This week was spent assembling the second bogie and connect the second DC motor and stepper motor to the relays and Arduino. I noticed some wires didn't have good connections on H-bridge circuit, and I had to fix them by checking how the connections were supposed to work through the Arduino. For example, 8 wires from 8 pins on the arduino didn't match up to the appropriate relay inputs. I had to shift the outputs from the ULN 2803A Darlington Transistor Array to match the inputs on the relay board.
Also during this week, I constructed a circuit to regulate voltage taken from the batter/wayside power into 5V for the Arduino (Figure 2). I used R1 = 470 Ohms and R2 = 1.5k Ohms.
This is my last week and my last day is Tuesday, July 25, 2017. Monday and Tuesday will be spent continuing debugging the assembled bogie with steering and propulsion/braking system.
Figure 1. SainSmart Relays H-bridge (From Google Images)
Figure 2. From LM317 Datasheet