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Arduino Meets Da Vinci In A Gesture-controlled Surgical Robot

June 16, 2016 by 34 Comments

Lots of us get to take home a little e-waste from work once in a while to feed our hacking habits. But some guys have all the luck and score the really good stuff, which is how these robotic surgical tools came to be gesture controlled.

The lucky and resourceful hacker in this case is one [Julien Schuermans], who managed to take home pieces of a multi-million dollar da Vinci Si surgical robot. Before anyone cries “larcency”, [Julien] appears to have come by the hardware legitimately – the wrist units of these robots are consumable parts costing about $2500 each, and are disposed of after 10 procedures. The video below makes it clear how they interface with the robot arm, and how [Julien] brought them to life in his shop. A quartet of Arduino-controlled servos engages drive pins on the wrist and rotates pulleys that move the cables that drive the instruments. A neat trick by itself, but when coupled with the Leap Motion controller, the instruments become gesture controlled. We’re very sure we’d prefer the surgeon’s hands on a physical controller, but the virtual control is surprisingly responsive and looks like a lot of fun.

When we talk about da Vinci around here, it’s usually in reference to 3D printers or a Renaissance-style cryptex build. Unsurprisingly, we haven’t featured many surgical robot hacks – maybe it’s time we started.

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Beautiful Cardboard Robot Build

June 16, 2016 by 16 Comments

[Miloslav Stibor] may have built Mimobot 2.1 out of cardboard so that it’s not very heavy, but the robot is absolutely no lightweight. Read through his logs (in Czech, or in translation) and you’ll see what we mean.

Our favorite feature is the recharging dock and docking connectors, made respectively out of spring-loaded rivet ferrules and copper-tape-covered cardboard. The video found on that page is also absolutely brilliant: watch in awe as it climbs over children’s books, pulls a wooden train, or scales a mountain of pillows.

We wrote [Miloslav] and asked about the continuous-rotation servos, because they ran so smoothly at low speeds. He replaced the potentiometer with a pair of “carefully matched” 2.2 k resistors, and drives them with a PWM signal. Sounds easy, and obviously works very well. We were always under the impression that it was a little bit more complicated to get proportional control of hobby servos. We’ll have to experiment.

The wheels and lightweight frame (made of “military grade” cardboard — saturated with a wood/paper glue) make it entirely capable in living-room environments covered in cables or rugs, which is something we can’t say about our purchased vacuum-cleaner-bot. And the cell-phone remote interface that lets him control the onboard camera and its elevation and lighting. Driving the thing around with the phone control looks fun.

In short, if you build small robots, give this one a look. Something very much like this is now on our short must-build list. And we can’t wait to see Mimobot v3!

Mechaduino- Closed Loop Stepper Servos For Everyone

June 1, 2016 by 50 Comments

Is it something in the water, or have there been a lot of really cool servo projects lately? Mechaduino is a board that sits on a regular stepper motor and turns it into a servo with a closed loop control of 0.1degree.

Whenever we post something about using cheap brushless motors for precision control, someone comments that a stepper is just a brushless motor with a lot of poles, why not just control it like one. That’s exactly what the Mechaduino does. They also hint at doing something very clever with a magnetic encoder on the board which allows them, after a calibration routine, to get the accuracy they’ve promised.

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Simple Robot Arm With Steppers Has Pleasingly Smooth Motion

May 2, 2016 by 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.

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Cardboard And Paperclip CNC Plotter Destined For Self-Replication

April 27, 2016 by 11 Comments

Last November, after [HomoFaciens]’ garbage-can CNC build, we laid down the gauntlet – build a working CNC from cardboard and paperclips. And now, not only does OP deliver with a working CNC plotter, he also plans to develop it into a self-replicating machine.

To be honest, we made the challenge with tongue firmly planted in cheek. After all, how could corrugated cardboard ever make a sufficiently stiff structure for the frame of a CNC machine? [HomoFaciens] worked around this by using the much less compliant chipboard – probably closest to what we’d call matboard here in the States. His templates for the machine are extremely well thought-out; the main frame is a torsion box design, and the ways and slides are intricate affairs. Non-cardboard parts include threaded rod for the lead screws, servos modified for continuous rotation, an Arduino, and the aforementioned paperclips, which find use in the user interface, limit switches, and in the extremely clever encoders for each axis. The video below shows highlights of the build and the results.

True, the machine can only move a pen about, and the precision is nothing to brag about. But it works, and it’s perfectly capable of teaching all the basics of CNC builds to a beginner, which is a key design goal. And it’s well-positioned to move to the next level and become a machine that can replicate itself. We’ll be watching this one very closely.

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Circuit Bender Artist Bends Fresnel Lens For Art

April 26, 2016 by 6 Comments

Give some mundane, old gear to an artist with a liking for technology, and he can turn it into a mesmerizing piece of art. [dmitry] created “red, an optic-sound electronic object” which uses simple light sources and optical elements to create an audio-visual performance installation. The project was the result of his collaboration with the Prometheus Special Design Bureau in Kazan, Russia. The inspiration for this project was Crystall, a reconstruction of an earlier project dating back to 1966. The idea behind “red” was to recreate the ideas and concepts from the 60’s ~ 80’s using modern solutions and materials.

The main part of the art installation consists of a ruby red crystal glass and a large piece of flexible Fresnel lens, positioned in front of a bright LED light source. The light source, the crystal and the Fresnel lens all move linearly, constantly changing the optical properties of the system. A pair of servos flexes and distorts the Fresnel lens while another one flips the crystal glass. A lot of recycled materials were used for the actuators – CD-ROM drive, an old scanner mechanism and old electric motors. Its got a Raspberry-Pi running Pure Data and Python scripts, with an Arduino connected to the sensors and actuators. The sensors define the position of various mechanical elements in relation to the range of their movement. There’s a couple of big speakers, which means there’s a beefy amplifier thrown in too. The sounds are correlated to the movement of the various elements, the intensity of the light and probably the color. There’s two mechanical paddle levers hanging in there, if you folks want to hazard some guesses on what they do.

Check out some of [dmitry]’s earlier works which we featured. Here’s him Spinning a Pyrite Record for Art, and making Art from Brainwaves, Antifreeze, and Ferrofluid.

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IntelliServo

April 22, 2016 by 32 Comments

Servos are extremely versatile actuators used in a large number of applications which need controlled mechanical movement. The usual way of driving them is by using a PWM output from a micro-controller. But if you’re building a robot or a drone which requires a large number of servos, then it makes sense to add smarts directly to the servo.

[Alvaro Ferrán Cifuentes] did just that by building IntelliServo – an add on board which makes regular servos smart by giving them enhanced capabilities as found in high-end versions. His approach is different compared to other takes on this theme. The IntelliServo is designed to replace the electronics in any regular servo and is not limited to any particular make or type. Once upgraded, it’s possible to read the servos position, temperature and current consumption. This allows interesting uses, such as controlling one servo by moving another one, or detecting collision or stalling by monitoring the servo current. Multiple servos can be daisy-chained and controlled over I²C from a micro-controller, or over USB directly from a computer. Each board features an LPC11U24 32-bit Cortex-M0 micro-controller, a DRV8837 motor driver, a TMP36 temperature sensor and a PCA9508 I²C repeater.

The project is open source and the Github repository contains the board design, Arduino library and examples, servo firmware and mechanical parts as well as use instructions. It’s a modular design which allows using either an external controller or running it directly via the on-board micro-USB socket. Check out the videos after the break to see the IntelliServo in action.

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