Front-Mounted ToF Cliff Detection for Faster Mobile Robots
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Solution Overview
Problem
Conventional mobile robots equipped with sensors attached to the bottom or cameras struggle to detect cliffs efficiently, leading to slow movement and inefficiency, as they can only detect the cliff when a part of their body is over the edge.
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 three different 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 must move at low speeds because it cannot detect the cliff until a portion of its body is physically over the edge
Solution Approach 1:
The patent transitions from detecting cliffs in the vertical dimension (under the robot) to detecting cliffs in the horizontal dimension (front of the robot). By attaching the ToF sensor to the front surface, the robot can detect cliff edges before physically approaching them, enabling early path planning and maintaining higher speeds.
Solution Approach 2:
The ToF sensor performs preliminary detection of cliff edges at a distance before the robot reaches them. This advance detection allows the robot to plan and execute path changes proactively, rather than reactively when already over the edge, thus maintaining higher speeds throughout operation.
2Reliability
If the robot moves at low speeds to allow time for cliff detection and path change, then the robot can safely change its path before falling, but the robot operates inefficiently
Solution Approach 1:
The system performs cliff detection and path planning in advance using the front-mounted ToF sensor, allowing the robot to maintain higher speeds while still executing safe path changes. The preliminary detection provides sufficient time for computation and actuation without constraining overall speed.
Solution Approach 2:
The ToF sensor acts as an intermediary that provides advance information about cliff locations, enabling the control system to plan paths proactively. This intermediary detection mechanism decouples the speed of movement from the timing of detection, allowing high-speed operation with safe path planning.
3Reliability
If a sensor is attached under the chassis of the mobile robot, then the robot can detect cliffs, but the robot cannot detect the cliff until a portion of its body is physically over the edge
Solution Approach 1:
The patent relocates the sensor from the bottom surface (vertical detection) to the front surface (horizontal detection), enabling the robot to detect cliffs at a distance before physical contact. This dimensional change transforms detection from a reactive process to a proactive one, eliminating detection time loss.
Solution Approach 2:
The front-mounted ToF sensor performs preliminary detection of cliff edges before the robot physically approaches them. This advance detection eliminates the time delay associated with waiting for the robot to move over the edge, enabling immediate path planning and execution.
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 a distance, optimizing its path and preventing potential falls, thus enhancing its operational efficiency.
Implementation Method 1
a time of flight (ToF) sensor... while the 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
Implementation Method 2
an array of single-photon avalanche diode (SPAD) sensors... receiving reflected signals by a plurality of zones configured by the array of SPADs
Data Source
AI summary
Cliff Detection in Robotic Devices A method of operating a robotic device includes: moving 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 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 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.