In-Wheel Motor Torque Control for Vehicle Trajectory Correction
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Solution Overview
Problem
Existing vehicle control systems fail to effectively return a vehicle to a targeted turning line at an early stage when it deviates, particularly during oversteer or understeer conditions.
Innovation Solution
A vehicle control device with a motor control unit that adjusts torques generated by in-wheel motors to apply braking torque to the outer front wheel during oversteer and increase drive torque to the inner rear wheel, and vice versa during understeer, to correct the vehicle's trajectory.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If conventional braking systems are used to correct vehicle trajectory during turning, then the vehicle can be brought back to the targeted turning line, but the response time is delayed and the vehicle cannot return to the targeted turning line at an early stage
Solution Approach 1:
The patent segments the braking function by wheel, applying independent braking torque to specific wheels (inner rear wheel or outer front wheel) based on the detected steering state (understeer or oversteer). This segmented approach allows targeted trajectory correction without delaying the response, enabling early return to the targeted turning line while maintaining control reliability.
Solution Approach 2:
The patent replaces the conventional hydraulic braking system with an electric motor-based torque control system. The motor control unit directly controls the torque of individual wheel motors, eliminating the delay associated with hydraulic pressure adjustment. This substitution enables immediate torque adjustment when understeer or oversteer is detected, allowing the vehicle to return to the targeted turning line at an early stage while maintaining reliable trajectory control.
2Productivity
If hydraulic brake pressure is adjusted individually for each wheel to correct trajectory, then the vehicle can be steered back to the targeted turning line, but the system complexity and response delay increase
Solution Approach 1:
The patent makes the motor control unit multi-functional by enabling it to perform both drive torque control and trajectory correction braking control. The same motor control unit that manages normal acceleration also handles the trajectory correction by adjusting torque to specific wheels when understeer or oversteer is detected. This eliminates the need for a separate hydraulic brake control system, reducing overall system complexity while maintaining fast trajectory correction capability.
Solution Approach 2:
The patent merges the trajectory correction function with the existing motor torque control system. Instead of using a separate hydraulic brake system for trajectory correction, the invention combines both functions into the motor control unit, which adjusts motor torque to achieve trajectory correction. This merging reduces system complexity and eliminates the response delay associated with hydraulic systems.
3Measurement precision
If conventional braking control is used during turning, then the vehicle can be stabilized, but the control precision and early intervention capability are insufficient
Solution Approach 1:
The patent implements a feedback mechanism where the control unit continuously monitors the steering state (detecting understeer or oversteer conditions) and automatically adjusts the torque of specific wheels in response. This closed-loop feedback system enables precise detection of steering state deviations and immediate corrective action, allowing the vehicle to return to the targeted turning line at an early stage with high precision and ease of operation.
Data Source
AI summary
A vehicle control device configured to control a vehicle configured to rotate each of four or more drive wheels by each of different motors, includes a motor control unit configured to control torques that are generated by the motors, and when oversteer has occurred during turning of the vehicle, the motor control unit performs a control upon oversteer, and when understeer has occurred during turning of the vehicle, the motor control unit performs a control upon understeer.