Multi-Axis Boundary Sensor Assembly for Robotic Mower Navigation
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Solution Overview
Problem
Robotic lawn mowers face challenges in accurately detecting boundary wires, especially on slopes or when approaching at oblique angles, due to roll, pitch, and yaw, which can lead to unreliable boundary sensing and navigation.
Innovation Solution
A boundary sensor assembly with multiple inductive sensors oriented at non-zero angles to each other, including at least two sensors with vertical and horizontal components, allows for accurate detection of the boundary wire by generating signals indicative of distance and orientation, enabling the robotic mower to adjust its movement accordingly.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a single inductive sensor is used for boundary detection, then the device complexity is low, but the measurement precision deteriorates when the mower is on slopes or approaches at oblique angles
Solution Approach 1:
The patent transitions from a single sensor measuring distance in one dimension to multiple sensors oriented at different angles (including vertical and horizontal components) to capture spatial information in multiple dimensions. This enables the system to distinguish between changes in distance caused by slope/terrain versus changes caused by the mower's approach angle, thereby maintaining measurement precision across varied operating conditions.
Solution Approach 2:
The boundary sensing function is segmented into multiple independent inductive sensors, each oriented along a different axis. This segmentation allows the system to process directional information separately and combine it to determine the mower's position and orientation relative to the boundary wire, improving detection accuracy without creating a single complex sensor unit.
2Reliability
If multiple inductive sensors oriented at non-zero angles are used, then the reliability of boundary sensing improves on slopes and oblique angles, but the device complexity increases
Solution Approach 1:
The multi-oriented sensor assembly performs multiple functions simultaneously: it detects the boundary wire's presence, determines the mower's distance from the boundary, and calculates the mower's orientation angle relative to the boundary. This multi-functionality is achieved through a unified sensor assembly that processes signals from multiple sensor elements, improving reliability without requiring separate systems for each function.
Solution Approach 2:
The system uses feedback from multiple sensors to continuously monitor and adjust for the mower's orientation and position. By comparing signals from sensors at different angles, the control unit can detect deviations caused by slopes or oblique approaches and compensate for them, maintaining reliable boundary sensing through active feedback correction.
3Adaptability or versatility
If sensors are oriented with vertical and horizontal components, then the ability to detect oblique approaches and slopes improves, but the manufacturing precision requirements increase
Solution Approach 1:
The system achieves adaptability to slopes and oblique angles by changing the orientation parameters of the sensor assembly. Instead of requiring each individual sensor to be perfectly aligned, the system uses multiple sensors with fixed but varied orientations (including vertical and horizontal components) and processes their combined signals to calculate the mower's actual orientation, thereby achieving versatility through parameter variation rather than precise single-point alignment.
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 enhances the robotic mower's ability to navigate boundaries accurately, even on uneven surfaces and at oblique angles, by providing reliable distance and orientation data to the control unit, ensuring efficient and precise mowing within designated areas.
Implementation Method 1
The sensor assembly includes at least two inductive sensors with a first inductive sensor oriented along a first axis, and a second inductive sensor oriented along a second, different, axis
Data Source
AI summary
A robotic mower sensor assembly for detecting a boundary wire signal. The sensor assembly includes a plurality of analog inductive sensors with a first inductive sensor oriented along a first axis and a second inductive sensor oriented along a second, different axis. Each inductive sensor is configured to generate a signal indicative of the distance of the robotic mower from the boundary wire. A control unit communicating with the sensor assembly is configured to operate the robotic mower in response to the signals from the sensor assembly which are indicative of the distance of the robotic mower from the boundary wire.