Steering Angle Control Smoothing Without Precision Loss
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Solution Overview
Problem
Existing turning control systems face issues with setting appropriate target steering angles due to cancellation of significant digits in numerical calculations, leading to vibrations and noise when control cycles become shorter, especially in advanced driver assistance systems (ADAS) with sophisticated information processing.
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, which calculates and distributes the differential value across control cycles using a coefficient to ensure smooth steering angle changes, preventing significant digit cancellation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If the turning control device distributes the difference between target steering angles among multiple control cycles to prevent vibration and noise, then the steering angle changes smoothly, but cancellation of significant digits occurs in the calculation when the difference is small, causing the target value to fail to be appropriately set
Solution Approach 1:
The patent changes the calculation parameter from directly distributing the raw differential value to distributing a scaled differential value (differential value multiplied by the number of control cycles). This parameter transformation prevents significant digit cancellation by maintaining adequate numerical magnitude throughout the calculation, thereby resolving the contradiction between smooth steering angle changes and calculation precision.
2Device complexity
If the turning control device uses a predetermined number of bits for storing the target value of the steering angle, then the device complexity is reduced, but cancellation of significant digits occurs when dividing small differential values, leading to loss of precision
Solution Approach 1:
The patent performs preliminary scaling of the differential value by multiplying it with the number of control cycles before distribution. This preliminary action ensures that the numerical value maintains sufficient precision throughout the subsequent distribution process, preventing significant digit cancellation and information loss while maintaining the simple fixed-bit storage structure.
Data Source
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AI summary
A turning control device (5; 5A; 92) includes: a target steering angle acquisition circuit (51; 921); a differential value calculation circuit (52; 922); a short-term target steering angle calculation circuit (53; 923) 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 (54; 924). The short-term target steering angle calculation circuit (53; 923) 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 (51; 921) has newly acquired a target steering angle, and on the target value of the steering angle before the acquisition.