Tag Archives: arduino

Arduino resurrects a washing machine that failed for silly reasons

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The maker movement often focuses on creation, but we should never overlook repair. In a consumer market increasingly moving towards planned obsolescence, manufacturers often fail to devote any resources towards the repair of their products. In many cases, replacement parts are unavailable or prohibitively expensive. But the maker skill set can provide recourse, as demonstrated by Balakrishnan Prashanth’s Arduino-based solution for a washing machine’s failed timer display.

Like many modern washing machines, Prashanth’s Whirlpool has a digital readout that displays the time remaining in a cycle. It’s a handy feature, but not one that is absolutely necessary to wash clothes. Unfortunately, this Whirlpool disagrees. They designed this model’s control board so that the entire machine’s functionality comes to a screeching halt if the digital display stops working. The control board sends data to the display and expects an acknowledgment. If it doesn’t receive that acknowledgment, it won’t let the washing machine run through a cycle. That’s what happened when Prashanth’s machine’s display failed.

Prashanth solved this problem using an Arduino Mega 2560. He determined that the Whirpool’s control board sends data to the display module via I2C and expects a confirmation from the module. Instead of trying to replicate the complete functionality of the display module, Prashanth chose to omit the display altogether — it is, after all, unnecessary. He put the Arduino in the display module’s place and programmed it to simply blink an LED when it receives I2C messages from the control board. It then sends a confirmation back to the control board, tricking it into proceeding with the normal wash cycle.

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Walk-Bot helps people with visual impairments navigate safely

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It is no secret that visual impairments — even those that don’t result in complete blindness — make it very difficult for people to live their lives. White canes can help people get around, but they require physical contact. Seeing eye dogs provide very valuable assistance, but they’re expensive and need care of their own. That’s why Nilay Roy Choudhury designed the Walk-Bot device to help people with visual impairments navigate safely.

Walk-Bot is a wearable navigation device that uses audible cues and haptic feedback to give visually impaired people a sense of their immediate environment. It has a host of sensors that let it identify nearby obstacles at any height from the floor to the ceiling. Walk-Bot performs onboard trigonometry to determine the distance to any obstacles that might interfere with its user’s ability to walk safely. And it is affordable and easy to build with common components.

Those components include an Arduino Nano board, two HC-SR04 ultrasonic sensors, a GP2Y0A02YK0F infrared sensor, a vibration motor, a buzzer, an MPU6050 gyroscope, and an HC-05 Bluetooth module. Those all fit inside a 3D-printed wearable enclosure.

One ultrasonic sensor faces upwards at a 45-degree angle to detect high obstacles. The second ultrasonic sensor faces directly forwards. The infrared sensor points downwards at a 45-degree angle to detect low obstacles and was chosen because ultrasonic sensors struggle with some common floor surfaces. The gyroscope lets Walk-Bot determine its own orientation in space. When it detects an obstacle, Walk-Bot sounds the buzzer and activates the vibration motor. It also includes a panic button that will tell Walk-Bot to connect to the user’s smartphone through the Bluetooth module to message a chosen contact in the event of an emergency.

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This DIY Apple Pencil writes with gestures

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Released in 2015, the Apple Pencil is a technology-packed stylus that allows users to write on iPad screens with variations in pressure and angle — all while communicating with very low latencies. Nekhil Ravi and Shebin Jose Jacob of Coders Café were inspired by this piece of handheld tech to come up with their own pencil concept, except this one wouldn’t need a screen in order to function.

The pair’s writing utensil relies on recognizing certain gestures as letters, and once one has been detected, outputs the result over USB or Bluetooth® to the host device. They started by first gathering many samples of different letters and how they correlate to the change in motion on the Arduino Nano 33 BLE Sense’s built-in accelerometer. From here, they designed an impulse in the Edge Impulse Studio to extract spectral features from the time series accelerometer data and pass it to a classification Keras neural network. The resulting model could accurately determine the correct letter from each gesture, making it suitable for deployment back to the Nano 33 BLE Sense.

