Vehicle Cornering Control Using Delay-Free Lateral Acceleration
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Solution Overview
Problem
Existing vehicle control systems face delays in applying additional deceleration due to secondary delay components dependent on vehicle specifications, leading to inappropriate timing of deceleration application during cornering.
Innovation Solution
A vehicle control system that calculates control lateral acceleration using a planar two degrees of freedom model, disregarding second-order delay components, and utilizes steering angular velocity to generate additional deceleration through a braking force generator, with low-pass filtering and dead band processing to stabilize the braking force application.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a planar two degrees of freedom model is used to calculate lateral acceleration, then the calculation is based on vehicle specifications, but a second-order delay component is introduced causing inappropriate timing of deceleration application
Solution Approach 1:
The patent extracts and removes the second-order delay component from the planar two degrees of freedom model by using a simplified calculation approach. Instead of using the full model equation (Eq. 1) that includes delay terms, the invention uses a simplified equation (Eq. 2) that excludes these delay components, thereby eliminating the timing inaccuracy while maintaining the essential lateral acceleration calculation functionality.
2Reliability
If additional deceleration is applied to improve cornering performance, then vehicle handling is improved, but braking system wear increases
Solution Approach 1:
The patent applies preliminary action by calculating and applying additional deceleration in advance during the initial phase of cornering, before the vehicle actually enters the curve. By using the simplified lateral acceleration calculation that responds more quickly to steering input, the system prepares the braking force beforehand, improving cornering performance while controlling braking wear through precise, timely application rather than continuous braking.
3Ease of operation
If the steering angle is used to calculate lateral acceleration, then the calculation is straightforward, but rapid fluctuations occur when steering information is discontinuous
Solution Approach 1:
The patent introduces steering angular velocity as an intermediary parameter between the steering angle sensor and the lateral acceleration calculation. Instead of directly differentiating the steering angle (which causes fluctuations when data is discontinuous), the system uses the velocity sensor output that represents steering angular velocity, providing a more stable intermediate value for the calculation that reduces rapid fluctuations while maintaining calculation simplicity.
Data Source
AI summary
A vehicle control system provided with a control device that includes a control lateral acceleration calculation unit that calculates a control lateral acceleration from a lateral acceleration obtained by using a planar two degrees of freedom model of a vehicle based on vehicle state information and disregarding a second order delay component determined from vehicle specifications, a steer drag differential value calculation unit that calculates a steer drag differential value, an additional deceleration calculation unit that calculates an additional deceleration to be applied to the vehicle according to the steer drag differential value, and an additional braking force calculation unit that calculates an additional braking force to be generated by the braking force generator according to the additional deceleration.