Toot Toot

 There's a bit of Shepherds Pi and the Farmyard Tour that gives points for audio control, so this is our take on it. This doesn't do much, listens for a whistle and then provides basic interpretation into commands. One whistle 'toot' is a command, as well as two and three, and after a brief interlude, the last command is cancelled. 

For this, a Pi pico is paired with a microphone....and a whistle...feeding the ADC of the pico with the audio signal, and then running an FFT against the signal to pick out the whistles' frequency, 2k7Hz in this case and converts blasts it into a logic signal.

As with the other attachments, this supports the WHOU enquiry, GPIO handshake and returns the info of TOOT, TOO2 and TOO3 as commands.  Power and serial comms are via USB for easy attachment.

Seems a bit of a small post, but it's a complete sub-project that contributes.

Using the remote

 With lots of challenging challenges, it has felt easy to ignore that the Farmyard Tours was to be remote control and not autonomous, so we needed a solution which was a bit more dextrous than a keyboard. Using a full RC set with adapters was always an option, but a more personal system was preferred and an almost universal games controller format was chosen. 

Could have been any brand, but it turned out as a low cost PS3 controller from a no-name Chinese source. As the main Pi controller just wanted a data feed it could translate, the interface chosen to the controller was Bluetooth run by a small ESP32 module dedicated to the communication. This was a lot less bother than direct comms and meant that the controller Pi wasn't cluttered with noisy code. Here is a larger dev board for testing, and mounted on a test chassis. The communication is via serial over USB and a simple handshaking option is used to request data from the PS3. 

One of the issues with this configuration is that when the controller times out and disconnects, the ESP32 code can't reconnect, so an extra pin was dedicated to reboot the ESP32 into connection mode again. 

Here's a brief video of the test chassis twirling in the arena..........and negotiating a bit of garden.

....and negotiating a bit of garden.

A new chassis

So after lots of testing....well a bit anyway...we needed to build a new chassis, if only because we'd drilled so many holes in the old one! 

First make the battery holder which is also part of the suspension. Here it is.

Well that's spectacular isn't it. It's very basic, is made from a piece of acrylic tube, one end has a fixed plastic plug with a battery contact permanently attached and the other has a plastic spring holding the other contact in, which is held in place with a screw. The tube itself forms the central pivot of the suspension.

The two halves of the chassis were updated to accommodate the positioning of the camera as well as the main controller and attachment processors.

This is the rear subframe from below, the motors fixed in place either side of a tunnel which houses the battery tube. 

And a picture of the front subframe, housing motors, a camera and illumination LEDs, with the second half of the battery tunnel shown.

Putting them together, with an empty tube in the middle. The two subframes can rotate independently of each other around the battery tube. This isn't of much use in the arena challenges, but when negotiating the farm tour obstacle course it's expected to come into its own to keep the chassis stable and in contact with the ground.

As mentioned previously, part of the rebuild was to accommodate a camera.

The camera is mounted below the attachment deck of the chassis, the bolt holes for attachments can be see top left and right, and faces down and forward, looking at the arena surface ahead of the robot. The LEDs are there to ensure it has plenty of illumination for the camera and isn't dependent on ambient light, eliminating an uncertain variable.

Close-up of the two subframes partly rotated against each other to show the suspension in operation. Already, with only the motor, LEDs and camera fitted there are a lot of wires in this robot and cable management is important, hence the prepared holes in the subframes.

From the outset we wanted interchangeable wheels to adapt to the different challenges. These are 'arena' wheels with their adapters. The adapters were always part of the design as with so many different motor shaft attachments available we needed to be able to switch them without having to remake whole wheels.

Now it looks a lot more like something with the wheels attached and wires routed. The front chassis  mounts for attachments can be seen, and that growing wiring is getting some management..

And suddenly there's a wire explosion!!! At the rear (right) is the main power switch, and just ahead is the controller pi board mounted vertically. At the far side is the power regulator. Raw power from the batteries is delivered at around 11V and used by the attachments, the regulator ensures the pi is supplied with a healthy 5V. 

Nearest the camera is the motor control pico which receives commands from the controller and incorporates a LED to provide a simple status display. This connects to the controller via USB. 

And here is the assembled new chassis with the Hungry Cattle hopper attachment. 

There's a lot of parts to this but it does work very well. Only a short video of this chassis working but it gives an idea of the basics.

Next up a  blog giving a description of the architecture of these robots.