Friction Compensation for Vehicle Steering Control
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Friction in the steering system of autonomous or semi-autonomous vehicles can cause vehicles to overshoot the center of a lane, leading to instability in lane-centering operations.
Innovation Solution
A computer-controlled system that uses image data from a camera to determine a friction-compensation torque, which is applied feedforward to the steering system to compensate for internal friction, thereby maintaining smoother lane centering without the delays associated with feedback systems.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If friction compensation is implemented using feedback control, then the system can reduce error caused by friction, but the system introduces delays between error detection and steering actuation
Solution Approach 1:
The patent calculates and applies friction compensation torque in advance based on the planned curvature of the path, rather than waiting for error to occur. By determining the required friction compensation before the steering action is needed, the system eliminates control delays while maintaining accurate error reduction. The friction compensation torque is computed as a function of the planned curvature and vehicle speed, allowing proactive compensation.
2Measurement precision
If additional sensing hardware is added to improve friction compensation accuracy, then measurement precision can be improved, but device complexity and cost increase
Solution Approach 1:
The system uses existing sensors already present in autonomous vehicles (cameras for path detection, speed sensors for vehicle velocity) to calculate friction compensation. Rather than adding dedicated friction sensors or complex measurement devices, the system self-servingly computes friction compensation torque from readily available data about planned curvature and vehicle operating conditions, thereby maintaining measurement precision without increasing device complexity.
3Device complexity
If friction compensation is not implemented, then device complexity remains low, but the vehicle experiences overshooting and instability in lane centering
Solution Approach 1:
The patent modifies the steering control by adding a friction compensation torque parameter to the existing control algorithm. This parameter is calculated based on the planned curvature and vehicle speed, and is added to the basic steering torque. By changing the control parameters rather than fundamentally redesigning the control system architecture, the patent achieves stable lane centering while maintaining relative simplicity of the overall device.
Data Source
AI summary
A computer includes a processor and a memory storing instructions executable by the processor to determine a planned curvature of a planned path of a vehicle, determine a friction-compensation torque based on image data received from a camera of the vehicle, and control a steering system of the vehicle based at least in part on the planned curvature and the friction-compensation torque. The friction-compensation torque compensates for friction internal to the steering system.