Laser Anemometer
Introduction: Laser Anemometer
This instructable explains how to make an anemometer from an Arduino Uno R3, two VL6180X laser distance modules, and a section of plastic drain pipe or similar.
Processing3 is used to display the wind speed and wind direction.
The wind direction is independent of the pipe dimensions.
The sensitivity to wind speed depends on the pipe dimensions and the amount of applied damping.
Construction is simple ... all you need is a drill , a hacksaw, and a hot-glue gun.
The anemometer is purely experimental and is published in the hope that the techniques will be of use to others.
The estimated cost to build this anemometer is between $20 and $50 depending on how many parts you have on-hand.
Images
* The cover photo shows the anemometer construction
* Photo 2 shows the display
* The video shows the anemometer in operation.
Supplies
The following parts were obtained from https://www.aliexpress.com/
* 2 only VL6180X Range Finder Optical Ranging Sensor Modules for Arduino I2C
* 1 only Arduino UNO R3
The following parts were obtained locally
* 1 only small length (150mm) 65mm inside diameter plastic downpipe [1]
* 1 only endcap to fit the above pipe
* 1 only length (500mm) 10mm inside diameter aluminium pipe
* 1 only 11/16” extension spring
* 1 only M4 bolt
* 1 only M4 nut
* 1 only self-tapping screw
* 6 only lengths of hookup wire (these are threaded through the pipe)
The estimated cost to build this anemometer is between $20 and $50 depending on how many parts you have on-hand.
Note
[1]
An opaque plastic drink bottle with the base cut off should also work providing it is circular.
Step 1: Theory
The cross-section of a pipe is a circle.
The points at which the two laser beams touch the inside of a pipe define the end points of a chord on this circle.
The length of this chord varies when the pipe is tilted (photos 1, 2, 3)
Knowing the pipe radius it is possible to calculate the X and Y displacement of the pipe from which the wind speed and direction may be calculated (photos 3, 4)
Step 2: Circuit Diagram
The anemometer circuit is shown in photo 1
Very few parts are required ... 16
just the Arduino and two Vl6180X laser distance modules.
Step 3: Construction
Step 1
(Photo 1)
* Cut one loop off the end of the 11/16” extension spring (I used a diamond file)
* Press the M4 nut inside the coiled spring
* Solder the nut through the spring ... the solder will not take to the spring but will prevent the nut pulling out.
* Push the other end of the spring down tube
* Fasten the spring in place using the self tapping screw. [1]
Step 2
(Photo 2)
* Cut 20mm from the bottom of an old credit card or similar.
* Cut the length to twice the height of a VL6180X sensor
* Lightly score the center and fold to 90 degrees
* Hot glue this plastic angle to the aluminium tube such that it will just be covered when the plastic downpipe (or bottle) is attached
Step 3
(Photo 3)
* Hot glue a VL6180X sensor to each of the plastic faces.
* Before doing this read Step 5: Calibration below
Step 4
(Photo 4)
* Drill a 5mm hole in the tube above the sensors
* Feed three pairs of twisted wires through the hole and out of the tube.
* One pair of wires is for VCC and GND
* The second pair of wires is for SDA and SCL
* Each of the remaining wires is attached to a sensor SHDN pin
Step 5
(Photo 5)
* Attach the pipe and end-cap
Step 6
(Photo 6)
* Mount the pipe vertically for testing [2]
Notes
[1]
* The amount of exposed spring determines the damping.
* If too much spring is exposed the tube will tend to oscillate much like a playground swing
* If too little is exposed the tube will require a large air flow before it will tilt.
[2]
* A multispeed hair-dryer is useful when testing.
Step 4: Software
Step 1
(Photo 1)
Download and install the Pololu VL6180X library. 611