Electrical Design
For the 2014 ENPH 253 Robot Competition, Indy was required to be motorized robot with tape following and 10kHz infrared beacon following capabilities. The robot was controlled by an ATMega128 based Wiring board called TINAH, using software generated in the Wiring language and Wiring IDE.
From our designs, the robot had to be able to utilize differential steering, which is characterized by running left and right motors at different speeds. The H-bridge circuit which uses two N-channel MOSFETS, two P-channel MOSFETS, two NPN bipolar junction transistors, and two PNP bipolar junction transistors to create two independent and exclusive pathways across the motors is perfect for this application. The inputs to the H-bridge chips we built were connected directly to outputs on the TINAH board and the schematic for the H-bridge circuit is shown below.
Tape following involved reading inputs from QRD1114 Reflectance Sensors, which could be wired directly to the TINAH microcontroller board with a single resistor. On the other hand, following the 10kHz infrared beacon required a circuit that could convert the signal read by the OP805 infrared sensors into a readable analog 0-5V analog signal to the microcontroller. The signal was amplified and filtered through a series of TL082 op-amps before entering the TINAH board. The schematic for the infra-red detector chips are shown below.
Watch our Software Lead, Bryan Luu, explain how the electronics work below:
