Building A Ball-Balancing Robot

robotBallBalance

If you want a different kind of feedback systems challenge, ditch the Segway-style robots and build one that can balance on a ball. UFactory is a startup in Shenzhen, and this impressive little guy is a way of showing their skills applied to the classic inverted pendulum. At nearly 18 inches tall and weighing just over six pounds, the robot boasts a number of features beyond an accelerometer and gyroscope: it has both a WiFi module and a camera, and can be controlled via a homemade remote control or a Kinect.

The build uses plastic omni-directional wheels attached to 3 brushed dc motors, which attach to the base of the robot with custom-made aluminum brackets. The UFactory gang constructed the robot’s body out of three acrylic discs, which hold the electronics directly above the wheels. The brain seems to be an STM32 microcontroller that connects up to the motors and to the sensors.

You won’t find the code on their Instructable yet, but according to the comments they have plans to make the entire project open source. If you’re desperate for more details, the UFactory team seems willing to provide source code and other information via email. Make sure you see the video after the break, particularly the end where they demonstrate interference and carrying loads. This isn’t the first ball pendulum we’ve seen; take a trip down memory lane with the BallP ball balancing robot from 2010.

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Hacking A Streetlight With Lasers

$20, some spare parts and a bit of mischief was a small price for [Chris] to pay for a reprieve from light pollution with this remote control laser hack. The streetlight in front of his house has a sensor that faces westward, and flips the lamp on once the sun has disappeared over the horizon. As it turns out, [Chris’s] third floor window is due west of this particular lamp, meaning he takes the brunt of its illumination but also conveniently places him in a prime location for tricking the sensor.

According to [Chris], the lamp’s sensor requires two minutes of input before it will switch off and stay off for around 30 seconds before cycling on again. The lamp does not zap straight to full brightness, though; it takes at least a minute to ramp up. [Chris] recalled a hack from a few years ago that essentially used LED throwies tacked onto the sensors with putty to shut off lamps for a guerrilla drive-in movie, but the sensors on those lamps were at the base and easily accessed. [Chris] needed to reach a sensor across the block and nearly three stories tall, so he dug around his hackerspace, found a 5V 20mA laser diode, and got to work building a solution.

[Chris] 3D printed a holder for the laser and affixed it via a mounting bracket to the wall near his third floor window, pointing it directly at the street lamp’s sensor. He plugged the laser’s power supply into an inexpensive remote control outlet, which allowed him to darken the street lamp at a touch of a button. This is certainly a clever and impressive hack, but—as always—use at your own risk. Check out a quick demo video after the break.

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Backseat USB Charger

backseatCharger

Whether you’re relegated to the backseat of your ride or just strapped for access to power, you may benefit from adding your own backseat USB charger. While this is a fairly straightforward hack, we’re surprised at how clean it turned out and at the convenience it provides.

[wongman2001] started by grabbing a socket wrench and unbolting his seat from the rails in the floor. He then disconnected the electrical plugs for the chair’s heating and power seat adjustment. With the chair disconnected and removed from the car, [wongman2001] further dissected its components, removing its back panel and test fitting a female cigarette adapter. Though this seat had plenty of room near the headrest, you may need to carve out some foam for a snug fit in your vehicle. To source the needed 12V, [wongman2001] tapped into the wiring for the seat’s motor, then soldered and insulated the connections to the cigarette lighter jack.

Check out some other clean-looking car hacks like the hidden MP3/USB Aux hack or the Nexus 7 double-DIN dashboard hack.

Towards A Low Cost, Desktop CT Scanner

For [Peter Jansen], the most interesting course in grad school was Advanced Brain Imaging; each class was a lecture followed by a trip to the imaging lab where grad students would take turns being holed up in a MRI machine. A few years into his doctorate, [Peter] found himself in a very opportune situation – his local hackerspace just acquired a shiny new laser cutter, he had some free time on his hands, and the dream of creating a medical imaging device was still in the back of his mind. A few weeks later, the beginnings of an open source CT scanner began to take shape.

