Braking Force Control System for Adaptive Cruise
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Solution Overview
Problem
Drivers experience a feeling of strangeness when performing brake operations during adaptive cruise control (ACC) due to sudden changes or drops in braking force, as existing systems either fail to supplement the required braking force or generate excessive force.
Innovation Solution
A braking force control system that includes a brake device and electronic control units to generate an actual braking force by combining an additional controlled braking force with the operational braking force required by the driver, allowing smooth transition and reflection of the driver's intention, while limiting excessive responses and eliminating unnecessary assistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the ACC is cancelled when the driver performs brake operation, then the driver can immediately return the initiative of vehicle speed control, but the braking force that has been generated before the cancellation disappears causing a drop of braking force
Solution Approach 1:
The system stores the braking force value generated by ACC before cancellation (Facc) and the brake operation amount at the timing of brake operation start (Ap0) in advance. This preliminary storage enables the system to reconstruct and maintain the braking force level after cancellation, preventing the drop that would normally occur when ACC is discontinued.
2Force
If the system generates a larger braking force when brake operation is performed during ACC, then the driver's braking requirement is met, but the driver experiences a feeling of strangeness from a change in braking force
Solution Approach 1:
The system continuously monitors brake operation amount Ap and compares it with the stored initial brake operation amount Ap0. Based on this feedback, the control unit calculates the ratio Ap/Ap0 and adjusts the additional braking force Fadd accordingly, ensuring that the total braking force changes smoothly and naturally in response to driver input while maintaining the desired braking effect.
Solution Approach 2:
The system dynamically adjusts the additional braking force Fadd based on the real-time brake operation amount Ap and the calculated ratio Ap/Ap0. This dynamic adjustment allows the braking force to adapt smoothly to driver intentions, preventing sudden changes that would cause a feeling of strangeness while ensuring adequate braking performance.
3Force
If the ACC is not cancelled during slight brake operation, then the drop of braking force is prevented, but the driver experiences a feeling of strangeness when brake operation does not result in expected braking force increase
Solution Approach 1:
The system introduces an additional braking force Fadd as an intermediary element between the ACC braking force and the driver's brake operation. This additional force is calculated based on the ratio of current to initial brake operation amount, acting as a mediator that ensures the total braking force always reflects the driver's intentions while maintaining stability during slight operations.
Data Source
AI summary
A braking force control system includes: a brake device and at least one electronic control unit. The brake device is configured to generate a braking force commensurate with a brake operation amount of a driver. At least one electronic control unit is configured to execute vehicle speed control for controlling a speed of a vehicle to a target speed by controlling a driving force and a braking force. The electronic control unit is configured to cause the brake device to generate an actual braking force corresponding to a total value of an additional braking force and an operational braking force when brake operation is performed during execution of the vehicle speed control. The additional braking force corresponds to a controlled braking force required by the vehicle speed control. The operational braking force is required through the brake operation.