For me, the difficult part of this project was trying to determine a relatively simple way of achieving the motion of a guy throwing himself forward in the chair he is chained and lashed into, shaking violently from 50,000 volts charging through his innocent body and also sporadically stomping his feet from the unbearable pain. I finally decided on using one air cylinder to throw his torso forward, another one to stomp his feet and then using a motorized vibration for his shaking. To see where my pivot points would have to be to make this work I went to the CAD system. In the photo on the left you will see the torso and arms attached to a 10" air cylinder located inside the seat box below, hinged at the bottom of the spine. Looking to the photo on the right you can see that I didn't need quite 10" of air cylinder to deliver the needed throw which in this case turns out to be 5 1/16", but it turned out to be easier to use than an 8" cylinder would be, as I would then only need to use a 1/2" spacer from the front wall of the seat box to attach my clevis (air cylinder pivoting mounting bracket) to. Above the air ram, 3 1/4" on the clevis and the lever I have shown a 12" spring that when installed will be slightly engaged, keeping the torso in an upright position when it is not activated and of course, bringing the torso back upright after activation. So at this point, it looks like we have succeeded with the first of the 5 animations our freaked out friend will hopefully wind up with. In this photo on the left you can see a close up of the mechanism.  

   Next I used the same drawing to lay out the leg animation, as this ensures absolute accuracy of the positions of the axis point that I hope to use for both the torso and the legs. In this photo you will find what seems excessive amounts of dimensions, but trust me when I say you will want every one of them. Using a short 7 1/2" air cylinder that is two way, I determine it would be easier to pull down on the back of the leg assembly to lift up the feet of our spastic friend than it would be to push them up. I choose to overlay a rail across both of the leg sections behind where his butt would be, creating a 1" additional hollow space, so I will use that for the attaching bracket. This small cylinder is more than ample to clear the very small distance of 1 5 /8" travel I will need of course. The top of the cylinder will need to protrude out of the top of the seat box by 2" for my ram's throw to be limited to what is needed.  This will give us a 4 1 /4" travel at the knee, which I determined to be adequate. So the next step is to put these two drawings together and make sure everything clears each other inside the seat as well as in the skeleton. In the first one, all is clear and working together, even allowing us enough space for the speaker under the raised floor section of the box. In the photo on the left we see that at the apex of it's cycle, both the skeleton and the air cylinder mechanisms are clearing by just enough to allow fluid motion. Success! Now it is only a matter of cutting some steel and aluminum!