detection

14 Articles

Cut Through The Noise, See Tiny Signals

November 1, 2018 by 18 Comments

An oscilloscope is a handy tool for measuring signals of all kinds, but it’s especially useful if you want to measure something with a periodic component. Modern oscilloscopes have all kinds of features built-in that allow you sample a wide range of signals in the hundreds of megahertz, and make finding and measuring your signal pretty easy, provided you know which buttons to push. There are some advanced oscilloscope methods that go beyond the built-in features of even the best oscilloscopes, and [AM] has a tutorial on one of them.

The method used here is called phase-senstitive detection, and allows tiny signals to be found within noise, even if the magnitude of the noise is hundreds of times greater than the signal itself. Normally this wouldn’t be possible, but by shifting the signal out of the DC range and giving it some frequency content, and then using a second channel on the oscilloscope to measure the frequency content of the source and triggering the oscilloscope on the second channel, the phase of the measured signal can be sifted out of the noise and shown clearly on the screen.

In [AM]’s example, he is measuring the intensity of a laser using a photodiode with a crude amplifier, but even with the amplifier it’s hard to see the signal in the noise. By adding a PWM-like signal to the power source of the laser and then syncing it up with the incoming signal from the photodiode, he can tease out the information he needs. It’s eally a fascinating concept, and if you fancy yourself a whiz with an oscilloscope this is really a tool you should have in your back pocket.  If you’re new to this equipment, we do have a primer on some oscilloscope basics, too.

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Detect Elevated Carbon Monoxide (Levels)

October 14, 2018 by 27 Comments

The molar mass of carbon monoxide (CO) is 28.0, and the molar mass of air is 28.8, so CO will rise in an ambient atmosphere. It makes sense to detect it farther from the ground, but getting a tall ladder is not convenient and certainly doesn’t make for fast deployment. What do you do if you don’t care for heights and want to know the CO levels in a gymnasium or a tall foyer? Here to save the day, is the Red Balloon Carbon Monoxide Detector.

Circuit.io generates the diagram and code to operate the CO sensor and turn a healthy green light to a warning red if unsafe levels are detected. The user holds the batteries, Arduino, and light while a red balloon lifts the sensor up to fifteen feet, or approximately five three meters. It is an analog sensor which needs some time to warm up so it pays to be warned about that wire length and startup.

Having a CO sentinel is a wise choice for this odorless gas.

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Object Detection, With TensorFlow

July 31, 2018 by 11 Comments

Getting computers to recognize objects has been a historically difficult problem in computer science, but with the rise of machine learning it is becoming easier to solve. One of the tools that can be put to work in object recognition is an open source library called TensorFlow, which [Evan] aka [Edje Electronics] has put to work for exactly this purpose.

His object recognition software runs on a Raspberry Pi equipped with a webcam, and also makes use of Open CV. [Evan] notes that this opens up a lot of creative low-cost detection applications for the Pi, such as setting up a camera that detects when a pet is waiting at the door to be let inside or outside, counting the number of bees entering and exiting a beehive, or monitoring parking spaces at an office.

This project uses a number of other toolkits as well, including Protobuf. It also makes extensive use of Python scripts, but if you’re comfortable with that and you have an application for computer vision, [Evan]’s tutorial will get you started.

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Add Broken Tool Detection To Your CNC Mill

January 26, 2017 by 38 Comments

A tool breaking in the midst of a CNC machining operation is always a disaster. Not only do you have a broken tool (no small expense), but if the program continues to run there is a good chance it’ll end up ruining your part too. In particularly bad cases, it’s even possible to for this to damage the machine itself. However, if the breakage is detected soon enough, the program can be stopped in time to salvage the part and avoid damage to your machine.

Many new machining centers have the ability to automatically detect tool breaks, but this is a feature missing from older machines (and inexpensive modern machines). To address this issue, [Wiley Davis] came up with a process for adding broken tool detection to an older Haas mill. The physical modifications are relatively minor: he simply added a limit switch wired to the existing (but unused) M-Function port on the Haas control board. This port is used to expand the functionality of the machine, but [Wiley] didn’t need it anyway.

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Minecraft Sword Lights Up When Nearby Friends

October 21, 2016 by 8 Comments

With All Hallow’s Eve looming close, makers have the potential to create some amazing costumes we’ll remember for the rest of the year. If you’re a fan of the hugely addict-*cough* popular game Minecraft, perhaps you’ve considered cosplaying as your favorite character skin, but lacked the appropriate props. [Graham Kitteridge] and his friends have decided to pay homage to the game by making their own light-up Minecraft swords.

These swords use 3D-printed and laser-cut parts, designed so as to hide the electronics for the lights and range finder in the hilt. Range finder? Oh, yes, the sword uses an Arduino Uno-based board to support NewPixels LEDs and a 433Mhz radio transmitter and receiver for ranged detection of other nearby swords that — when they are detected — will trigger the sword to glow. Kind of like the sword Sting, but for friendlies. Continue reading “Minecraft Sword Lights Up When Nearby Friends” →

RadarCat Gives Computers A Sense Of Touch

October 21, 2016 by 18 Comments

So far, humans have had the edge in the ability to identify objects by touch. but not for long. Using Google’s Project Soli, a miniature radar that detects the subtlest of gesture inputs, the [St. Andrews Computer Human Interaction group (SACHI)] at the University of St. Andrews have developed a new platform, named RadarCat, that uses the chip to identify materials, as if by touch.

Realizing that different materials return unique radar signals to the chip, the [SACHI] team combined it with their recognition software and machine learning processes that enables RadarCat to identify a range of materials with accuracy in real time! It can also display additional information about the object, such as nutritional information in the case of food, or product information for consumer electronics. The video displays how RadarCat has already learned an impressive range of materials, and even specific body parts. Can Skynet be far behind?

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Redesigning The RC Tank

July 21, 2012 by 6 Comments

[youtube=http://www.youtube.com/watch?v=–YZHMqHzPw]

[Vincent] started building this tank (translation) with a regular hobby model: the Heng Long Tiger 1. However, after considering some goals for the project, he decided to nearly gut the tank and redesign it, basing it on the Arduino and a standard Motor Shield. The possibilities with this setup are nearly endless. In its current form, the ArduTiger detects obstacles in front of it by way of three servo-mounted infrared rangefinders. The tank’s trajectory can be adjusted automatically based on feedback from the servo positions. Two additional short-range rangefinders detect if there is ground for the tank to roll over, keeping it safe from cliffs and black holes.  [Vincent] plans on updating this beast by adding a Raspberry Pi for live video and advanced control… and maybe even adding a Geiger counter!