Vehicle Control Apparatus Slip Ratio Optimization
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Solution Overview
Problem
Conventional vehicle control systems fail to optimize the balance between target tire lateral force and target tire longitudinal force due to differences in tire lateral force and tire longitudinal force characteristics with respect to the slip ratio.
Innovation Solution
A vehicle control apparatus calculates an optimal slip ratio by minimizing the sum of differences between actual and target tire lateral forces and actual and target tire longitudinal forces, using a weighted combination of these differences to output instructions to actuators for achieving this optimal slip ratio.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single slip ratio is used for both lateral and longitudinal force control, then the control system is simple, but the balance between target tire lateral force and target tire longitudinal force cannot be optimized
Solution Approach 1:
The patent divides the single slip ratio control into two separate slip ratios: a first slip ratio for optimizing tire lateral force and a second slip ratio for optimizing tire longitudinal force. This segmentation allows independent optimization of each force component, resolving the contradiction between control simplicity and force balance optimization.
2Manufacturing precision
If separate slip ratios are used for lateral and longitudinal forces, then force balance is optimized, but control system complexity increases
Solution Approach 1:
The patent dynamically switches between using a single slip ratio and two separate slip ratios based on vehicle operating conditions. The ECU determines whether to use one or two slip ratios according to the magnitude of target tire forces, making the control system adaptable rather than statically complex.
Solution Approach 2:
The patent changes the control parameter from a single slip ratio to conditionally using one or two slip ratios. By adjusting the number of slip ratio parameters based on operating conditions, the system achieves optimization without permanent complexity increase.
3Ease of operation
If target tire forces are controlled without considering force characteristics, then control is straightforward, but spin avoidance and line traceability are reduced on low-μ road surfaces
Solution Approach 1:
The patent applies different control strategies to different force components based on their characteristics. Lateral force control and longitudinal force control use different slip ratios optimized for their respective force characteristics, improving reliability on low-μ surfaces while maintaining operational simplicity through automated selection.
Data Source
AI summary
The present invention provides a vehicle control apparatus, a vehicle control method, and a vehicle control system capable of optimizing balance between a target tire lateral force and a target tire longitudinal force. A vehicle control apparatus outputs an instruction for achieving an optimal slip ratio corresponding to a minimum value of a sum of a first difference and a second difference to an actuator regarding braking/driving of a vehicle. The first difference is a difference between a tire lateral force and a target tire lateral force with respect to an arbitrary slip ratio in a correlative relationship between a slip ratio and the tire lateral force of a tire of a wheel portion. The second difference is a difference between a tire longitudinal force and a target tire longitudinal force with respect to the arbitrary slip ratio in a correlative relationship between the slip ratio and the tire longitudinal force.