Defcon Side Trip: Pololu And Robots

PololuDuring our trip out to Vegas for Defcon, we were lucky enough to catch up with a few of the companies that should be of interest to Hackaday readers. One of the companies based out of the area is Pololu, makers and purveyors of fine electronics and robots. In an incredible bit of lucky scheduling, LV Bots, the Las Vegas area robot builders club, was having an event the same weekend we were there. A maze challenge, no less, where builders would compete to build the best robot and write the best code to get a pile of motors and electronics through a line-following maze in the fastest amount of time.

The Bots

The LV Bots events are held in the same building as Pololu, and unsurprisingly there were quite a few Pololu employees making a go at taking the stuff they developed and getting it to run through a maze. At least one bot was based on the Zumo kit, and a few based on the 3pi platform. Interestingly, the Raspberry Pi Model B+ was the brains of quite a few robots; not extremely surprising, but evidence that the LV Bots people take their line-following mazes seriously and are constantly improving their builds.

Each robot and builder ‘team’ was given three runs. For each team, the first run is basically dedicated to mapping the entire maze. A carefully programmed algorithm tries to send the robot around the entire maze, storing all the intersections in memory. For the second and third runs, the bot should – ideally – make it to the end in a very short amount of time. This is the ideal situation and was only representative of one team for that weekend’s event.

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Flex Sensing for a DIY Data Glove

cyber

[Cyber] has been testing out intuitive input methods for virtual reality experiences that immerse the user further into the virtual world than archaic devices like a keyboard or mouse would allow. One of his biggest interests so far was the idea of a data glove that interacts with an Arduino Uno to interface with a PC. Since commercial products are yet to exist on a readily available level, [Cyber] decided to build his own.

He started out with a tiny inertial measurement unit called a Pololu MinIMU-9 v2 that tracks orientation of the 3-axis gyro and accelerometer. The USB interface was soldered into place connecting the wires to an Arduino Uno. From there, he hooked up a flex sensor from Spectra Symbol (which were supposedly used in the original Nintendo Power Gloves) and demoed the project by tracking the movement of one of his fingers. As the finger bent, the output printed on the serial monitor changed.

[Cyber] still needs to mount a glove on this system and construct a proper positional tracking method so that physical movement will be mirrored in a simulation.

[Cyber's] day job has had him busy these last few months, which has forced the project into a temporary hold. Recently though, [Cyber] has been an active member and an influence in the local Orange County VR scene helping to build a nice development culture, so we’re hoping to see more updates from him soon.

To view what he has done up to this point, click the link at the top of the page, and check out the video after the break:

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The Stepper Driver Driver

KONICA MINOLTA DIGITAL CAMERA

The Stepstick and Pololu motor drivers are the heart of just about every Reprap electronics board, but they can go bad. The usual way of testing these things is to rig up a microcontroller on a breadboard, grab some cables, and wire something up. [Ken]‘s Easy Stepper Motor Controller is a much simpler solution to the problem of testing these drivers and could, with a bit of practice, be constructed on a single-sided homebrew PCB.

The Easy Stepper Motor Controller is a very simple board with connections to a motor, a power supply, and headers for a single Pololu or Stepstick motor driver. Two buttons and a pot control the rotation of the motor with the help of an ATtiny10, and jumpers for up to 16x microstepping are right there on the board.

There’s a video after the break showing what this stepper motor driver driver can do. It’s not much, but if you’re just testing a driver, it’s all you need.
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GRBL compatible Arduino CNC shield

arduino-cnc-shield

By the time you get to the point in a home CNC build where you’re adding control electronics you may be ready for the simplest means to an end possible. In that case, grab your Arduino and heat up that etching solution to make your own GRBL compatible shield.

This familiar footprint manages to contain everything you need for a three-axis machine. The purple boards slotted into the pairs of SIL headers are Pololu Stepper motor drivers. Going this route makes replacing a burnt out chip as easy as plugging in a new module. The terminal block in the center feeds the higher voltage rail necessary for driving the motors. The DIL header on the right breaks out all of the connections to the limiting switches (two for each axis), spindle and coolant control, as well as three buttons for pause, resume, and abort. There’s even a header for SPI making it easier to add  custom hardware if necessary.

This is a dual-layer board which may not be ideal for your own fabrication process. [Bert Kruger] posted his Gerber files for download if you want to put in a small run with OSH Park or a similar service.

 

Robot can barely move with so much hardware strapped to it

web-server-robot

We think that [Andrej Škraba] needs to start looking for a beefier motor platform. This little robot has so much hardware strapped to it the motors can barely keep up. But with a little help it can make its way around the house, and it takes a whole lot of connectivity and computing power along for the ride.

The white stick on the top is a single-board computer. The MK802 Mini sports an A10 processor and up to a gig of ram. Just below that is a USB hub which is sitting on top of a USB battery pack. This powers the computer and gives him the ability to plug in more than one USB device. The robot chassis is from Pololu. It uses an Arduino and a motor shield for locomotion, with commands pushed to it via USB.

This setup makes programming very easy. Here [Andrej] has a keyboard and HDMI monitor plugged in to do a little work. When not coding it can be disconnected and driven over the network. He makes this happen using an Apache server on the MK802 and node.js. See a demo of the system in the clip after the break.

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Bang-banging your way to a perfect cake

bang-bang-oven-control

[Rob Spanton’s] house is equipped with a rather cheap oven, which was discovered while his roommate tried using it to bake part of a wedding cake. If someone took a shower during the baking process, a large portion of unit’s gas pressure was diverted to the boiler, causing the oven to shut off completely. This is obviously not a good situation for baking cakes, so the housemates decided to construct a makeshift controller to keep temperatures in line.

They started by installing a pulley on the oven’s knob, which is connected to a small motor via a long rubber belt. The other end of the belt connects to a small motor, which is controlled by a Pololu 18v7 motor controller. A K-type thermocouple monitors the oven’s temp, feeding the data through a MAX6675 converter to (presumably) [Rob's] computer.

Since they were in a bit of a time crunch, [Rob] and his roommate [Johannes] decided the best way to keep the oven at a steady temperature was via bang-bang control. While you might imagine that cranking the gas knob between its minimum and maximum settings repeatedly wouldn’t be the ideal way to go about things, their solution worked pretty well. The cake came out perfectly, and the maximum temperature swing throughout the entire baking process was only 11.5°C – which is pretty reasonable considering the setup.

10 Meter long moving light show is mesmerizing

light-show

[Marcus] was recently commissioned to put together the electronics for a slick 10 meter long LED installation at the Hsinchu Biomedical Science Park Exhibition Center in Taiwan. While you might assume that he was asked to construct a large LED matrix, this project is a little bit different from what you probably expected.

The display is actually a long light tunnel made up of 30 moving triangles suspended from the ceiling. The triangle movement is governed by 60 separate stepper motors, while the lighting is provided by 30 HL1606 RGB LED strips he picked up from Adafruit. The display’s logic is handled completely by an XMOS controller, which is beefy enough to handle controlling all of the stepper motors and the LEDs simultaneously.

After he hand assembled all of the motor driver boards and tested things in his workshop, the whole lot was shipped over to Taiwan for assembly by the on-site crew. After a bit of troubleshooting, they were able to get things working properly, and the display looks great as you can see from the image above.

[Marcus] says that he doesn’t have video of the display in action just yet, though he will update his post whenever he does.

[Thanks, Paul]

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