Monthly Archives: May 2013

Chicken Coop – Automatic Door

I decided our chickens needed an automated door to let them out of their coop and into a run through the day (and secure them at night).

After a bit of research the Arduino Chicken Coop Controller by Robot-Chicken on instructables looks like a good guideline.

I purchased a $10 cordless screwdriver with charger from Canadian Tire as the motor unit. The motor controller and arduino were purchased from ebay. I decided to connect a raspberry pi to schedule the door opening/closing the door. I am using the simple app Sunwait to calculate the sunrise/set based on my latitude and longitude. At the scheduled time the raspberry pi will send a ‘D’ over its serial port to put the door up or a ‘d’ to put the door down.

Code is available on github.

At present, I didn’t bother to build the auto-latching mechanism out fully on the door. As they have the additional fence around their run it didn’t seem necessary to start with.

I am placing the various power supplies and electronics in a cheap toolbox I screwed to the top of the coop. This should provide them a modicum of weather/dust protection (the whole thing is tucked in under the house so it isn’t expected to get rained on).

A video of the maiden run on the door:

Tricopter Flight Control Board

The hobby king KK2 board looks like a good low cost option at only $30. If you just want something cost effective and simple this seems a solid route to go.

Longer term though; I like the idea of autonomous flight capabilities and, even when manually controlled, the ability to automatically return to the launch site should something go awry.

To achieve these goals, the Ardupilot system looks quite good. Direct from DIY Drones, the creator, it costs $180 + shipping. RCTimer sells a copy called the ArduFlyer for $89.99 they also sell the u-Blox CN-06 GPS Receiver V2.0 for $26.99 ($116.09 + shipping total). Their version seems well reviewed so I opted for it given the savings.

Based on comments it sounds like the GPS receiver from RCTimer isn’t optimally configured out of the box. If you install uBlox’s u-center software and upload the 3DR-Ublox.txt configuration file as documented here it appears to get a lock faster and the baud rate is increased from 9600 to 38400. You will need a 5V TTL to USB adapter; I used a CP2102 Module USB to USART(UART) 3.3V TTL USB To COM which was $2.80 shipped from ebay (it works with 3.3v or 5v devices).

You will need to use some jumper wires to connect the GPS to the TTL/USB adapter as the pinouts aren’t quite the same. Also, note you want to connect TX -> RX and RX -> TX for them to communicate properly. Going TX to TX and RX to RX will not work.

I found loading the settings to the GPS would make it ~3/4 of the way through and then error out. I believe this is due to the baud rate of the GPS changing partway through the config loading. To get around the problem I initially set the u-center software to 9600 baud and loaded the config as far as it would go. I then swapped to 38400 baud and re-loaded the full config; this second runs seemed to complete without issue.

I found this guide quite helpful for getting the arducopter mission planner software installed and setup. I attempted to install the latest tricopter firmware on my ArduFlyer before connecting to it as they instruct. I found the auto com port detect seemed flakey but after manually selecting the correct port (9 in my case) everything seems solid.

Transmitter

A number of people recommend the Spektrum DX6i transmitter for use with tricopters. It appears to go for around $110 shipped and, as the name implies, has 6 channels.

Further research indicated the Turnigy 9x is a better buy. It is only $54 from hobby king and comes with an 8 channel receiver. This transmitter utilizes an atmel microcontroller and has aftermarket er9x firmware available. Additionally, it is very popular to mod (backlight, better radio module, etc.)

Hobby King also provides a newer Turnigy 9xr. This model aesthetically didn’t appeal to me as much. Apparently it also has less internal space for putting in mods and isn’t quite as ergonomic.

Tricopter – Airframe Selection

The RCExplorer Tricopter V2.5 appears a strong option. Unfortunately, when I was ordering bits the motors they recommend were not in stock. Not wanting to munge my motor/esc/batter mix, risk being under/over powered or otherwise messing up, I decided to skip this design.

Upon further research the INFINITY T3 – DIY Carbon Fibre Tricopter looks like a great option. It appears to have excellent 12-15 minutes of battery life and looks to be an excellent platform for putting a GoPro on.

The official design is made primarily out of carbon fiber. My initial go of it will be out of wood to reduce expense when I inevitably crash it. Once my flying skills improve I’ll upgrade the frame.

The T shape appears to provide better visual orientation than the Y designs which is a plus.