Steer-by-Wire Torque Steer Mitigation via Segmented Control Modules
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Traditional torque steer mitigation software for electric power steering (EPS) systems interferes with roadwheel position controllers, causing unintended steering and unexpected effort in vehicles during torque steer events.
Innovation Solution
A steer-by-wire system that includes a transmission torque sensor, handwheel position sensor, and a controller with an angle-based load calculation submodule and torque steer ratio calculation submodule to estimate and mitigate torque steer without interfering with other EPS components, using a torque control module to generate a handwheel torque command signal.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional torque steer mitigation software is used in EPS systems, then torque steer can be mitigated, but it interferes with roadwheel position controllers causing unintended steering and unexpected effort
Solution Approach 1:
The controller is divided into distinct functional modules: a roadwheel position controller that independently manages roadwheel positioning, and a torque control module that separately calculates torque steer mitigation. This segmentation allows torque steer mitigation to be implemented without interfering with the roadwheel position controller's operation, resolving the contradiction between torque steer mitigation and steering control stability.
Solution Approach 2:
The patent introduces a torque control module as an intermediary component that receives inputs from both the roadwheel position controller and transmission torque sensor, processes torque steer mitigation independently, and outputs torque commands that are integrated into the overall steering control. This intermediary structure enables torque steer mitigation to function without directly interfering with the roadwheel position controller.
2Object-affected harmful factors
If torque overlay is applied for torque steer mitigation, then torque steer is reduced, but it interferes with roadwheel position controllers
Solution Approach 1:
The system implements a feedback mechanism where the torque control module continuously monitors transmission torque through the transmission torque sensor and adjusts torque steer mitigation in real-time based on actual torque steer conditions. This feedback approach allows the system to apply torque overlay only when and where needed, preventing interference with roadwheel position controllers while effectively mitigating torque steer.
Solution Approach 2:
The torque control module applies torque steer mitigation locally at the torque control level rather than globally affecting the entire EPS system. By calculating torque steer ratio and applying compensation specifically to the torque component, the system mitigates torque steer without disrupting the overall coordination between roadwheel position control and torque control functions.
Data Source
AI summary
A steer-by-wire system includes a transmission torque sensor, a handwheel position sensor, and a controller. The transmission torque sensor is configured to measure and output a transmission torque signal. The handwheel position sensor is configured to measure and output a handwheel position signal. The controller includes an angle-based load calculation submodule, a torque steer ratio calculation submodule, and a torque control module. The angle-based load calculation submodule is configured to transform the transmission torque signal and the handwheel position signal into an estimated second load value. The torque steer ratio calculation submodule is configured to transform the estimated second load value, a first load value indicative of roadwheel load including torque steer influence, and the transmission torque signal into a torque steer ratio. The torque control module is configured to transform the first load value, the handwheel position signal, and the torque steer ratio into a handwheel torque command signal.