Autonomous Steering Manual Override via Torque Analysis
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Solution Overview
Problem
Autonomous vehicles lack an efficient method to seamlessly transition from autonomous mode to manual mode based on driver input, often resulting in driver discomfort and potential safety issues due to the lack of clear control handover mechanisms.
Innovation Solution
A steering system for autonomous vehicles that includes a steering wheel, shaft, motor, torque sensor, and controller, which monitors torque and angle inputs from the driver to determine when to override autonomous mode and switch to manual mode by analyzing the difference between expected and measured torque and angle signals, allowing for smooth transition based on driver intent.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Extent of automation
If autonomous steering control is implemented without manual override detection, then automation level is improved, but driver safety and comfort deteriorate due to inability to take control when needed
Solution Approach 1:
The system continuously monitors driver torque input through torque sensors and provides feedback to the controller. When driver torque exceeds a threshold, the system detects this feedback signal and transitions from autonomous to manual mode, ensuring driver safety while maintaining automation during normal operation
Solution Approach 2:
The steering system dynamically switches between autonomous and manual modes based on real-time driver input conditions. The controller adjusts the level of autonomous intervention by disabling torque application from the steering wheel motor when manual override is detected, allowing the system to adapt its control characteristics based on driver needs
2Reliability
If manual override capability is added to autonomous steering, then driver safety is improved, but system complexity increases due to additional sensors and control logic
Solution Approach 1:
The steering wheel motor serves multiple functions: it provides torque for autonomous steering control during normal operation and simultaneously acts as a sensor through torque monitoring to detect manual override attempts. This multi-functionality reduces the need for separate dedicated components for each function
Solution Approach 2:
The system uses its own existing torque sensing capabilities and control architecture to detect manual override conditions. The controller analyzes torque signals that are already being processed for autonomous steering, repurposing this existing data stream to also serve manual override detection without requiring entirely separate sensing systems
3Speed
If torque threshold for mode switching is set low, then responsiveness to driver input is improved, but false activations increase due to normal steering vibrations
Solution Approach 1:
The system pre-establishes a torque threshold that distinguishes between normal steering vibrations and genuine manual override attempts. This threshold is determined in advance through calibration and is stored in the controller, allowing immediate and reliable mode switching when exceeded without requiring additional real-time analysis
Solution Approach 2:
The system changes the torque parameter threshold based on operating conditions and calibration data. By optimizing this parameter, the system achieves high responsiveness to legitimate driver input while filtering out false activations from normal steering vibrations, balancing speed and reliability of mode transition
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
Enables a smooth and efficient transition from autonomous to manual mode, reducing driver discomfort and enhancing safety by accurately interpreting driver input, thereby providing a more intuitive and responsive driving experience.
Implementation Method 1
The torque sensor is coupled to the steering shaft and outputs a signal indicating an amount of torque being applied to the steering shaft
Implementation Method 2
The steering wheel motor is coupled to the steering shaft and is configured to apply a torque to the steering shaft
Data Source
AI summary
A method of control includes operating in autonomous mode and steering according to a tracking angle. The method also includes receiving a torque signal indicating a measured torque being applied to a steering control device and determining a difference between an expected torque and the measured torque, and based on a direction of the expected torque, the direction of the measured torque, and the difference between the two, switching from autonomous mode of operation to manual mode operation.