Our old name, “Group 10 – Planar Cable-Suspended Haptic Interface for the Rehabilitation of Fine Motor Skills” is too long for our table’s sign. So we needed a shorter, hipper name for the Expo this week. We looked through a few names, and ultimately settled on the snazzy “Cable-Assisted Scripting with Haptics” (CASH for short). Our project has very little to do with money, but I digress.

Meanwhile, progress continues apace! Our new motor shields have arrived today. These use H-bridges (essentially a set of switches, relays, or transistors that can allow a large voltage to be applied “forwards” or “reverse” to a circuit) to allow our low-voltage control circuts to safety direct the relatively strong motor power supplies. A good analogy would be the transmission in a car, which allows a human to force the engine to drive the wheels forward or backwards, even though it’s much stronger than we are.

Our previous motor shields blew up (almost literally; there were sparks and smoke!) under normal operating conditions. We had planned to replace them some time ago, but there were errors and delays with shipping our order. In the meantime, we had to improvise some repairs! A few power lines had to be re-soldered, but mostly the issue was that the H-bridges burnt out and would only toggle “forward” or “off.” Fortunately, by splicing multiple H-Bridge channels together, we were able to engage one bridge to drive a motor forwards and another to reverse it. This is like having two cars that cannot reverse, and welding their rear bumpers together! Then you can drive the two cars backwards by putting the rear vehicle in gear and the front vehicle in neutral. It’s cumbersome, but it worked during the prototype stage.

Now that the new shields are here, we can finalize our circuits and have them running at full power for the Expo, which is this Thursday in Lerner Hall from 12-3!