Stewart Platform Ball Bearing Balancer

PID balancing a ball on a plate

For their Mechanical Engineering senior design project at San Jose State University, [Tyler Kroymann] and [Robert Dee] designed and built a racing motion simulator. Which is slightly out of the budget of most hackers, so before they went full-scale, a more affordable Arduino powered Stewart platform proof of concept was built. Stewart platforms typically use six electric or hydraulic linear actuators to provide motion in six degrees of freedom (6 DOF), surge (X), sway (Y), heave (Z), pitch, roll, and yaw. With a simple software translation matrix, to account for the angular displacement of the servo arm, you can transform the needed linear motions into PWM signals for standard hobby servos.

The 6 DOF platform, with the addition of a resistive touch screen, also doubled as a side project for their mechatronic control systems class. However, in this configuration the platform was constrained to just pitch and roll. The Arduino reads the resistive touch screen and registers the ball bearing’s location. Then a PID compares this to the target location generating an error vector. The error vector is used to find an inverse kinematic solution which causes the actuators to move the ball towards the target location. This whole process is repeated 50 times a second. The target location can be a pre-programmed or controlled using the analog stick on a Wii nunchuck.

Watch the ball bearing seek the target location after the break.

Thanks to [Toby] for sending in this tip.

[Read more...]

Speedy Drinkmaker Keeps Party Guests Hydrated

the rumbot

After five weekends of work, [Alex] completed his automatic drink maker, the RumBot. What makes this automated bartender different from others is the fact that it is fast. VERY fast. It can serve drinks to five different locations in as little as 3 seconds per drink. By [Alex]‘s estimation, this could keep a party of 100 people going without anyone waiting on a drink.

The RumBot can make either of five pre-programmed drinks at varying levels of alcoholic intensity, ranging from 1 (“Virgin”) to 10. And for that extra push over the cliff, you can turn the knob to 11 (“Problem”).

Drink selection itself is handled by a simple digital I/O on an Arduino with a 1950s-styled user interface. The frame is built out of wood and uses 3D Printed plastic parts. It houses a very robust servo on a belt screw-driven stage to move the drink nozzle, and special sensors placed at either of the five drink locations detect a cup ready to be filled. Any cup placed at any of the positions will automatically be filled based on the RumBot’s settings at any particular time.

Based on the quality of the build and the increased speed of this automatic drink maker, this should be a huge hit at any party. With all the knobs turned to 11 though, it might be a good idea to have a breathalyzer on hand! All of the code and schematics for the project are available at the project site as well.

[Read more...]

Steam Gauge Keeps Track of Your Internet Usage

Pressure Gauge Used to Monitor Internet Usage

There’s a certain appeal to analog gauges in a vastly digital world. [Ed Konowal] is a Network Operations Supervisor for a school district in Florida — part of his job is to ensure a stable and fast internet connection, so he decided to make an internet usage gauge for his office.

What we really like about this hack is the fact that [Ed] had no idea how to do it. It’s a simple enough idea, right? Google was his friend and Ed started learning about all kinds of things. Raspberry Pi’s and Arduinos, wireless receiver/transmitters, servos and steppers, Python…

After quite a bit of trial and error, [Ed] eventually settled on a wired design which uses a Raspberry Pi running a Python program to poll the internet bandwidth, which in turn calculates the servo position for the dial and sends that number to the Arduino to move it into position. This repeats every 10 seconds. Pretty cool!

Kind of reminds us of this project to make custom gauges using a stepper motor breakout board!

[Thank Justin!]

Beach Buddy is a Boombox, Phone Charger, and Sunburn Warner

The Beach Buddy

When you venture out onto the beach for a day in the sun, you’re probably not preoccupied with remembering the specifics about your sunscreen’s SPF rating—if you even remembered to apply any. [starwisher] suffered a nasty sunburn after baking in the sunlight beyond her sunscreen’s limits. To prevent future suffering, she developed The Beach Buddy: a portable stereo and phone charger with a handy sunburn calculator to warn you the next time the sun is turning you into barbecue.

After telling the Beach Buddy your skin type and your sunscreen’s SPF rating, a UV sensor takes a reading and an Arduino does a quick calculation that determines how long until you should reapply your sunscreen. Who wants to lug around a boring warning box, though?

