Mega – DIY Database

This robot can dynamically change its wheel diameter to suit the terrain

A vehicle’s wheel diameter has a dramatic effect on several aspects of performance. The most obvious is gearing, with larger wheels increasing the ultimate gear ratio — though transmission and transfer case gearing can counteract that. But wheel size also affects mobility over terrain, which is why Gourav Moger and Huseyin Atakan Varol’s prototype mobile […]

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If all else were equal (including final gear ratio), smaller wheels would be better, because they result in less unsprung mass. But that would only be true in a hypothetical world on perfectly flat surfaces. As the terrain becomes more irregular, larger wheels become more practical. Stairs are an extreme example and only a vehicle with very large wheels can climb stairs.

Most vehicles sacrifice either efficiency or capability through wheel size, but this robot doesn’t have to. Each of its wheels is a unique collapsing mechanism that can expand or shrink as necessary to alter the effective rolling diameter. Pulley rope actuators on each wheel, driven by Dynamixel geared motors by an Arduino Mega 2560 board through a Dynamixel shield, perform that change. A single drive motor spins the wheels through a rigid gear set mounted on the axles, and a third omni wheel provides stability.

This unique arrangement has additional benefits beyond terrain accommodation. The robot can, for instance, shrink its wheels in order to fit through tight spaces. It can also increase the size of one wheel, relative to the other, to turn without a dedicated steering rack or differential drive system.

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See how this homemade spectrometer analyzes substances with an Arduino Mega

The post See how this homemade spectrometer analyzes substances with an Arduino Mega appeared first on Arduino Blog.

Materials, when exposed to light, will reflect or absorb certain portions of the electromagnetic spectrum that can give valuable information about their chemical or physical compositions. Traditional setups use a single lamp to emit white light before it is split apart into a spectrum of colors via a system of prisms, mirrors, and lenses. After hitting the substance being tested, a sensor will gather this spectral color data for analysis. YouTuber Marb’s Lab realized that by leveraging several discrete. LEDs, he could recreate this array of light without the need for the more expensive/complicated optics.

His project uses the AS7431 10-channel spectrometer sensor breakout board from Adafruit due to its adequate accuracy and compact footprint. Once it was attached to the clear sample chamber and wired to a connector, Marb got to work on the electromechanical portion of the system. Here, a stepper motor rotates a ring of six LEDs that are driven by a series of N-channel MOSFETs and a decade counter. Each component was then wired into a custom-designed control board, which acts as a shield when attached to the Arduino Mega 2560 below.

The sketch running on the Mega allows for the user to select between photometer (single wavelength) and spectrometer (multiple wavelengths) modes when sampling the substance. Once the data is captured, the user can then choose one of three interpolation modes to get a smooth curve, as seen here when measuring this chlorophyl.

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This perplexing robotic performer operates under the control of three different Arduino boards

Every decade or two, humanity seems to develop a renewed interest in humanoid robots and their potential within our world. Because the practical applications are actually pretty limited (given the high cost), we inevitably begin to consider how those robots might function as entertainment. But Jon Hamilton did more than just wonder, he actually built […]

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It is hard to describe this robot without sounding like a Mad Libs game filled out by a cyberpunk-obsessed DJ. Hamilton designed it to give performances, primarily in the form of synthetic singing accompanied by electronic music. It looks like a crude Halloween mask given life by a misguided wizard sometime in the 1980s. It is pretty bonkers and you should probably watch the video of it in action to wrap your head around the concept.

Hamilton needed three different Arduino development boards to bring this robot to life. The first, an Arduino Giga R1 WiFi, oversees the robot’s operation and handles voice interaction, as well as audio playback. The second, an Arduino Mega 2560, moves the robot’s neck according to input from two microphones (one on the left, the other on the right). The third, an Arduino Uno R4 WiFi, controls the rest of the servo movement.

The result is a robot that is both impressive and also pretty disconcerting.