Before testing their new inferencing code on the hardware, a simple 3D-printed case was designed to fit around the board to look like the real Apple Pencil. Additionally, the team made a simple website that could receive data from the board over BLE and display the corresponding letter within the browser window. To see more about this project, you can watch their video below!

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A 3D-printable, Arduino-controlled star tracker great for astrophotography

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Most modern digital cameras are perfectly capable of capturing photos of the stars. But many of them have trouble collecting the small amount of light available in a short amount of time, which means that you need to leave the shutter open for 30 seconds or more to get a decent exposure. That presents a problem, because the Earth rotates. As it does, the light from the stars leaves trails in your long-exposure photo. To overcome that issue, Ondra Gejdos designed this 3D-printable star tracker.

The purpose of a star tracker like this one is to move the camera in the opposite direction of the Earth’s spin in order to keep the stars still in the frame. That lets astrophotographers keep the shutter open as long as they need to to get proper exposure without star trails. The “OG-star-tracker” mounts to a standard tripod and the camera attaches to it. A single stepper provides rotation, and it is up to the user to set the angle properly for their position on the planet.

An Arduino Uno board controls the movement, though Gejdos also uploaded firmware for the Nano. It controls the stepper motor through a TMC2209 stepper driver. The 3D-printable design includes a gear box that dramatically reduces the stepper motor output, resulting in very smooth movement that shouldn’t create any blurriness in the photos.

The documentation is a little bit rough at the moment, but all of the files are on the GitHub page so you can build your own star tracker.

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DIY focus stacking device aids in macro photography

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If you’re ever tried to capture some macro photographs (very close-up pictures), you’ve probably noticed that it is difficult to get proper focus. Because the depth-of-field (DoF) for macro lenses is so small, you can only keep a narrow range of distance in focus at any given time — everything else is blurry. One solution is “focus stacking,” in which you take many photos and then mash them together in software. Curious Scientist designed a macro photography focus stacking device that makes this technique easier.

The focus stacking technique requires several photos, each with a slightly different area of the subject in focus, until you’ve covered the entire subject. Then you can use photo editing software, like Photoshop, to blend the pictures together. The result is a macro photo where the entire subject is in focus. You can perform that process without any special equipment, but it is tedious and difficult to achieve consistent focus changes. Curious Scientist’s device speeds up the process and has perfect consistency.

Instead of refocusing the lens between photos, this device moves the entire camera. With auto-focus disabled and the lens manually focused to the nearest point of the subject, the whole camera moves forward by a predetermined distance after each photo.

The primary components in this project are an Arduino Nano board, a linear actuator with stepper motor, a stepper motor driver, a 1.8” LCD panel, and control buttons. With the LCD and buttons, the user can set the focus stacking parameters: f-stop, magnification, and so on. The device then calculates how far to move between shots. It uses a standard shutter trigger and should work with most cameras.

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This pen plotter gets nervous when observed

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The whole purpose of machine automation is to eliminate human needs and errors. A CNC machine doesn’t get tired, doesn’t need breaks, and performs a task exactly the same way every time. But what if that weren’t true? What if machines experienced human emotions and let it affect their work like we do? That’s the idea behind Devlin Macpherson’s Nervous Drawing Machine.

By all outward appearances, this is just a standard two-axis pen plotter. Like many laser cutters and 3D printers, it has a stepper motors controlled by an Arduino board that follows g-code commands. A command might be something like “move the X axis 2mm to the right.” By chaining hundreds or thousands of those commands together, the machine can follow complex toolpaths that form letters, symbols, pictures, or anything else. Macpherson equipped the pen plotter with a continuously fed roll of paper so it can draw indefinitely.

Under normal conditions, the machine plots row after row of little squares. A video camera points at the plotter as it works and the video feed streams through a website. And this is where things get interesting. If someone visits the website and watches the stream, the pen plotter becomes nervous about being observed. It will then start to make mistakes, like drawing scribbles instead of squares. Once the visitor leaves the website and the machine is unobserved once again, it will return to drawing perfect rows of squares.

Macpherson built the Nervous Drawing Machine for his thesis project titled ICFWYWM (I Can’t Focus When You’re Watching Me). Like all good interactive art installations, it reflects the human condition.

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