Building the Mechanical Aspect of our Design

Two pieces of 3/4" plywood were cut into 24" diameter cylinders at the Drexel Hess lab, as shown in Figure 12.  Then, the wood pieces were glued and nailed together, and sanded on the sides. This 1 1/2" thick cylindrical base will be mounted on top of the swivel base.

The code first determines what devices are currently connected to the machine, and upon locating them, it creates a session to interface with a given vendor ID. Then, it sets the sampling rate to 48,000 and time information. Next, it sets the number of samples to be obtained or the duration (in seconds) for which the code must run.

Figure 12: Two circular pieces of swivel base

After receiving almost all parts of the mechanical design, a few pitfalls were encountered:

1.      The linear actuator, fully retracted, reaches from the top of the cylindrical base to the bottom of the chair. Simply, the linear actuator is too long This means that our team will have to mount the chair on top of a another box-like structure and put the linear actuator inside the box to make its base lower than the chairs base, as shown in Figure 13.

Figure 13: A possible redesign solution to the linear actuator height problem

2.      The gear motor, running on 12 volts, has very low torque. The swivel base purchased is very hard to turn, adding more concern to the low torque motor. A very high ratio gearbox will have to be purchased. The timing belt will be placed around this gear box, and then nailed to the cylindrical base. 

3.      The motor and gear box used to turn the swivel base must be mounted at the same height as the cylinders mounted on the swivel base. A simple extra box can be constructed to fix this problem.                         

4.      The timing belt may slip off of the cylindrical base; a guard must be constructed around the top and bottom of the cylinder holding the belt. This can be made out of the aluminum sheet we have already purchased.