[raffi383]

Here's a detailed explanation of how the arm works.

There is a gas strut that is attached to the lower portion of the arm. When a latch at the back end of the lower arm is released, the strut raises the lower portion of the arm.

When the lower arm is near its fully upright position, a cable attached to the robot and to the bottom end of the upper arm begins to tighten.

Once the lower arm is at its upright position, the cable attached to the upper arm is holding the upper arm in its fully extended position.

As the upper arm gets near its fully upright position, a second cable (bike brake cable) that is attached to the lower arm and a release hook that retains the hanging hook holder in its folded position is pulled and the hanging hook holder swings into position.

With the hanging hook over the tower bar, the winch is turned on. The kevlar line that we use to lift (instead of the original steel cable that looked like a screwed up pretzel after Kettering) is routed through another retention hook that holds the bottom of the gas strut in place. Since we didn't want to have the arm in the deployed position when lifting to avoid bending it and didn't want to have to compress the gas cylinder to bring the arm down, we just release the bottom end of the gas strut and it slides rearward which lets the arms drop.

The hanging hook is held to its holder by magnets. Once the gas strut retention hook is released and the arm begins to drop, the magnets disengage from the arm and the hook remains on the tower.

For resetting after the match, we have a clutch on the winch that we can pull out by hand so we can unwind the line from the pulley without power. There is also a ratchet on the winch to keep it from backdriving after we turn the power off. The gas strut is automatically reset when the arm is manually lifted to the extended position.

There is a lot of "magic" in our arm. It took a while to get it to work.

Hopefully we will be in Ypsi hanging around at the end of the Finals.

Stop by the pits for a demonstration.

Raffi