A Robot Arm From The Cupboard

Building a simple robot arm is a lot more straightforward than it used to be.  If you have a laser cutter, or a bit of cash and don’t mind waiting for postage, there are inexpensive kits like the MeArm. If you have a 3D printer, there are any number of 3D-printed designs for you to tackle. What if you need to satisfy your urge to build a robot arm really quickly, and you don’t have a laser cutter or 3D printer? You’ve got a pile of servos from that remote-control project, how can you make the rest?

If you are [roboteurs], you raid the stationery cupboard, and create an arm using rubber bands, paper clips, and binder clips. The binder clips grip the servo arms and hold the whole thing together, the rubber bands provide extra attachment , and the paper clips are bent to form the jaws. It’s not the prettiest or perhaps the most capable of arms, but it undeniably is an arm, and we’d doubt it could be done any more cheaply.

In this particular case, the arm serves as a demonstration piece for [roboteurs]’ Printabots Maker Kit for people without a 3D printer. It uses their controller board, but there is no reason why it could not be used with any other board capable of driving servos.

We’ve covered innumerable robot arms over the years, This one may be the cheapest, but another contender might be this cardboard arm. None of them, however, are as cool as this steam-powered Armatron toy.

TensorFlow Robot Recognizes Objects

Children can do lots of things that robots and computers have trouble with. Climbing stairs, for example, is a tough thing for a robot. Recognizing objects is another area where humans are generally much better than robots. Kids can recognize blocks, shapes, colors, and extrapolate combinations and transformations.

Google’s open-source TensorFlow software can help. It is a machine learning system used in Google’s own speech recognition, search, and other products. It is also used in quite a few non-Google projects. [Lukas Biewald] recently built a robot around some stock pieces (including a Raspberry Pi) and enlisted TensorFlow to allow the robot to recognize objects. You can see a video of the device, below.

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Simulate Your Robot Before You Build It

[Nurgak] shows how one can use some of the great robotic tools out there to simulate a robot before you even build it. To drive this point home he builds the tutorial off of the easily 3D printable and buildable Robopoly platform.

The robot runs on Robot Operating System at its core. ROS is interesting because of its decentralized and input/output agnostic messaging system. For example, if you leave everything alone but swap out the motor output from actual motors to a simulator, you can see how the robot would respond to any arbitrary input.

[Nurgak] uses another piece of software called V-REP to demonstrate this. V-REP is a simulation suite for robotics and has a few ROS nodes built in. So in order to make a simulated line-following robot, [Nurgak] tells V-REP to send a simulated camera image to the decision making node of the robot in ROS. It then sends the movement messages back to V-REP which drives the pretend robot around.

He runs through a few more examples, proving that it’s entirely possible to become if not a roboticist, at least a really good AI programmer without ever dropping the big money on parts to build a robot.

Line Follower with No Arduino

There’s hardly a day that passes without an Arduino project that spurs the usual salvo of comments. Half the commenters will complain that the project didn’t need an Arduino. The other half will insist that the project would be better served with a much larger computer ranging from an ARM CPU to a Cray.

[Will Moore] has been interested in BEAM robotics — robots with analog hardware instead of microcontollers. His latest project is a sophisticated line follower. You’ve probably seen “bang-bang” line followers that just use a photocell to turn the robot one way or the other. [Will’s] uses a hardware PID (proportional integral derivative) controller. You can see a video of the result below.

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The Arduino Sleeps with the Fishes

[Eric Dirgahayu] wanted to explore underwater with some sensors and cameras. First, he needed a platform to carry them. That led to his Arduino-controlled swimming fish. The fish is made from PVC and some waterproof servos. From the video (see below) it isn’t clear how much control the fish has, but it does swim with an undulating motion like a real fish.

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Canary Island Team Wins World Robotic Sailing 2016

If you’re like us, you had no idea that there even was a World Robotic Sailing Championship. But we’re glad that we do now! And congratulations to the team of A-Tirma G2, the winning boat. (Link in Spanish, difficult to translate — if you can figure out how, post in the comments?)

The Championship has apparently been going on for nine years now, and moves to a different location around the world each year. The contests for 2016 (PDF) are by no means trivial. Besides a simple there-and-back regatta, the robot boats have to hold position, scan a prescribed area, and avoid a big obstacle and return quickly back to their lane. All of this with wind power, of course.

