Get a Grip
I gathered the materials listed in the Sidebar and
decided to create a gripper of my own that could be
incorporated into one of my robot designs.
Adding a vacuum pump or a powerful air mover
seemed difficult and probably unnecessary. Any sort of
suction pump would add weight to a robot, and use up
precious electrical power. In addition, it seemed wasteful
to have a pump running the whole time an object was
grasped. I thought of using solenoid-powered valves, but
the suction pump just seemed too wasteful.
So, I started to think about vacuums.
Suck It Up
I remembered that when they were filming “An
American Werewolf in London” that Rick Baker used
hypodermic syringes hooked up in a line. When a really
big syringe was compressed at the end of the line, the
little ones popped up creating the appearance of a spinal
column erupting below the skin of the creature’s back.
The tubing connecting the syringes created a closed
system that seemed to be pretty elegant.
I decided that the same idea might work with my
In addition, I thought that using a funnel could work
nicely for balloon support. Working through some
thought experiments, I saw an issue with the initial
contact between the gripper and the goal object. In the
video, a robotic arm moved the gripper into position and
brought it down. Each time, the goal object was on a flat
surfaced tabletop. So, what if you were dealing with
objects at different heights or on uneven surfaces?
I realized that adding a pressure sensor inside of the
funnel would allow the Arduino to apply suction only
when the balloon came into contact with the object to
pick up. This led me to Plusea and her instructables article
www.instructables.com/id/Conductive-Thread-Pressure-Sensor) using Velostat by 3M, conductive
thread, and neoprene. It seemed that I had all of the
solutions before me.
46 SERVO 01.2012