Week 12 - September 26 - October 2

The tasks completed this week are related mainly to the mechanical module. The wheels and motors are ready to be attached to the cart. We received some aluminum sheet metal (Figure 12.1) that we will cut early next week with the help of a machinist, so that we can bolt the assembly to the bottom of the cart and start mechanical testing. The metal will be placed above the wire rack on the bottom of the cart and we will drill holes into it so that our devices can be bolted underneath.

Figure 12.1 - Aluminum Sheet Metal

The next part of the mechanical module that was worked on was the motor drivers. First, the PCBs needed to be prepped for use. This means attaching the pins to the board. Figure 12.2 shows the board disassembled. We needed to decide which pins we wanted to use and where they would be attached.

Figure 12.2 - Motor Driver Disassembled

Figure 12.3 shows the bottom of the motor driver with the pins soldered through the through hole connections.

Figure 12.3 - Motor diver with soldered pins

The next step is to clean the board. Flux was used during soldering to ensure that the electrical connection was strong. However, flux can get everywhere and becomes very sticky. So, isopropyl alcohol was used to clean the board. This was chosen because it breaks down the flux but evaporates quickly in the air, so it does not damage the electrical devices like water would. Proper PPE (Personal Protection Equipment) was used while handling the chemicals shown in Figure 12.4.

Figure 12.4 - Isopropyl Alcohol used to clean PCBs

Now that the board is cleaned, the pins had to be trimmed down so that they wouldn't get bent and come into contact with each other. Figure 12.5 shows the cleaned and trimmed pins. This process was repeated for the second motor driver.

Figure 12.5 - Motor Driver with pins cleaned and trimmed

Work was continued on the program for the motor drivers and the secondary microcontroller. Also, great progress was made on the report, with chapter 4 and 1 completed, and Chapter 2 is close to completion.