Autonomous Lawnmower Sensor for Subsurface Boundary Detection
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Solution Overview
Problem
Existing landscape maintenance devices, such as autonomous lawnmowers, face challenges in efficiently defining work areas without physical barriers, accurately detecting obstacles, and minimizing damage from collisions, as they rely on either high-installation-effort edging wires or ineffective tactile and ultrasonic sensors.
Innovation Solution
A sensor device that can distinguish between different properties of the subsurface using the normalized differentiated vegetation index (NDVI) and fluorescence spectroscopy, allowing for precise detection of vegetation and obstacles without external aids, enabling the device to autonomously navigate and avoid collisions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If edging wire is used to delimit work area, then work area definition reliability is improved, but installation effort and device complexity increase
Solution Approach 1:
The patent removes the edging wire component entirely from the system. Instead of using external physical barriers to define the work area, the lawnmower uses its own sensor capabilities to detect and identify the boundary between grass and non-grass areas, thereby extracting the boundary definition function from an external wire system to the mower's onboard detection system.
Solution Approach 2:
The lawnmower performs self-boundary-definition using its sensor device. The system autonomously detects the work area boundaries by sensing the optical properties of the grass, eliminating the need for external assistance in the form of edging wires. The mower serves itself by integrating boundary detection capabilities directly into its navigation system.
2Manufacturing precision
If edging wire is used to delimit work area, then work area boundaries are defined, but clean cut at outer limit cannot be ensured and post-processing is required
Solution Approach 1:
The sensor device provides continuous feedback to the control unit about the proximity to grass boundaries. This feedback mechanism allows the control unit to adjust the mower's path in real-time, ensuring that cutting stops precisely at the grass edge without requiring manual intervention or post-processing trimming.
Solution Approach 2:
The sensor device detects the grass boundary before the mower reaches it, allowing the control unit to preemptively adjust the cutting path. This preliminary detection and adjustment prevents the mower from cutting into non-grass areas, eliminating the need for post-processing to correct boundary errors.
3Reliability
If tactile sensor units are used to detect obstacles, then collision detection is achieved, but object and lawnmower damage occur and flat objects cannot be detected
Solution Approach 1:
The patent replaces mechanical tactile sensors with an optical sensor device that uses light reflection properties to detect obstacles. This substitution eliminates the need for physical contact between the mower and obstacles, preventing damage while maintaining detection capability. The optical system can detect flat objects like hands in the grass that tactile sensors would miss.
Solution Approach 2:
The sensor device acts as an intermediary between the mower and obstacles, providing advance warning of potential collisions through optical detection. This intermediary system allows the control unit to take preventive action before physical contact occurs, eliminating the harmful effects of direct collision while maintaining obstacle awareness.
4Measurement precision
If ultrasonic sensor units are used to detect obstacles, then distance measurement is improved, but detection range is limited to minimum distance and ground objects cannot be reliably detected
Solution Approach 1:
The patent replaces ultrasonic acoustic sensors with an optical sensor device that uses light reflection properties. This substitution extends detection capability to include flat objects on the ground surface that ultrasonic sensors cannot reliably detect, while maintaining accurate distance measurement through optical means.
Solution Approach 2:
The sensor device detects obstacles by measuring changes in optical parameters such as light reflection intensity and patterns. By monitoring these optical parameter changes, the system can reliably detect ground-level objects and determine their distance, overcoming the limitations of ultrasonic sensors that struggle with flat, low-reflectivity surfaces.
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 reduces installation effort, minimizes post-processing needs, and effectively prevents collisions by accurately differentiating between work and non-work areas and detecting obstacles, enhancing the safety and efficiency of autonomous landscape maintenance operations.
Implementation Method 1
the sensor device is designed in such a way that it can detect and assign different properties of a subsurface below and/or in the immediate vicinity of the device based on the degree of reflection of a radiation emitted by the sensor device and reflected on the subsoil
Implementation Method 2
it can detect and assign different properties of a subsurface below and/or in the immediate vicinity of the device by determining the normalized, differentiated vegetation index NDVI
Implementation Method 3
The sensor device has a light source that is designed in such a way that it can emit light in the visible spectral range at a wavelength of about 620 to about 700 nm and light in the infrared range at a wavelength of about 725 to about 1100 nm
Data Source
Figure 1
Figure 2a~2b
Figure 3a~3b
AI summary
The invention relates to a device (100) for landscape maintenance, particularly a lawn mower, comprising at least one sensor unit (107; 130), wherein the at least one sensor unit (107; 130) is composed such that it may detect and allocate various structures of a subsurface (113) beneath and/or in the environment of the device.