A Robot Arm From The Cupboard

October 16, 2016 by Jenny List 4 Comments

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.

1980s Toy Robot Arm Converted To Steam And Other Explorations

August 3, 2016 by Gerrit Coetzee 19 Comments

We were doing our daily harvest of YouTube for fresh hacks when we stumbled on a video that eventually led us to this conversion of a 1980s Armatron robot to steam power.

The video in question was of [The 8-bit Guy] doing a small restoration of a 1984 Radio Shack Armatron toy. Expecting a mess of wiring we were absolutely surprised to discover that the internals of the arm were all mechanical with only a single electric motor. Perhaps the motors were more expensive back then?

The arm is driven by a Sarlacc Pit of planetary gears. These in turn are driven by a clever synchronized transmission. It’s very, very cool. We, admittedly, fell down the google rabbit hole. There are some great pictures of the internals here. Whoever designed this was very clever.

The robot arm can do full 360 rotations at every joint that supports it without slip rings. The copper shafts were also interesting. It’s a sort of history lesson on the prices of metal and components at the time.

Regardless, the single motor drive was what attracted [crabfu], ten entire years ago, to attach a steam engine to the device. A quick cut through the side of the case, a tiny chain drive, and a Jensen steam engine was all it took to get the toy converted over. Potato quality video after the break.

Continue reading “1980s Toy Robot Arm Converted To Steam And Other Explorations” →

Taming Robot Arm Jump With Accelerometers

June 24, 2016 by Rud Merriam 46 Comments

Last fall, I grabbed a robot arm from Robot Geeks when they were on sale at Thanksgiving. The arm uses servos to rotate the base and move the joints and gripper. These work well enough but I found one aspect of the arm frustrating. When you apply power, the software commands the servos to move to home position. The movement is sufficiently violent it can cause the entire arm to jump.

This jump occurs because there is no position feedback to the Arduino controller leaving it unable to know the positions of the arm’s servos and move them slowly to home. I pondered how to add this feedback using sensors, imposing the limitation that they couldn’t be large or require replacing existing parts. I decided to try adding accelerometers on each arm section.

Accelerometers, being affected by gravity when on a planet, provide an absolute reference because they always report the direction of down. With an accelerometer I can calculate the angle of an arm section with respect to the direction of gravitational acceleration.

Before discussing the accelerometers, take a look at the picture of the arm. An accelerometer would be added to each section of the arm between the controlling servos.

Continue reading “Taming Robot Arm Jump With Accelerometers” →

Hackaday Prize Entry: A Low-Cost Robot Arm

May 13, 2016 by Brian Benchoff 10 Comments

Robot arms are cool, and to judge from the SCARA arms and old Heathkit robots tucked away in a cupboard of every computer science department in every university in the world, they’re still remarkably educational. You can learn a lot about control systems with a robot arm, or you could build a clone of the old Radio Shack Armatron; either way, you’re doing something very cool. Right now, there aren’t many educational robot arms available, and the ones you can get are tiny. For [Jonathan]’s Hackaday Prize project, he’s building a low-cost robot arm with a one meter reach.

There’s a reason you won’t find many large, low-cost robot arms: the square cube law. An ant can carry many times its own body weight, but if you scaled that ant up to the size of a human, its legs couldn’t support itself. Likewise, a small, handheld robot arm will work perfectly well with hobby servos, but scaling this up requires big heavy stepper motors.

Continue reading “Hackaday Prize Entry: A Low-Cost Robot Arm” →

Simple Robot Arm With Steppers Has Pleasingly Smooth Motion

May 2, 2016 by Gerrit Coetzee 16 Comments

The usual go-to when building a simple robot arm is the ever-pervasive hobby servo. However, these devices are not precise, and are typically jerky and unreliable. They have their advantages, but if strength is not needed a stepper motor would provide much better motion in the same price range.

Those are the lines along which [Bajdi] was thinking when he forked the Mearm project, and adapted it for small stepper motors. First he tried printing out the servo version on thingiverse. It worked, but the parts were not ideal for 3D printing, and he didn’t like the movement.

So he purchased some 28BYJ-48 motors. These are tiny little geared steppers that tend to show up in the odd project. He modified and simplified the files in FreeCAD. With the addition of a CNC shield and an Arduino he had every thing he needed for the upgrade. A servo is now only used for the gripper.

The robot is almost certainly weaker in its payload ability, but as you can see in the before and after videos after the break, it is dramatically smoother and more accurate.

Continue reading “Simple Robot Arm With Steppers Has Pleasingly Smooth Motion” →

Project Giant Robot Arm

December 26, 2015 by James Hobson 21 Comments

[Antoniopenamaria] is working on a giant robot arm. The beauty is, he’s posting a step-by-step guide (translated) of his entire journey from start to finish.

Why does he want to build a giant robot arm? Well, the idea originally came to him a few years ago when he was soldering something together and thought, “Man, I could really use another hand!”. So he got out a Meccano set, and built a mini robot arm. Nothing fancy, but it worked. From there, he decided to program it, and was able to teach it to move things from point A to point B… as he continued to expand on his little project, the vision grew, and now he’s working on project D.I.M.E.R. — a giant robot arm.

Continue reading “Project Giant Robot Arm” →

Human Gestures Control This Robot Arm

July 31, 2015 by James Hobson 1 Comment

[Ray Kampmeier] just finished writing some code to allow him to control his robotic arm using force-sensitive hand gestures! He calls it the Robo Marionette.

He’s using a MeArm 4 DOF robotic arm, a Sensel touch interface, an Arduino Uno, and a servo shield for the Arduino to control the MeArm. All the code you need is available on his GitHub, but unfortunately the Sensel touch interface isn’t actually available to the public yet.

Continue reading “Human Gestures Control This Robot Arm” →