Published on Feb 28, 2016
The original objective for this project was to optimize the car for the speed with which it navigated the path. To do this, we would have increased the speed when little compensation was needed, and decreased the speed as more was needed.
This optimization, however, did not require much more effort on our part than the heuristic outlined above. This is because the speed is mechanically regulated by the gradual acceleration(increae/decrease) of the car in balance with the direction reversal for large corrections.
The hardware for this project was the bulk of the work. Because we were making a moving vehicle, we decided that it would be best not to have any of the circuitry on breadboards. Breadboards are also expensive, so we probably would have had to disassemble the car after its demonstration. We therefore chose to wire-wrap all of the circuitry.
This required a fair amount of labor, but it was well worth it in the end. The car we selected is fairly simple to operate. It has a simple two wheel drive, , which is powered by a DC motor. The steering is achieved by applying a difference of voltages acroos the two batteries. We used two H-bridges (L293D) to deliver power to the steering and the drive motor.
Because of the current requirements (the drive motor and steering solenoid could draw several amps), we used 20-gauge wire for the high-current areas of the H-bridges rather than the 30-gauge wire used for the rest of the circuit.
The photodetectors were mounted just ahead of the front wheels on a threaded rod to allow reposition them as necessary. The current through the photo-transistor depends on the intensity it detects which is dealt with in the sensor characterisation section