Docking port demonstrations

After a few very heavy weeks of work we've got two docking ports constructed for a demonstration. Mechanically these are identical to the ports expected to be used on the finished robot design, electrically each of them is a little different to what will be in a finished robot, for the demo each port controls a wheel motor directly as based on sensor readings while in a finished robot the electronics of each port will instead report sensor readings to the Raspberry Pi via I2C where more detailed decisions can be made before motors are commanded.

Two docking ports, note the black coloured central regions around the LED to minimise reflection of IR light.

We plan to show these two ports at TAROS along with our poster on Self-repair with Modular Robots during Continuous Motion.

An assembled docking port, note the large tubular structure behind the wheel (upper right) which will later act as a mount for the central hinge gearing on a finished robot.

The docking hooks work very nicely and reliably lock together, steadying their angle if they start out a little misaligned. The actuation takes under half a second.

An assembled port (above) docked to a partially assembled port (below), a pair of the interlocking hooks are visible (orange) between the two screw heads just below the middle of the image.

The phototransistors to detect the cone of light cast by an infrared LED on the port that is being approached also function, although they suffered a little bit of damage during assembly which unfortunately means one of the phototransistors is giving occasional false readings and severely reducing our previously >80 cm range. This should be trivial to fix when constructing a full robot, but unfortunately there isn't time before TAROS.

A test of the infrared emission from the LED at the centre of a docking port, note the 5KHz waveform on the oscilloscope.

We hope to post some videos of the hooks in action and the wheels moving so a port can guide itself in to dock using sensor readings of the infrared cone.