Impedance Blending for Semi-Autonomous Steering Control
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Solution Overview
Problem
Semi-autonomous driving features in land vehicles often oppose intended driver maneuvers, requiring disengagement and reengagement, which is inconvenient and disrupts the driving experience.
Innovation Solution
A system and method that blend driver-generated steering inputs with computer-generated inputs using an impedance controller to adjust steering commands, allowing seamless integration of manual and autonomous control without disengagement, by generating an impedance-adjusted steering angle command based on tunable parameters and measured driver torque.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If semi-autonomous control features are used to maintain lane centering, then lane keeping accuracy is improved, but driver maneuver freedom deteriorates when opposing manual maneuvers
Solution Approach 1:
The system dynamically adjusts the impedance parameters (M, B, K) based on the detected driver steering torque. When the driver applies significant torque indicating a manual maneuver intent, the system reduces the opposing control torque, allowing the driver to override the lane keeping feature smoothly. When driver torque is minimal, the full lane keeping control is applied to maintain accuracy.
Solution Approach 2:
The system changes the control parameters (impedance values M, B, K) based on driver input conditions. The impedance-adjusted steering angle command modifies the control torque magnitude dynamically, allowing the system to adapt between strong lane keeping and driver override modes without disengaging the feature.
2Measurement precision
If semi-autonomous control features oppose driver maneuvers to maintain control path, then trajectory accuracy is improved, but driver convenience deteriorates requiring disengagement and reengagement
Solution Approach 1:
The system maintains continuous semi-autonomous control without requiring driver disengagement. The impedance blending allows the driver to smoothly override the control feature during maneuvers, and the system automatically returns to lane keeping after the maneuver, eliminating the need for manual disengagement and reengagement steps.
Solution Approach 2:
The system continuously monitors driver steering torque and uses this feedback to adjust the control torque in real-time. When the driver releases the steering wheel or reduces torque, the system automatically returns to the original lane keeping control, providing seamless transition without driver intervention.
3Measurement precision
If computer-generated steering commands are applied strongly to correct trajectory error, then positioning accuracy is improved, but steering feel deteriorates
Solution Approach 1:
The system merges the computer-generated steering commands with the driver's steering input through impedance blending. The measured driver steering torque is combined with the control torque using the impedance equation, creating a blended command that maintains positioning accuracy while preserving natural steering feel and driver control.
Data Source
AI summary
A method for generating a steering command for controlling a vehicle is provided. The method includes: generating a first vehicle steering control torque command by a steering controller in the vehicle while the vehicle is driven in a semi-autonomous mode; generating an impedance-adjusted vehicle steering angle command based on a first vehicle steering angle command that was generated to compensate for a trajectory error, and a measured driver steering torque command generated in response to navigation of the vehicle using a steering wheel; generating an impedance-adjusted vehicle steering control torque command by the steering controller in the vehicle based on a difference between the impedance-adjusted vehicle steering angle command and a measured vehicle steering angle command; generating a steering command by a power steering system in the vehicle based on the measured driver steering torque command and the impedance-adjusted vehicle steering control torque command; and operating the vehicle in accordance with the steering command.