Mower Position Estimation Switching for GPS Signal Loss
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Solution Overview
Problem
Existing lawn mowers with automatic traveling capabilities face a decrease in self-position estimation accuracy when navigating through areas with tree coverages, as GPS measurements become unreliable in such conditions.
Innovation Solution
A mower equipped with both a satellite positioning system for initial position estimation and a sensor unit for secondary estimation, along with a detection unit using RGB image data and ortho image data to identify plant coverages, allowing the mower to switch to sensor-based estimation when GPS accuracy is compromised.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If GPS satellite positioning system is used for self-position estimation, then position estimation is available under normal conditions, but accuracy decreases when traveling route is covered with trees or plants
Solution Approach 1:
The patent combines multiple position estimation methods (GPS satellite positioning and sensor-based estimation using odometry and inertial sensors) into a unified system. The automatic travel control unit switches between or fuses these methods depending on the environment, ensuring reliable position estimation whether the mower is in open areas or under tree cover where GPS signals are blocked.
Solution Approach 2:
The system dynamically adapts its position estimation approach based on environmental conditions. When GPS signals are available, the system uses satellite positioning; when the route is covered with plants or trees, the system switches to sensor-based estimation using wheel odometry and inertial measurement units, maintaining continuous and accurate position tracking throughout the mowing operation.
2Measurement precision
If dual position estimation units are provided, then position estimation accuracy is maintained in challenging conditions, but device complexity increases
Solution Approach 1:
The sensor unit serves multiple functions: it provides position estimation when GPS is unavailable, enables detection of plant-covered areas through its sensors, and can potentially provide backup or complementary data for GPS-based positioning. This multi-functionality justifies the added complexity by providing a versatile component that enhances system performance in multiple ways.
Solution Approach 2:
The automatic travel control unit acts as an intermediary that manages the two position estimation units. It receives data from both the GPS receiver and the sensor unit, determines which method is more reliable in current conditions, and selects or fuses the appropriate position estimates. This intermediary layer simplifies the overall system architecture by providing a unified control interface despite the dual estimation units.
Data Source
AI summary
The mower includes a mower body having a mower blade portion for mowing grass, a first position estimation unit for estimating a self position of the mower main body using a satellite positioning system, a second position estimation unit for estimating a self position of the mower body using a sensor portion provided in the mower body, a detection unit for detecting a portion covered with grass and tree on a preset travel path, and an automatic travel control unit for causing the mower body to travel on the travel path with reference to the self position estimated by the first position estimation unit, and for causing the mower body to travel by switching to refer to the self position estimated by the second position estimation unit at a portion covered with the grass and tree detected by the detection unit.