Steering Torque Compensation for Low-Temperature EPS Friction
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Electric power steering systems experience an undesired steering feeling or strangeness due to increased friction from viscosity changes in grease and mechanical contraction at low temperatures, leading to a larger steering force requirement.
Innovation Solution
A torque compensation apparatus and method that includes a temperature sensor, motor position sensor, and timer to calculate a compensation gain based on initial temperature, motor angles, and operation time, using lookup tables to adjust motor output torque and alleviate the heavy steering feeling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If the vehicle operates at low temperature, then the steering system experiences increased friction due to grease viscosity and mechanical contraction, but the motor output torque becomes insufficient to compensate for this increased friction
Solution Approach 1:
The patent applies parameter changes by dynamically adjusting the compensation gain based on temperature parameters, operation time, and motor angle. The controller modifies the motor output torque parameters in real-time to compensate for the harmful friction effects at low temperatures, transforming the fixed compensation approach into a dynamic parameter-adjustment system.
Solution Approach 2:
The patent implements feedback mechanisms by continuously monitoring temperature, operation time, and motor angle, then using this feedback information to calculate and adjust the compensation gain. This closed-loop feedback system enables the controller to adaptively respond to changing friction conditions and optimize the steering torque compensation.
2Force
If the compensation gain is increased to counteract friction, then the steering torque is improved, but the torque accuracy deteriorates due to excessive or improper compensation
Solution Approach 1:
The patent applies local quality by providing differentiated compensation strategies for different operating conditions. Instead of uniform compensation, the system adjusts the compensation gain locally based on specific combinations of temperature, operation time, and motor angle, ensuring accurate and appropriate torque compensation for each local operating state.
Solution Approach 2:
The patent implements dynamics by making the compensation gain dynamic rather than static. The compensation gain changes continuously based on real-time operating conditions (temperature, time, motor angle), allowing the system to adapt to varying friction characteristics and maintain torque accuracy across different operating states.
3Force
If temperature-based compensation is applied, then the steering torque is adjusted, but the compensation accuracy decreases due to sudden temperature changes and unexpected steering feelings
Solution Approach 1:
The patent applies preliminary action by pre-calculating and storing compensation gain values in lookup tables for different temperature and motor angle conditions. This pre-prepared compensation data allows the controller to quickly retrieve appropriate compensation values without sudden calculations, ensuring smooth and reliable torque adjustment even during rapid temperature changes.
Solution Approach 2:
The patent implements periodic action by using the timer to track operation time and periodically updating the compensation gain based on accumulated operating time. This periodic adjustment ensures that the compensation adapts gradually to temperature changes and mechanical warm-up, preventing sudden torque variations and improving compensation stability.
Data Source
AI summary
A torque compensation apparatus for an electric power steering system may include: a temperature sensor configured to sense the initial temperature around the electric power steering system when a vehicle is started; a motor position sensor configured to sense a motor angle of the electric power steering system; a timer configured to detect an operation time of the started vehicle; and a controller configured to calculate a compensation gain when the initial temperature corresponds to a preset low-temperature state, the compensation gain reflects the increasing ambient temperature, and is based on the motor angles accumulated during steering and the accumulative operation time detected through the timer after the start of the vehicle; and the controller outputs the compensation gain to compensate for a motor output torque of the electric power steering system.