Vehicle Control Device Torque Adjustment for Cruise Control Vibration
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Solution Overview
Problem
Vehicles equipped with driving motors experience vibrations during cruise control mode due to sudden changes in torsion in the power transmission shaft, particularly on undulating or hilly roads, leading to fluctuations in torque and vehicle speed deviations.
Innovation Solution
A vehicle control device with a controller that predicts torsion release in the power transmission shaft and adjusts the torque command value by reducing the absolute value of the proportional control component, thereby minimizing torque fluctuations and vibrations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If proportional control is used to maintain vehicle speed at target speed during cruise control mode, then vehicle speed stability is improved, but torque fluctuations and vibrations occur when torsion in the power transmission shaft is released
Solution Approach 1:
The controller predicts whether torsion in the power transmission shaft is to be released before it actually occurs. When torsion release is predicted, the controller preliminarily adjusts the proportional control gain to reduce the absolute value of the proportional control component in the torque command value. This preliminary action prevents the harmful torque fluctuations and vibrations that would otherwise occur when torsion is released, while still maintaining adequate vehicle speed stability through the adjusted control parameters.
2Object-affected harmful factors
If torque command value is adjusted to reduce proportional control component when torsion release is predicted, then vibrations are suppressed, but response speed to actual torsion release may be reduced
Solution Approach 1:
The controller uses a prediction mechanism to determine in advance whether torsion release is about to occur. By adjusting the proportional control gain before actual torsion release happens, the system suppresses vibrations proactively rather than reactively. This preliminary adjustment maintains adequate response speed because the control parameter is optimized in advance based on predicted conditions, allowing the system to respond appropriately when torsion actually releases without the lag that would occur with reactive adjustment only.
Data Source
AI summary
A vehicle control device includes an identifier identifying a vehicle speed of a vehicle having a driving motor, based on a rotation speed of a power transmission shaft, and a controller controlling operation of the driving motor. The controller can switch between a normal mode of controlling acceleration/deceleration in accordance with a driver's acceleration/deceleration operation, and a cruise control mode of maintaining the vehicle speed at a target speed without being dependent on the acceleration/deceleration operation. During the cruise control mode, the controller calculates a torque command value for the driving motor by using proportional control based on a deviation between the vehicle speed and the target speed. If a prediction indicates that torsion in the shaft is to be released, the controller adjusts the torque command value such that an absolute value of torque of a proportional-control component is smaller than when the torsion is not to be released.