Monday, 31 December 2012

Quadcopter radio setup

My Spektrum DX6i receiver arrived this morning, which means I can test the quadcopter electronics :)

After some of the usual trial, error and Googling, I found the following process worked for getting my X600 quadcopter kit up and running:


 [SAFETY NOTE - do not put the propellors on!]

1. 'Bind' the RC transmitter and receiver (For Spektrum this requires a 'bind plug' that shorts the bind signal pin to its ground pin). Follow the bind instructions for your radio kit

2. Connect each ESC in turn directly to the receiver's throttle channel. Then follow section 2 of this guide:
- disconnect all ESCs from the board (only servo cables)
- connect ESCs one after the other directly to RX's throttle channel in order to proceed for calibration
- turn TX on
- move stick to full throttle
- Power the ESC
- wait for initialization beeps + 2 beeps
- after 2 beeps, move throttle stick to minimum
- wait for beeps (generaly 3 + 1 or 1 + 1)
- Unpower ESC and disconnect
- Repeat until all 4 are calibrated and you're done

Here's the ESC manual - there are a lot of poorly Englishised manuals in internet land :(

3.  Re-connect the KK multicopter board to the right ESCs (as in this guide)

4. Power up the quadcopter and 'arm' the KK multicopter board by holding the throttle/rudder stick down and right until the IMU board light comes on again - see chapter on 'Setting up the KKmulticontroller' of this guide

5. Go through the checks in the rest of the KKMulticontroller guide, testing that:
  • The throttle works
  • The pitch/roll/yaw commands are mapped correctly to elevator/aileron/rudder controls
  • The gyros work in the correct way (if you tip the quadcopter then the arm that is being dropped should rev up to stop the tipping motion - detecting yaw correction can be done similarly by twisting the quadcopter and noting if the front/back motors speed up or slow down.

Having wired up my quad in a 'plus' configuration (as advertised) I found that one of the arms didn't react properly. I also noticed that on dropping one arm two motors would speed up. This suggested that the KK multicontroller had an 'X' configuration loaded. To fix I had two options;
  1. Dig out an Arduino and flash it with the AVR ISP so I could compile and re-flash the KK multicopter ATMEGA168 with the quadcopter 'plus' config, or...
  2. Rebuild the 'copter in 'X' configuration.
I went with option 2 as less risky and simpler :) The new 'X' config seems to work in the correct way

Saturday, 29 December 2012

DIY CNC mill first 3-axis run drawing G-code from Inkscape

Quadcopter kit project

Santa pushed the boat out this year and, completely unprompted, gave me a quadcopter kit for Christmas :)

The kit included an airframe, battery, motors, propellors and motor control electronics. The airframe is a CSL X600

In the box were a load of bagged bolts, screws, aluminium section and cut glass-fibre board (?) and absolutely NO instructions.

I found a 'guide' here, a time lapse video here both of which helped to work out how this thing goes together as the design seems to have had some tweaks since the seller website was put up, so looking at the pictures there can be confusing.

The quadcopter is basically assembled in four parts:
1. The central chassis
2. The arms and motor mounts
3. The landing gear
4. Mounting the electronics and motors on the chassis and arms

I started with the central chassis and added the arms, working my way through the bits so I knew what fitted where. The process involved a bit of trial and a lot of error, but below is a pictorial build log...

This plate is the TOP of the quadcopter - here it is upside-down for fitting

Arms mounted

Arms - note that they have a top and bottom side. The tiny hole on the far right shows the bottom of the outer end of the arm - that hole is used by the tension spring in each landing leg

Folded arms

The bottom two plates - make sure that the arms can still fold once this plate is installed!

Motor mount and brushless motor

Motor fixing - use the round-head bolts supplied in the kit and ignore the counter-sunk screws that come with the motor

Landing gear - note this config looks different to the selling website pics

Landing gear spring

Landing gear in action

Out of all the bits supplied with the motor and prop, heres what I think you need...

Assembled prop

Finished build with electronics fitted

 Now to wait for a shiny new Spektrum radio set to arrive in the post...