Independent Wheel Drive Torque Control for Center-of-Gravity Yaw Compensation
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Solution Overview
Problem
In vehicles with independent right and left wheel drive, changes in the position of the vehicle's center of gravity due to occupants or loads lead to differences in yaw moments between the right and left wheels, compromising traveling stability and operability.
Innovation Solution
A driving force control device that includes a center-of-gravity estimation unit to determine the position of the vehicle's center of gravity and a torque correction unit to add correction torque to the output torque of the right and left electric motors, canceling the yaw moment generated by changes in the center of gravity position.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the same torque is output from right and left electric motors in independent wheel drive, then the drive system is simple and easy to control, but a yaw moment is generated when the center of gravity position changes, deteriorating traveling stability and operability
Solution Approach 1:
The control device dynamically changes the torque output parameters of the right and left electric motors based on the detected center of gravity position. When the center of gravity shifts, the control device adjusts the torque distribution to compensate for the resulting yaw moment, thereby maintaining traveling stability without requiring a mechanically complex differential mechanism.
2Productivity
If torque is split according to ground contact load via differential mechanism, then driving force is optimized for each wheel, but the system becomes mechanically complex and cannot adapt to center of gravity changes in independent wheel drive
Solution Approach 1:
The patent replaces the mechanical differential mechanism with an electronic control system that independently regulates the torque output of each electric motor. This substitution eliminates the need for complex mechanical torque-splitting components while achieving adaptive torque distribution based on real-time center of gravity detection, thereby maintaining driving force efficiency without mechanical complexity.
3Ease of operation
If compensation torque is output based on predetermined specifications, then turning inhibition yaw moment is canceled, but yaw moment is generated when center of gravity position changes, deteriorating operability
Solution Approach 1:
The control device implements a feedback mechanism where the center of gravity position is continuously detected and used to adjust the torque output of the electric motors. This feedback loop enables the system to adapt to changing center of gravity positions caused by occupants or loads, canceling yaw moments and maintaining vehicle operability under various loading conditions.
Data Source
AI summary
A left electric motor for driving a left wheel and a right electric motor for driving a right wheel paired with the left wheel are provided, and a center of gravity position of the right and left wheel independent drive type vehicle is estimated, and a correction torque for canceling a yaw moment generated in accordance with a difference between the estimated center of gravity position of the right and left wheel independent drive type vehicle and a predetermined center of gravity position determined in advance is added to an output torque of the left electric motor and the right electric motor.