Vehicle Curvature Path Control Under Differential Lock Yaw
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Solution Overview
Problem
Current vehicle automation systems face challenges in accurately following a desired curvature path, particularly when differential locks are activated, leading to deviations due to yaw moments that existing compensation methods fail to adequately address.
Innovation Solution
A method that calculates and compensates for yaw moments caused by differential locks using feed-forward compensation, integrating this calculation into the force generation part of the vehicle's control system to optimize steering angles and maintain the vehicle on a desired curvature path, especially suitable for semi-autonomous and fully autonomous vehicles.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If differential lock is activated to improve traction, then vehicle stability is improved, but deviation from desired curvature path increases due to yaw moment
Solution Approach 1:
The control unit calculates the yaw moment caused by differential lock activation in advance and applies compensatory steering angle adjustment before the vehicle deviates from the desired curvature path. This preliminary counter-action prevents the deviation rather than correcting it after occurrence, maintaining both stability and path accuracy.
Solution Approach 2:
The control unit continuously monitors the vehicle's actual curvature path and compares it with the desired curvature path. When differential lock is activated, the system calculates the resulting yaw moment and adjusts the steering angle accordingly to maintain accurate path following, creating a closed-loop feedback control system.
2Manufacturing precision
If feed forward compensation is applied to compensate for yaw moment, then curvature path following accuracy is improved, but steering angle optimization becomes more complex
Solution Approach 1:
The control unit performs feed-forward compensation by calculating the expected yaw moment from differential lock activation and pre-adjusting the steering angle accordingly. This preliminary action compensates for the yaw moment effect before it causes significant deviation, improving path accuracy through advance planning rather than reactive correction.
Data Source
AI summary
A method for having a vehicle follow a desired curvature path is provided. The vehicle has at least one differential with a differential lock connected to at least one driven wheel axle of the vehicle. The method includes providing information regarding state of the differential lock, the state being either that the differential lock is activated or unlocked, and when the differential lock is activated, calculating a yaw moment of the vehicle caused by the differential lock; and compensating for a deviation from the desired curvature path caused by the yaw moment such that a resulting steering angle is equal to or less than a maximum allowed steering angle of the vehicle. The compensation is a feed forward compensation.