Raspberry Pi

 

I took part in the Cambridge Jam PiWars event at the weekend, it was held at the Cambridge Institute of Astronomy, me and Phil Willis built the robot and we took part representing the Ipswich Makerspace. It was a great event and many thanks must go to the organisers Mike Horne, Tim Richardson and Andy Batey.

The Event consisted of a number of challenges, more can be found on the PiWars website, but the challenges were as follows:

* Code Quality
* Aesthetics
* Sumo (remote control)
* Straight Line Speed (remote control)
* Obstacle Course (remote control)
* Line Following (autonomous)
* Three Point Turn (autonomous)
* Golf (remote control)
* Object Avoidance (autonomous)

The above challenges were scored and a number of other prizes where awarded, but the main two prizes were awarded for best overall robot, one for under £75 and one for over £75.

We took part in all the challenges with our robot TractorBot, Phil coded all the software whilst I designed and built the hardware!

Sumo
Was interesting, there was a wide variety of bots of different sizes and shapes, our first competitor was a worthy opponent and very balanced and it took a while, but with some skilled control we eventually won. The second round was easy and a bit unfair, Harold was a two wheeled bot, we had more control and power so it was over quickly. Our final competitor was a monster, BiggerTrak was a six wheeled bot with full suspension hiding beneath a pirate ship. We clearly was not going to win this one based on strength, it swamped us, but we knew his control could play up a bit. So we danced around a bit and avoided the monster a few times, but eventually it had to happen, we were pushed out and out of the Sumo challenge.

Straight Line Speed Test
Phil took the controls for this one, it was a straight track with edges and timing was carried out with timing beams and a Raspberry Pi by [PiBorg](https://www.piborg.org/). We were hoping to put bigger wheels on for this challenge to give us a bit more speed, but time just did not allow, accourding to the [PiBorg video](http://youtu.be/nKRGZbmyCiU) it looks like we came 5th, with three very consistent speed runs.

Three Point Turn
I was not very confident with this challenge, mainly because I had not seen the bot attempt it, so we set the bot in the starting box and set it to do its thing. Thanks to Phil, it did reasonably well, getting back tot the start line but not quite back tot he starting box. A much better result than I was hoping for.

Golf
I was really hoping we would do well in this challenge, we had a custom designed ball catcher and restraint system so was hoping to be able to easily pick up the ball and shoot it through the goal. It has worked very well in tests on a smooth surface, however the challenge was on carpet tiles. We picked up the ball shot it through the hole and ….., it wedged in the ball catcher. Eventually we managed to get it in the hole by using the ball restrainer as a bat and kick it through the hole, so we completed it but far slower than we had hoped. I have a feeling the ball may have been very slightly bigger than our test ball, making it wedge, but we live and learn.

Object avoidance
The aim of this challenge was to approach a wall and stop as close as we can without touching the wall. It had to be competed three times and the sum of the distances would be our score. It we hit the wall we got a penalty of 30cm.

Attempt One, we got about 15mm
Attempt 2, we got about 2mm
attempt 3, ouch, we just hit the wall, oh well, lots of other people were doing this also.

Line Following
We had started off wanting to do this with a camera and the Raspberry Pi tracking and following the line with OpenCV, this worked well, but we felt was a little slow. To speed it up we finally decided to use IR line following sensors and in tests it had worked very well.

However on the day, TractorBot just did not want to play ball, we could barely get past the start line, we need to do some investigation as to why it did not work, but at this moment I have no idea what went wrong, this was a big disappointment for us.

Obstacle Course
From the very beginning we had wanted to do well at this challenge, although TractorBot was quite a basic chassis we had designed it to be four wheel drive with a reasonable ground clearance. This was our final challenge and we had done some reconnaissance and had pre-planed our route. So off we went, straight over the polished stones without hardly a hesitation, round the corner and through the mass of square blocks at varying heights, we got though that one too, round another bend and through a slarlam, over the sea–saw and steamed on to the finishing line. Our time 21 seconds, it seemed reasonable to us, we could not have done any better. The judge then confirmed we had been the fastest, bonus, this was our crowning achievement.

Prize Giving
We then all assembled for the prize giving, it was quite tense, we had no idea how we were going to do. But we did end up with a few prizes.

* 1st in the Obstacle course
* Best overall bot in the remote controlled challenges
* Best robot overall in the sub £75 category

So we actually won the big one, the best bot costing less than £75. There were only two trophy’s one for sub £75 and one for over £75 and we had won, what an amazing achievement.

All in all, it was an amazing event and we all really enjoyed it.

We would like to thank Rapid Electronics for their very kind sponsorship as well as Cedarcroft Productions for providing a brilliant laser cutting service and lets not forget the CamJam  team for organising the whole event and of course the support of Ipswich Makerspace

Keith Ellis