Robotic Drive Train Is Nearly All 3D Printed

January 7, 2018 by Al Williams 2 Comments

There are lots of ways to move a robot ranging from wheels, treads, legs, and even propellers through air or water. Once you decide on locomotion, you also have to decide on the configuration. One possible way to use wheels is with a swerve drive — a drive with independent motors and steering on each wheel. Prolific designer [LoboCNC] has a new version of his swerve drive on Thingiverse. The interesting thing is that it’s nearly all 3D printed.

You do need a few metal parts, a belt, two motors, and — no kidding — airsoft BBs, used as bearings. There are 3 parts you have to fabricate, which could take some work on a lathe, so it isn’t completely 3D printed.

[LoboCNC] points out that the assembly is lightweight and is not made for heavy robots. Apparently, though, his idea of lightweight is no more than 20 pounds per wheel, so that’s still pretty large in our book. The two motors allow for one motor to provide drive rotation while the other one — which includes an encoder — to steer. Of course, the software has to account for the effect of steering each wheel separately, but that’s another problem.

This robotic drivetrain is just thing for a car-like robot. If you are a little lonesome you could always print out ASPIR, instead. Or if you want an exotic 3D printed way to move things, you might get some inspiration from Zizzy. If you want a swerve drive that doesn’t require any machining or 3D printing, you might enjoy the video from another FIRST team, below.

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See This Slick RC Strandbeest Zip Around

January 3, 2018 by Donald Papp 8 Comments

Bevel gears used to mount motors vertically.

Theo Jansen’s Strandbeest design is a favorite and for good reason; the gliding gait is mesmerizing and this RC version by [tosjduenfs] is wonderful to behold. Back in 2015 the project first appeared on Thingiverse, and was quietly updated last year with a zip file containing the full assembly details.

All Strandbeest projects — especially steerable ones — are notable because building one is never a matter of simply scaling parts up or down. For one thing, the classic Strandbeest design doesn’t provide any means of steering. Also, while motorizing the system is simple in concept it’s less so in practice; there’s no obvious or convenient spot to actually mount a motor in a Strandbeest. In this project bevel gears are used to mount the motors vertically in a central area, and the left and right sides are driven independently like a tank. A motor driver that accepts RC signals allows the use of an off the shelf RC transmitter and receiver to control the unit. There is a wonderful video of the machine zipping around smoothly, embedded below.

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Remember When Scratch-Built Robots Were Hard?

January 2, 2018 by Mike Szczys 10 Comments

Even simple robots used to require quite a bit of effort to pull together. This example shows how far we’ve come with the tools and techniques that make things move and interact. It’s a 3D printed rover controlled by the touchscreen on your phone. This achieves the most basic building block of wheeled robotics, and the process is easy on you and your pocketbook.

We just can’t stop loving the projects [Greg Zumwalt], aka[gzumwalt], is turning out. We just saw his air-powered airplane engine and now this little rover perks our ears up. The design uses the familiar trick of two powered wheels with a ball bearing to avoid problems with differential turning. But the simplicity is all in the implementation.

This bot is 3D printed using eight very simple pieces: four gears, two axles, a cap and a single tray to mount everything. The cap captures the ball bearing which pokes out a hole in the bottom of the tray to form an omnidirectional wheel. Two 9G servos modified for continuous rotation. The mating teeth of the gears are found on the wheel sections which have grooves for neoprene O-rings to provide traction. The entire thing is driven by an ESP8266 in the form of an Adafruit Feather Huzzah. This is programmed using the Arduino IDE and your phone can connect directly or through a WiFi router.

We’re not crazy, right? Robots didn’t used to be this easy to pull together? This goes for the power of 3D printing versus traditional basement fabrication methods, but in the availability of powerful yet inexpensive embedded systems and the available tools and libraries to program them. Kudos to you [Greg] for showing us how great the currently available building blocks are in the hands of anyone who wants to channel their engineering creativity. He certainly has… this chassis ultimately powers Santa’s sleigh.

Need a bigger printing challenge? Here’s a 3D printed rover that goes all-in with the suspension system.

