2. The platform

What makes reality hard, and the platform that solves it

From a simulator to the platform

The bridge slide “From simulator to reality” asks how hard it can be to go from a swarm in a simulator, which you start yourself in step 3, to real robots on the floor. Then the instructor presents the platform that makes it possible: the robot, how it finds its position, how it talks, how it gets new programs, and the software you drive it with. It starts with the robot itself, in Figure 1.

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Figure 1: DotBot v3 in 3D. Drag to turn, hover a part. The full 3D page lists every part.

Open the slides

The pillars

Each one names the problem it solves, and links to its paper on the references page.

  • The robot, DotBot v3: low cost, and a charge in seconds. ICRA 2024 workshop
  • Lighthouse 2, each robot’s position: low cost, and it scales, since each robot computes its own position on board. IEEE RA-L 2024, calibration, IEEE RA-L 2025
  • Mari, the radio link: scales to many robots, fast enough for interactive control, reliable thanks to TSCH. Ad Hoc Networks 2026
  • SwarmIT, programs over the air: your app runs in a sandbox, so the testbed keeps full control of every robot. DCOSS-IoT 2026
  • PyDotBot, the dotbot command, controller and simulator: fits it all together. Its docs

The robot at a glance

DotBot v3
Size about 95 x 95 mm seen from above
Drive two wheels, each on a geared DC motor with an encoder, and a ball caster at the front
Top speed about 0.8 m/s
Energy two 120 F supercapacitors, no battery
Charging about 30 s to full, from the barrel jack or the charging station
Running time about 1 h in typical use, about 20 min driving non-stop at full speed
On and off the ON/OFF switch (SW3) at the left edge of the top side; switching OFF also discharges the supercapacitors through a 4.7 Ω resistor, so a robot that is off holds no stored energy
Processor and radio nRF5340: two Arm Cortex-M33 cores and a 2.4 GHz Bluetooth LE radio, which runs Mari
Position a Lighthouse 2 photodiode and receiver on top

Figure 2 and Figure 3 label the board’s two sides, rendered from the board design files (build 1.3a); each dot is the documented position of the part. Figure 4 and Figure 5 are photos of a real robot, from an earlier build (1.2a), so a few small parts differ.

Render of the DotBot v3 board top side with labels for the switch, buttons, LEDs, nRF5340 module, add-on headers, motor drivers, photodiode, charger, USB-C and programmer.
Figure 2: The top side. The front of the robot is at the top.
Render of the DotBot v3 board underside with labels for the supercapacitors and their terminals, barrel jack, coin cell, motors, ball caster mount and bumper connectors.
Figure 3: The underside, seen from below like Figure 5, so left and right are swapped: the right motor, M2, is on the left.
Photo of a DotBot v3 from above, with its two wheels.
Figure 4: The top side of a real robot. The sticker shows its label, the last six characters of its address.
Photo of the underside of a DotBot v3 showing two orange-wrapped supercapacitors.
Figure 5: The underside of a real robot: the two supercapacitors, the coin cell and the ball caster.

Datasheets. The DotBot v3 schematic (PDF), the nRF5340 product specification, the BQ24640 supercapacitor charger, and the TPS61021A and TPS61022 boost converters.