Variable Damping Filter for Vehicle Brake Phase Control
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Solution Overview
Problem
Existing brake control systems fail to enhance brake feeling by delaying the timing at which the driver senses the brake becoming effective, leading to reduced feedback and comfort during braking.
Innovation Solution
A braking force control device that adjusts the damping ratio of filter processing to advance or delay the phase of the braking force command value relative to the required braking force, allowing the driver to promptly sense the brake's effectiveness and reducing overshooting of acceleration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If filter processing with a fixed damping ratio is used to generate the braking force command value, then the pitch motion of the vehicle can be controlled, but the brake feeling is reduced because the timing at which the driver senses the brake becoming effective is delayed
Solution Approach 1:
The damping ratio of the filter processing is made variable rather than fixed. The control unit changes the damping ratio based on the change amount of the required braking force: using a smaller damping ratio when braking force increases (to advance phase and improve brake feeling) and a greater damping ratio when braking force decreases (to suppress pitch motion). This dynamic adjustment resolves the contradiction between pitch motion control and brake feeling.
Solution Approach 2:
The damping ratio parameter of the filter is changed according to the braking conditions. By adjusting this parameter dynamically based on the change amount of required braking force, the system achieves both good pitch motion control and improved brake feeling, as the parameter change allows the filter characteristics to adapt to different operating conditions.
2Ease of operation
If the phase of the braking force command value is advanced to improve brake feeling, then the driver can promptly sense the brake becoming effective, but overshooting of acceleration generated on the driver's head occurs when braking force decreases
Solution Approach 1:
The damping ratio parameter is changed based on whether the required braking force is increasing or decreasing. When braking force increases, a smaller damping ratio advances the phase to improve brake feeling. When braking force decreases, a greater damping ratio delays the phase to suppress overshooting acceleration. This conditional parameter change resolves the contradiction between brake feeling and overshooting suppression.
Solution Approach 2:
The filter characteristics are made dynamic by adjusting the damping ratio according to the direction of change of braking force. This dynamic adaptation allows the system to advance phase when needed for brake feeling and delay phase when needed to prevent overshooting, effectively resolving the contradiction.
3Ease of operation
If a smaller damping ratio is used in filter processing, then the phase of the command value is advanced to improve brake feeling, but the pitch motion control becomes less effective
Solution Approach 1:
The damping ratio is dynamically adjusted based on the change amount of required braking force. A smaller damping ratio is used when braking force increases to advance phase and improve brake feeling, while a greater damping ratio is used when braking force decreases to maintain effective pitch motion control. This dynamic switching resolves the contradiction between brake feeling and pitch motion control.
Data Source
AI summary
A braking force control device includes an actuator configured to control a braking force generated in vehicle wheels of a vehicle and a control unit configured to output a braking force command value to the actuator. The control unit is configured to perform at least one of the following processes of generating a braking force command value by performing a filter processing on a required braking force based on a braking operation amount using a filter having a smaller damping ratio than a damping ratio of a pitch motion of the vehicle when the required braking force increases, or generating the braking force command value by performing the filter processing on the required braking force based on the braking operation amount using a filter having a greater damping ratio than the damping ratio of the pitch motion of the vehicle when the required braking force decreases.