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Software engineer Josh Robertson decided to come up with his own take on a marriage proposal, building a reverse geocache device for the job that uses not one, but two Arduino Uno boards

The unit, which is made out of a wine box, is unlocked by three servos that actuate rods to release a trio of clasps. His not-yet-fiancé had to first input the correct sequence on a keypad, then turn potentiometers to the right position, and finally traipse to the accurate location—sensed via GPS—for it to open up.

As the project’s I/O requirements went beyond a single Uno, Robertson linked a pair together using the I2C protocol, allowing the master to read GPS coordinates and control a small LCD screen, while the second Arduino takes care of user input and servo actuation. 

The result was a “yes” to the proposal, and while we can’t guarantee the same outcome if you build one yourself, more info on the contraption is available here. Congrats, Josh!

Normally guitar pedals take in a signal from your instrument, then some modification to an amplifier. ElectroSmash’s open source device, however, looks like a guitar pedal, connects to a guitar and amp like a guitar pedal, but actually leaves the signal unmodified. Instead, it displays a variety of info about what you’re playing on its 16 x 16 LED matrix.

The Arduino Audio Meter uses an Uno for control and analysis, and acts as a VU meter by reading the incoming audio and creating LED animations. It also features a tuner function, visual metronome, frequency detector, and a simple lamp, which could all certainly be useful when playing. 

User input (besides the1/4-inch audio jack) is via a potentiometer and encoder, and it even has a few games available for it if you need to blow off some steam between sets! Build kits are available here if you’d like to make your own.

As shown in the video below, Tristan Calderbank is a very talented singer and guitar player, but what’s perhaps most interesting about his performance is the percussion section. Instead of a person (or an entire band) standing beside him, a robotic shaker, tambourine, snare drum and bass drum all play together under MIDI control.

Each device is activated by an HS-311 servo—or two in the case of the snare—powered by an Arduino Uno and MIDI shield. Signals are sent to the Arduino by a laptop running Ableton Live, and servo velocity can be varied to further control sound. 

A write-up on Calderbank’s build process can be found here, including what didn’t work, plus info on sound isolation from the servos. Arduino code is available on GitHub.

If you fly drones for fun—or perhaps even for work—you know that piloting them can sometimes be a difficult tasks. Imagine, however, trying to control four drones simultaneously. While also “challenging,” researchers at the Skolkovo Institute of Science and Technology in Russia have come up with a new approach, dubbed for commanding such a swarm using only arm movements.

SwarmTouch takes the form of a wrist and finger-mounted device, with an array of eight cameras tracking its position. When the operator moves their arm, the drones react to the hand motion and the other flying robots in the group, as if there was a mechanical system linking each one together. 

Feedback is provided by an Arduino Uno connected to the control station via an XBee radio, which tells the operator whether the swarm is expanding or contracting using finger-mounted vibration motors. The setup is on display in the video below and its research paper can be found here.

We propose a novel interaction strategy for a human-swarm communication when a human operator guides a formation of quadrotors with impedance control and receives vibrotactile feedback. The presented approach takes into account the human hand velocity and changes the formation shape and dynamics accordingly using impedance interlinks simulated between quadrotors, which helps to achieve a life-like swarm behavior. Experimental results with Crazyflie 2.0 quadrotor platform validate the proposed control algorithm. The tactile patterns representing dynamics of the swarm (extension or contraction) are proposed. The user feels the state of the swarm at his fingertips and receives valuable information to improve the controllability of the complex life-like formation. The user study revealed the patterns with high recognition rates. Subjects stated that tactile sensation improves the ability to guide the drone formation and makes the human-swarm communication much more interactive. The proposed technology can potentially have a strong impact on the human- swarm interaction, providing a new level of intuitiveness and immersion into the swarm navigation.

Joop Brokking has been experimenting with a miniature candle-powered steam engine. It’s an amazing little device, able to push a piston over and over to turn a flywheel, releasing the steam via a mechanically-controlled valve. But just how fast does it go?

Of course, there are a plethora of ways to determine its speed, but Brokking chose to do so using an Arduino Uno, a potentiometer and an LED that’s arranged over the piston assembly. 

The light source is programmed to pulse on and off, with a frequency that can be adjusted using the potentiometer. He then aligned this pulsing with the piston’s cyclic rate, visually “freezing” the device in time. This frequency and RPM numbers are output over the serial monitor, giving him a speed of around 1850 RPM.

YouTuber Oracid1 has developed a unique series of four-legged robots, dubbed “FiveBarQuads.”

The quadrupeds all feature ultrasonic sensing for navigation and a body made out of LEGO components — and as seen in the first video below, his latest (and largest) version is able to navigate quite nicely on its own. It’s even able to traverse a grate and maneuver around a potted plant, though chair legs are understandably a bit tricky.

The robots use an Arduino Uno for control along with a total of 16 micro servos in its shoulders (four each) in order to move the limbs. Two servos are employed to actuate each upper linkage for the legs, which are attached to bottom sections, and finally to the feet portion through a series of joints. This allows for an interesting locomotion capability that could be applicable in a variety of situations.

What really happens when you open the refrigerator door? Sure, you know intuitively that cold air escapes, but just how much? And how fast does the food inside actually heat up? To find out, Ryan Bates came up with his own data logging setup using an Arduino Uno, a custom sensor shield, and a microSD card reader.

His device uses a photoresistor to tell when the door has been opened, as well as a DHT22 temperature/humidity sensor to log the air temperature and door status. Along with this, TMP36 sensors are placed around the fridge to get a more granular look at temperatures, including one attached to a pickle jar. 

The results seen in the video below are quite interesting, and more information on the build can be found here if you’d like to try something similar.

Hearing live music is certainly enjoyable, but if the musician is using a drum machine, things can eventually get static. To add a bit more spontaneity into this class of robo-musician, Matt Bradshaw has created DrumKid — a handheld, battery-powered unit that uses random numbers to determine the rhythm and sound of a beat.

The device goes through a drum sequence, with a series of LEDs to indicate its progression, but also inserts randomly generated drum hits to the original beat. It features a variety of controllable parameters to alter how it sounds when played live via four knobs and six buttons.

The DrumKid was developed on an Arduino Uno and breadboard, then transferred to a PCB for the final version that will be for sale later this year. More info on the build is available in Bradshaw’s project write-up, while code and design files are on GitHub if you’d like to make your own!

As described in this project’s write-up, “The brachistochrone curve is a classic physics problem, that derives the fastest path between two points A and B which are at different elevations.” In other words, if you have a ramp leading down to another point, what’s the quickest route?

Intuitively—and incorrectly—you might think this is a straight line, and while you could work out the solution mathematically, this rig releases three marbles at a time, letting them cruise down to the Arduino Uno-based timing mechanism to see which path is fastest. 

The ramps are made out of laser-cut acrylic, and the marbles each strike a microswitch to indicate they’ve finished the race. The build looks like a great way to cement a classic physics problem in students’ minds, and learn even more while constructing the contraption!

Servo motors form the basis of many Arduino projects, but few use them in as interesting a manner as Doug Domke’s piece of electronic art.

The device features 36 servo motors arranged on a pegboard to produce various patterns, and can even be used in an interactive mode where it follows a person’s hand around with the help of ultrasonic sensors. 

Everything is driven by an Arduino Uno along with three 16-channel PWM control modules, and popsicle sticks show the servo movement to onlookers. 

Details, including Arduino code, can be found in the Domke’s write-up. To really appreciate this project’s visuals, be sure to take in the coordinated movements in the video below! 



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