Tilted Ultrasonic Sensor Rings for Cliff Detection
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Solution Overview
Problem
Devices that move on or operate on surfaces face challenges in effectively detecting surface information, such as wetness, dirtiness, hardness, softness, and detecting cliff-like drop-offs and estimating their depth, due to high noise levels from direct echo path reflections.
Innovation Solution
The use of defined rings, either debossed or embossed, around the acoustic opening ports of ultrasonic sensors disrupts sound pressure in the gap between the sensor and the surface, reducing direct echo path reflections and increasing signal amplitude. These rings can also shape beam patterns of transmitted and returned sonic signals.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If ultrasonic sensors are used to detect surface information and cliffs, then detection capability is improved, but direct echo path reflections cause high noise levels that deteriorate measurement precision
Solution Approach 1:
An acoustic interface housing is introduced as an intermediary component between the ultrasonic sensor and the surface. This housing includes an acoustic opening port that mediates the acoustic path, allowing the sensor to detect surfaces while reducing direct echo path reflections through controlled acoustic transmission and reflection geometry.
Solution Approach 2:
The acoustic interface housing extends the acoustic detection path into a third dimension by creating a tilted acoustic path relative to the surface. This dimensional change allows the sensor to detect cliffs and depth information while separating the detection path from direct echo paths that cause noise.
2Measurement precision
If the sensor is positioned close to the surface for detailed detection, then detection resolution is improved, but direct echo path reflections increase causing higher noise levels
Solution Approach 1:
The acoustic interface housing creates a tilted acoustic detection path that extends into the third dimension. This allows the sensor to operate at close proximity to the surface for high-resolution detection while the tilted geometry redirects direct echo path reflections away from the sensor, reducing noise.
3Productivity
If the device moves at higher speeds for increased productivity, then output is improved, but cliff detection latency increases reducing reliability
Solution Approach 1:
The tilted acoustic interface housing enables preliminary cliff detection by creating an acoustic path that intersects potential cliff edges before the device reaches them. This preliminary action allows the system to detect cliffs earlier, providing sufficient time for response even at higher operating speeds.
4Loss of time
If the sensor is tilted to detect cliffs earlier, then cliff detection timing is improved, but signal amplitude from the surface decreases
Solution Approach 1:
The acoustic interface housing is designed with specific geometric parameters including tilt angle and opening port dimensions that optimize the balance between early cliff detection and surface signal amplitude. By carefully controlling these parameters, the system achieves both reduced detection latency and maintained signal strength.
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 defined rings significantly reduce direct echo path noise, enhancing the signal-to-noise ratio and improving the device's ability to detect surface types and cliffs, while allowing for increased speed and reliability in surface navigation.
Implementation Method 1
The use of defined rings, either debossed or embossed, around the acoustic opening ports of ultrasonic sensors disrupts sound pressure in the gap between the sensor and the surface, reducing direct echo path reflections and increasing signal amplitude.
Implementation Method 2
A variety of devices exist which move about on or operate on floors or other surfaces... ultrasonic sensors... transmit sonic signals and receive returned sonic signals
Implementation Method 3
the sonic sensor transmits the sonic signals toward the surface and receives corresponding returned signals that are reflected from the surface
Data Source
AI summary
A robotic cleaning appliance includes a housing to which is coupled a surface treatment item and a sensor assembly with first and second transducers and an acoustic interface. The first sonic transducer transmits sonic signals through an acoustic interface and out of a first acoustic opening toward a surface beneath the robotic cleaning appliance. The sonic signals reflect from the surface as corresponding returned signals received by the second sonic transducer via a second acoustic opening port of the acoustic interface. A first annular ring is defined around the first acoustic opening port and a second annular rings is defined around the second acoustic opening port. The annular ring attenuate direct path echoes between the acoustic opening ports. The first and second acoustic opening ports are coupled the first and sonic transducers, respectively, via first and second horns; and the horns are tilted from orthogonal with the surface.