Operation Manual

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4.2 Mobile beacon (“hedgehog”)
- The mobile and stationary beacons can be easily interchanged by selecting the
option in the Dashboard
- The mobile beacons designed to be
placed on a robotic vehicle,
copter/drone, AGV, or helmet to trace its
location. Formally speaking, location of
the mobile beacon is traced—not the
robot itself. Since the sizes and the
location of the central point of the mobile
beacon and the robot are different, the
difference taken into account in the
robot’s software (SW)
- It is recommended to place the mobile
beacon horizontally to provide optimal
ultrasonic coverage in the upper
hemisphere
- Its sensors must not be covered with
anything that can reduce the strength of
ultrasonic signal. For example, the
system won’t normally work, if one puts the mobile beacon in a plastic box
- The beacon’s coordinates are updated according to the rate set on the
Dashboard
- The system may contain one or several mobile beacons. Current implementation
relies on a time-division multiple access approach. Thus, if two mobile beacons
are activated, they share the same system bandwidth. It means that, if the 16 Hz
update rate is selected in the Dashboard and there are 2 mobile beacons in the
system, each beacon’s location will be updated with the rate of 16Hz/2 ~ 8Hz. If
there are 3 mobile beacons => 16Hz/3 ~ 5Hz, etc. Future SW implementation
may contain different solution that will improve update rates in setups with
multiple mobile beacons
- Location data is obtained either from the “hedgehog” via USB (virtual UART),
UART, SPI, or from the modem/router via USB (virtual UART). More information
on interfaces can be found here
- Data from the beacon sent in a streaming format identical to that of GPS (NMEA
0183)
- There are 433MHz and 915MHz versions available. Proprietary radio protocol is
used for communication and synchronization
- The “hedgehog” has been successfully integrated with Windows PC, Linux
machines, Raspberry Pi, Arduino boards, Intel boards, etc.