Front ToF Cliff Detection for Faster Mobile Robots
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Solution Overview
Problem
Conventional mobile robots equipped with sensors or cameras attached to the bottom or under the chassis cannot detect cliffs until they physically extend over the edge, leading to inefficient operation due to the need for slow speeds and inability to anticipate path changes.
Innovation Solution
A mobile robot equipped with a time of flight (ToF) sensor featuring an array of single-photon avalanche diode (SPAD) sensors attached to the front, which senses reflected signals to detect an approaching cliff from multiple distance ranges, allowing the robot to change its propulsion before reaching the edge.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a sensor or camera is attached under the mobile robot to detect cliffs, then the robot can detect cliff edges, but the robot cannot detect cliffs until it physically extends over the edge, requiring slow speeds and reducing efficiency
Solution Approach 1:
The patent transitions from detecting cliffs in the vertical dimension (under the robot) to detecting them in the horizontal dimension (in front of the robot). By mounting the ToF sensor on the front surface, the system detects cliff edges before the robot reaches them, enabling early path adjustment without sacrificing operational efficiency.
2Reliability
If the robot moves at low speeds to allow time for cliff detection and path change, then the robot can safely detect and avoid cliffs, but the robot operates inefficiently
Solution Approach 1:
The system performs cliff detection in advance by positioning the ToF sensor on the front surface, allowing the robot to identify cliff edges before reaching them. This preliminary detection enables the robot to maintain higher speeds while still having sufficient time to adjust its path safely.
3Reliability
If the sensor is attached under the chassis, then the robot can detect cliffs, but the robot cannot anticipate path changes and must move slowly
Solution Approach 1:
By mounting the ToF sensor on the front surface rather than under the chassis, the system detects cliff edges before the robot reaches them. This allows advance path planning and adjustment, reducing the time needed for reactive maneuvers and improving overall operational efficiency.
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
Enables the mobile robot to travel at faster speeds by anticipating cliff edges from various distances, optimizing its path and preventing falls, thus enhancing operational efficiency.
Implementation Method 1
a time of flight (ToF) sensor featuring an array of single-photon avalanche diode (SPAD) sensors attached to the front, which senses reflected signals
Implementation Method 2
senses reflected signals to detect an approaching cliff
Implementation Method 3
including an array of single-photon avalanche diode (SPAD) sensors
Data Source
Figure 1A~1B
Figure 1C
Figure 2A~2B
AI summary
A method of operating a robotic device includes: moving (402) the robotic device towards an edge of a cliff while a ToF sensor senses reflected signals having been transmitted by the ToF sensor, the reflected signals being generated by the signals transmitted by the ToF sensor being reflected off a target object back to the ToF sensor, the ToF sensor being attached to a front of the robotic device and including an array of single-photon avalanche diode, SPAD, sensors; comparing (404) a statistical distribution of the reflected signals received at a plurality of different rows of zones configured by the array of SPADs in a region of interest, ROI, of the ToF sensor and based on the comparing detecting (406) an approaching of the edge of the cliff; and in response to detecting the approaching of the edge, changing a propulsion of the robotic device before reaching the edge.