After a grueling 13 weeks of researching, designing, building and refining Bumblebee was created!

Adding last minute touches to Bumblebee

Bumblebee was mostly made out of corrugated plastic. The material was durable and lightweight which was why we initially chose it (plus I had heaps of it lying around at home anyway). We covered up the plastic with yellow paper and black tape to make it look more presentable. 

Out of the four motions, we had the most trouble with the propel motion. The problem was that the wheels connected to the axle of the motors wouldn't stick properly, resulting in the wheels slipping off. It didn't help that we used six wheels instead of four, resulting in an indeterminate structure. We quickly solved the problem by moving the motorized wheels to the front because provided the EMS with more digging power and raised the front outside wheels so they wouldn't touch the ground. The outside wheels are mainly for presentation but the ones at the back provided stability. 

The swing motion was probably the second most troublesome motion we encountered. Our initial designs involved a pulley system with a central shaft in the middle to allow the upper structure to pivot around the shaft. Due to time constraints and lack of material we decided to directly connect the motor to a lazy susan. The initial material used to connect the motor to the lazy susan was wood. We quickly found out that the motor would wear out the hole so we used plastic from a chopping board which solved the issue. 

For the dump motion we utilized an electrical solenoid latch system. The initial solenoid we purchased was too weak to open the latch of the dipper. Purchasing a larger solenoid solved the problem. During demo day the dipper managed to scoop on average 750 grams per pass. With 8 passes within the 5 minutes we managed to shift about six kilograms of chickpeas. In addition, the trapezoidal shape of the dipper allowed it to be easily filled

The hoist motion was done by using a winding drum inside the EMS. The initial drum was 4 cm in diameter which resulted in the dipper slowly moving down when it was hoisted to the top. Although having a larger drum would increase the hoisting speed, we decided to use a smaller drum to ensure the dipper doesn't move down on its own when hoisted up. This was done to ensure we had enough clearance height to unload the chickpeas into the truck.

The control system was made from an old extension cord. We removed some the rubber covering to get the individual wires for the circuits. A lot of soldering and testing was involved when making the control system. I also realized how expensive electrical parts were. The switches we purchased were $2.95 from Jaycar. We used five switches altogether meaning we spent $14.75 on switches! 

Here's a short video during one of the EMS tests. 

To be honest, during the first two weeks I had no idea what the hell I was doing. We were given the task to create an electric mining shovel (EMS) under a certain criteria. Having literally no experience in this kind of stuff I didn't know where to start. At that point, I didn't even know what forces were! Fast forward another 11 weeks and I feel like I've got a decent grasp of the project and the requirements. If I had to redo this project I could probably get it done in two weeks.