TOF

12 Articles

Touchless Shop Doors Over-Engineered To A Blissful Level

March 11, 2018 by 13 Comments

When [John Saunders] wanted an automatic door for his shop, rather than settle for a commercial unit, he designed and built a proximity-sensing opener to ease his passing. Sounds simple, right?

Fortunately for us, there are no half-measures at Saunders Machine Works, thanks to the multiple Tormach workcells and the people who know how to use them. The video below treats us to quite a build as a result; the first part is heavy on machining the many parts for the opener, so skip ahead to 8:33 if you’re more interested in the control electronics and programming.

The opener uses time-of-flight distance sensors and an Arduino to detect someone approaching, with a pneumatic cylinder to part a plastic strip curtain. [John] admits to more than a little scope creep with this one, which is understandable when you’ve got easy access to the tools needed to create specialized parts at will.

In the end, though, it works well for everyone but [Judd], the shop dog, and it certainly looks like it was a fun build to boot. [John]’s enthusiasm for mixing machining and electronics is infectious; check out his automated bowl feeder for assembly line use.

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Hackaday Prize Entry: MappyDot, A Micro Smart LiDAR Sensor

August 21, 2017 by 41 Comments

[Blecky]’s entry to the Hackaday Prize is MappyDot, a tiny board less than a square inch in size that holds a VL53L0X time-of-flight distance sensor and can measure distances of up to 2 meters.

MappyDot is more than just a breakout board; the ATMega328PB microcontroller on each PCB provides filtering, an easy to use  I2C interface, and automatically handles up to 112 boards connected in a bus. The idea is that one or a few MappyDots can be used by themselves, but managing a large number is just as easy. By dotting a device with multiple MappyDots pointing in different directions, a device could combine the readings to gain a LiDAR-like understanding of its physical environment. Its big numbers of MappyDots [Blecky] is going for, too: he just received a few panels of bare PCBs that he’ll soon be laboriously populating. The good news is, there aren’t that many components on each board.

It’s great to see open sourced projects and tools in which it is clear some thought has gone into making them flexible and easy to use. This means they are easier to incorporate into other work and helps make them a great contestant for the Hackaday Prize.

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Measuring Air Flow With Ultrasonic Sensors

July 26, 2017 by 23 Comments

Measuring air flow in an HVAC duct can be a tricky business. Paddle wheel and turbine flow meters introduce not only resistance but maintenance issue due to accumulated dust and debris. Being able to measure ducted airflow cheaply and non-intrusively, like with this ultrasonic flow meter, could be a big deal for DIY projects and the trades in general.

The principle behind the sensor [ItMightBeWorse] is working on is nothing new. He discovered a paper from 2015 that describes the method that measures the change in time-of-flight of an ultrasonic pulse across a moving stream of air in a duct. It’s another one of those “Why didn’t I think of that?” things that makes perfect sense in theory, but takes some engineering to turn into a functional sensor. [ItMightBeWorse] is using readily available HC-SR04 sensor boards and has already done a proof-of-concept build. He’s getting real numbers back and getting close to a sensor that will go into an HVAC automation project. The video below shows his progress to date and hints at a follow-up video with more results soon.

Here’s wishing [ItMightBeWorse] the best of luck with his build. But if things go sideways, he might look to our post-mortem of a failed magnetic flow meter for inspiration.

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Digitize Your Room With LIDAR

May 15, 2017 by 20 Comments

What’s the best way to image a room? A picture? Hah — don’t be so old-fashioned! You want a LIDAR rig to scan the space and reconstruct it as a 3D point map in your computer.

Hot on the heels of [Saulius Lukse]’s scanning thermometer, he’s replaced the thermal camera on their pan/tilt setup with a time-of-flight (TOF) camera — a Garmin LIDAR — capable of 500 samples per second and end up scanning their room in a mere fifteen minutes. Position data is combined with the ranging information to produce a point cloud using Python. Open that file in a 3D manipulation program and you’ll be treated to a sight like this:

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Ball Balancing Robot Uses New TOF Sensor

February 14, 2015 by 24 Comments

By now, you’ve most likely have seen or even played with an ultrasonic distance sensor. They work by emitting a sound, and then listening for the “ping” to return. The sensor can then tell how far an object is away by calculating the time in between. With sound waves traveling at 343.2 meters per second (768 mph), it’s no small task to measure the short time it takes for the sound to be emitted, then hit something a few feet away, and return. Now, imagine trying to do that with light.

Light in comparison moves at a whopping 299,792,458 meters per second (or about 671 million miles per hour). You’re going to have to have a pretty fast finger on a stopwatch to measure the time it takes for light to bounce back from an object a few inches away.

[Paul Bristow] is doing just that with the use of a new Time of Flight (ToF) sensor called the TeraRanger One. Developed in cooperation with CERN, this sensor uses a very narrow beam of light (listed as +/- 2 degrees) to accurately measure the position of an object to a resolution of 5mm, with distances up to 14 meters away. It boasts an impressive update rate of >1000 samples a second, and is very micro-controller friendly with UART, I2C, SPI, and PWM output.

[Paul] and his fellow hackers at the Post Tenebras Lab Hackerspace in Geneva got their hands on this sensor, and in a short time had a ball balancing robot up and running. The crude program is not running a PID controller, so the results seen in the video after the break aren’t that impressive. Also, the sensor isn’t exactly cheap at about $180 USD. Despite that, it will be interesting to see what applications these sensors will be used for. If you have any ideas, leave them in the comments below.

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