Drive Assist Control Apparatus Lateral Acceleration Segmentation
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Solution Overview
Problem
In electric power steering systems, reducing lateral acceleration to improve driver steering feel is challenging as it diminishes both driver-assist and driver-steering control, leading to inadequate assistance.
Innovation Solution
A drive assist control apparatus that calculates a distribution ratio between driver-steering and drive-assist angle command values, determines if lateral acceleration needs reduction, and uses a low-pass filter to progressively correct the drive-assist angle command value when necessary, without affecting the driver-steering command.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If the amount of control performed by the motor is reduced to decrease lateral acceleration, then lateral acceleration is reduced, but both drive-assist control and driver-steering control are reduced, leading to insufficient steering assistance
Solution Approach 1:
The patent segments the total angle command value into two distinct components: a first angle command value from the drive-assist control and a second angle command value from the driver-steering control. By calculating and correcting only the first angle command value based on lateral acceleration, the system selectively reduces drive-assist control while preserving driver-steering control, thus resolving the contradiction between reducing lateral acceleration and maintaining steering assistance.
2Object-affected harmful factors
If the first angle command value is corrected without differentiation from the second angle command value, then lateral acceleration is reduced, but the driver's steering operation cannot be sufficiently assisted
Solution Approach 1:
The patent divides the angle command value into separate components (first angle command value for drive-assist and second angle command value for driver-steering) and applies correction only to the first component. This segmentation enables selective reduction of lateral acceleration while preserving the driver's steering feel and assistance.
Solution Approach 2:
The patent applies different quality treatment to different components of the angle command value. The first angle command value is corrected based on lateral acceleration to reduce harmful effects, while the second angle command value is left unchanged to maintain driver steering quality. This local differentiation resolves the contradiction between reducing lateral acceleration and maintaining steering ease of operation.
Data Source
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AI summary
In a drive assist control apparatus, based on a pinion angle command value ¸p and an LKA angle command value ¸LK, a distribution ratio calculation unit (52) calculates a distribution ratio D that is a proportion of the LKA angle command value ¸LK in a sum of the LKA angle command value ¸LK and the pinion angle command value ¸p. An LA determination unit (54) compares an LA threshold T with a lateral acceleration LA' that is related to the LKA angle command value ¸LK and that is a product of a lateral acceleration LA and the distribution ratio D, and determines whether or not to attenuate the lateral acceleration LA'. When the lateral acceleration LA' is determined to be attenuated, an LKA angle command value correction unit (55) uses a low pass filter (55a) to progressively reduce the LKA angle command value ¸LK to generate a filtered LKA angle command value ¸LK'.