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.
S000000
P0000
X00285
Y-0184
Z-0374
V00050
…
.
E
Frame
Delimiter
Point
Delimiter
X [mm]
Y [mm] Z [mm]
V [no Unit]
Frame
Terminator
S000000
P0000
X00285
Y-0184
Z-0374
V00050
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 TS3 at 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
Command
sReje
Effect
Sets the minimum amplitude for echoes above which
they are considered valid detections. A low value will
result in a higher number of detections but also a
higher probability of false detections
Parameter
5-digit unsigned integer representing the threshold
Applicable Values
Default = 1, min. = 0, max. = 20
Example
CsReje00001\r
for a threshold offset of 1
Noise Indicator Threshold
Command
sNois
Effect
Sets a threshold which is applied to the normalized
noise level readings from the raw ADC signals.
Detections above this threshold are flagged as "noisy"
Parameter
1.4-digit unsigned float representing the threshold
Applicable Values
Default = 0.5, min. = 0.0000; max. = 0.9999. Please
note: only values between 0 and 0.9999 are
recommended
Example
CsNois05000\r
for a mark threshold of 0.5
Number of Pulses
Command
sPuls
Effect
Sets number of ultrasonic pulses emitted by the piezo
transducer in every transmission cycle. Increasing the
value will allow the detection of objects that are
further away, decreasing it will increase the quality of
detections in close range
Parameter
5-digit unsigned integer representing the number of
pulses to be sent out
Applicable Values
Default = 8, min. = 0, max. = 20
Example
CsPuls00010\r
for 10 pulses
Peak Detection Window
Command
sPeak
Effect
Sets the kernel size (window width) that is applied on
raw ADC signals to detect valid echoes (peaks in the
raw ADC signal). A low value will allow for better
separation of multiple objects that are close to each
other. A high value will result in "smoother" and more
stable detections
Parameter
5-digit unsigned integer representing the size of the
the object filter
Applicable Values
Default = 3, min. = 1, max. = 5
Example
CsPeak00003\r
for size of 3
3
Preliminary Prototype | All right reserved | All Information without warranty
