Steering Torque Feedback for Differential Braking Hand-Moment Control
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Solution Overview
Problem
Conventional methods fail to effectively predict and manage the sudden change in steering hand moment caused by differential braking systems, which affects driver experience due to their reliance on front wheel steering angle changes and passive suppression strategies.
Innovation Solution
A steering wheel torque feedback optimization control method that estimates tire lateral force using a two-degree-of-freedom vehicle model and nonlinear tire model, predicts vehicle states under differential and non-differential torque conditions, calculates continuous tire lateral force changes, and corrects the desired steering power motor moment to suppress hand moment changes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If conventional methods based on front wheel steering angle changes are used to predict hand moment changes, then the prediction works for active steering systems, but it becomes inapplicable to differential braking systems where steering angle does not change
Solution Approach 1:
The patent changes the prediction parameter from steering angle (which remains constant in differential braking) to tire longitudinal force (which changes during differential braking). By using the relationship between tire longitudinal force and hand moment, the system adapts the prediction method to work specifically for differential braking systems where the original steering-angle-based method fails.
2Reliability
If passive suppression strategies are used to manage hand moment changes after they occur, then the system responds to changes, but it cannot predict or prevent sudden changes in steering hand moment
Solution Approach 1:
The patent performs preliminary action by predicting the change in hand moment before it actually occurs. The system calculates the expected hand moment change based on the differential braking force, then proactively adjusts the steering assistance moment to counteract this change. This prevents the sudden hand moment change from affecting the driver, rather than merely responding after the change occurs.
Solution Approach 2:
The patent applies preliminary anti-action by introducing a compensating steering assistance moment that opposes the predicted hand moment change caused by differential braking. The compensation moment is calculated in advance based on the relationship between tire longitudinal force and hand moment, and is applied to counteract the adverse effect before it reaches the driver.
3Device complexity
If the steering assistance system does not compensate for differential braking effects, then the system remains simple, but sudden changes in steering hand moment occur affecting driver experience
Solution Approach 1:
The patent implements feedback by continuously monitoring the differential braking force applied to the wheels and using this information to adjust the steering assistance moment. The system establishes a relationship between the braking force (input) and the required compensation moment (output), creating a closed-loop control that automatically compensates for hand moment changes while maintaining relatively simple system architecture.
Data Source
AI summary
Disclosed is a steering wheel torque feedback optimization control method for a differential braking system, including: estimating a tire lateral force of a vehicle; predicting a state of the vehicle at a next moment under a non-differential torque condition; predicting a state of the vehicle at the next moment under a differential torque condition with an additional yaw moment; calculating tire lateral forces at the next moment under the differential torque condition and the non-differential torque condition separately based on the predicted states of the vehicle at the next moment under the differential torque condition and the non-differential torque condition, and obtaining a predicted one-step change value of a front tire lateral force by performing subtraction; performing integral calculation based on time, and obtaining a continuous change amount of the tire lateral force; and correcting a desired moment of a steering power motor.