Hi-Tech Tool For Measuring Your Kid’s Height

Sure we can have our kids back up against a wall, force them to stand up straight, and use a ruler on their head to mark their height on the wall, but what kind of hacker would we be? There isn’t a single microcontroller or any electronic component involved! The DIY-family that calls themselves [HomeMadeGarbage] stood tall and came up with a high-tech tool to measure their kid’s height.

In place of the ruler they got a small wooden box to place on the head. Under the box, at the rear end facing down, they mounted a VL53L0X laser ranging sensor. With a range of 2 meters it’s sure to work with any child. But the box has to be sat level on the child’s head, otherwise the laser will be pointing down at an angle. To handle that they put an MPU6050 6-axis motion sensor in the box along with an Arduino Nano to tie it all together. A LCD display, measurement push-button and LED are mounted outside the box on the rear facing side.

To use it, a parent sits the box on the child’s head, making sure the laser sensor isn’t blocked and can see the floor. The LCD shows the height, along with the acceleration in the x and y directions. The LED is red if the box isn’t level and green if it is. Holding the measurement button pressed puts the tool in measurement mode and when it’s level, the LED turns blue and the LCD display freezes so you can make a note of the height. You’re good for a while, depending on your child’s age. See it being used to measure a child after the break as well as an additional clip showing what the output looks like when waving a hand up and down below it.

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Smartphone and IR Line Laser Measure Distance

Measuring the distance using lasers is a mainstay of self-driving vehicles and ambitious robotics projects. The fine folks at MIT’s Computer Science and Artificial Intelligence Laboratory (CSAIL) decided to tackle the problem in an innovative way. [Jason H. Gao] and [Li-Shiuan Peh] used an infra-red (IR) line laser and the camera on a smartphone. Their prototype cost only $49 since they used a smartphone that was on hand. The article reports good results using the device outdoors in direct sunlight which is often a challenge for inexpensive lidars.

The line laser creates a horizontal line that is reflected back to the camera on the phone. The vertical position of the laser on the camera image lets the phone calculate the distance by parallax. To bring out a faint laser reflection, the algorithm compares four images – two with the laser on and two with it off – and subtracts the background. Using a smartphone for this is ideal since it automatically adjusts for light level and can easily be upgraded to a newer phone with a better camera later.

This should be a cheap and easily replicable setup. If you make one of these, let us know. If you need something more refined, check out this post on interfacing the Neato vacuum cleaner’s XV-11a lidar with the Raspberry Pi.

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A Mechanically Scanned LIDAR For Autonomous Robots

LIDAR[Patrick] has spent a lot of time around ground and aerial based autonomous robots, and over the last few years, he’s noticed a particular need for teams in robotics competitions to break through the ‘sensory bottleneck’ and get good data of the surrounding environment for navigational algorithms. The most well-funded teams in autonomous robotics competitions use LIDARs to scan the environment, but these are astonishingly expensive. With that, [Patrick] set out to create a cheaper solution.

Early this year, [Patrick] learned of an extremely cheap LIDAR sensor. Now [Patrick] is building a robotics distance measurement unit based on this sensor.

Early experiments with mechanically scanned LIDAR sensors centered around the XV-11 LIDAR, the distance sensor found in the Neato Robotics robot vacuum cleaner. [Patrick] became convinced a mechanically scanned LIDAR was the way forward when it came to distance measurement of autonomous robots. Now he’s making his own with an astonishingly inexpensive LIDAR sensor.

The basic idea of [Patrick]’s project is to take the PulsedLight LIDAR-Lite module, add a motor and processing board, and sell a complete unit that will output 360° of distance data to a robot’s main control system. The entire system should cost under $150 when finished; a boon to any students, teams, or hobbyists building an autonomous vehicle.

[Patrick]’s system is based on the PulsedLight LIDAR – a device that’s not shipping yet – but the team behind the LIDAR-Lite says they should have everything ready by the end of the month, all the better, because between these two devices, there’s a lot of cool stuff to be done in the area of autonomous robots.