Embedded Files
Goals: We wanted to make sure our control unit was easily attachable/detachable, which means that we wanted to create a casing for the battery and remote controls that would allow us to avoid using adhesive or drilling new holes into the board.
Our base framework turns on the motor for a specific amount of time after feeling the initial acceleration of a push. We wanted to account for the fact that there are different accelerations that aren't a push, but might still trigger the accelerometer. One challenge we faced was finding a way to feel the initial push, without feeling the flex from shifting weight or forward acceleration that tends to occur when the user gets off the board.
Implementation: We realized that we could replace the risers (a part that sits between the truck and the bottom of the board) with a 3-D printed part. This would allow us to use the existing screw holes, that tend to be pretty standard between boards, to hold our part up. We created our housing to replace the risers and contain the electronics that we had added, as well as the remote control. We also had to make sure that our housing was large enough to fit all of our parts, but not be large enough to crack because of the flex in the board or drag on the ground. Our next step to complete our design is to create a housing for the battery pack and receiver for the remote signals.
Drivetrain Design: Belt-driven motor vs in-hub motors
- To turn the wheels of an electric skateboard, two popular options exist. The first one, belt-driven motor system, has been traditional way of creating an electric skateboard. This system works by the concept of a pulley system. A motor is connected to the axle of a skateboard by a pulley chain. Then, when battery power is supplied to the motor, the motor spins and thus causes the axle of the skateboard to spin as well, which ultimately spins the wheels.
- The second option, in-hub motors, has become a relatively new alternative to pop up within the past few years. These work on the basis of an AC motor, or more specifically rotor and stator. Additionally, these hub motors are outrunners (meaning that the outer wheel is what turns), and for each motor revolution the wheel turns one revolution.
- We ultimately decided to implement the in-hub motor into our electric skateboard design for the following benefits:
- Sleek design: In-hub motors eliminate the bulk of a motor and its pulley chain. This helps streamline our battery pack, control unit, truck, and wheels into a singular, mobile, slim, lightweight, and quieter package.
- Natural feel: If you forget to charge the battery and it runs out, in-hub motors offer significantly less resistance to turning than do belt-driven systems. Thus, the minimal cogging from the residual magnetization of the in-hub motors still allows for a natural feel when you kick-push the board, unlike the belt system which creates uncomfortable friction and requires significantly more force to naturally kick-push.
- Durable: In-hub motors contain no brushes, gears, or pulleys, and all components are internally shielded from dirt, rocks, and debris.
- Efficient: In-hub motors offer direct motor-to-wheel power. This means less drag (no pulleys or gears) and higher efficiency, resulting in longer battery life.
Google Sites
Report abuse