Design

6-Bar Tesegrity Robot Arm

The fully assembled 6-Bar Robotic Arm!

This picture is the almost completed arm. It still requires some adjustment depending on how testing turns out, but overall, this will be its final form. It can be abstracted down to 4 mechanical parts (rods, pivots, bases, and motors). The strings, while important, had little desing work involved and were chosen because of the constraints of the system.











The fully assembled 6-Bar Robotic Arm!

This is the schematic for the rod. As you can see, the rod is divided up into 2 parts, which swivel independently of one another. This is achieved by using a skateboard bearing at the central connection piece.











The fully assembled 6-Bar Robotic Arm!

Another schemetic, except it is the pivots picture. These are mounted on the baseplates and connect to the rods. They provide wide range of motion with little resistance. Like the split assembly rod, a skateboard bearing is used.












The fully assembled 6-Bar Robotic Arm!

Finally, this is the baseplate, which asts as a mount for the entire setup. The servos and pivots are secured here, and when modularity is introduced, the tensegrity modules will together here.












Testing

Testing was a matter of figuring out the range of motion of the tensegrity module. By measuring how the module was able to move in a given direction, we were able to determine how successful the module was.


X-Y Directions:

The X and Y directions were limited. While it was able to noticably move, it was unable to achieve more than a few inches before it would become unbalanced. This may not be an issue depending on the environment you are working in (e.g. space).


Z Direction:

By far the best direction of the robot prototype. It was able to easily and quickly move up and down. The final position was off by a few inches at most heights.


Phi-Theta Directions:

This direction was also limited. It was able to make small angles with the top plate, but was unable to do anything to significant.


Psi Direction:

Also limited. From some positions it was able to make a little twisting motion.


Comparision

We matched all but one of the specifications of this project. We were able to move a robot tensegrity arm with 6 degrees of freedom. The one thing we were unable to do was put modularity in the final product. The robot arm attaches to no other arm and works alone.


Parts List/Bill of Materials

Tensegriteam's current BOM can be downloaded here .

DFMEA

Tensegriteam's DFMEA can be downloaded here .