Bow down, bitches

Thats right. It works. In fact, it works well. We didn't have the time to calculate its maximum force ouput, but it should be on the order of 15N at the key tip where the user would play it. We had it working all day today at the design expo and it went pretty well. Used LabView and a control algorithm to tie in sensors and stuff. When the key was pressed, our control algorithm output a pulse of current into the coil. If you guys have any questions and down wanna read whats below, just put 'em in the comments and I'll edit my post to answer them. I can post more pictures too.

Since this probably just looks like a big mess I'll try to explain the design....

Basic Hardware: The key is attached to a big long shaft because we did not have time to design a super instense hinging mechanism, and the long shaft allowed us to restrict lateral motion of the key. If the shaft were shorter, the bearings would allow some play and the key would wobble left and right, contacting the disk, which is obviously bad. Also, our entire prototype was moving all over the place because the table we were stuck with was bent, so we have the base supported with bubble wrap in the picture above lol.

Controllers: We used a hall effect sensor to detect position/movement of the key. You can see it at the end of the white wires under the key tip. To read the motor speed, we had to interface its encoder with LabView. Then, we used a feedback loop that keeps the motor at a constant speed. For instance, if the electromagnet outputs a force, then there is back-torque on the motor, which slows the motors speed, so we needed to implement a feedback loop. The interfacing with LabView is done with two amplifiers - one behind the motor which you can see, and one inside the giant box to the left which you cannot. The amplifier you cannot see is contained within the 1000W power supply and controls the electromagnet's current. We interface with that amplifier and power supply with the smaller board that has wires coming off of it.

Power Input: To power this prototype, we needed 3 power supplies. One is for the electromagnet (1000W), another to power the motor, and a third to power the hall effect sensor and the motor encoder.

Electromagnet: The two coils of the electromagnet were wired in parallel for the Expo. This does not necessarily prove our model as we have not altered the model to include the magnetic field generated by two coils with different currents running through them. Although that is true, we used this arrangement because it allowed us to run 34 Amps through the coil (Yea, wow), giving us a higher maximum force output.

Future crap: Basically, this is going to go on and become some poor grad. student's project from hell. We managed to get a force transducer set up to read the output forces, but didn't have time to do many experiments. The transducer has its own little mounting system that attaches on top of the bracket in the picture which has nothing attached to it. We decided it'd be best that way for the design expo, because it was more important for people to actually feel the difference instead of just seeing more Newtons of force on a computer screen lol. I *might* be able to do some independent research in the fall with my professor, but I'm not sure just yet. He needs to figure out exactly what hes going to research over the summer, and if its still there I'll continue with this project.