The convergence of mechanics and electronics in robotics brings with it a lot of challenges. Thanks to 3D printing and low cost components, it’s possible to quickly and easily experiment with a variety of robotics mechanism for various use cases. [Paul Gould] has been doing exactly this, and is giving us a taste of ten designs he will be open sourcing in the near future. Video after the break.
Three of the designs are capstan mechanisms, with different motors and layouts, tested for [Paul]’s latest quadruped robot. Capstan mechanisms are a few centuries old, and were originally used on sailing ships to give the required mechanical advantage to tension large sails and hoist cargo.
Two of the mechanisms employ GUS Simpson Drives, which use a combination of belts and a rolling joint. These were inspired by the LIMS2-AMBIDEX developed at the University of Korea. The ever-popular cycloidal gearbox also makes and appearance in the form of a high torque dual disk linked, two stage, NEMA17 driven gearbox.
[Paul] also built a room sized skycam-like claw robot for his daughter, suspended by four ball chain strings reeled in by four brushless motors with ESP32 powered motor controllers. We are looking forward to having a close look at these designs when [Paul] releases them, and to see how his quadruped robot will turn out.
[Thanks TTN for the tip!]
[David] has created a four cable drawing machine for the Telus Spark Science Centre in Canada. Hackaday has featured [David’s] unconventional drawing contraptions before, specifically his center pivot pen plotter. The drawing machine is a new take on a drawbot, and could be considered to be close cousins with [Dan’s] SkyCam. The premise is simple: A stepper motor with a reel of string is placed at each corner of a square. The strings for all four motors come together at a center weight. When all four strings are taut, the weight is lifted off the drawing surface. When a bit of slack is added into the strings, gravity pulls the weight down to touch the sand.
It’s at this point that a simple premise becomes a complex implementation. Moving the weight in one direction is a matter of reeling out string on one motor, and reeling in string on the other. But what about the two “un driven” strings? They have to be slack enough to allow movement in the driven direction, but not so slack that the weight can dig in and tumble on the sand, causing a tangle. To handle some of these questions, [David] called on [Kevin] to write some software. [Kevin] created a custom kinematics module for LinuxCNC to control the drawing machine. The drawing machine runs on Gerber Code, similar to a CNC. Simply feed the machine Cartesian coordinates, and [Kevin’s] module converts to steps.
Continue reading “Four Cable Drawing Machine Pulls Our Strings”
With the Olympics on there are a lot of really great camera shots shown during the events. One of the best is the overhead view, which is provided by a camera suspended between cables. It’s not new for the Olympics, SkyCam has been around for over twenty years. What is new is [Dan Royer’s] attempts to build his own aerial camera setup.
He’s not starting from zero with this project. [Dan] has done some really great work with the Drawbot. It’s a two-motor, two-axis plotter which uses CNC to draw on a white board. For this project he combined two Drawbots in order to add a third axis. The image above shows the camera mount suspended between the four strings. He’s been working hard on getting the software ready for this kind of addressing. Along the way he broke the strings a few times because he was too far from the kill switch to stop it in time. But what he’s got is a nice start and we hope to see a more illustrative follow-up soon.
One of the things that SkyCam has going for it is a stabilization system. We wonder if a spinning gyroscope would work as well as it did for that balancing bike.