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How The Hero Droid BB-8 Rolls

January 1, 2018 by Roger Cheng 10 Comments

By now we’ve come to expect a bountiful harvest of licensed merchandise to follow every Star Wars film. This year’s crop included many flavors of BB-8 so every fan can find something to suit their taste. At the top of this food chain is a mobile interactive “Hero Droid BB-8”. For those who want to see how it works, [TheMikeSenna] cracked open his unit to feed our curiosity.

Also called “Spin Master BB-8” for the manufacturer, this toy is impressively sophisticated for its price point. The video surveyed the mechanical components inside the ball. Showing how the droid travels, and how the head articulates.

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BeefBot: Your Robotic Grill Master

December 30, 2017 by James Hobson 6 Comments

Have you ever been too busy to attend to the proper cooking of a steak? Well, lament no more, and warn your cardiologist. A trio of students from Cornell University have designed and built the steak-grilling BeefBot to make your delicious dinner dreams a reality.

[Jonah Mittler], [Kelsey Nedd], and [Martin Herrera] — electrical and computer engineering students — are the ones you should thank for this robot-chef. It works as follows: after skewering the steak onto the robot’s prongs, BeefBot lowers it onto the grill and monitors the internal temperature in a way that only the well-seasoned grillmaster can replicate. Once a set temperature is reached, the steak is flipped — sorry, no crosshatch grillmarks here — and cooked until a desired doneness. A small screen displays the temperature if you want to babysit BeefBot — some manual adjustment may be needed after the steak flip to ensure it is cooking evenly — but it is otherwise a hands-off affair. If you don’t mind salivating over your screen, check out the project demonstration after the break.

At first glance you might think this a YouTube stunt, but this is real science. The writeup is exquisite, from the design and fabrication, to the math behind temperature calibration and regulation. Kudos to the hungry Cornell students who slaved over a hot griddle bringing this one to life!

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A Robot Arm For Virtual Beer Pong

December 15, 2017 by Kristina Panos 2 Comments

Leave it to engineering students to redefine partying. [Hyun], [Justin], and [Daniel] have done exactly that for their final project by building a virtually-controlled robotic arm that plays beer pong.

There are two main parts to this build: a sleeve worn by the user, and the robotic arm itself. The sleeve has IMUs at the elbow and wrist and a PIC32 that calculates their respective angles. The sleeve sends angle data to a second PIC32 where it is translated it into PWM signals and sent to the arm.

There’s a pressure sensor wired sleeve-side that’s worn between forefinger and thumb and functions as a release mechanism. You don’t actually have to fling your forearm forward to get the robot to throw, but you can if you want to. The arm itself is built from three micro servos and mounted for stability. The spoon was a compromise. They tried for a while to mimic fingers, but didn’t have enough time to implement grasping and releasing on top of everything else.

Initially, the team wanted wireless communication between the sleeve and the arm. They got it to work with a pair of XBees, but found that RF was only good for short periods of use. Communication is much smoother over UART, which you can see in the video below.

You don’t have to have a machine shop or even a 3-D printer to build a robot arm. Here’s another bot made from scrap wood whose sole purpose is to dunk tea bags.

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Solving A Rubik’s Cube With Just Two Motors

December 2, 2017 by Dan Maloney 11 Comments

We’ve all seen videos of Rubik’s cube champions who can solve the puzzle in less than 5 seconds. And there are cube-twisting robots that can solve the cube even faster, often in under a second. This Rubik’s cube solver is not one of those robots, but it’s still pretty cool.

The reason we like Dexter Industries’ “BricKuber” is not for its lightning speed — it takes a minute or two to solve the puzzle. What we like is the simplicity of the approach to manipulating the cube. Built from LEGO parts, including Mindstorms motors and a BrickPi controller, the BricKuber uses only two motors to work the cube. One motor powers a square turntable upon which the cube sits, while the other powers an arm that does double duty — it either clamps the cube so the turntable can rotate a layer, or it rakes the cube to flip it 90° on the turntable. With a Pi Cam overhead, the rig images all six faces, calculates a solution to the cube, and then flips and twists the cube to solve it. It’s simultaneously mind-boggling and strangely relaxing to watch.

All the code is open source, and we strongly suspect a similar and possibly faster robot could be built without the LEGO parts. You might even be able to build one with popsicle sticks and an Arduino.

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