Stepper Motor Robot Arm Has Smooth Moves

January 22, 2018 by Steven Dufresne 17 Comments

[Tobias Kuhn] had watched a YouTube video about a robot arm which used servo motors, and wanted to try making one himself. But he found it hard to get slow or smooth movements out of the servos. Even removing the microcontroller and trying to work with the servo’s driver-IC and potentiometer from an Arduino Nano didn’t get him satisfaction.

Then he found the very affordable 28BYJ-48 stepper motor. After some experimenting, he came up with a smooth moving robot arm with four steppers controlled from an Arduino Mega and A4988 stepper motor drivers. Rather than write a bunch of stepper motor code himself, he installed and ran a four-axis fork of grbl on the Arduino, turning it into a stepper motor controller. One minor hitch was that the A4988 motor drivers are for bipolar stepper motors but 28BYJ-48 steppers are unipolar. Luckily he knew of a very simple hack which our [Brian Benchoff] wrote about for turning a unipolar motor into a bipolar motor.

To tell the robot arm what to do, he built a replica arm with potentiometers in place of the stepper motors. As he manipulates the replica, the values of the potentiometers are read by a Raspberry Pi and some custom Python code which sends the appropriate G-code to the Arduino/grbl controlled robot arm. There’s a bit of a lag but when he moves the replica arm, the robot arm does the same move. See it in action in the video below.

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Robotic Arm Rivals Industrial Counterparts

November 8, 2017 by Brian McEvoy 21 Comments

We’ve seen industrial robotic arms in real life. We’ve seen them in classrooms and factories. Before today, we’ve never mistaken a homemade robotic arm for one of the price-of-a-new-home robotic arms. Today, [Chris Annin] made us look twice when we watched the video of his six-axis robotic arm. Most of the DIY arms have a personal flare from their creator so we have to assume [Chris Annin] is either a robot himself or he intended to build a very clean-looking arm when he started.

He puts it through its paces in the video, available after the break, by starting with some stretches, weight-lifting, then following it up and a game of Jenga. After a hard day, we see the arm helping in the kitchen and even cracking open a cold one. At the ten-minute mark, [Chris Annin] walks us through the major components and talks about where to find many, many more details about the arm.

Many of the robotic arms on Hackaday are here by virtue of resourcefulness, creativity or unusual implementation but this one is here because of its similarity to the big boys.

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Soon You’ll Sit Inside A Robot’s Head At Work

October 10, 2017 by Lauren Faris 28 Comments

MIT’s Computer Science and Artificial Intelligence Lab, CSAIL, has created a process of teleoperating a Baxter humanoid robot with an Oculus Rift VR headset. This project is partially aimed towards making manufacturing jobs ~~a hell of a lot of fun~~ telecommutable. It could even be a way to supervise robot workers from a distance.

In a nutshell, the user controls the robot remotely in a virtual reality environment. The user does this specifically in a VR environment modeled like a control room with multiple sensor displays, making it feel like they are sitting inside the robot’s head. By using hand controllers, users can match their movements to the robot’s to complete various tasks. If you’ve seen Pacific Rim, you are probably envisioning a Jaegar right about now — minus the psychic linking.

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The (Robot) Body Electric

September 4, 2017 by Al Williams 13 Comments

If you deal with electronics, you probably think of static electricity as a bad thing. It blows up MOSFETs and ICs and we take a lot of pains to prevent that kind of damage. But a start-up company called Grabit is using static electricity as a way to allow robots to manipulate the real world. In particular, Nike is using these robots to build shoes. You can see a demo video, below.

Traditional robots use human-like hands or claw-like grippers to mimic how humans handle material. But Grabit has multiple patents on electroadhesion. The original focus was wall-climbing robots, but the real pay off has been in manufacturing robots since the electrostatic robots can do things that mechanical hands are a long way from duplicating.

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Hackaday Prize Entry: A Six Axis Robotic Arm With Fingertip Control

August 4, 2017 by Jenny List 3 Comments

If you were a child of the 1980s whose fascination extended to the contents of your local Radio Shack store, you may remember the Armatron robot arm as a particular object of desire. It was a table top robot arm operated not by motors or a microcontroller, but by a clever set of gears directed manually from a pair of joysticks. If you took a look at it with an eye to control from your 8-bit home computer you were likely to be disappointed, but nevertheless it was an excellent toy.

The Armatron may be long gone, but if you hanker for a similar device you should take a look at [3D Meister]’s finger controlled six axis arm. This is an arm similar to the Armatron in size, but with far more capabilities. Control is via cable loops to sliders at the arm’s base, and in addition to the usual arm movements there is an extra loop which can be used to operate any of a selection of tools including a gripper, a magnet, and a clipper. The video below the break shows the arm in action, and for the faint-hearted it should be noted that it contains the gratuitous death of some innocent plants.

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Evezor Robotic Arm Engraves 400 Coasters

May 22, 2017 by Adam Fabio 15 Comments

When you’re running a Kickstarter for a robotic arm, you had better be ready to prove how repeatable and accurate it is. [Andrew] has done just that by laser engraving 400 wooden coasters with Evezor, his SCARA arm that runs on a Raspberry Pi computer with stepper control handled by a Smoothieboard.

Evezor is quite an amazing project: a general purpose arm which can do everything from routing circuit boards to welding given the right end-effectors. If this sounds familiar, that’s because [Andrew] gave a talk about Evezor at Hackaday’s Unconference in Chicago,

One of the rewards for the Evezor Kickstarter is a simple wooden coaster. [Anderw] cut each of the wooden squares out using a table saw. He then made stacks and set to programming Evezor. The 400 coasters were each picked up and dropped into a fixture. Evezor then used a small diode laser to engrave its own logo along with an individual number. The engraved coasters were then stacked in a neat output pile.

After the programming and setup were complete, [Andrew] hit go and left the building. He did keep an eye on Evezor though. A baby monitor captured the action in low resolution. Two DSLR cameras also snapped photos of each coaster being engraved. The resulting time-lapse video can be found after the break.

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Pneumatic Rotary Vane Joints Lend A Gentle Helping Hand

May 3, 2017 by Steven Dufresne 20 Comments

Festo has released a video showing the workings of their BionicCobot, a pneumatic robot arm developed for lending a helping hand to humans at a workstation. Since it works intimately with humans, it has to be safe, producing no harmful movements, and reacting when encountering an obstacle such as an arm containing delicate human bone. This it does using pneumatics and rotary vanes.

The arm has seven degrees of freedom, three in the shoulder, one in the elbow, another in the lower arm, and two in the wrist. But you won’t find any electric motor or gears. Instead each contains a rotary vane. Compressed air pushes on both sides of the vane. If the air pressure is the same on both sides of the vane then it doesn’t rotate. But with more pressure on one side than the other, the vane rotates. This is much like in a human arm, where two muscles work together to bend the arm, one muscle contracts while the other relaxes. Together they’re referred to as an antagonistic pair. In addition, each joint has a circuit board with two pressure sensors for monitoring the joint.

Using pneumatics, if an obstacle is encountered, the pressure can be released, making it instantly safe. And air being compressible, the joint can behave like a spring, further adding to the safeness. By controlling the pressure, the spring can be made more or less tense.

You can see it in action in the video below the break, along with more details such as how they use ROS, the popular, open system Robot Operating System which we’ve seen here a lot before, along with their Festo valve bank, one of which our own [James Hobson] used for his slick elysium exoskeleton. The video also covers how they handled running the hoses, the kinematics and the UI software.

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