Our assembly does not require electronics to function. We did not use any electronics in this device. The primary reasons for this choice were that we were aiming for overall simplicity in the design and lower-cost manufacturing. A simpler, lower-cost design would make the device easier to use and fix if broken, as well as more accessible for users with lower income.
The user creates the input force required to make the mechanism move. The fan on the pulley creates the necessary resistance to allow the user to perform a bicep curl. Additionally, the bungee cord at the end of the chain allows for the mechanism to "reset" and only provides a minimum about of resistance to the mechanism. By finding the spring force of the bungee, we found the resistance of the bungee to be approximately 2 pounds and deemed it unnecessary to include in calculations for our mechanism.