Hydraulic Robot Arm

This hydraulic robot arm was a school project while studying hydraulics in May. When we first got the assignment, I had no idea what to do. So I came up with my typical response, “Let’s build a robot!”

This particular robot is manually controlled, using only big huge syringes, valves, and tubing. I also had to be creative with my methods of motion since the syringes obviously don’t spin like a motor, but push like a solenoid.

As you coud tell from the video, this was an on the spot job. I barely planned, though I knew enough about robot arms before even starting. All that was learned mainly from two sources: Robot Builder’s Bonanza (Third Edition) and from The Society of Robots website. Both are very useful sources for all kinds of robotics and I recommend them both.

The first part of the arm that I made was the gripper. Using a piece of strong plywood, I hammered in two pieces of cardboard in the shape of two quarter circles. Then, using some metal ribbon with predrilled screw holes, I firmly attached the syringe to the plywood. If the shaft of the syringe pushed out, it would push out the cardboard claw. Though if the shaft was pulled in, then the gripper should have closed, riiiight? Wrong, I needed to attach the shaft to the claw somehow. Using a thick gauged wire, I lace it through two holes I punctured in the gripper, and around the end of the shaft with a plastic pull-tie. Voila!!! After I hammered it to the “forearm” of the robot.

The elbow joint was fairly simple. I drove a nail through two pices of wood, leaving a little bit sticking out the back as a mild counterweight.

Attaching the syringe was a different story. Using the same metal ribbon, I managed to attache the syringe to the side of the “upper arm”. This time, though, I used a stronger wire to attach to the syringe considering the larger amount of weight.

The base is fairly similar, only with a few design changes including the rock used as a counter-weight so the Hydraulic robot arm can support itself. It also had to be made stronger because of the larger amount of weight it supported. After the construction was over, all that there was left to do was to connect the plastic tubing to the syringes and to fill them with water. I was fortunate to have a few valves, alowing me to open and close the flow of water.

This is obviously very rough, and crude work. There are several improvements I would have liked to make though no longer can. It isn’t perfect, but it works. This is a strong and fairly capable robot arm. there are obviously some problems with the articulartion of the joints, and it may look a little ugly, but it works. Normally in home made robotics, this is the outcome you will get, though don’t be discouraged. Hope you have fun while trying to build your own!

Page last updated October 8, 2008.


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