cable-driven robotics

Research example:

Ben Peters’s Spiderbot is a concept for a large-envelope 3D printer, where the print head is suspended by cables from four fixed points. The print head has its own winches on board, and so the ends of the cables may be fixed to nearby tall sturdy objects like trees or buildings without any need for actuation at the affixing site. Peters describes some challenges with his design, including difficulty quelling oscillations that leads to lower-than-desired accuracy. I think this is an interesting prototype of an actuator type that might be used for a broad range of applications. It demonstrates that even simple, low-cost iterations of this can work.

See http://www.bnpeters.com/spiderbot.html for video (which is not embeddable here)

Commercial example:

The Skycam is a cable-driven large-envelope robot that carries a fairly heavy load (a steadicam and some control electronics) over the filed at sporting events to enable previously impossible angles on the action. The flying part (camera and electronics) only needs to actuate pan/tilt, since the four winches driving the cables are located near the four high corner points of the stadium. The system is very fast and accurate and allows the operator to quickly move the camera to anywhere inside of a defined envelope, with safety boundaries established so the device and its cables won’t hit any people or equipment during flight.

Another cable-driven commercial robot, this one load-bearing:

Art robot:

The Four Cable Drawing Machine was built by artist David Bynoe for the Telus Spark Science Centre in Calgary. It has four stepper motors attached directly to cable spools and a dangling cylindrical mass that draws by dragging itself through a sand pit. The robot is programmed to draw geometric patterns and abstract shapes but of course could draw anything constructed of line segments, dots, and curves. The project is beautiful and simple and I’m sure it’s very captivating to its installation audience at the museum. Note that it only moves in Z to start or stop drawing.