Where am I? Sensors and Methods for Mobile Robot Positioning

120 Part I Sensors for Mobile Robot Positioning
Figure 4.29: LightRanger data plotted from scans of a room. An open door at the upper left
and a wall in the corridor detected through the open doorway are seen in the image to the
left. On the right a trail has been left by a person walking through the room. (Courtesy of
Transitions Research Corp.)
4.2.5 Swiss Federal Institute of Technology's “3-D Imaging Scanner”
Researchers at the Swiss Federal Institute of Technology, Zürich, Switzerland, have developed an
optical rangefinder designed to overcome many of the problems associated with commercially
available optical rangefinders [Adams, 1995].
The design concepts of the 3-D Imaging Scanner
have been derived from Adam's earlier
research work at Oxford University, U.K.
[Adams, 1992]. Figure 4.30 shows the working
prototype of the sensor. The transmitter consists
of an eye-safe high-powered (250 mW) Light
Emitting Diode (LED) that provides a range
resolution of 4.17 cm/( of phase shift between
Table 4.13: Preliminary specifications for the 3-D
Imaging Scanner. (Courtesy of [Adams, 1995].)
Parameter
Value Units
Maximum range 15 m
50 ft
Minimum range
0 m
LED power (eye-safe)
1 mW
Sweep (horizontal)
(vertical — “nod”)
360 (
130 (
Resolution (range) ~20 mm
0.8 in
(azimuth) 0.072 (
Sample rate
8 kHz
Size (diameter×height) 14×27 cm
5.5×10 in
(electronics) Not yet determined
Weight
Not yet determined
Power
+12 V @ 400 mA
-12 V @ 20 mA
Figure 4.30: The 3-D Imaging Scanner consists of a
transmitter which illuminates a target and a receiver to
detect the returned light. A range estimate from the
sensor to the target is then produced. The mechanism
shown sweeps the light beam horizontally and
vertically. (Courtesy of [Adams, 1995].)