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ThermoGrasp brings thermal feedback to virtual reality

Imagine playing Half-Life: Alyx and feeling the gun heat up in your hand as you take down The Combine. Or operating a robot through augmented reality and feeling coldness on your fingers when you get close to exceeding the robot’s limits. A prototype device called ThermoGrasp brings that thermal feedback to the mixed reality applications. ThermoGrasp is […]

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Imagine playing Half-Life: Alyx and feeling the gun heat up in your hand as you take down The Combine. Or operating a robot through augmented reality and feeling coldness on your fingers when you get close to exceeding the robot’s limits. A prototype device called ThermoGrasp brings that thermal feedback to the mixed reality applications.

ThermoGrasp is a wearable thermal feedback system designed for virtual reality and augmented reality, created by Arshad Nasser and Khalad Hasan of the University of British Columbia. It consists of thermoelectric modules attached to the user’s fingers with Velcro straps. Those are capable of creating thermal sensations — both warm and cold — in response to what happens in the virtual world. Those sensations can relate to any condition or event that the developer chooses, whether for immersion or utility.

Nasser and Hasan built the prototype using an Arduino Mega 2560 board, which controls the thermoelectric modules through custom H-bridge drivers. Those thermoelectric modules are Peltier devices, which are normally associated with cooling. They can create a cooling feeling on the skin, but can also do the opposite and produce a warm feeling. The Arduino controls the drivers through pulse-width modulation (PWM), allowing for granular adjustment. The thermoelectric modules are capable of changing temperature at a rate of 3.5°C per second and so can produce a noticeable sensation within just a couple of seconds.

In testing, users found that cool sensations were easier to detect than warm sensations, but that both were useful and increased immersion.

Image credit: A. Nasser et al.

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Venderoo is an Arduino Mega-powered DIY vending machine

For now-college student Joel Grayson, making something that combined his interests in mechanics, electronics, and programming while being simultaneously useful to those around him was a longtime goal. His recent Venderoo project is exactly that, as the creatively named vending machine was designed and built from the ground up to dispense snacks in his former […]

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Constructing Venderoo started with a sketch that featured the dimensions, vending mechanism, and the electronics panel on the left. Then through a combination of a CNC router and a jigsaw, Grayson meticulously cut out each plywood panel and assembled them together along with clear acrylic sheets so students could observe the machine in-action. On the electronics side, an Arduino Mega 2560 is responsible for handling selections on the keypad, displaying commands/feedback to users via the character LCD, accepting money, and rotating the motors when it’s time to dispense.

When a student first approaches Venderoo, they are greeted by a message instructing them to select their snack of choice, after which the price will appear and ask for a combination of $1 or $5 bills, depending on the price. Once the balance has met the threshold, Venderoo will find the location of the snack and spin the appropriate motor thanks to powerful MOSFET drivers.

To see more about how Grayson’s Venderoo vending machine works, watch the video below!

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Explore underwater with this Arduino-controlled DIY ROV

Who doesn’t want to explore underwater? To take a journey beneath the surface of a lake or even the ocean? But a remotely operated vehicle (ROV), which is the kind of robot you’d use for such an adventure, isn’t exactly the kind of thing you’ll find on the shelf at your local Walmart. You can, […]

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Amarasinghe is a 16-year-old Sri Lankan student and this is actually the second iteration of his ROV design. As such, he’s dubbed it “ROV2” and it appears to be quite capable. All of its electronics sit safely within a 450mm length of sealed PVC tube. That mounts onto the aluminum extrusion frame structure that also hosts the six thrusters powered by drone-style brushless DC motors.

ROV2’s brain is an Arduino Mega 2560 board and it drives the BLDC motors through six electronic speed controllers (ESCs). It receives control commands from the surface via an umbilical. The operator holds a Flysky transmitter that sends radio signals to a receiver floating on the water. An Arduino UNO Rev3 reads those and then communicates the motor commands to the Mega through the tethered serial connection. That limits the maximum length of the tether to about 40 meters, which subsequently limits the maximum operating depth.

With the specified lithium battery pack, ROV2 can traverse the depths for 30-45 minutes. And when equipped with the 720p FPV camera, pilots can see and record all of the underwater action.

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