Robotic Lift and Collision Detection Using Dual Distance Thresholds
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Solution Overview
Problem
Existing robotic work tools, such as lawnmowers, face challenges in accurately distinguishing between lift and collision events due to shared movement in the Z-direction, leading to false positives and operational impairments, and require complex and costly designs to differentiate between hard collisions and false positives.
Innovation Solution
A robotic work tool with a lift/collision detection device comprising a first and second sensor element connected to a controller, where the controller receives distance values and compares them to distinct thresholds to differentiate between lift and collision events, with different transmission ratios for horizontal and vertical movements to ensure accurate detection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single sensor arrangement is used for both lift and collision detection, then device complexity is reduced, but measurement precision deteriorates due to inability to distinguish between lift and collision events
Solution Approach 1:
The single sensor arrangement is segmented into two functional components: a first sensor element for detecting Z-direction movement (lift detection) and a second sensor element for detecting XY-plane movement (collision detection). This segmentation allows the system to use one sensor arrangement for both purposes while maintaining measurement precision by directing each sensor element to detect specific movement types.
Solution Approach 2:
Different sensor elements within the same sensor arrangement are assigned different detection functions based on their local orientation and positioning. The first sensor element is configured to detect vertical displacement while the second sensor element detects horizontal displacement, allowing each element to have specialized local quality for its specific detection task.
2Reliability
If a pivotable joystick member is used to allow hard collisions without false positives, then reliability improves, but device complexity and manufacturing cost increase
Solution Approach 1:
The joystick member is segmented into a pivotable component for collision detection and a slidable component for lift detection. This segmentation allows the system to detect hard collisions reliably through the pivotable element while using the slidable element to distinguish lift events from collision events, preventing false positives without requiring an overly complex joystick structure.
Solution Approach 2:
The detection system utilizes two different dimensional movements of the same sensor arrangement: Z-direction vertical movement for lift detection and XY-plane horizontal movement for collision detection. By detecting movements in different dimensions, the system achieves reliable collision detection while maintaining a simpler overall structure.
3Measurement precision
If the sensor arrangement is designed to detect only Z-direction movement, then lift detection sensitivity improves, but collision detection capability deteriorates
Solution Approach 1:
Within the same sensor arrangement, the first sensor element is optimized with local quality for Z-direction sensitivity (lift detection) while the second sensor element is oriented with local quality for XY-plane sensitivity (collision detection). This allows the sensor arrangement to maintain high lift detection sensitivity while simultaneously具备 collision detection capability.
Solution Approach 2:
The sensor arrangement is designed as a universal detection system that can perform both lift detection and collision detection functions. By incorporating multiple sensor elements with different orientation sensitivities within a single arrangement, the system achieves multi-functionality without requiring separate detection systems for each event type.
Data Source
AI summary
A robotic work tool having a chassis, a cover and a controller for controlling the operation of the robotic work tool. The robotic work tool further has a lift/collision detection device (300) connected to the controller for providing sensor input, and which Hft/coUision detection device (300) includes a first sensor element (340) and a second sensor element (345), The controller ( 1 10) is configured to receive sensor input of a distance value indicating a distance between the first sensor element (340) and the second sensor element (345), determine that a lift has been detected, fay comparing the distance value with a lift detection threshold and/or determine that a collision has been detected, by comparing the distance value with a collision detection threshold, wherein the collision detection threshold is different from the lift detection threshold.