Legged Robots Put On Wheels And Skate Away

We don’t know how much time passed between the invention of the wheel and someone putting wheels on their feet, but we expect that was a great moment of discovery: combining the ability to roll off at speed and our leg’s ability to quickly adapt to changing terrain. Now that we have a wide assortment of recreational wheeled footwear, what’s next? How about teaching robots to skate, too? An IEEE Spectrum interview with [Marko Bjelonic] of ETH Zürich describes progress by one of many research teams working on the problem.

For many of us, the first robot we saw rolling on powered wheels at the end of actively articulated legs was when footage of the Boston Dynamics ‘Handle’ project surfaced a few years ago. Rolling up and down a wide variety of terrain and performing an occasional jump, its athleticism caused quite a stir in robotics circles. But when Handle was introduced as a commercial product, its job was… stacking boxes in a warehouse? That was disappointing. Warehouse floors are quite flat, leaving Handle’s agility under-utilized.

Boston Dynamic has typically been pretty tight-lipped on details of their robotics development, so we may never know the full story behind Handle. But what they have definitely accomplished is getting a lot more people thinking about the control problems involved. Even for humans, we face a nontrivial learning curve paved with bruised and occasionally broken body parts, and that’s even before we start applying power to the wheels. So there are plenty of problems to solve, generating a steady stream of research papers describing how robots might master this mode of locomotion.

Adding to the excitement is the fact this is becoming an area where reality is catching up to fiction, as wheeled-legged robots have been imagined in forms like Tachikoma of Ghost in the Shell. While those fictional robots have inspired projects ranging from LEGO creations to 28-servo beasts, their wheel and leg motions have not been autonomously coordinated as they are in this generation of research robots.

As control algorithms mature in robot research labs around the world, we’re confident we’ll see wheeled-legged robots finding applications in other fields. This concept is far too cool to be left stacking boxes in a warehouse.

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ESP32 Rover With PCB Chassis Is Ready To Roll

The microcontrollers are cheap, the sensors are cheap, even the motors are cheap. So why are all the good wheeled robotics platforms so expensive? [Dimitris Platis] wanted to develop an affordable platform for experimenting with rovers, but the cheap plastic chassis he was using gave him all sorts of problems. So he did what any good hacker would do, and built a better version himself.

Interestingly, [Dimitris] decided to go with a chassis made from two PCB panels. The motors, mounted to small angled brackets, bolt directly to the lower PCB. These aren’t your standard $2 DC cans either. Each JGB37-520 gearhead motor comes complete with an encoder that allows your software to determine speed, distance, and direction. The upper PCB connects to the lower with several rows of pin headers, and plays host to whatever electronics payload you might be experimenting with at the time.

For the controller, [Dimitris] says the ESP32 is hard to beat by pretty much any metric you want to use. With integrated wireless and considerable computational power, there’s plenty of options for controlling your little rover either remotely or autonomously. But he also says that every effort has been made to ensure that you could switch out the microcontroller with something else should you want to spin up a customized version.

The whole idea reminds us a bit of quadcopters we’ve seen in the past, where the PCB wasn’t just being used structurally as a place to bolt the motors and hardware to, but actually contained functional traces and components that reduced how much wiring you needed to do. Naturally, this means that any damage to the chassis might cripple the electronics, but presumably, that’s what the big foam bumpers are there for.

[Dimitris] designed this project for educational use, so he assumes you’ll want to build 10 or 12 of these for your whole classroom. In those quantities, he says each bot will cost around $60. If you wanted to reduce the price a bit more, he says swapping the motors would be your best bet as they’re the single most expensive component of the design. That said, $60 for a quality open source rover platform sounds pretty fair to us.

Still too much? You could check out one of the 3D printable rover designs we’ve covered over the years. Or see if you can get lucky and pick up a cheap robot from the clearance rack and hack it.

Pi-Controlled Billy From The Saw Horror Flicks

[David0429] has made a very scary Raspberry Pi controlled puppet. Scary that is if you’ve seen the Saw movies where a serial killer uses one like it, called Billy, to communicate with his victims. If you haven’t, then it’s a pretty neat remote-controlled puppet-on-a-tricycle hack.

