3D Mouse Drives Robot Arm

July 28, 2015 by Al Williams 17 Comments

You’ve built the perfect robotic arm. How do you drive it? If you are [angrymop] you interface a 3D mouse from 3DConnexion via a few microcontroller boards. The Spacenavigator mouse is a staple anywhere professional CAD people are working, and it looks like it is a natural fit for a robot arm.

According to [angrymop], the Raspberry Pi can read the mouse’s commands via /dev/hidraw (that’s the raw human interface device). Each motion generates two lines of output. Each line has a unique identifying byte and values corresponding to the axis positions.

The Raspberry Pi then uses an SPI interface to talk to an ARM microcontroller and that drives the servos. The arm (the robot arm, not the processor) itself is well done, made from Lego Technic parts and common RC servos. Not that this is the most amazing thing we’ve ever seen built from Technic, but it is still pretty impressive.

You have to wonder if other 3D controllers might be useful for controlling robot arms or how the Spacenavigator would do controlling a bigger, more capable arm. Then again, maybe this arm would be the right size to build something inspired by Escher.

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This Home-Made 6-Axis Robotic Arm Is Quite The Looker

October 28, 2014 by Sarah Petkus 41 Comments

With a background in software engineering, [Kris Temmerman] decided to make a physical demonstration of his knowledge in the form of a six axis robotic arm… the final product is a delicious display of mechanical eye candy.

Built from mostly aluminum stock, [Kris] machined the bulk of his parts with a CNC mill which he picked up for cheap from China. These custom pieces coupled with some hefty stepper motors ensure the arm’s accuracy as it twists freely and slides along the gantry it’s mounted to. Though the majority of the arm is metal, the hand at the end of his robot was built with 3D printed parts and can be switched out with the future attachments [Kris] plans to design. This classic gripper piece is driven separately with its own Arduino brain controlling the individual servos in the fingers.

Each finger includes some load bearing sensors which [Kris] harvested from an old scale so that the gripper can tell whether or not it has a hold of an object without crushing it. To orchestrate the robot’s movement, he wrote some nice looking software in C++ which visualizes the inverse kinematics at work in each point of articulation. For the sake of demonstrating his creation in action, he whipped up a basic demo that can locate and move colored blocks laid at random on a surface. A small camera mounted on the hand determines the orientation of the blocks relative to the machine so that the wrist can rotate itself in the proper alignment in order to pick them up.

[Kris] documented the build of his robot in a fascinating speed video which includes footage of the finished arm in action at the end:

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The Un-Digital Robotic Arm

June 3, 2014 by Brian Benchoff 23 Comments

556 When you think of a robotic arm, you’re probably thinking about digital control, microcontrollers, motor drivers, and possibly a feedback loop. Anyone who was lucky enough to have an Armatron knows this isn’t the case, but you’d still be surprised at how minimal a robotic arm can be.

[viswesh713] built a servo-powered robotic arm without a microcontroller, and with some interpretations, no digital control at all. Servos are controlled by PWM signals, with a 1 ms pulse rotating the shaft one way and a 2 ms pulse rotating the shaft the other way. What’s a cheap, popular chip that can easily be configured as a timer? Yep, the venerable 555.

The robotic arm is actually configured more like a Waldo with a master slave configuration. [viswesh] built a second arm with pots at the hinges, with the resistance of the pots controlling the signal output from a 556 dual timer chip. It’s extremely clever, at least until you realize this is how very early robotic actuators were controlled. Still, an impressive display of what can be done with a simple 555. Videos below.

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Measuring Magnetic Fields With A Robotic Arm

March 30, 2014 by Nick Conn 13 Comments

MagneticArm

Learning how magnets and magnetic fields work is one thing, but actually being able to measure and see a magnetic field is another thing entirely! [Stanley’s] latest project uses a magnetometer attached to a robotic arm with 3 degrees of freedom to measure magnetic fields.

