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Fixing Misaligned PVC With Kerf Bends

misalignment-coupler

Our old pal [Jeremy Cook] is doing his own remix of [Theo Jansen]‘s Strandbeest, and like the original, he’s using PVC pipe. Unlike the originals, he’s powering it with motors, not wind, and this has caused a few problems in transmitting mechanical power through a piece of PVC. Nothing is perfect, and in a few points in the legs movement the shaft shakes violently. One motor was lost and another nearly so before [Jeremy] came up with a flex coupler made from PVC.

The technique [Jeremy] is using has seen a lot of use with people building laser cut enclosures. It’s called kerf bending, and it works simply by cutting a few slits in a panel that allow it to bend slightly. This technique was replicated by [Jeremy] on a miter saw, cutting eight slots halfway through a one inch PVC pipe, with each successive cut offset 90 degrees.

The new design works well for transmitting power, and he’s not ruining motors any more. Check out the video below.

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Measuring Magnetic Fields with a Robotic Arm

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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A Mini Op-Amp Based Line Following Robot

LineRobot

There’s no denying it. Super small robots are just cool. [Pinomelean] has posted an Instructable on how to create a mini line following robot using only analog circuitry. This would make a great demo project to show your friends and family what you’ve been up to.

Analog circuitry can be used instead of a microcontroller for many different applications, and this is one of them. The circuit consists of two op-amps that amplify the output of two phototransistors, which control each motor. This circuit is super simple yet very effective. The mechanical system is also quite cool and well thought out. To keep things simple, the motors drive the wheel treads, rather than directly through an axle. After the build was completed, the device needed to be calibrated by turning potentiometers that control the gain of each op-amp. Once everything is balanced, the robot runs great! See it in action after the break.

While not the smallest line follower we have seen, this robot is quite easy to reproduce. What little robots have you build lately? Send us a tip and let us know!

[via Embedded Lab]

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Telepresence Robot Proves It’s A Small World After All

jolvoy[Chris] works as part of a small team of developers in Cambridge, Massachusetts in the US. [Timo], one of their core members, works remotely from Heidelberg, Germany. In order to make [Timo] feel closer to the rest of the group, they built him a telepresence robot.

It was a link to DoubleRobotics that got the creative juices flowing. [Chris] and his team wanted to bring [Timo] into the room, but they didn’t have a spare $2499 USD in their budget. Instead they mated a standard motorized pan/tilt camera base with an RFduino Bluetooth kit. An application running on [Timo's] phone sends gyroscope status through the internet to the iPad on the robot. The robot’s iPad then sends that data via Bluetooth to the RFduino. The RFduino commands pan and tilt movements corresponding with those sensed by the gyroscope.  A video chat application runs on top of all this, allowing [Timo] to look around the room and converse with his coworkers.

All the source code is available via GitHub. The design didn’t work perfectly at first. [Chris] mentions the RFduino’s Bluetooth API is rather flaky when it comes to pairing operations. In the end the team was able to complete the robot and present it to [Timo] as a Valentine’s Day gift. For [Chris'] sake we hope [Timo] doesn’t spend too much of his time doing what his homepage URL would suggest: “screamingatmyscreen.com”

[Thanks Parker]

3 DOF Open Source Robot Arm Is Just the Beginning

Arm3-v1

[Dan Royer] of Marginally Clever had a dream. A dream to build an open-source 6 DOF robot that anyone can make! To do so, he’s been learning robotics for the past two years, and has just finished the first step — he’s designed and built an open source 3 DOF palletizing robot!

He’s based this little guy off of the commercial ABB 460 palletizing robot, which is a tried and true industrial robot. It features all laser cut parts, a few nuts and bolts, some stepper motors and an Arduino UNO for the brain. He’s released all of the design files on Thingiverse and the firmware on GitHub – yet another project we’d like to build if only we had a laser cutter!

And don’t worry, the Arduino UNO is only being used for this first prototype — he’s already started writing code for the RUMBA (Reprap Universal Mega Board with Allegro-driver) controller for revision 2.

Stick around to see it write its first greeting with a marker — Hello World!

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Open Source Humanoid Robot Is Awesom-o

awesome-o

Coming from a lab in France is The Poppy Project, an open source humanoid robot that’s at least as cool as ASIMO.

Poppy was designed as an affordable bipedal robot for use in education and art. It’s a small robot at just over 80 cm in height, but it can walk, move its arms, rotate its torso, and interact with bags-of-meat humans with two cameras and an LCD face.

Although Poppy is open source, that doesn’t mean it’s exactly cheap; the current design includes twenty-one Robotis Dynamixels MX-28 robotic actuators, actually servos with magnetic encoders, temperature sensor, and an ARM microcontroller. These actuators sell for about $200, meaning Poppy contains $4000 in motors alone. The estimated cost of the entire robot is €7500-8000, or about $10,000 to $11,000 USD.

Still, there’s an incredible software platform that comes along with Poppy, and being open source any enterprising engineer can take up the project and attempt to bring the costs down. We’d love to take one out for a walk. Just get rid of the hands. That’s too far down the uncanny valley for us. Video below.

 

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Building The Mountainbeest

mounainbeest-pic

Builder extraordinaire and Hackaday alum [Jeremy] was asked by a friend about “doing something really crazy” for his local Makerfaire this year. That Makerfaire clock is ticking down, and not wanting to build awesome from scratch, referred his friend to a few of the temporarily shelved projects from the last year. The winning incomplete build was the Mountainbeest, a four-legged mechanical walker inspired by [Theo Jansen]‘s Strandbeest.

We’ve seen the beginnings of the Mountainbeest before, starting with [Jeremy] building the linkages for one leg. This build turned into two legs and now it’s a full-on quadruped, theoretically capable of rambling over the lush mountains in [Jeremy]‘s backyard.

The plan now is for [Jeremy] to get is Beest walking with the help of windshield wiper motors left over from a failed hexapod build. He’s not ging all the details yet, but it looks like the power train will be made out of bike parts. Video of the current state of the project below.

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