Autonomous Utility Vehicle Positioning via Magnetic Field Mapping
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Solution Overview
Problem
Conventional control apparatuses for autonomously navigating utility vehicles, such as lawn mowers, face challenges in accurately determining the vehicle's position within a working area delineated by a boundary wire, relying on costly geomagnetic field sensors for calibration, which increases the overall cost and complexity.
Innovation Solution
The apparatus employs a pair of laterally spaced magnetic sensors to detect magnetic field strength, generating a travel route and using this data to identify the vehicle's position without the need for a geomagnetic field sensor, by memorizing and comparing magnetic field strengths during trace mode to determine the vehicle's position in work mode.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a geomagnetic field sensor is used to calibrate the angular velocity sensor and improve position identification accuracy, then the position detection accuracy is improved, but the device cost and complexity increase
Solution Approach 1:
The patent extracts and removes the geomagnetic field sensor from the system, relying solely on the magnetic sensor to detect boundary wire signals for both trace mode navigation and work mode position identification, thereby simplifying the device configuration while maintaining positioning accuracy
Solution Approach 2:
The magnetic sensor is given multiple functions: it detects boundary wire signals during trace mode for navigation and also detects magnetic field strength during work mode for position identification, eliminating the need for separate geomagnetic field sensors
2Measurement precision
If multiple sensors (geomagnetic field sensor, magnetic sensor, angular velocity sensor, wheel speed sensor) are used to ensure accurate position identification, then the position detection accuracy is improved, but the device complexity and cost increase
Solution Approach 1:
The patent merges the functions of multiple sensors into a unified system where the magnetic sensor and boundary wire signal processing work together for both trace mode and work mode operations, reducing the number of separate sensor systems needed
Solution Approach 2:
The system uses its own magnetic sensor detections from trace mode to create a bitmap map that serves as a reference for position identification during work mode, making the system self-sufficient without external geomagnetic field sensors
3Device complexity
If the position is identified based on angular velocity sensor and wheel speed sensor values, then the device complexity is reduced, but the position identification accuracy deteriorates
Solution Approach 1:
The system uses feedback from magnetic sensor detections during trace mode to create a bitmap map, which then provides feedback during work mode to correct and refine position identification based on angular velocity and wheel speed sensor data, improving accuracy without adding geomagnetic sensors
Solution Approach 2:
The system performs preliminary trace mode operations to map the boundary and create a bitmap reference before work mode begins, preparing position reference data in advance that improves subsequent position identification accuracy during work mode
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 solution allows for accurate vehicle positioning within the working area, reducing costs by eliminating the need for geomagnetic field sensors and enhancing positional accuracy, even in areas with varying terrain or obstacles.
Implementation Method 1
magnetic sensors to detect magnetic field strength (intensity) generated by electric current passing through the boundary wire
Implementation Method 2
detect moving direction displacement and travel distance of the utility vehicle at this time using an angular velocity sensor and a wheel speed sensor, respectively
Data Source
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AI summary
In an apparatus controlling an autonomously navigating utility vehicle with a prime mover to travel about a working area delineated by a wire, are provided a travel controlling unit (312) controlling operation of the prime mover to make the vehicle travel along the wire in trace mode based on a value detected by one magnetic sensor while positioning other magnetic sensor inside the wire, a route generating unit (313) generating a route along the boundary based on detected turning angle and travel distance in trace mode, a memory unit (314) memorizing the magnetic field strength detected by the other magnetic sensor in the trace mode in association with the travel route, and a position identifying unit (315) compareing the magnetic field strength detected by the magnetic sensors with one memorized in the memory unit and identifies the vehicle position in the work mode based on a result of the comparison.