Brake Control Device Slope Torque Correction
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Solution Overview
Problem
Conventional brake control systems fail to effectively prevent a vehicle from nosediving and swinging back when stopping on an ascending slope, leading to a high possibility of the vehicle going back downward.
Innovation Solution
A brake control device that calculates a required brake axle torque based on vehicle deceleration, adjusts it from an initial to a final value over a correction duration, and estimates the stop time using wheel speed sensor data to adjust the brake torque in accordance with the slope steepness, thereby reducing the likelihood of nosediving and swinging back.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If deceleration is suppressed just before the vehicle stops to reduce nose diving and swinging back, then passenger conformability is improved, but the vehicle may go back downward on ascending slopes
Solution Approach 1:
The brake control device dynamically adjusts the brake force application strategy based on real-time detection of vehicle speed and slope conditions. When an ascending slope is detected, the system switches to a different control mode that applies brake force differently compared to flat terrain, allowing the vehicle to maintain stability without excessive nose diving. This dynamic adaptation resolves the contradiction by making the brake system flexible rather than fixed.
Solution Approach 2:
The system changes key control parameters including the timing of brake force application, the magnitude of brake force, and the duration of brake application based on detected slope conditions and vehicle speed. By adjusting these parameters dynamically, the system achieves both passenger comfort (reduced nose diving) and vehicle stability (preventing backward movement on slopes) under different operating conditions.
2Reliability
If brake force is increased to surely stop the vehicle on ascending slope, then vehicle stability is improved, but nose diving and swinging back occur
Solution Approach 1:
The brake control device employs dynamic control that continuously monitors vehicle speed and slope angle, adjusting the brake force magnitude and application timing in real-time. This prevents excessive brake force that would cause nose diving while ensuring sufficient force to prevent backward movement on slopes. The system transitions smoothly between different brake force levels rather than applying maximum force abruptly.
Solution Approach 2:
The system performs preliminary detection of slope conditions and vehicle speed trends before applying brake force. By detecting the ascending slope condition and vehicle deceleration state in advance, the system can apply brake force at the optimal timing and magnitude to prevent backward movement without causing excessive nose diving or passenger discomfort.
3Speed
If the correction duration is shortened to quickly change required brake axle torque on steep slopes, then response speed is improved, but control precision may be reduced
Solution Approach 1:
The correction duration is dynamically adjusted based on the detected slope steepness and vehicle speed. On steeper slopes where rapid response is critical, the correction duration is shortened to quickly change brake torque. On milder slopes, the correction duration is extended to achieve more precise torque control. This dynamic adjustment of the correction timeline resolves the contradiction between response speed and control precision.
Solution Approach 2:
The system changes the correction duration parameter based on operating conditions. By making this parameter variable rather than fixed, the system can optimize the balance between response speed and control precision for each specific situation, achieving quick response when needed while maintaining precision when conditions allow.
Data Source
AI summary
When the vehicle decelerates on the ascending slope, a required brake axle torque is calculated in accordance with vehicle deceleration, so that the swinging back is suppressed. At start timing after that, initial and final values of the required brake axle torque and a correction duration are determined. During the correction duration from the start timing, the required brake axle torque is decreased from the initial value to the final value. Then, based on change in a detected vehicular speed at or before a time which is a last moment of a period in which the detected vehicular speed detected based on detection signals of the wheel speed sensors are equal to or larger than a minimum detectable vehicular speed, a stop time at which an actual vehicle speed becomes zero is estimated, a period from the start time to the stop time is identified as the correction duration.