How To Train Your Robot

Somehow we managed to miss a blog update in November - how time flies. 

November was all about software. The saws, screwdrivers, crimping tools and sellotape were put away, and out came the laptop. 

One of the aims of building this robot was for me to learn Python. After a couple of weeks, I was threatening to name this blog '10 things I hate about Python' but I persevered and am beginning to forgive it. 

I decided to keep it simple and implement a single, multi-threaded application, rather than trying to have multiple processes. I drew out a simple design - just to keep me on track using UMLet. This is the best free tool I've found for sketching out rough designs really quickly. This was just to give me a rough idea about the classes and what needs to know about what.. 

Initial Class Diagram

Tears, Cheers and Motor Gears

October has been a tough month for us. After rebuilding the robot in plywood (much easier to work with than acrylic) and putting in some motors with more torque, we were ready to test again.

The motors we tried were, again, micro metal motors from pimoroni - but 298:1 gear ratio instead of 50:1. It went forward - and backwards - but again, even with the extra torque refused to turn well. It was better - we could get it to turn if we put on some less grippy wheels - or were moving at the time. But not great. The large, soft, wide wheels we want to use (to give us some natural suspension over obstacles) just have too much grip. 

If at first you don't succeed ...

After days sawing, drilling, redrilling and redrilling (honestly - some parts are looking like a sieve!) some sheets of 3mm acrylic, and then bolting on all the motors and electronics, Sputnik 0.3 emerged.
The first robot free from lego.

With hope and suspense in the air, the Raspberry Pi (and currently unused Arduino) were powered up. The controller was paired and we were delighted to see the motors turned in the correct direction when we moved the controller without having to swap round all the wires. That has never happened before! Hopes were high.

Sad(ish) News

The days of waiting are over. No need to press refresh on the email app every 5 seconds. The email from Pi Wars has arrived.

Unfortunately Sputnik did not make the cut for Pi Wars 2019.

However, not all is bad. We did make the reserve list - so the build is still on!

Lots to do ....

CAD Phase Complete

Looking at some of the other Pi Wars competitor's blogs and seeing the wonderful designs rendered in CAD packages we thought we'd have a go ourselves. However after 5 minutes with FreeCAD it quickly became clear that the only thing we would have by March next year would be a design.

Less is More

Sputnik 0.1 has been stripped down completely to make way for Sputnik 0.2

As you can hopefully see from the comparison above, it's much smaller and lighter. The purpose of this build was to test out the 4tronix RoboHat motor controller, paired with a power supply of 2 x 18650 Lithium Ion batteries. 

The First Robot

Actually - this should be titled the first 'successful' robot. We've had a couple of previous attempts but the motors weren't mounted very well, so it flopped about like a baby calf with legs akimbo - and as a result didn't move very well.

As soon as the idea for Pi Wars came up, I sent off for some cheap motors, wheels, a few L298 motor controllers and a battery pack.  I also bought a terminal block breakout module for easy pin access to the Raspberry Pi pins. A couple of attempts with a robot shoe box, and a two motor lego robot proved we could build a simple robot and control it with a PS3 controller.

At this point we sent off the application.

The Pi Wars Challenge Begins

In a moment of madness we've submitted an application for the Pi Wars 2019.

So we're committed to building a working robot for next March - whether we're accepted or not - since we'll hopefully be on the reserve list.

Since the reboot of Robot Wars a couple of years ago, robots have been a popular theme in our household with both our boys (now 5 and 8) building and battling robots from lego, or playing with the Hexbug robot wars toys.