Technology
Operational Information
Toposens’3D Echolocation Sensor work by combining the time-of-flight
principle of conventional ultrasonic sensors with triangulation and
advanced signal processing algorithms.
At the beginning of each measurement cycle, the transducer on the
sensor sends out an ultrasonic pulse. This pulse is reflected by
surrounding objects and received by an array of microphones on the
sensor. Based on the time of flight of echoes arriving at the individual
microphones, the origins of the echoes are calculated as 3D
coordinates. These 3D coordinates are put out at the end of each
measurement cycle.
Theory of Operation
[1] the transducer (red) sends out an ultrasonic pulse, [2] the wave is
carried forward by the air molecules, [3] the wave is reflected by an
object, [4] a portion of the echo is directed back to the sensor, [5] the
echo is sequentially captured by the microphone array, arriving first at
(a) the left microphone, and then at (b) the right microphone, [6] a 3D
location of the echo’s origin (light red) is determined from the signal’s
time-of-flight and the delay between microphones receiving the echo.
Interface
The USB- and Serial Connection must not be used simulatiously –
This can damage the Sensor and connected Devices
The data stream for both output connections is identical. Both
connection modes support all configurations and modes.
Data Frame
The sensor outputs the measurements as a list of points in a human
readable ASCII format.
S000000P0000X00285Y-0184Z-0374V00050….E
Each measurement data frame starts with S000000 and ends with E,
while individual points in a frame are separated by P0000. If noise is
detected during the measurement, the affected frames are flagged
with the frame delimiter S100000.
Data contained in each point: coordinates x, y & z in millimetres;
relative signal strength v in range 0 to 255.
Commands and Acknowledgment Messages
There are two types of commands, that can be sent to TS3: “Set"-and
“Get"-commands. “Set”-Commands change the sensor's settings and
trigger an acknowledgment message, which is returned by the sensor.
“Get”-Commands issue a request, which retrieves current settings and
information from the sensor.
•TS3 only receives a single command at a time
•Default values for parameters are applied at start up.
In case multiple commands are to be sent to TS3at once, it is necessary
to wait for the acknowledgment message for each respective command
before issuing the next command.
Available "set"-Commands
“Set”-commands change the sensor’s settings. When executed the
sensor answers with an acknowledgement.
Structure for each command: C <command> <value> \r
Length of string: C**********\r = 13 characters
Echo Rejection Threshold
the minimum amplitude for echoes above
are considered valid detections. A low value
in a higher number of detections but also
probability of false detections
-digit unsigned integer representing the threshold
00001\r for a threshold offset of 1
Noise Indicator Threshold
a threshold which is applied to the
level readings from the raw ADC
above this threshold are flagged as
.4-digit unsigned float representing the threshold
= 0.5, min. = 0.0000; max. = 0.9999.
: only values between 0 and 0.9999
05000\r for a mark threshold of 0.5
Number of Pulses
number of ultrasonic pulses emitted by the
in every transmission cycle. Increasing
will allow the detection of objects that
away, decreasing it will increase the quality
-digit unsigned integer representing the number
00010\r for 10 pulses
Peak Detection Window
the kernel size (window width) that is applied
ADC signals to detect valid echoes (peaks in
ADC signal). A low value will allow for
of multiple objects that are close to
. A high value will result in "smoother" and
-digit unsigned integer representing the size of
00003\r for size of 3
3
Preliminary Prototype | All right reserved | All Information without warranty