The winning boat used solid sails, which act essentially as vertical wings, and was designed for rough weather. This paid off in the area-scanning test; the winds were so strong that the organizers considered calling it off, but team A-Tirma’s boat navigated flawlessly, giving them enough points to win the event even though camera malfunction kept them from completing the obstacle avoidance.

stationkeepingtrackingUnless you’ve sailed, it’s hard to appreciate the difficulty of these challenges to an autonomous vehicle. It’s incredibly hard to plan far ahead because the boat’s motive power source, the wind, isn’t constant. But the boat has, relatively speaking, a lot of inertia and no brakes, so the robot has to plan fairly far in advance. That any of the 2-4 meter long boats could stay inside a circle of 20 meters is impressive. Oh, and did we mention that A-Tirma did all of this calculating and reacting on solar power?

Because the wind is so fickle, drone sailboats are much less popular than drone motorboats — at least using the Hackaday Blogpost Metric ™. The hackerboat project is trying out sails, but they’re still mostly working on powered propulsion. We do have an entry in the 2016 Hackaday Prize, but it’s looking like the development process is in the doldrums. Still, sailing is the best way to go in the end, because windpower is essentially free on the open ocean, which means less work for the solar panels.

As far as role-models go, you’ve basically got the entrants in the World Robotic Sailing Championships. So kudos to the A-Tirma team, and thanks [Nikito] for the tip!

Hacklet 124 Running Robots and The Claw

You never know what you’ll find when you open the projects feed on Hackaday.io. Most weeks, The Hacklet follows a theme of some sort. Sometimes I find projects that just look so cool that I have to get the word out about them.

runner1Such is the case with this week’s first project, Mr. Runner created by [Alex Martin]. Mr. Runner is a quadruped robot that really looks the part. In fact, I’d say it looks like it’s ready to jump off the bench top. Like many of us, [Alex] has been inspired by Boston Dynamics, specifically their Wildcat robot. Wildcat had [Alex] searching the net for walking robot designs. He struck up something he liked with the work of [Dr. Fumiya Iida] and [Dr. Rolf Pfiefer]. In the mid 2000’s, the pair worked out of the University of Zurich. Mr. Runner is based upon their work, with plenty of design tweaks from [Alex].

runner2The basic design is a quadruped with two servos per leg. The servos are at the body and the upper half of the leg. The knee and lower leg are connected by levers and a spring, forming something of a 4 bar linkage. The spring acts as a tendon, absorbing shock, and allowing energy from the servo to be stored and released while the robot runs. [Alex] is experimenting with gaits, controlled by a PC.

Mr. Runner wouldn’t be doing much running without a way to control those 8 servos. [Alex] started with an Arduino and a LynxMotion serial servo controller. This pairing served him well for the first generation of Mr. Runner. For the new version of the robot, he’s rolling his own board based upon Lynxmotion’s
BotBoarduino. The Gerber files have been sent off to OSH Park, and in about a week, Mr. Runner will be off to the races.

claw-1-aAnother great recently updated project is Arcade Claw Game Claw Build by [Alex Anderson]. I spent way too many hours of my youth in arcades, and more than a few quarters went into claw games. Sure, they’re usually rigged, but who hasn’t been pulled in by the chance to test your skill and win a prize? A friend asked [Alex] to design an arcade style claw for a game. A seasoned CNC and 3D printing master, [Alex] grabbed his notebook and started sketching. Rack and pinion designs would work well, but didn’t within the constraints of the game. A leadscrew based design would also work, but would be two expensive. Finally, [Alex] settled on a design and fired up his CAD software. He started with two jaw systems to prove out the basic system. Once that was complete, [Alex] moved to a 4 jaw setup.

claw1Much like the arcade games, the claw is actuated by a central plunger. The plunger drives linkages which move the 4 claw jaws. Everything looks good on paper, but when the CAD drawings meet the real world, things get complicated quickly. The initial design relied on a 3D printed part which connected the plunger to the jaw linkages. Any slop in this part would be magnified through the rest of the mechanical system. 3D printers aren’t perfect, and there was some slop — enough that the parts would pinch and bind up while moving.

[Alex] already has a revised design in mind. This is very much a work in progress. That’s the beauty of well documented projects on Hackaday.io — you get to see what works, as well as all the trials and tribulations it took to get to a final working project. Keep at it [Alex], you’re almost there!

That’s it for this week’s Hacklet, As always, see you next week. Same hack time, same hack channel, bringing you the best of Hackaday.io!