Autonomous Vehicle Direction Detection Using Single-Channel Encoder Phase Analysis
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Solution Overview
Problem
Autonomous vehicles equipped with single-channel wheel encoders face challenges in determining direction changes, especially at low speeds or during starting and stopping, as these encoders only provide rotation rate information without indicating the direction of rotation, leading to difficulties in precise navigation and position estimation.
Innovation Solution
A system that combines information from multiple single-channel encoders on different wheels to characterize time-series relationships and identify shifts in these patterns, allowing the determination of direction changes by analyzing the relative phase offsets between the encoder outputs, enabling accurate speed and direction estimation for navigation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If single-channel encoders are used to reduce hardware complexity and cost, then device complexity is reduced, but the ability to determine direction of rotation is lost
Solution Approach 1:
The patent combines outputs from multiple single-channel encoders on different wheels to extract direction information. By analyzing the relative timing and phase relationships between encoder outputs from multiple wheels, the system determines vehicle direction without requiring dual-channel encoders on each wheel, thus reducing hardware complexity while recovering direction information.
2Ease of manufacture
If single-channel encoders are used to simplify the system, then ease of manufacture is improved, but measurement precision of direction is degraded
Solution Approach 1:
The patent uses the vehicle's multi-wheel configuration as an intermediary to resolve the limitation of single-channel encoders. By treating the system as a whole rather than individual sensors, the relative phase relationships between multiple single-channel encoder outputs provide sufficient information for accurate direction determination, maintaining measurement precision while simplifying individual encoder requirements.
3Measurement precision
If dual-channel encoders are used to provide direction information, then measurement precision of direction is improved, but device complexity increases
Solution Approach 1:
The patent segments the direction detection function across multiple single-channel encoders rather than concentrating it in dual-channel encoders. By distributing the sensing function across multiple wheels with single-channel encoders, the system achieves direction determination capability without requiring the complex dual-channel encoder hardware on each wheel, thus reducing overall device complexity while maintaining measurement precision.
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
This approach allows for precise detection of direction changes and vehicle position estimation, even at low speeds, enhancing the autonomous vehicle's navigation capabilities and robustness by using redundant information from multiple encoders.
Implementation Method 1
The single channel encoders can operate by Hall Effect or magnetoresistive sensors detecting regularly spaced magnetic and/or metallic features on the rotating portion of the wheel
Implementation Method 2
The single channel encoders can operate by Hall Effect or magnetoresistive sensors detecting regularly spaced magnetic and/or metallic features on the rotating portion of the wheel
Data Source
AI summary
A system for an autonomous vehicle is disclosed that combines information from single-channel encoders serving as wheel speed sensors on multiple wheels of the vehicle. A pattern of the outputs from the single-channel encoders is characterized while the vehicle is traveling in a first direction. A shift in the characterized pattern is associated with a change in direction of the autonomous vehicle. Such detection of changes in direction can be used to determine the position of the vehicle at low speeds or while starting and/or stopping where the vehicle can potentially rock back and forth.