Wheel-Speed-Synchronized Brake Control on Winding Roads
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Solution Overview
Problem
Existing vehicle control devices suppress torque variation of the axle and drive shaft but may inadequately decelerate the vehicle, especially on winding roads, due to setting brake hydraulic pressure equal to or below a threshold, leading to potential increases in braking distance.
Innovation Solution
A vehicle control device that predicts the temporal waveform of wheel speed during braking on winding roads and adjusts braking force application in synchronization with wheel speed variations, using machine learning to enhance prediction accuracy and execute reduction control to suppress torque variation and facilitate quicker deceleration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If brake hydraulic pressure is set equal to or lower than a threshold value to suppress torque variation of the axle and drive shaft, then torque variation is suppressed, but vehicle deceleration is suppressed and braking distance increases
Solution Approach 1:
The braking force is applied periodically in synchronization with the wheel speed variation waveform. The control unit executes reduction control to apply reduced braking force at specific timing points (e.g., every other peak or valley of the waveform) rather than continuously, allowing torque variation suppression while maintaining effective deceleration through timed intermittent application
Solution Approach 2:
The braking force magnitude is dynamically adjusted based on the predicted wheel speed waveform characteristics. The control unit determines the amplitude and timing of braking force application adaptively, varying the braking force between 0 and a maximum value based on the instantaneous wheel speed variation state, rather than applying a fixed threshold-based braking force
2Speed
If constant braking force is applied regardless of wheel speed variation on winding roads, then vehicle deceleration is maintained, but torque variation occurs in the axle and drive shaft
Solution Approach 1:
The control unit uses predicted wheel speed waveform information as feedback to dynamically adjust the braking force application timing and magnitude. By monitoring the wheel speed variation pattern and applying braking force in synchronization with these variations, the system maintains deceleration effectiveness while preventing torque variation through adaptive timing control
Solution Approach 2:
Instead of constant braking force, the system applies braking force periodically synchronized with the wheel speed variation waveform, creating a rhythmic application pattern that matches the natural variation cycle, thereby maintaining deceleration while avoiding resonance-induced torque variation
3Stability of the object's composition
If brake hydraulic pressure is reduced to suppress torque variation, then torque variation is suppressed, but braking distance increases
Solution Approach 1:
The braking force is applied in periodic pulses synchronized with wheel speed variations rather than as a continuous reduced force. This timing-based periodic application maintains deceleration effectiveness by utilizing the kinetic energy variations naturally present in the wheel speed waveform, achieving shorter braking distance compared to constant reduced braking force
Solution Approach 2:
The control unit predicts the wheel speed waveform in advance and pre-determines the optimal timing for braking force application. By anticipating the wheel speed variation pattern and preparing the braking force application timing beforehand, the system maximizes deceleration efficiency while minimizing braking distance
Data Source
AI summary
A vehicle control device that controls a motor and a braking force application device predicts a time waveform of a wheel speed when a required braking force based on a braking request is applied when a braking request is made while traveling on a winding road. The vehicle control device executes reduction control for controlling the braking force application device so that the reduced braking force is applied from the required braking force from the braking force application device in accordance with the timing of the variation of the wheel speed in the time waveform of the predicted wheel speed.