Last Friday there was no blog input as the race to the wall had just finished and our robots were taken apart and finished with. Ronan found a great website called finger tech which as of the 5th of March I ordered 2 motors and 2 gears from the company in Canada. The wheels were made of the highest traction polyurethane material in the market paired with 16mm gold spark gear motors, leaving us as a force to be reckoned with.
So a week has past and we are still waiting for the gear to arrive. The next sensor we have to understand and learn its concept is the range finder. John was kind enough to show us in the 1st 1 hour’s class and that the key trick was that it needed to be mounted 2cms back to get the full range of the entire board. Our designed is as though the robot itself is a ramp so what will be needed is that the range finder has to be flush and not to stick out which will sure to give us difficulty as it’s a quite compact design. The following too photos were given to us to fully understand the rangefinder and how to wire it, although our pin set up might slightly vary.
Once this was given to us we all went down to the lab to dish out tasks and try tackling the very last sensor. Sean was doing some research; Nathan was trying to see if he could design the body for it to be lazier cut, while Ronan and I worked on the range finder. The sensor itself is quite simple but doesn’t sound as so. It has four terminals, a live, a ground, a trigger and an echo. To put it simply the trigger sounds out a signal and the echo catches any of the bounce back cause a potential difference of around 5V. Unfortunately this is too high for the processer and will damage it. This was why a diode was placed on the echo in reverse bias and a pull down resistor leaving around 3V at the input pin. Ronan and I decided that the best range for our Robot would be 80cm as the table is only 100cm in diameter. So Ronan and I set out marks on the table up to 80cm. We then tested span of voltage at different distances and using different resistors and found 3kohms to be the best suited resistor. Everything seemed ready and rearing to go……….
But wait………………………………………………………….…………………………..THE EAGLE HAS LANDED!!!!!!!!!!!!
As I get home the packet has been delivered on the Friday evening. I opened it up and the motors and wheels have been delivered.
So after a bit of building I put this little beauty together down below. The idea is to have only 2 wheels with a razor sharp front and a metal wedge at the rear with the colour sensor mounted on it and so it cant be flipped. The front colour sensor will be through a hole at the front. I am yet to design the the cover but should be like a ramp with the heavy batteries at the front under the roof