These impressive videos from YouTube user [hinamitetu] have been appearing on the internet for a few days now, covered by various news and blog sites, but there seems to be very little information about them.
They appear to be home-made robots that can swing themselves around a horizontal bar like a gymnast, and then perform a somersault dismount and land (hopefully) on its feet. One of the latest videos shows a well-executed quadrupal backflip and flawless landing.
[hinamitetu]‘s youtube channel “About” section says (in Japanese, this is me trying to parse and paraphrase the Google Translation as best as I can)
I used a 2-axis accelerometer located in the head to measure gravity. The measured value varies depending on the robot’s angle of rotation.
The sensors zero when the robot is level on the ground.
[garbled, something about using four distinct sensor regions to detect position and rotation using rise/fall of the sensor information]
Based on these signals, the robot determines when to stretch or bend the leg
While these appear to be relatively simple robots, their build is very neat (perhaps they’re a mod of a toy?), using accelerometers and presumably a microcontroller (I’d be very impressed if it were controlled by a fully analog circuit), running some code to swing its leg(s) just like a gymnast, to build up angular momentum and eventually gracefully dismount. (I wonder if it would be beneficial to add a single-axis mems gyroscope sensor to provide more accurate rotation measurements as you would in an IMU device?)
Judging by the number of (often amusing) blooper videos in his channel, lot of trial and error appears to be involved over the course of several years, which of course is all the fun of it. We wish [hinamitetu] the best of luck and continued success.