Robotic Mower Area Coverage Control via Sensor Feedback
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Solution Overview
Problem
Robotic lawn mowers often leave uncut areas of grass due to inefficient grass length sensors and the need to return to a charging station before completing large areas, leading to incomplete coverage within known boundaries.
Innovation Solution
A robotic mower equipped with a load sensor, boundary sensor, and timer, controlled by a vehicle control unit that selects area coverage types based on sensor inputs, adjusting its path to ensure complete coverage by offsetting from the boundary wire when necessary, using spiral patterns for uncut areas and straight lines for cut areas.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the robotic mower uses random motion within the boundary wire, then the mower can operate automatically without guidance, but it leaves uncut areas of grass that human observers can easily detect
Solution Approach 1:
The system dynamically adjusts the mowing pattern based on real-time sensor feedback. The controller transitions from random motion to structured patterns (spiral, parallel, or concentric) depending on boundary sensor detections and grass length sensor readings, optimizing coverage completeness while maintaining automatic operation
Solution Approach 2:
The system uses multiple sensors (boundary sensors, grass length sensors, load sensors) to continuously monitor the mowing environment and provides feedback to the controller. This feedback loop enables the system to detect uncut grass and adjust the mowing pattern accordingly, ensuring complete coverage while operating automatically
2Device complexity
If the robotic mower relies on probability for convergence of coverage, then the mower can operate with simple sensors, but the grass length sensors are unable to efficiently find uncut grass
Solution Approach 1:
The system performs preliminary boundary mapping by detecting boundary wires before actual mowing begins. This preliminary action establishes a known workspace geometry that guides subsequent mowing patterns, enabling efficient coverage without requiring complex real-time grass detection algorithms
Solution Approach 2:
The boundary wire acts as an intermediary that provides structural guidance for the mowing pattern. Instead of relying solely on grass length sensors to detect uncut areas, the system uses the boundary wire geometry to organize systematic coverage patterns, improving efficiency while keeping sensors simple
3Duration of action of moving object
If the robotic mower must return to the charging station, then the mower can recharge for continued operation, but it cannot complete mowing a large area
Solution Approach 1:
The system performs preliminary boundary mapping and calculates the total mowing area before beginning operation. Based on this preliminary assessment and battery capacity, the system can determine whether the current charge is sufficient to complete the entire area, allowing it to commit to complete coverage without premature returns to the charging station
4Manufacturing precision
If the robotic mower uses a specified boundary coverage offset from the boundary wire, then the mower can ensure complete boundary coverage, but the mower path must be dynamically adjusted based on boundary proximity
Solution Approach 1:
The system changes the offset parameter dynamically based on boundary proximity. When the boundary sensor detects the mower is close to the boundary wire, the system adjusts the offset distance to maintain optimal coverage near edges, while using larger offsets in open areas. This parameter adaptation ensures complete boundary coverage without requiring complex path planning algorithms
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
The solution ensures more complete lawn coverage by dynamically adjusting the mowing path based on grass length and proximity to the boundary wire, reducing uncut areas and improving overall mowing efficiency.
Implementation Method 1
a boundary sensor on the robotic mower indicating the distance from the boundary sensor to a boundary wire
Implementation Method 2
The load sensor may sense current in the cutting blade motor.
Data Source
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AI summary
A robotic mower area coverage system, includes a load sensor on the robotic mower (100) signaling a load on a cutting blade motor (112); a boundary sensor (119) on the robotic mower (100) indicating the distance from the boundary sensor (119) to a boundary wire (103, 104); a timer on the robotic mower (100) indicating when the robotic mower (100) last used a specified boundary coverage; a vehicle control unit (101) on the robotic mower (100) selecting the type of area coverage based on inputs from the load sensor, the boundary sensor (119) and the timer, and commanding a pair of traction drive motors (110, 111) to drive the robotic mower (100) using the selected type of area coverage.