Using servos and aluminium mounting hardware purchased from eBay, [Stanley] build a simple robot arm. He then hooked an HMC5883L magnetometer to the robotic arm. [Stanley] used an Atmega32u4 and the LUFA USB library to interface with this sensor since it has a high data rate. For those of you unfamiliar with LUFA, it is a Lightweight USB Framework for AVRs (formerly known as MyUSB). The results were plotted in MATLAB (Octave is free MATLAB alternative), a very powerful mathematical based scripting language. The plots almost perfectly match the field patterns learned in introductory classes on magnetism. Be sure to watching the robot arm take the measurements in the video after the break, it is very cool!

[Stanley] has graciously provided both the AVR code and the MATLAB script for his project at the end of his write-up. It would be very cool to see what other sensors could be used in this fashion! What other natural phenomena would be interesting to map in three dimensions?

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Trainable Robotic Arm

December 22, 2013 by James Hobson 8 Comments

customer_projects_arm-learning

When [Robert] realized Adafruit is now selling analog feedback servos, he decided he just had to make a programmable robot arm that could be trained like the commercially available Baxter robot.

The neat thing with the analog feedback servos is it takes all the complexity out of training a robot. All you have to do is put the robot in teach mode, physically move the robot’s joints to the positions you want, and save your program! Depending on your application, it certainly beats trying to work out the fun kinematics equations…

Anyway, the full guide available on Adrafuit’s learning system provides instructions on how to build your own arm from scratch (well, with a 3D printer) or how to replace the servos in a pre-made toy robotic arm you might already have sitting around. It’s very thorough and includes all the code you need for your Arduino too.

Stick around after the break to see how the robot works!

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Robot Bartender Mixes A Mean Drink

March 25, 2013 by Ryan Fitzpatrick 11 Comments

Back in 2002, [Dave] came across a discarded PUMA robotic arm and quickly set his sights on turning it into a bartender to serve drinks at his parties. Unfortunately, the arm was far from operational and being an engineer at his day job meant that working on this project was the last thing he wanted to do when he came home. So, progress trickled along slowly for years. He eventually announced a public deadline to spur him to action, and this years Pi(e) party saw the official debut of ‘Sir-Mix-a-Bot’ – the robot bartender .

With the exception of having to build a new hand for it, mechanically, the arm was still in good condition when [Dave] found it. The electronics were another story however. Using some off the shelf components and his own know-how, [Dave] had to custom build all the controls. The software was written from scratch as well. (He lucked out and had help from his brother who was taking a Ph.D. program in robotics at the time).

As if the robotics aspect of the project wasn’t enough, [Dave] even created a beautiful custom table that both houses and displays his masterpiece. The quality of craftsmanship on his table alone is worth the time to check this out – there’s a short video after the break.

[Thanks Dave]

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Sexy Six Axis Robotic Arm Is A Work Of Art

September 10, 2012 by Brian Benchoff 14 Comments

We don’t know if it’s a mid-life crisis or just the result of way too many solder fumes, but [sparten11] on Instructables is building one of the coolest robotic arm we’ve ever seen, and we thank him for that.

The build began with a set of brushed DC motors running capable of running on 60 volts at up to 8 amps. These motors were attached rotary encoders that, with the gearing [sparten11] is using, provide 400,000 steps per revolution.Combined with a heavy duty motor controller, [sparten]’s arm has more than enough power and control for just about any industrial process.

Of course muscles are useless without a skeleton or brain, so [sparten] milled the structural and mechanical members of his arm in his home machine shop. It’s an impressive bit of kit; the base of his robot tested the capacity of his lathe, and the waterjet-cut arms form a graceful skeleton of an absurdly powerful robotic arm. The electronics for the build consist of a Pico PC running Windows XP with servo control board etched from a copper clad board.

The build isn’t quite done yet, but judging from the videos after the break, [sparten] will have a fabulous robotic arm shuffling around his workshop in short order.

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