Vehicle Control Device for Slip Suppression and Torsional Vibration
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Solution Overview
Problem
Existing vehicle control systems face challenges in quickly suppressing wheel slip and preventing torsional vibration of drive shafts, which degrades controllability, especially when using motors connected to tires via drive shafts, due to time delays in feedback control and torsional vibration issues.
Innovation Solution
A vehicle control device and method that calculates a reference rotation speed by adding a torsional amount to the drive unit's rotation speed, allowing for instantaneous slip determination and control, switching between motor and tire rotation speed feedback to suppress slip and reduce torsional vibration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If feedback control is based on tire rotation speed from a sensor, then time delay in detection is increased, but slip suppression is achieved
Solution Approach 1:
The patent introduces a reference rotation speed as an intermediary value that represents the expected tire rotation speed based on drive unit rotation speed and transmission characteristics. This reference value mediates between the drive unit sensor data and the actual tire sensor data, enabling earlier slip detection by comparing actual tire speed against the predicted reference speed, thus reducing detection time delay while maintaining suppression effectiveness
Solution Approach 2:
The system performs preliminary calculation of the reference rotation speed using drive unit rotation speed and transmission characteristics before actual slip occurs. By having this reference value pre-computed and ready for comparison, the system can immediately detect slip conditions without waiting for tire speed sensor data to show the actual slip, thereby reducing detection time delay
2Loss of time
If feedback control is based on drive unit rotation speed from a sensor, then time delay is decreased, but torsional vibration degrades controllability
Solution Approach 1:
The system pre-calculates the reference rotation speed based on drive unit rotation speed and transmission characteristics before control actions are needed. This preliminary computation allows the system to use drive unit sensor data for rapid detection without suffering from torsional vibration effects during the measurement process, as the reference value is computed in advance
Solution Approach 2:
The reference rotation speed serves as an intermediary that decouples the control system from direct dependence on drive shaft mechanical connections. By comparing actual tire speed against this computed reference rather than directly controlling based on drive unit speed, the system achieves rapid response without being affected by torsional vibration in the drive shaft
3Reliability
If control continues based on motor rotation speed after slip determination, then slip suppression is maintained, but torsional vibration reduces controllability
Solution Approach 1:
The reference rotation speed is pre-computed based on drive unit rotation speed and transmission characteristics before control actions are executed. This allows the system to maintain slip suppression through continuous reference updates without requiring continuous direct feedback from the drive shaft, thereby avoiding torsional vibration interference while maintaining suppression effectiveness
Solution Approach 2:
The reference rotation speed acts as an intermediary that allows the system to maintain slip suppression control without directly coupling to the drive shaft. By using this computed reference value for control decisions rather than direct drive unit feedback, the system maintains suppression reliability while avoiding the controllability degradation caused by torsional vibration
Data Source
AI summary
A vehicle control device includes motors that drive respective tires via drive shafts, a reference rotation speed calculating module that calculates torsional amounts of the drive shafts on the basis of a required torque, and outputs a reference rotation speed for a slip determination, the reference rotation speed being obtained by adding the torsional amounts to rotation speeds of the motors, the rotation speeds corresponding to a vehicle speed, and slip determiners that compare the rotation speeds of the motors with the reference rotation speed to determine whether or not the tires are slipping, and a rotation speed control module that controls the rotation speeds of the motors on the basis of a target rotation speed when it is determined that the tires are slipping.