Amazing 3D-Scanner Teardown and Rebuild

0_10ea1b_776cdc71_origPour yourself a nice hot cup of tea, because [iliasam]’s latest work on a laser rangefinder (in Russian, translated here) is a long and interesting read. The shorter version is that he got his hands on a broken laser security scanner, nearly completely reverse-engineered it, got it working again, put it on a Roomba that was able to map out his apartment, and then re-designed it to become a tripod-mounted, full-room 3D scanner. Wow.

The scanner in question has a spinning mirror and a laser time-of-flight ranger, and is designed to shut down machinery when people enter a “no-go” region. As built, it returns ranges along a horizontal plane — it’s a 2D scanner. The conversion to a 3D scanner meant adding another axis, and to do this with sufficient precision required flipping the rig on its side, salvaging the fantastic bearings from a VHS machine, and driving it all with the surprisingly common A4988 stepper driver and an Arduino. A program on a PC reads in the data, and the stepper moves another 0.36 degrees. The results speak for themselves.

This isn’t [iliasam]’s first laser-rangefinder project, naturally. We’ve previously featured his homemade parallax-based ranger for use on a mobile robot, which is equally impressive. What amazes us most about these builds is the near-professional quality of the results pulled off on a shoestring budget.

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Vibrating Distance Torch Illuminates the Dark without Light

If you’ve ever had to move around in a dark room before, you know how frustrating it can be. This is especially true if you are in an unfamiliar place. [Brian] has attempted to help solve this problem by building a vibrating distance sensor that is intuitive to use.

The main circuit is rather simple. An Arduino is hooked up to both an ultrasonic distance sensor and a vibrating motor. The distance sensor uses sound to determine the distance of an object by calculating how long it takes for an emitted sound to return to the sensor. The sensor uses sounds that are above the range of human hearing, so no one in the vicinity will hear it. The Arduino then vibrates a motor quickly if the object is very close, or slowly if it is far away. The whole circuit is powered by a 9V battery.

The real trick to this project is that the entire thing is housed inside of an old flashlight. [Brian] used OpenSCAD to design a custom plastic mount. This mount replaces the flashlight lens and allows the ultrasonic sensor to be secured to the front of the flashlight. The flashlight housing makes the device very intuitive to use. You simply point the flashlight in front of you and press the button. Instead of shining a bright light, the flashlight vibrates to let you know if the way ahead is clear. This way the user can more easily navigate around in the dark without the risk of being seen or waking up people in the area.

This reminds us of project Tacit, which used two of these ultrasonic sensors mounted on a fingerless glove.

A Simple Posture Sensor


If you are on the computer for a large part of the day, posture becomes a serious issue that can negatively impact your health. [Wingman] saw this problem, and created a hack to help solve it. His simple posture sensor will monitor the position of your head relative to the chair, and reminds you to sit up straight.

The posture sensor is built around the HC-SR04 ultrasonic distance sensor, an Attiny85, and a piezo speaker. We’ve seen this distance sensor used in the past for a few projects. Rather than going down the wearable route, which has its own drawbacks, [Wingman] decided to attach his sensor on the back of his chair. The best part is that the sensor is not mounted directly on the chair, but rather on a piece of fabric allowing it to be easily moved when needed.

Given how low-cost and small the sensor is, the project can be easily expanded by adding multiple sensors in different locations. This would allow the angle of the back and possibly the neck to be determined, giving a more accurate indicator of poor posture. There are very few hacks out there that address bad posture. Do you have a project that helps address bad posture? Have you used video processing or a wearable device to monitor your posture? Let us know in the comments an don’t forget to send post links about them to our tips line.

A longboard speed and distance computer


Why should cyclists have all of the fancy toys? Bicycle computers are very common these days but you won’t find similar hardware for skateboards and longboards. [KobraX22] isn’t taking it lying down. He built this speed and distance computer for his longboard. It doesn’t use very many components and should be easy to install.

The device monitors the rotation of one of the wheels by mounting a reflectance sensor on one of the trucks. It points toward the inside of a wheel which has a piece of black tape on it. Every time the tape passes it prevents the IR led from reflecting back at its paired receiver. This lets the Arduino count the revolutions, which are then paired with the wheel diameter to calculate speed as well as distance traveled. Of course the wheels wear down over time to so frequent riders will have to take new measurements at regular intervals.

[KobraX22] went with a QRB1114 sensor. It costs less than $2 and doesn’t require him to embed a magnet in the wheel like a hall effect sensor setup would have. It also shouldn’t interfere with any other fancy wheel hacks you’ve done, like adding a POV display.

[via Reddit]

Garage parking monitor guides you in every time


The live Adafruit Show and Tell stream from last weekend featured this project put together by [Silent Jeff]. He’s called “Silent” because when it came time to present his project on the show his microphone wasn’t working. As you can see in the video after the break, [PT] and [Ladyada] worked together to explain the project (of which they had no prior knowledge) using a game of charades. This is one of the follow-up images he sent them which details his parking spotter project.

[Ladyada] compliments [Jeff] on the finished look of the device and we agree. Not only does this do a great job of letting a driver know if they have pulled far enough into the garage, but it’s finished appearance ensures it won’t ever look out-of-place. The two silver discs near the lower end of the box are the sensors of an ultrasonic rangefinder. You mount this box so that the sensor is measuring distance between itself and the bumper of your vehicle. As the distance decreases the LEDs change to let you know when to stop. Inside the case you’ll find a voltage regulator and single-chip running the Arduino bootloader. [Jeff] says this is just his second Arduino project and we hope that at this rate we’ll be looking for big things from him in the not too distant future!

This is basically the same idea as cars that use parking assist sensors in the bumper. It’s just attached to the building instead of to the vehicle itself.

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Sensor rig finds out if motorists are sharing the road with cyclists

Apparently there’s some cause for concern when it comes to bikes and automobiles sharing the roads in Austin, Texas. [Christopher Stanton] wrote in to tell us there’s a law on the books now that requires motorists to give three feet of space when passing a cyclist. This is pretty difficult to enforce as there’s no solid proof like the radar gun provides when it comes to speed limits. The hardware above is seeking to help by collecting data on passing habits. It measures and records the distance of each vehicle that passes you while on the bike. The goal isn’t to ticket more drivers, it’s to collect statistical data that might help change dangerous driving habits.

As you can see, a front equipment rack hosts the hardware for easy installation on a bike. It has an arm that extends to the side the same distance as the handle bars. The HD camera with wide-angle lens is set to snap a photo which can be used to determine the bike and vehicle positions in the lanes, along with the distance readout from the sensor.

We’d certainly be interested in seeing the numbers for average passing clearance in a heavily traveled urban environment. Even with bike lanes, things can feel pretty tight on a busy day!