Autonomous Allsky camera with Raspberry PI.

[OlegKutkov]

Allsky camera and weather station is very important parts of the modern observatory.
Here I wanna describe project that I build for my observatory.
I started a new topic because I believe that this project is unique and I hope this description may be useful because project is open source/open hardware.
This device contains two cameras, one is for beautiful daytime shots (over the horizon) and second for useful night shots. Also there is a lot of sensors: clouds, ir, light, temperature and humidity.
Heart of the device is Raspberry PI 2 microcomputer.

Everything is built in waterproof electrical box which can be found in hardware stores.
Yep this exterior is not very nice looking due to silicone sealant. But nice looking is not most important part, especially when mounting device somewhere on a roof

Acrylic dome is from CCTV camera.

Inside the box I glued a thermal insulation and copper foil which acts like a EMI shield. This foil is connected to the building grounding circuits.

All devices inside the box:
- Raspberry PI 2
- internal temperature/humidity sensor
- powering system (+3.3, +5, +12 volts)
- ethernet lightning protection
- tsl2561 ir/luminosity sensor
- mlx90614 cloud sensor
- cooling system
- rtc with a back-up baterry

External temperature/humidity sensor is mounted in separate aluminium can.

Cameras module is mounted on the bronze pcb stands and will be described below.

Raspberry PI runs all device software except database and long-time storage of the images.
Camera can be accessed through simple web interface which running on nginx server.
All data collecting and generation software is wrote on C, Python and Bash.
All processes is starting by the CRON.

Database is working on the remote server with reliable storage system and can be accessed through network. I'm using Mysql in this project.
I found that this solution is more reliable and convenient rather than local storage on the SD card.

All images are postprocessed by the software. Dark frames is extracted (only for night camera) and generated some text information on the bottom of the image.

[OlegKutkov]

Cameras module is placed under the dome.
You can see mechanical construction on the photo below.

Vertical camera is allsky. This is a popular and cheap QHY5-IIM astrocam. Lens is also CCTV, Сomputar 1.8-3.6mm 1.6
This lens contains iris motor which is used to close the camera in a day time to prevent damage of the image sensor.

Second horizontal camera is a Raspberry camera module, first version. This module is also equipped with CCTV lens using handmade adapter.

QHY camera is accessed with my custom software.
RPI cam module is working with standard raspistill utility.

[OlegKutkov]

On the image below you can see all logical connection between device modules.
Most of the sensors is accessed by the I2C bus which is very convenient.

[OlegKutkov]

This device requires only one external cable which is used as 100mb ethernet and for powering by the free pairs (variant of PoE).

I'm using black outdoor ethernet cable.

On the both sides of the cable I've mounted protection circuits.
Schematics is attached.

[OlegKutkov]

Camera down-converter is used to deliver 3.3 volts for the sensors, 5 volts for the Raspberry and QHY and 12 volts for the FANs and IRIS motor.

This is two impulse converters and one linear. Also on this board I placed simple FAN driver.

[OlegKutkov]

Here is web interface. Powered by Bootstrap with additional Javascript code and custom styles.
All graphs is generating by the Python matplotlib. Text messages is also generated by the Python code with some Bash wrappings.
Every images and text data is reloading automatically every 40 seconds.

[OlegKutkov]

Every morning special script is collecting all cameras images from the last day and compiling movies using ffmpeg.
Then this movies is uploading to the camera's Youtube channel: https://www.youtube.com/channel/UC9mot5kKa6-PNMAXGx5_Sig

[OlegKutkov]

You can find and discover all camera software on Github: https://github.com/olegkutkov/allsky

Source code is always under development and under modifications

[stash_old]

Impressive work done - well done

[happy-kat]

That's clever stuff, great project.

[gentlebear76]

Veeery nice! I've been working on something similar but got stuck on the iris thing. Do you happen to have the model number for your Computar lens?

[OlegKutkov]

On 15.05.2018 at 13:25, gentlebear76 said:

Veeery nice! I've been working on something similar but got stuck on the iris thing. Do you happen to have the model number for your Computar lens?

Hi!

My lens is Computar 1.8-3.6mm 1:1.6 1/3 CS.

To be able to control iris I made a little changes to the lens electronics.
Discovering board I found operational amplifier which controls output motor driver. Pulling down one of the amplifier inputs causes closing the iris.
I added little npn transistor key (you can see on attached photo). Base of this transistor is connected to the Raspberry GPIO pin through 1k resistor.
So when GPIO is high - transistor is opened and amplifier pin is pulled to the ground, iris closed.