Turning Control With Steering-Angle Feedback for Assist Torque Stability
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Solution Overview
Problem
The variation in the ratio between the steering angle and the turning angle due to the universal joint causes an unintended change in assist torque, leading to a strange feeling for the driver.
Innovation Solution
A turning control device that includes a processor to execute processes for acquiring a turning-corresponding angle, estimating a rudder angle variable, setting a basic assist torque, calculating adjusting torque, and controlling the assist motor torque based on these variables, ensuring the torque is set appropriately relative to the steering angle.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If the assist motor applies torque closer to the turning wheel than to the universal joint, then the torque transmission efficiency is improved, but the adjusting torque unintentionally varies depending on the steering angle due to the universal joint's varying ratio
Solution Approach 1:
The control device acquires the actual steering angle through sensors and uses feedback control to calculate the adjusting torque. The processor continuously monitors the steering angle and adjusts the assist motor torque accordingly, ensuring that the adjusting torque accurately reflects the intended steering state rather than being distorted by universal joint variations.
Solution Approach 2:
The system dynamically changes the torque parameter based on the detected steering angle. By using the actual steering angle as a variable input, the adjusting torque is continuously adapted to match the current steering state, compensating for the non-linear effects introduced by the universal joint's varying transmission ratio.
2Device complexity
If the adjusting torque is set depending on the rotational angle of the transmitting shaft, then the control is simplified, but the adjusting torque varies unintentionally depending on the steering angle
Solution Approach 1:
Instead of using only the transmitting shaft angle, the system incorporates feedback from a sensor that directly measures the steering angle. The processor uses this feedback information to calculate the adjusting torque, ensuring accuracy while maintaining relatively simple control logic through direct measurement rather than complex multi-parameter calculations.
Solution Approach 2:
The sensor acts as an intermediary that directly measures the steering angle, providing accurate input data to the processor. This intermediary measurement device bridges the gap between the steering input and the assist motor control, eliminating the need for complex calculations based on transmitting shaft angle while ensuring torque consistency.
Data Source
AI summary
A turning control device includes a processor. The processor is configured to execute a turning-corresponding angle acquisition process, a rudder angle variable estimation process, a basic assist torque setting process, an adjusting torque calculation process, and a manipulation process. The basic assist torque setting process is a process of setting the value of a basic assist torque variable depending on a steering torque. The adjusting torque calculation process is a process of calculating the value of an adjusting torque variable. The manipulation process includes a process of manipulating a drive circuit of an assist motor, so as to control the torque of the assist motor to a torque depending on the sum of a torque indicated by the value of the basic assist torque variable and a torque indicated by the value of the adjusting torque variable.