Four-Wheel Drive Torque Control Using Axle Speed Difference
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current four-wheel drive vehicles experience wheel slip issues due to high motor torque response speed, particularly under special circumstances, which are inadequately controlled by existing closed-loop and open-loop control methods, leading to power consumption and reduced driving performance.
Innovation Solution
Implementing a vehicle torque control method that adjusts drive shaft torque based on the equivalent axle speed difference between the front and rear axles, allowing for double-shaft closed-loop control across all vehicle speeds, using motor and wheel speed data to balance axle torque dynamically.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If closed-loop control is performed when vehicle speed is within a certain range, then wheel slip can be controlled at low speeds, but wheel slip cannot be effectively controlled at high speeds
Solution Approach 1:
The patent implements a unified closed-loop control strategy that functions across the entire vehicle speed range, replacing the traditional segmented approach (closed-loop at low speeds, open-loop at high speeds). The control system universally applies equivalent axle speed difference calculation and torque adjustment regardless of vehicle speed, enabling effective wheel slip control in both low-speed and high-speed conditions through a single adaptable mechanism.
2Speed
If motor torque response speed is increased, then vehicle acceleration performance is improved, but the vehicle becomes susceptible to wheel slip under special circumstances
Solution Approach 1:
The patent employs a closed-loop feedback control mechanism that continuously monitors equivalent axle speeds, calculates speed differences, and adjusts motor torque in real-time based on detected wheel slip conditions. This feedback system enables rapid torque modulation to counteract wheel slip caused by high torque response, maintaining acceleration performance while preventing harmful slip through active torque management.
Solution Approach 2:
The control system dynamically adjusts motor torque based on real-time equivalent axle speed differences, allowing the torque response characteristics to adapt to changing driving conditions. By making torque adjustment dynamic rather than fixed, the system can rapidly respond to wheel slip conditions while maintaining optimal acceleration performance across varying operational states.
3Ease of operation
If wheel slip is controlled by adjusting torque based on speed, then control response can be achieved, but power is consumed gratuitously and driving performance is reduced
Solution Approach 1:
The patent applies torque adjustment only when equivalent axle speed difference exceeds a threshold indicating actual wheel slip conditions, rather than continuously adjusting torque based on speed. This partial action approach activates control only when necessary, avoiding gratuitous power consumption during normal driving while maintaining rapid responsiveness when wheel slip occurs.
Data Source
AI summary
A vehicle torque control method is provided for a four-wheel drive vehicle. The vehicle torque control method includes acquiring a front axle equivalent axle speed and a rear axle equivalent axle speed of a vehicle, and determining an equivalent axle speed difference between front axles and rear axles of the vehicle according to the front axle equivalent axle speed and the rear axle equivalent axle speed. The vehicle torque control method also includes determining a drive shaft torque adjustment value according to the equivalent axle speed difference; and adjusting an output torque of a drive shaft motor according to the drive shaft torque adjustment value.