Road-Adaptive Vehicle Trajectory Control on Slippery Surfaces
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Solution Overview
Problem
Existing vehicle control methods, such as sliding mode control, do not adequately consider the state of the road surface, leading to deteriorated trajectory-following capabilities on slippery surfaces, resulting in potential vehicle destabilization.
Innovation Solution
A vehicle control device that generates a switching hyperplane based on both the vehicle's travel state and the road surface conditions, using a deviation computation unit, state estimation unit, and control input computation unit to adjust steering and speed inputs accordingly.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If sliding mode control is applied to steering control by correcting the switching hyperplane according to vehicle speed, then overshoot of the vehicle is suppressed, but trajectory-following capability deteriorates on slippery road surfaces
Solution Approach 1:
The invention changes the parameters of the switching hyperplane from only vehicle speed-dependent to include both vehicle speed and road surface state-dependent parameters. Specifically, the switching hyperplane is defined as σ = s1·ey + s2·ėy + s3·eθ + s4·ėθ where coefficients s1-s4 are determined based on both vehicle speed and road surface friction characteristics, allowing the control system to adapt to different road conditions and maintain trajectory-following capability on slippery surfaces while preserving stability
2Ease of operation
If the switchinghyperplane is determined only based on vehicle speed, then control simplicity is maintained, but control performance deteriorates on varying road surfaces
Solution Approach 1:
The invention applies preliminary action by pre-establishing the relationship between road surface states and switchinghyperplane parameters through friction characteristic estimation. The system estimates road surface friction characteristics in advance using observable vehicle dynamics, and uses this estimation to determine appropriate switchinghyperplane parameters before trajectory-following control is executed, enabling the system to adapt to different road surfaces without complex real-time adjustments
Solution Approach 2:
The invention implements feedback by continuously estimating road surface friction characteristics based on vehicle state information and using this feedback to adjust the switchinghyperplane parameters. The state estimation unit monitors vehicle dynamics to infer road surface conditions, and this information feeds back to the switchinghyperplane generation unit to optimize control parameters, creating a closed-loop system that adapts to changing road surfaces
Data Source
AI summary
In a vehicle control device, a switching hyperplane generation unit generates a switching hyperplane based on a travel state of a vehicle and cornering stiffness dependent on a travel surface state as a state of a road surface on which the vehicle travels. A deviation computation unit calculates a deviation between a target trajectory and an actual trajectory of the vehicle. A state estimation unit estimates a state to be controlled of the vehicle based on the deviation calculated by the deviation computation unit. A target steering angle and acceleration/deceleration computation unit calculates a target steering angle and a target acceleration/deceleration rate of the vehicle based on the switching hyperplane generated by the switching hyperplane generation unit and an estimated state as the state estimated by the state estimation unit.