[starwisher] went to the trouble of crafting a truly useful all-in-one device by modifying this stereo and this charger to fit together in a sleek custom acrylic enclosure. There’s a switch to activate each function—timer, charger, stereo—a slot on the side to house your phone, and an LCD with some accompanying buttons for setting up the UV timer. You can check out a demo of all the Beach Buddy’s features in a video below.

[Read more...]

Voice Controlled RGB LED Lamp

Voice Controlled Lamp

[Saurabh] wanted a quick project to demonstrate how easy it can be to build devices that are voice controlled. His latest Instructable does just that using an Arduino and Visual Basic .Net.

[Saurabh] decided to build a voice controlled lamp. He knew he wanted it to change colors as well as be energy-efficient. It also had to be easy to control. The obvious choice was to use an RGB LED. The LED on its own wouldn’t be very interesting. He needed something to diffuse the light, like a lampshade. [Saurabh] decided to start with an empty glass jar. He filled the jar with gel wax, which provides a nice surface to diffuse the light.

The RGB LED was mounted underneath the jar’s screw-on cover. [Saurabh] soldered a 220 ohm current limiting resistor to each of the three anodes of the LED. A hole was drilled in the cap so he’d have a place to run the wires. The LED was then hooked up to an Arduino Leonardo.

The Arduino sketch has several built-in functions to set all of the colors, and also fade. [Saurabh] then wrote a control interface using Visual Basic .Net. The interface allows you to directly manipulate the lamp, but it also has built-in voice recognition functionality. This allows [Saurabh] to use his voice to change the color of the lamp, turn it off, or initiate a fading routing. You can watch a video demonstration of the voice controls below. [Read more...]

Hacking A Bee Hive


[Marc] created a self-contained monitoring platform that enabled him to record the temperature and humidity of his bee hives.’

The health of colony can be determined based on a few factors. One is temperature which is an early indicator of whether or not the bees are about to swarm. Once temperature spikes are noticed, the bee wrangler can take the necessary steps to reduce the chance of losing the hive to a neighbor. Another indicator of bee health is humidity. If the area is too damp, it can damage the hive.

With that in mind, [Marc] developed a system to alert him via SMS or email if the sensor readings go beyond a certain range. In addition, he monitored the weight of the hive to see how much honey is inside. Frequency of the buzz was also recorded, and so was the activity of the entrance. He used an Arduino Duo and a DHT22 temperature/humidity sensor. A solar panel powered the bee monitoring system.

There were some challenges that needed to be overcome. Initially the Arduino wasn’t sending out data, but that was fixed with a simple debugging session. From there, he was able to broadcast the information creating graphs with the data. Battery levels, temperature, and humidity were all recorded. With the bee hive hacked and monitored, [Marc] was able to make progress on his system making great use of an Arduino.

NFC Ring Lock Box

NFC Ring Lock Box

[Nairod785] wanted to build a lock box that would lock from the inside. He started with an inexpensive, plain wooden box. This kept the cost down but would also allow him to easily decorate the box later on using a wood burning tool.

To keep the box locked, he installed a simple latch on the inside. The latch is connected to a servo with string. When the servo rotates in one direction, it pulls the string and releases the latch. When the servo is rotated in the opposite direction, the latch closes and locks the box once again.

If you are going to have a locked box, then you are also going to need a key to open it. [Nairod785] used a ring with a built-in NFC tag, similar to the ring featured back in March. Inside of the box is a PN532 NFC module. The walls of the box were a little too thick for the reader to detect the ring, so [Nairod785] had to scratch the wall thickness down a bit. The NFC module is connected to an Arduino Nano. Communications are handled with I2C.

The NFC ring actually has two different NFC tags in it; one on each side. [Nairod785] had to program both of the tag ID’s into the Arduino to ensure that the ring would work no matter the orientation.

The system is powered by a small rechargeable 5V battery. [Nairod785] wired up a USB plug flush with the box wall so he can easily charge up the battery while the box is locked. It also allows him to reprogram the Arduino if he feels so inclined. There is also a power switch on the side to conserve energy.


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