dynamically changes the motor output torque parameter by adding friction compensation values to the basic motor torque. This parameter adjustment compensates for the natural degradation of mechanical friction in the steering gear, maintaining steering characteristics consistent with when the vehicle was new.
2Reliability
If friction compensation is implemented through continuous monitoring and calculation, then steering feeling consistency is maintained, but device complexity increases
Solution Approach 1:
The system uses the vehicle's existing torque sensor and control unit to perform friction monitoring and compensation automatically. The control unit executes pre-programmed algorithms that compare current torque values with reference values and self-adjust the motor output without requiring external intervention or complex additional hardware.
Solution Approach 2:
The control unit performs multiple functions: it controls the motor output torque, monitors steering torque through the existing torque sensor, compares values with reference data, calculates friction compensation, and adjusts motor output. This multi-functionality reduces the need for separate dedicated components for friction compensation.
Data Source
AI summary
A device for compensating friction of a motor driven power steering system, comprising a sensing unit for sensing at least one of a steering angle, an angular speed and a vehicle speed, and a steering torque corresponding to the at least one of the steering angle, the angular speed and the vehicle speed; and a control unit for storing the steering torques sensed through the sensing unit in a storage unit when the at least one of the steering angle, the angular speed and the vehicle speed sensed through the sensing unit falls into the respective setting range. The control unit calculates an average value of the stored steering torques when the number of steering torques stored in the storage unit is equal to or higher than a reference number, and computes a friction-compensating torque based on a result obtained by comparing the average value with a reference value.