Hi! We wanted to create an environment where we could test our Stretch robot while tethered without having to worry about cables getting in the way. We ended up constructing a cable gantry that suspends an AC power cable above the Stretch, and can slide easily in the X and Y directions to give the robot more room to navigate.
The gantry uses aluminum square tubing for the frame, which has garage door rollers and slides into our existing garage door tracks in our lab. Perpendicular to this, we have a round aluminum tube with which the cable is able to easily slide across. In addition to translating in X and Y, we had to make it so the cable could also rotate around Z to prevent the cable from twisting. To accomplish this, we used a cheap 3-wire slip-ring that we found on Sparkfun. Our Stretch robot would likely be able to pull the slip ring apart, so we 3D printed an enclosure that had a sturdy bearing to resist the cable being pulled, as well as a linear bearing such that the slip-ring assembly could easily slide across the aluminum tube.
Video link
Gantry:
See comments for slip ring images.
Bill of materials:
- Aluminum square tubing (about 24 ft)
- Aluminum round tube, 1/8" or greater wall thickness, 10 ft
- Aluminum plate, 24" x 24" x 1/8"
- Garage door rollers
- M6 bolts, nuts, nylon lock nuts
- M4 & M5 bolts, square nuts
- U-bolts, 1" inner diameter
- Shower curtain rings (to hold extra cable to the round rube)
- Slip-ring, 3-wire, 10A
- Ball bearing (Mcmaster # 5972K315)
- Linear bearing, 1" ID (Mcmaster # 1052K14)
- 3D printed housing
Feel free to check out our CAD here!
