Some features that Vincii possessed:
1) Four wheeler vehicle having the rear wheels as drive wheels.
2) Front wheels are skateboard trucks which helps in changing direction based on the user’s position on the vehicle. Leaning right will turn right and vice versa.
3) Rear wheels are trike freewheels, converted to drive wheels.
4) The drive shaft is coupled to a bicycle chain-sprocket system. The cranks of the bicycle chain ring is attached with four bar linkages (instead of pedals). The crank arm of the four bar linkage is extended upwards so that they can be moved back and forth by hands. The movement pattern of the hands are similar as in an elliptical trainer with handles on it.
5) The vehicle can be operated in coast mode just as a bike, thus, cranking is not always required to continue motion.
6) Because of the coast feature, the two rear wheels can be freely rotated as the device is carried like a carry-on luggage.
7) The two crank arms can be folded while carrying the device.
To develop the crank arm's swinging motion (similar to an elliptical trainer), the crank-rocker theory was applied.
The two images above present the four bar mechanism’s formulas. The values for T1, T2 and T3 needs to be +, - and – for getting a crank-rocker mechanism out of the four bars. These formulas were used to verify if the assigned values for the link lengths are appropriate.
After a number of iterations for possible link lengths and simulating it in the online four bar linkage simulator (also based on our system constraints), the values of 6.3”, 2”, 6.5” and 5.8” for the links (q, s, l, p) were ascertained to be the best dimensions.
1) Tormach CNC router
2) Shopbot CNC router
3) Vacuum former
4) TIG welder
6) Drill press
7) Metal lathe
8) Vertical bandsaw
9) Cold saw
10) Spray paint
11) English wheel
12) Powder coater
DFM and DFA analyses were done in parallel with the design, to ease manufacturability and assembly. The added benefit was when it is ready for mass production, the fabrication techniques don't have to be revamped.
A wooden mold is made using a Shopbot CNC router. The CNC router can only machine up to 3 inches in depth. Due to this limitation, multiple MDF boards were machined separately and then glued one on top of the other. Some wood bondo was applied to the entire mold in order to smoothen it out. It is now ready for vacuum forming.