Lawn Mower Wheel Tracking Using Offset Magnetic Position Sensing
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Solution Overview
Problem
Existing motion tracking systems for lawn maintenance devices, such as lawnmowers, lack precision and effectiveness in controlling their movements, particularly in detecting wheel positions and orientations, leading to potential issues like slipping or damage due to adverse environmental conditions.
Innovation Solution
A motion tracking system for lawn maintenance devices that includes a wheel with detectable elements offset from the central axis, a detector to sense these elements, and control circuitry to determine the wheel's position and orientation, enabling precise control and adaptive responses to environmental conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a simple motion tracking system is used, then the device complexity is reduced, but the measurement precision of wheel position and orientation deteriorates
Solution Approach 1:
The motion tracking system is segmented into distinct functional components: a detectable element (magnet) attached to the wheel, a detector (magnetic sensor) mounted on the vehicle body, and control circuitry. This segmentation allows each component to be optimized independently while maintaining overall system precision without excessive complexity.
Solution Approach 2:
A magnetic field is introduced as an intermediary between the wheel and the detector. The detectable element (magnet) generates a magnetic field that the magnetic sensor detects, enabling non-contact measurement of wheel position and orientation with high precision while keeping the physical system relatively simple.
2Measurement precision
If advanced motion tracking with multiple sensors is implemented, then the measurement precision improves, but the device complexity increases
Solution Approach 1:
The magnetic sensor serves multiple functions: detecting the position of the detectable element, determining wheel rotation angle, and calculating wheel orientation relative to the vehicle body. This multi-functionality achieves high measurement precision with a single sensor type, avoiding the complexity of multiple specialized sensors.
Solution Approach 2:
The system measures changes in magnetic field parameters (strength and direction) as the wheel rotates and changes orientation. By monitoring these parameter changes over time, the control circuitry calculates precise positional and orientational information without requiring complex hardware.
3Measurement precision
If a detectable element is radially offset from the central axis, then the measurement precision of angular orientation improves, but the manufacturing precision requirements increase
Solution Approach 1:
The magnetic sensor provides continuous feedback on the position and orientation of the detectable element. The control circuitry uses this feedback to calculate wheel parameters and can compensate for minor manufacturing variations in the radial offset position, maintaining high angular orientation precision without stringent manufacturing tolerances.
Solution Approach 2:
The detectable element is pre-positioned at a specific radial offset distance from the central axis during wheel assembly. This preliminary positioning establishes the geometric relationship needed for accurate angular measurement, and the system is calibrated to account for this fixed offset, reducing the need for high-precision manufacturing variations.
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
Enhances the control and handling of lawn maintenance devices by accurately detecting wheel positions and orientations, allowing for improved traction control and adaptive responses to adverse events, thereby preventing slipping and damage.
Implementation Method 1
the detector is a magnetic sensor and the detectable element is a magnet
Data Source
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AI summary
Lawn maintenance devices and tracking systems and methods for lawn maintenance devices are provided. A lawn maintenance device includes a frame; a wheel supporting the frame, wherein the wheel comprises: a body defining a central axis about which the body is rotatable; and a detectable element radially offset from the central axis; a detector that detects a relative position of the detectable element; and control circuitry that receives information from the detector and determines a position of the wheel based on the received information, the information associated with the detected relative position of the detectable element.