So for my second project I wanted to do a simplified version of a model railway, with three trains and stations and the coal chute from the first project, however after short consideration, it became clear that this was not practical merely from the size and expense of the project.
I resolved instead to doing cars.
These cars would take the form of one Land Rover and two sports cars. The sports cars would act boisterous and run out of power fast, whereas the land rover would be a dependable, slower car. I also wanted it to respond to a distress call from the other cars.
I started by ripping apart a cheap remote control car from a toy shop, to see how the drive train would work, and then started retro fitting it to work with my arduino board.
The retro fits worked well out of the design, but as soon as they were applied in situ. it was clear they were non functional.
I put the retro build to one side and began to retro fit a new model of a Lamborghini. This was a lot easier and allowed me to focus on my new code, which included an H bridge and LEDs. The H bridge was used to allow forward/backward and left/right movement. The first working model was here! all it did was move forward/backwards whilst going in a circle – essentially doing endless 3 point turns. Great Success!
Then I started building the second car – the Land rover. (and also ditched the idea of a third car- Too Much WORK!)
Made of 6mm acrylic which was heavy but robust. it also was clear so I could easily see all the parts as they moved.
The next stage was getting the second car moving and the first car sensing the distance in front of – a prospect I underestimated greatly in terms of time consumption.
After much ado and time and stress, I found the NewPing library on the arduino site that allowed me to take a median of values to average out any erroneous spikes or anomalies in the distance sensor.
I then mounted in a Servo into the Landy. the first plan I had for the landy was to have a makeshift radar dish on the front. this became too much hassle and I resolved instead for something a bit simpler and more pleasing- when the distress beacon came from the lambo, the landy would stop, lift its bonnet and pretend to overheat, instead of going to help out…
By this stage time was running out and frustration with code and hardware was increasing == stress & a short tempered- tired- && most importantly; hungry, student was often seen at dusk, scurrying toward the soldering iron.
Eventually it got to the stage where the RF link could be put in.
The transmitter was easy – I just wanted a signal pulse to say to the other car- help.
The receiver was, it turned out, a lot harder.
The problem I encountered was getting the receiver to accept the right signal. There are so many random signals flying about that even with thresholds etc. It was still picking up a load of random signals and acting on erroneous data.
I got it working for all of these signals but in the end had to give up on master & (disobedient)slave relationships, and settle instead for independency of each other.