We started the fabrication process by water jetting the wheel side and wing. This was good and bad. We found a lot of little problems that we had to fix, it helped us find problems in our design and fix them. It was bad because the wheel side and win that we cut are not perfect. We then started to design for fabrication. The wheel halves were hard to fabricate due to undercuts and poor designing. We simplified the design and changed both halves to be symmetrical. We also changed the right wheel mount. It was previously too big and wasted material. We refined the design to make it smaller and cleaner.
There are many different electronics elements in Transit Wheel. To connect them we have the main PCB. The PCB holds the Arduino, two analog to digital converts, a gyroscope, an accelerometer, a compass, two level shifters and voltage monitor. This allows us to manage all the sensor on transit wheel in a compact way.
To measure the amount of forward or backward lean that the user provides, we have pressure pads on the wings. We spent a lot of time looking at sensors but could not find one that was long enough for our purposes. We decided to make the sensors ourselves. We are using velostat, a material that is more resistive the more pressure put on it. We will have strips of that glued to a flexible PCB with the other surface touching the metal of the wing. This will allow us to measure the placement of the person's weight to see how much they are leaning.
The gears had to be held in place using two gear mounts, one on either side. The Planetary gear set has two layers of three gears. The Gears have bearings that ride on three rods. The two gear box halves have to be attached somehow. We had to add three extra rods to hold the gearbox halves together. We can't put screws through the gear shafts because the process of drilling and tapping them would make the shafts bulge and not be as precise as we need them. The gearbox is attached to both wheel sides. This is for two reasons. First, the gearbox will align the wheel halves, it also disperses the force evenly along the two wheel sides.