Monday, April 30, 2012

Quadrocopter Build - Part 10 - Notes and new frame work

Hello!
I have a few things to note that I have learned lately. I also want to put up a few of the things that I have been working on for the next frame.


Lessons learned:
- Practice. Lots. This may involve crashing. I need more practice.
- Read*. Lots. The more you know the better you are for yourself and anyone else you may talk with about this stuff. *=Reading does not just mean reading. I hate reading. YouTube videos are often good too. As with everything, the quality of the information depends on the source.
- Talk to people that have done it before. In forums, on YouTube, whatever. It will save you time and save you from making mistakes that they have already made.


The frame that I am working on next is a carbon fiber quad frame. It will be between 700 and 1100mm. I have some of the parts that I will need for it. I will need to make a lot of the parts because I cannot find things that I like/want to use for some things.

I have 4 carbon fiber tubes that are each 500mm long (19.7 inches).
I have a sheet of 1mm thick carbon fiber. It is around 15 inches (381 mm) by 21 inches (533 mm).

Here are a few images of my design for the main body parts which will be cut from the sheet of carbon fiber.


(Created with Google Sketchup)

This was a quick and dirty blog post, but its slightly better than o blog post...

Sunday, April 22, 2012

Quadrocopter Build - Part 9 - Education

To start, I will provide an update on my quardcopter. My X525 quadrocopter is still grounded, but I have propellers now. My issue is battery. I borrowed two different batteries from someone. It showed me that my quad was somehow draining batteries very very very fast. I have a video demonstrating that here:

Secondly, I have four purchased carbon fiber tubes (12mm x 10mm x 500mm) and a carbon fiber sheet (1mm thick) to build my own quad frame. I am waiting on more parts to put that together. I have to design and somehow cut (maybe get someone with a CNC to help?) out the frame pltes after i design them. Should be fun.


Now for the promised education.
I want to talk about something that is not clearly explained with many multicopter flight controllers/'boards'; and that is Gyroscopes vs Accelerometers

As far as I know, every board has Gyroscopes. Slightly more expensive boards use gyroscopes and Accelerometers. More expensive than that and you start to add barometer, then magnetometer, then GPS. Each of these sensors add another degree of stability or control.

Lets clarify what a gyroscope does. A gyroscope can sense rotation. That's it. They can tell that orientation of an object. One gyroscope can measure one angle for one axis. Some flight controllers use three gyroscopes to measure all three axis. There are also 3 axis gyroscopes. It does the same thing as three different gyroscopes, but generally takes up less space on the board.

Accelerometers measure linear motion (including gravity). Generally I have only seen 3 axis accelerometers used. This is likely also due to the space savings of having one over three different ones. An accelerometer can detect that affect of the wind causing something that is flying to 'drift'.

The KK multicopter flight conttroller I have been using have three different gyroscopes. It has no accelerometers. This makes flying require a lot more user action to keep it stable in wind or the air coming back from a propeller pushing air when close to the ground.

I have been looking at other flight controller boards. I think that my next board will be something that I will be able to fly with less effort by my. I would also like to have it control/stabilize a camera tilt/pan mount. I am looking for a board with:
Gyroscopes
Accelerometers
Barometer
Magnetometer
GPS
Camera stabilization

The one I am really considering is the ArduPilotMega 2.0. However the price is a little high. But with an all-in-one solution I am not sure that I have many other options. I have not seen much about camera stabilization with APM2.0, but it appears to be possible based on their site.

Let me know if you have another board idea for me with these features. I have been shying away from MultiWii and MK due to the number of add-on boards required in order to get all the features I want. I also have not considered DJI or xAircraft boards due to their prices.I can get an APM2.0 shipped to me from CanadaDrones.com for $310.

Feel free to ask me any questions, give me your opinions or just say hi!.
Bye now.

Monday, April 9, 2012

Quadrocopter Build - Part 9 - New Transmitter but still grounded

I have been waiting for propellers from GoodLuckBuy for a while. They shipped my package, but the props where not included. The order status is "Partial Shipped". I contacted GoodLuckBuy and they just replied as if the whole thing was already shipped. I emailed them back to saw that it only some items were shipped. No reply yet...

I like the items at GoodLuckBuy, and they have the best prices. But this service (or lack of) is getting annoying. I have two other orders after that now that are sitting at "Processed" for up to 6 days now.


On an unrelated note, I was talking on RCCanada.ca with a few guys and they suggested that I use 'expo' mode. To which I replied 'what?'. Then they sent these to me:
Transmitter Dual Rate and Expo Theory, Part 1 of 2
Transmitter Dual Rate and Expo Theory, Part 2 of 2

I already knew I wanted to get a better transmitter/remote at some time, but now I have a reason. Expo mode makes it easier to fly. That would be helpful. So I bought a Turnigy 9X from someone on RCCanada.ca. Now I have to make sure the channels are going the right direction and try controlling it.


I also thought I'd order more props from multiple place online. So I did. Two different sellers, and two different prop sizes. However I learned later that I should be using smaller props for the higher speed motors that I am using (1200kv). That being said, all the props I had on order would not work very well. I got talking to Mark from FliteLab.com and he suggested smaller props and could ship them to me much faster from Halifax than I can get any from China. I ordered 10 props from him. They should be here this week so that I can finally fly again.


I also got thinking about building a lighter, larger quad frame. I found several items from different sources (all at the best prices I could find) and ordered what I will need to build a ~1100mm frame. I am sure there is a reason why people don't usually build them that large, so I can always cut the carbon fiber tubes done if needed. I also will be running into issues with mounting the motors as GoodLuckBuy did not include the motor mounts with the motors :( GoodLuckBuy also gave me what appears to be 6mm prop adapters, so I ordered 5mm (standard from what I understand) prop adapters from Mark at FliteLab.com. Thanks again Mark.

Lots of things going on is all different areas with my quad, transmitter, new frame build, new battery on order but not shipped.... I hope to spit it all out in another blog post shortly. For now I gotta run. Feel free to ask questions here, on RCCanada.ca, YouTube or even Twitter.

Sunday, April 1, 2012

Quadrocopter Build - Part 8 - Setting pots/gain on KK flight controller

Latest video:

Here is some of the most stable flight yet. During this video I set the potentiometers for the KK board (blackboard hardware version 5.5) with firmware version 4.7.

I have spent quite a lot of time in the past trying to stop the quad from drifting side to side, ect. I have worked out most of those issues by changing the values used as center on the transmitter using the PC. That aside, now I work on the pot settings.

Near the end one of the two blade props I am using broke at the shaft hole. This is because they shaft holes were too small and I had to drill them out to make them fit. New tree blade props are already on order.

Here are the steps to adjust the pot settings. Do these outside or where you have at least 10 square feet to work.
"Pot function for flight

1. Yaw = 50% to start with (This is the P and I parameter of the Yaw control loop), (on my quads all of them works @ 100%)
Adjust this parameter the following way:
Increase the pot until you notice oscillation in the Yaw.
When it is oscilliting reduce it a bit..

2. Pitch = 0 to start with (this is the I parameter of Roll and Pitch control loop)
Adjust this parameter the following way:
When hovering, trigger the Roll or Pitch stick.
If the quad does not wobble after stick release, increase the pot until it does wobble. (1% at a time, its extremely sensitive)
When its starting to wobble, reduce the pot a bit.

3. Roll = 40% to start with (this is the P parameter of Roll and Pitch control loop)
Adjust this parameter the following way:
Increase the pot until you notice oscillation during hovering.
When it is oscilliting reduce it a bit."