Summary of Summer Research

I began my summer research by teaching myself FORTRAN-77 and MATLAB programming. I had programmed in C++ before, but these two languages were new to me, as was the VAX system. After learning enough to get by, my task was to figure out how to link FORTRAN subroutines to MATLAB. MATLAB provided an External Interface Guide but it only contained one example of how to link FORTRAN subroutines, and it offered no explanation for how the code was designed. Through trial and error, frustration, and some help from Dr. vanPutten I managed to figure out the purpose of each piece of the code. This project took three or four weeks to complete. For my presentation at the end of the summer, I gave a brief synopsis of how to link FORTRAN subroutines to MATLAB.

Then, I began working on a project involving electronics. My advisor, Dr. vanPutten had designed an operational amplifier circuit that used force sensitive resistors. These resistors changed from infinite resistance to a finite value when they were pressed. By looking at the circuit's output, the experimenter would be able to tell which resistors were being pressed at a given time. This system will be used by Dr. Thelen to assess how the human foot makes contact with the ground after a fall. My job began with testing the circuit on a breadboard, then designing and making a circuitboard. In this part of the project, I had a lot of help from Brad Mulder, the circuitboard specialist (among other specialties). Since a circuitboard is small and connections need to be precise, it was necessary to use a CAD program to lay out the circuitboard. After making a transparency of our final design, we used an involved chemical process used to etch the unwanted copper from the board. The copper connections were then plated with solder to guard against corrosion. After Brad showed me the ropes, I used the Bridgeport press to drill holes for the components. Brad also gave me a basic lesson on soldering, and I mounted the components on the circuitboard. I tested the circuitboard to confirm all the connections were correct and then I began to think about a box for the circuitboard. This box needed to have a power switch, two connectors for reading the output voltage, and two input connectors that went to the force sensitive resistors on the subject's feet. A late addition were two connectors for a multimeter, so that the voltage of the 9V battery could be monitored. Modular telephone jacks were used to connect the main box to a smaller box that will be secured to the subject's back. From this smaller box, there are eight phono jacks (four for each foot) which connect to the force sensitive resistors in the subject's shoe.