Evaluation of Sensors for a Smart Wheelchair
Edmund F. LoPresti & Richard C. Simpson, University of Pittsburgh, PA
David Miller, Kiss Institute for Practical Robotics, Norman, OK
Illah Nourbakhsh, Carnegie Mellon University, Pittsburgh, PA
Slide text:Detection distance and detection angle measured for large, flat obstacles, for 8 materials:
Detection angle was measured for thin, cardboard obstacles for 8 obstacles widths:
MINIMUM DETECTION DISTANCE (Median Across Materials)
The graph for minimum detection distance shows the shortest distance for which each sensor could reliably detect an obstacle. For each sensor model, the median is shown across all obstacle materials. The values are:Polaroid 600: 8.2 cm; Polaroid 9000: 25.6 cm; Sharp GP2D02: 3.0 cm; Sharp GP2D12: 0.8 cm; Massa: 34.6 cm; Sonaswitch: 21.8 cm; Devantech: 0.8 cm.
The graph shows that the minimum distance was quite small for the Devantech sonar and both Sharp infrared sensors, slightly farther away for the Polaroid 600, and noticeably farther for the Polaroid 9000, Massa, and Sonaswitch.
MAXIMUM DETECTION DISTANCE(Median Across Material)
Graphic description:The graph for maximum detection distance shows the largest distance for which each sensor could reliably detect an obstacle. For each sensor model, the median is shown across all obstacle materials. The values are:Polaroid 600: 348.9 cm; Polaroid 9000: 405.3 cm; Sharp GP2D02: 63.2 cm; Sharp GP2D12: 75.6; Massa: 248.3 cm; Sonaswitch: 238.2 cm; Devantech: 183.8 cm.
The graph shows that the two Polaroid sensors were able to detect obstacles at the greatest distance, followed by the Massa, Sonaswitch, and Devantech, and finally the two Sharp infrared sensors.
DETECTION ANGLE FOR LARGE OBSTACLES (Median Across Materials)
The first graph shows Detection Angle, the angle at which each sensor could detect a large obstacle (between 40 and 150 cm wide). For each sensor model, the median is shown across all obstacle materials.
The values are:Polaroid 600: 56.9 degrees; Polaroid 9000: 66.2 degrees; Sharp GP2D02: 141.7 degrees; Sharp GP2D12: 141.2 degrees; Massa: 43.6 degrees; Sonaswitch: 68.0 cm; Devantech: 79.4 degrees. The graph indicates that the two Sharp infrared sensors could detect obstacles at the greatest angles.
MAXIMUM DISTANCE ACROSS MATERIALS, SHARP GP2D12
The second graph shows the effect of obstacle material properties on detection distance for the Sharp GP2D12 infrared sensor. The detection distances were bare drywall: 98.9 cm; white drywall: 115.8 cm; black drywall: 30.9 cm; wood: 100.2 cm, glass: 28.2 cm; carpet: 89.8 cm; marble: 39.2 cm; brick: 61.4 cm. The graph indicates that infrared detection distance was lowest for black drywall, black marble and glass.
SONASWITCH VOLTAGE-DISTANCE RELATIONSHIP
The third graph shows Sonaswitch Voltage-Distance Relationship. The Sonaswitch sensor voltage response is near zero until eight inches, after which it rises in an almost linear manner until an object is 38 inches away, at which point the voltage remains near five volts.
SHARP GP2D12 VOLTAGE-DISTANCE RELATIONSHIP
The fourth graph shows Sharp GP2D12 Voltage-Distance Relationship. The infrared sensor reading rises steeply from zero volts at zero inches to almost three volts at three inches, then falls asymptotically until it reaches zero volts near 42 inches.
Updated: May 6, 2003
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Please note: This information is provided a archival information from the Rehabilitation Engineering Research Center on Wheeled Mobility from 1993 to 2002.