Turning Control Circuit for Smooth Steering Angle Updates
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Solution Overview
Problem
Existing turning control devices in vehicles face issues with setting the target steering angle accurately due to cancellation of significant digits in numerical calculations, leading to vibration and noise when the difference between target steering angles is small, causing the target value to remain unchanged until the next update.
Innovation Solution
A turning control device that includes a target steering angle acquisition circuit, a differential value calculation circuit, and a short-term target steering angle calculation circuit to distribute the difference in steering angles across multiple control cycles, using a coefficient to adjust the target value for each cycle, ensuring smooth angle changes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If the turning control device distributes the difference between target steering angles across multiple control cycles to prevent vibration and noise, then the steering angle changes smoothly, but cancellation of significant digits occurs in numerical calculations when the difference is small, causing the target value to remain unchanged
Solution Approach 1:
The patent changes the calculation parameter from directly distributing the raw difference value to distributing a scaled difference value. By multiplying the difference between target steering angles by a scaling factor (e.g., 10 or 100) before distribution across control cycles, the patent ensures that the distributed increments remain above the LSB threshold even when the original difference is small, thus preventing significant digit cancellation and enabling smooth steering angle changes.
2Speed
If the control cycle is shortened to improve responsiveness, then the control becomes more responsive, but the target value of steering angle fails to update properly due to numerical precision limitations
Solution Approach 1:
The patent introduces a scaling parameter to the control system that allows short control cycles to operate effectively. By scaling the steering angle difference before distribution, the system can use very short control cycles (high update frequency) without suffering from numerical precision loss, as the scaled values ensure that each control cycle's increment is sufficiently large to be represented accurately in fixed-point or integer arithmetic.
3Productivity
If the turning control device uses fixed-point arithmetic with predetermined bits to store target steering angle, then the calculation is efficient, but the target value remains unchanged when the distributed increment is smaller than the least significant bit
Solution Approach 1:
The patent applies a scaling factor to the steering angle difference calculation to compensate for the limited resolution of fixed-point arithmetic. By multiplying the difference by a scaling factor (such as 10, 100, or 2^k) before distributing it across multiple control cycles, the patent ensures that the incremental updates remain above the LSB threshold of the fixed-point representation, enabling efficient fixed-point arithmetic to maintain adequate precision for smooth steering control.
Data Source
AI summary
A turning control device includes: a target steering angle acquisition circuit; a differential value calculation circuit; a short-term target steering angle calculation circuit that calculates, by distributing a differential value, a short-term target steering angle that is a target value of the steering angle for each control cycle shorter than an acquisition cycle; and a motor control circuit. The short-term target steering angle calculation circuit calculates the short-term target steering angle based on a multiplied value obtained by multiplying the differential value by a coefficient according to the number of times of the control cycle since the target steering angle acquisition circuit has newly acquired a target steering angle, and on the target value of the steering angle before the acquisition.