“Look Ma, No Gyros!”: A Self-Balancing Mechanical Velociraptor

You’ve got to walk before you can run, right? Perhaps not, if this bipedal dino-like running robot is any indication.

Officially dubbed a “Planar Elliptical Runner,” the bot is a test platform for bipedal locomotion from the Institute for Human and Machine Cognition. Taking inspiration from the gait of an ostrich — we think it looks more like a T. rex or velociraptor, but same difference — [Jerry Pratt]’s team at IHMC have built something pretty remarkable. Contrary to all the bipedal and quadrupedal robots we’ve seen, like Boston Dynamics’ Big Dog and PETMAN, which all fairly bristle with sensors and actuators, the PER is very stripped down.

A single motor runs the entire drive chain using linkages that will look familiar to anyone who has taken an elliptical trainer apart, and there’s not a computer or sensor on board. The PER keeps its balance by what the team calls “reactive resilience”: torsion springs between the drive sprocket and cranks automatically modulate the power to both the landing leg and the swing leg to confer stability during a run. The video below shows this well if you single-frame it starting at 2:03; note the variable angles of the crank arms as the robot works through its stride.

The treadmill tests are constrained by a couple of plastic sheets, but the next version will run free. It’s not clear yet how directional control will be achieved, not is it obvious how the PER will be able to stop running and keep its balance. But it’s an interesting advance in locomotion and we look forward to seeing what IHMC’s next trick will be.

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Robots and Crickets

If you watch science fiction movies, the robots of the future look like us. The truth is, though, many tasks go better when robots don’t look like us. Sometimes they are unique to a particular job or sometimes it is useful to draw inspiration from something other than a human being. One professor at Johns Hopkins along with some students decided to look at spider crickets as an inspiration for a new breed of jumping robots.

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Shakerbot leverages inertial for locomotion

This robot uses the concept of a snakeboard for getting around. [Sevag Babikian] built the project, and has gone out of his way to explain how it works.

We’d recommend skimming over his explanation, but it was the video after the break that made all things clear to us. There is a large fly-wheel at the center. This is not continuously rotating, but oscillates a few inches in either direction. This inertial change shifts the center of gravity for the entire frame, causing motion. By oscillating the front and rear axles at the appropriate time the beast can move forward in a surprisingly straight line.

It’s doing this with just three motors. [Sevag] speculates that with further testing and refinement this could be a very efficient way to move the bot around. We have our doubts about that, but we are mesmerized by the undulations and how well they really do propel the thing along.

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Super Simple Inch worm mechanism

Sticklers for the definition of “robot” should simply avert your gaze for the opening title of the video. [Randofo] has posted this beautifully simple inch worm mechanism using only a ruler, some connectors, a switch, a servo, a comb, some batteries, and a couple Tupperware containers. It inches, as it was designed to do, quite well. We’re especially fond of the use of a comb as an easily modifiable switch activator.