Page 340 - Robots Androids and Animatrons : 12 Incredible Projects You Can Build

Air Muscle Loop

16.25 Attaching opposite end of air muscle to
machine screw to extend air muscle

Pass a double strand of wire through the plastic hole and front loop
of the air muscle. Twist the ends of the wire together securing the
components together. If there is excessive wire left from twisting,
clip it off using wire cutters.

The top view should look something like Fig. 16.24. We can now 319
see how the finger will contract. As the air muscle is pressurized,
it contracts. The contraction pulls the plastic stem of the finger
pull, which in turn contracts the finger. When pressure from the
air muscle is released, the rubber band extends the air muscle
back into its original extended position.

At this point it’s a good idea to static test the finger. Connect the
air supply to the muscle to ensure it operates in the manner just
described. The prototype required a pressure of 42 psi to fully
contract the index finger.

When the finger operates properly, connect the air muscles to the
remaining fingers in the same manner described. Figure 16.26 is
a close-up of the air muscles connected to all the finger pulls.
The thumb

The thumb is the most important finger on the hand. It makes
grasping, holding, and using tools much easier. Don’t think so? Try
picking up a coin off a table or floor without using your thumb.
Now try using a few tools, like pliers, wire cutter, hammer, or drill.
To make the thumb, cut off the small finger assembly from the
second hand unit purchased. Assemble this finger section lower
and at a 45 degree angle to the other fingers (see Fig. 16.27).
Team LRN Android hand