This isn’t an MRI machine that [Peter] so fondly remembered from grad school. A good thing, that, as superconducting magnets chilled with liquid helium is a little excessive for a desktop unit. Instead, [Peter] is building a CT scanner, a device that takes multiple x-ray ‘slices’ around an axis of rotation. These slices can then be recompiled into a 3D visualization of the inside of any object.

The mechanics of the build are a Stargate-like torus with stepper motor moving back and forth inside the disk. This, combined with the rotation of the disk and moving the bed back and forth allow the imager to position itself anywhere along an object.

For the radioactive detector, [Peter] is using a CCD marketed as a high-energy particle detector by Radiation Watch. Not only does this allow for an easy interface with a microcontroller, it’s also much smaller than big, heavy photomultiplier tubes found in old CT scanners. As for the source, [Peter] is going for very low intensity sources, most likely Barium or Cadmium that will take many minutes to capture a single slice.

The machine operates just above normal background radiation, so while being extremely safe for a desktop CT scanner, it is, however, very slow. This doesn’t bother [Peter], as ‘free’ time on a CT scanner allows for some very interesting, not seen before visualizations, such as a plant growing from a seed, spreading its roots, and breaking the surface as a seedling.

[Peter] still has some work to do on his desktop CT scanner, but once the stepper motor and sensor board are complete, he should be well on his way towards scanning carrots, apples, and just about everything else around his house.

Hackerspacing In Europe: ACKspace In Heerlen

ACKspace group photo

Welcome to the ACKspace in Heerlen. So far this has been one of the coolest hackerspaces we have visited — and super hospitable! What makes this space really neat is the location. It’s on the first floor of a mostly empty office building. They have three official rooms on the first floor. The Hackspace, the Slackspace, and the Stackspace — quite self-explanatory.

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Inexpensive Robot Tracking System Is Swarm Ready

RobotWebcam

[Ladvien] has figured an inexpensive way to control a robot from a remote PC with a static webcam. Inspired by swarming robot videos such as those from the UPENN Grasp lab, [Ladvien] wanted to build his own static camera based system. He’s also managed to create one of the more eclectic Instructables we’ve seen. You don’t often find pseudo code for robot suicide mixed in with the project instructions.

Fixed cameras are used in many motion capture systems, such as the Vicon system used by numerous film, game, and animation studios. Vicon and similar systems cost tens of thousands of dollars. This was a bit outside [Ladvien’s] budget. He set about building his own system from scratch. The first step was the hardest – obtaining permission from his wife to screw a webcam into the ceiling. With that problem overcome, [Ladvien] brought openCV and python to bear. He created Overlord, his webcam vision and control system. A vision system with nothing to control would be rather boring, so [Ladvien] created DotMuncher, Overlord’s radio controlled robot slave.

The basic processing system is rather simple. DotMuncher carries a magnetometer on board, which it uses to send heading information to Overlord. Overlord is pre-calibrated with an offset from magnetic north to “video game north” (toward the top of the screen). Overlord then uses openCV’s color detection to find DotMuncher in the current scene.
Overlord finally generates a virtual “Dot” on screen, and directs DotMuncher to drive over to it. When the robot gets to the dot, it is considered munched, and a new dot is generated.

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Serial USB For Any AVR Microcontroller

If you’re using an AVR microcontroller and you’d like to add USB to a project, there are a lot of options out there for you. Both LUFA and V-USB add some USB functionality to just about every AVR micro, but if you’d like a native serial port, your only options are to look towards the USB-compatible Atmel micros.

[Ray] looked at the options for adding a USB serial port and didn’t like what he saw; seemingly, this was an impossible task without a second, more capable microcontroller. Then he had an idea: if the goal is only to transfer data back and forth between a computer and a microcontroller, why not write an HID-class USB serial port?

[Ray] based his project on The V-USB library and created a new HID descriptor to transfer data between a micro and a computer. While it won’t work with a proper terminal such as Putty, [Ray] managed to whip up a serial monitor program in Processing that’s compatible with Windows, Linux and OS X.

In the video below, you can see [Ray] using an ATmega328p with a standard V-USB setup. He’s transferring analog values from a photoresistor as a proof of concept, but just about everything that would work with a normal serial port will work with [Ray]’s library.

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