Dual-Axle Steering Control Using Yaw Rate and Lateral Velocity
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Solution Overview
Problem
Current multi-axle steering systems for vehicles, particularly in construction equipment, lead to instability at high speeds or on low friction surfaces, limiting vehicle freedom of movement and safety.
Innovation Solution
A computer system determines steering angles for vehicles with two steered axles using a bicycle model, based on desired yaw rate and lateral velocity, allowing decoupling of yaw rate and lateral movement, and employing feedforward or path-following controllers for precise control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If simple counter-steering of one axle relative to the other is used, then the steering control is simple to implement, but the vehicle becomes unstable at high speeds or on low friction surfaces
Solution Approach 1:
The patent changes the control parameters from simple proportional counter-steering to a comprehensive strategy that independently controls yaw rate and lateral velocity. The rear axle steering angle is calculated based on desired yaw rate and lateral velocity parameters rather than simply mirroring the front axle angle, enabling stable operation at high speeds and on low friction surfaces while maintaining reasonable system complexity.
2Device complexity
If rear steered axle is used only for translational lateral movement, then the control strategy is simplified, but the vehicle freedom of movement is limited
Solution Approach 1:
The patent makes the rear steered axle universal by enabling it to perform multiple functions: it can provide translational lateral movement when needed, but also contribute to comprehensive steering control by independently controlling yaw rate. The rear axle is no longer limited to a single function but can adaptively perform different steering tasks based on driving conditions, thereby increasing vehicle freedom of movement without significantly complicating the control strategy.
Data Source
AI summary
A computer system and computer-implemented method for determining a steering angle for a steered axle of a vehicle having two steered axles are disclosed. The computer system has processing circuitry to acquire a desired yaw angle of the vehicle at a second location; determine a desired yaw rate for the vehicle based on the desired yaw angle and a time for the vehicle to travel from a first location to the second location; acquire a lateral distance between the first location and the second location; determine a desired lateral velocity for the vehicle based on the lateral distance and the time for the vehicle to travel from the first location to the second location; and determine a steering angle for a steered axle of the vehicle using a bicycle model and based on the determined yaw rate and the determined lateral velocity.