Developers:  Jason Allan
  Eric Helander
 
    Supervisor:  Dr.A.K.S Bhat
 
 
 
 
 
 
 
 
 
 
 
 
Objective
 
The objective of our design project was to increase the functionality of the Zappy scooter produced by Zap, a manufacturer of electric vehicles located in Santa Rosa, California. The Zappy is designed with only one control device, a finger-activated switch to turn the motor on and off. It has no speed control. This design limitation results in a sudden high rate of acceleration once the motor is activated causing a substantial current draw, making the scooter difficult to control and steer. The manufacturer suggests that to mitigate these performance deficits, the user should manually push off to begin moving the scooter before activating the motor.

To make the scooter more user friendly, we developed a variable speed throttle device similar to those used on electric wheelchairs. Design considerations included the following.

    1. For marketing purposes, the new throttle circuit would have to be easily installed by the user to replace the stock relay.
    2. The new system would have to be capable of the same top speed as with the stock system to maintain the product's benefits for the consumer.
    3. The system would have to be inexpensive to fabricate.
We chose to design a DC motor control based on a DC chopper circuit because it met these design considerations.


 


Zap Zappy Scooter