A stepper motor hidden under the front fender moves the trike by rotating the front wheel. It does this using a small 3D printed wheel that’s attached to the motor’s shaft and that presses against the trike’s wheel. Steering is done using a 3D printed gear mounted above the fender and attached to the steering column. That gear is turned by a servo motor through another gear. And another servo motor in the puppet’s head moves its mouth up and down.

All these servos and motors are wired to an Adafruit stepper motor HAT stacked on a Raspberry Pi hidden under the seat. Remote control is done from a webpage in any browser. The Flask python web framework runs on the Pi to both serve up the webpage and communicate with it in order to receive commands.

[David0429] took great care to make the puppet and tricycle look like the one in the movie. Besides cutting away excess parts of the trike and painting it, he also ran all the wires inside the tubular frame, drilling and grinding out holes where needed.  The puppet’s skeleton is made of wood, zip ties and hinges but with the clothes on, it’s pretty convincing. Interestingly, the puppet in the first movie was constructed with less sophistication, having been made out of paper towel rolls and papier-mâché. The only things [david0429] would like to do for next time are to quieten the motors for maximum creepiness, and to make it drive faster. However, the need for a drive system that could be hidden under the fender resulted one that could only work going slowly. We’re thinking maybe driving it using the rear wheels may make it possible provide both speed and stealth. Ideas anyone?

In any case, as you can see in the video below, the result is suitably creepy.

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Hackaday Prize Entry: Experiments With Wheeled Legs

If you’ve been keeping tabs on recent developments in robotics, you surely remember Handle — the awesome walking, wheeled robot from Boston Dynamics. There’s a good reason why such a combination is a good choice of locomotion for robots. Rolling on wheels is a good way to cover smooth terrain with high efficiency. But when you hit rocky patches or obstacles, using legs to negotiate these obstacles makes sense. But Handle isn’t the only one, nor is it the first.

[Radomir Dopieralski] has been building small robots for a while now, and is especially interested in how they move. He is sharing his experience while Experimenting with Wheeled Legs, with the eventual aim of “building an experimental walking+rolling robot, to more efficiently kill all humans and thus solve all the problems”. His pithy comments aside, investigating and experimenting with different forms of locomotion to understand which method is most efficient will pay rich dividends in the design of future robots.

During an earlier version of the Hackaday Prize, [Radomir] snagged a coupon for laser cutting services. He used it to build a new robot based on a fresh look at some of his earlier designs. This resulted in the Logicoma-kun — a functional model of a Logikoma (a logistics robot designed to be a fast all-terrain vehicle for transporting weapons and ammunition) from “Ghost in the Shell: Arise”. Along the way, he figured out how to save some servo channels. For gripping function, he needed to drive two servos in sync with each other, but in opposing directions. This would usually require two GPIO’s and a few extra lines of code. Instead, he dismantled a servo and reversed the motor AND the servo potentiometer connections.

But this is still early days for [Radomir]. He is fleshing out ideas, looking for feedback and discussions on robotic locomotion. This fits in perfectly with the “Design Your Concept” phase of the Hackaday Prize 2017. He has already made some progress on Logicoma-kum by having it move in either the wheeled or walking modes — check out the videos after the break.

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A Robot… That Can See Through Walls!

Robots on four wheels are fun on their own merits, but one thing that most lack is the ability to see through walls.  With it’s onboard radar system, this bot is equipped to see objects that a person couldn’t normally detect on the other side of the wall.

Although some of the more “nuts and bolts” details of this build are missing, the robot uses an Ultra-Wideband Radar system called the [D1] Radar System. This system can, according to their documentation, “Avoid false positives caused by vapor, dust, smoke, rain or other small particles.” Apparently this means drywall as well if programmed correctly.

In the video after the break, the robot’s sensor package is programmed to ignore anything within 1.5 meters. This allows the robot to mirror the movement of the apparent shelving unit on the other side. This sensor could certainly have some interesting robotics applications besides imitating a rolling shelf, so we’re excited to see what it will be used for!

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