Vehicle Steering Control for Turning Stability
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Solution Overview
Problem
Three-wheel vehicles experience unpleasant steering sensations and reduced control robustness due to inertial forces and centrifugal forces acting on the vehicle body during turning, leading to potential lifting of wheels and instability.
Innovation Solution
A vehicle design with a tilt actuator and controller that steers the front and rear wheels in opposite directions immediately after turning begins, reducing inertial forces and maintaining road contact, and adjusts steering angles based on the steering wheel operation to enhance stability and control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If the vehicle body is forcibly tilted toward the center of turning by the actuator immediately after turning starts, then the vehicle body tilts correctly for turning, but ground contact load concentrates on the front wheel or outer wheel causing wheel lift and reducing stability
Solution Approach 1:
The controller performs preliminary steering of the rear wheel in the opposite direction before the tilt actuator fully tilts the vehicle body. This preliminary action counteracts the inertial force that would otherwise cause wheel lift, ensuring all wheels maintain ground contact during the transition into the turn.
Solution Approach 2:
The rear wheel is steered in the opposite direction to the turning direction as a counter-action to the inertial force generated by body tilting. This anti-action prevents the harmful effect of ground contact load concentration and wheel lift, maintaining stability throughout the maneuver.
2Ease of operation
If the vehicle body is tilted toward the center of turning, then the turning performance is improved, but the acceleration change in the lateral direction acting on the driver becomes large causing upper body swing and impairing control robustness
Solution Approach 1:
The rear wheel steering is activated in advance of the full body tilt, gradually introducing the turning motion. This preliminary action reduces the suddenness of lateral acceleration changes, allowing the driver's upper body to adjust more smoothly and maintain better control.
Solution Approach 2:
The system dynamically coordinates the tilt actuator and rear wheel steering actuator to achieve a smooth transition into the turn. By controlling the timing and magnitude of each actuator, the lateral acceleration change is optimized to provide good turning performance while minimizing driver discomfort and maintaining control robustness.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The solution reduces unpleasant steering sensations and improves vehicle stability by minimizing inertial forces, ensuring proper vehicle travel and maintaining road holding performance during turns.
Implementation Method 1
a tilt actuator which tilts the vehicle body in a roll direction
Implementation Method 2
one or more steering actuators which can be controlled by the controller, and the front wheel and the rear wheel can be steered by a steering mechanism
Implementation Method 3
immediately after the turning of the vehicle is started, an inertial force and a centrifugal force attributable to the tilt will act on the vehicle body toward the opposite side from the center of turning
Implementation Method 4
an inertial force and a centrifugal force attributable to the tilt will act on the vehicle body
Data Source
AI summary
The steering angles of front wheels 3f and rear wheels 3r of a vehicle 1 can be respectively controlled by a front wheel steering angle control actuator 35 and a rear wheel steering angle control actuator 44. If a steering wheel 20 is operated in a turning direction of the vehicle 1 while the vehicle 1 is traveling in a straight line, then a controller 60 changes the steering angle of the front wheels 3f to approach to a steering angle specified on the basis of an operation amount after the steering wheel 20 is operated, and also controls the front wheel steering angle control actuator 35 and the rear wheel steering angle control actuator 44 to change the steering angles of the rear wheels 3r to the opposite direction of the turning direction of the vehicle 1 immediately after the steering wheel 20 is operated.