Vehicle Steering Torque Vectoring for Off-Road Understeer
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Solution Overview
Problem
In low traction conditions such as mud or snow, existing vehicle steering systems experience understeer or oversteer due to reduced friction, making it difficult for drivers, especially inexperienced ones, to maintain control and navigate through challenging terrain without risking damage or loss of traction.
Innovation Solution
A vehicle control system that includes a low-speed progress control system and stability control system, which uses selective powertrain, traction control, and braking actions to maintain vehicle speed and stability, actively managing wheel slip and torque distribution between wheels to assist the driver in navigating difficult terrain by inducing a turning moment and improving traction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If off-road speed control mode is engaged to automatically maintain pre-set speed, then driver workload is reduced, but vehicle control precision deteriorates in high steering angle low friction conditions causing understeer
Solution Approach 1:
The system continuously monitors actual vehicle rate of turn against expected rate of turn (derived from steering angle and vehicle speed) and uses this feedback to detect understeer conditions. When understeer is detected, the system automatically applies braking force to the inside rear wheel to correct the vehicle's path, thereby maintaining control precision while speed control remains active
Solution Approach 2:
The control system acts as an intermediary between the driver's steering input and the vehicle's actual motion. It processes the discrepancy between intended and actual vehicle behavior, and intervenes by applying corrective braking force through the brake system to mediate and correct the understeer condition
2Reliability
If off-road speed control mode is disengaged to improve vehicle control in difficult conditions, then driver workload increases as engine speed and transmission ratio must be controlled manually
Solution Approach 1:
The system merges speed control and steering control functions into a single integrated off-road progress control mode. The driver provides only steering input while the system automatically manages both speed maintenance and understeer correction, combining multiple control functions that would otherwise require separate driver attention
3Productivity
If vehicle attempts to gain sufficient traction to climb out of ruts, then progress is possible, but vehicle may become trapped in ruts due to loss of traction
Solution Approach 1:
The system applies braking force selectively to the inside rear wheel rather than uniformly to all wheels. This localized intervention creates a turning moment that helps the vehicle rotate and exit the ruts, while maintaining traction on the outside wheels that is crucial for progress
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The system enables vehicles to maintain control and progress in low traction conditions by actively managing wheel slip and torque, reducing driver workload and the risk of understeer or oversteer, allowing for safer navigation through slippery or rutted terrain without requiring constant manual intervention.
Implementation Method 1
Vehicle steering relies upon friction between the vehicle tyres and the ground
Data Source
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AI summary
The application relates to a system and method for motor vehicle control. System and method are operable in a steering assist mode and configured to detect a steering angle and to induce a yaw torque via torque vectoring. The application is in particular operable in a first, low speed mod suitable for off road driving, with emphasis on getting the vehicle out of ruts. A second, high-speed mode for highway driving is also provided.