Quadcopter frame version2
I went with 12mm C channel aluminium to save a bit on weight. My Turnigy Plush 30A ESCs didn't fit inside the 24mm tube.
Tricopter Aerial Photos – Tatura
The first real aerial photos taken with the GoPro mounted on the Tricopter frame version 2. The wind was light until I started getting a bit of height.
How To Add Bluetooth to your MultiWiiCopter
For not much more than $10, a Bluetooth adaptor is a cheap and easy way to get in-flight real time feedback from the onboard sensors and allows quick and easy modification to PID values via the MultiWiiConf software. Here's how to do it.
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Buy a serial to bluetooth adaptor - "Serial Bluetooth RF Transceiver Module RS232 w/ Backplane Enable & State Pin". The one from goodluckbuy.com is simple and works fine with the Arduino.
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Connect the USB FTDI adaptor to the BT adaptor. I used my breadboard wiring leads to hook up the pins in the following order.
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FTDI BT VCC VCC GND GND TXO RXD RXI TXD - Connect the FTDI USB Adaptor to a PC. The BT adaptor should now be powered with a blinking red led. Before using it with an Arduino running muliwii software, the baud rate of the BT adaptor has to be changed to 115200 from the default 9600. Now this is the part that stumped me for ages and sent me off looking up forums, updating bluetooth stacks etc etc until I figured out what I was doing wrong. To configure the BT adaptor, you need it physically connected to the PC via the FTDI USB adaptor but you don't want to connect the PC to the BT adaptor .... yet. The BT adaptor can only be configured when it's in an un-connected state. In your "Bluetooth Places" you should be able to see the device (by default called "Linvor") but it should show "not connected") and the red light should be flashing on the BT adaptor.
- I used Advanced Serial Port Terminal to connect to FTDI USB. The AT commands must be copy and pasted to send to the device because it constantly polls and if you can't type fast enough to complete a command before it reads it in.
- Send the "AT" command. BT responds with "OK"
- Send "AT+NAMEMultiWiiCopter" to change the default from Linvor.
- Send "AT+BAUD8" to change the Baud rate to 115200.
- Now connect to the Arduino as per the connections in the table above.
- Run the MultiWiiConf software and choose the BT COM port.
- Now you can fly around and see the gyro and accelerometer inputs change while in flight!
I found a page with quite a lot of detailed information on the BT adaptor during my searches. While it's native language looks Chinese, the Google Chrome browser seems to do a pretty good job translating it.
Quadcopter specs / parts list
The frame as shown with just the motors and plastic housing weighs 780 grams / 27.4 ounces. Maybe it's getting a bit on the heavy side with 24.5 mm aluminium frames but the aim for this one is primarily rugged and simple. If it does turn out to heavy and flight time is severely restricted, aluminium tubes half the size would do the job. Why not use them in the first place? Aesthetics was part of it as the fully enclosed 24mm frames might let me hide some wires and speed controllers to make it look more tidy.
The motors are 520mm apart which is probably the minimum separation for motors / equipment of this size - see the tips here on setting up and general rules of thumb for quads.
Parts List:
2 x CONNECT-IT Aluminium 600mm lengths: $5.81 each.
1 x 6 way joiner $2.24.
4 x End Caps: $0.49.
1 x Food container with clip on lid $3.36.
4 x 2830-14 750KV Outrunner Brushless Motor inc Mounts & prop adaptor: $9.99 each.
2 x 1 Pair 10x4.5" EPP1045 Counter Rotating Propellers: $3.49 each.
2 x New Styles 10 Pair 3.5mm Gold Plated Connector N3.5: $4.99 each.
4 x Turnigy Plush 30 Amp Speed Controller: $11.54 each
1 x warthox FPV/180_LLC - MultiWiiCopter board - v2.0 Plug-n-Play: $158
OrangeRx Futaba FASST won’t centre
Setting up the Seagull Decathlon radio gear showed the twin elevator servos wouldn't centre when the sticks were released. Swapping out the HobbyKing OrangeRx Futaba FASST Compatible 8Ch 2.4Ghz Receiver for a genuine Futaba receiver showed that the problem wasn't with the servos as the genuine Futaba Rx worked fine. By default the HobbyKing FASST receivers are set to HS Mode for digital high speed servos which is not so great for the analog servos in the Decathlon. The Frsky manual shows how to change between the modes as does this YouTube video.
$20 Quadcopter frame from Bunnings
Snap together parts all from Bunnings. The arms are 25.4 x 25.4 x 1.2 x 600mm aluminium which will be cut down to around 300mm so I'll get two arms out of each length. The arms are probably bigger than they need be at 25.4 mm but they should be good for easily fitting the wires and ESCs within. They fit together in the middle via a 5 way joiner which keeps all four arms held on pretty firmly. I needed a rubber mallet to get them off again. The 6 way joiner was used as it provides ready made access to the meeting point of all the arms which will be ideal for routing the wires to the four speed controllers and keeping them hidden from view. The aim with this frame is to have zero external wires. External means outside of the arms or central dome.
The CONNECT-IT 600mm lengths are $5.81 each, the 6 way joiner $2.24, End Caps $0.49, Food container with clip on lid $3.36. Grand total $19.18
Tricopter vibration mount testing
This clip shows sample footage from four different camera mounts on my tricopter. The aim was to counter the effect of vibration on the quality of the video and remove the "jello" effect as much as possible.
The best result achieved so far was probably the simplest and cheapest: a HD keychain (#11) velcroed directly to the frame.
The biggest improvement was can probably be attributed to using an accurate prop balancer as you might notice the noise in the last two videos is significantly reduced.
The next test will be with a GoPro.
Tricopter Simple Yaw Mount
A hard landing recently put the yaw servo out of action on the tricopter. The yaw mount was a block of solid pine with two pieces of piano wire connected directly to the servo arm. It was overly complicated and had a bit too much slack in it for my liking. The yaw servo needed replacing so it's as good a time as any to "upgrade" the yaw mount.
The Super Simple yaw mount takes the blade grip from a 500 size heli, along with some linkage balls and rods, and combines to make a simple, cheap and slop free yaw mount. There's not much too the construction of the mount as shown in the photo. Probably the hardest part is drilling a hole down the centre of the 12mm x 12mm oak arm that's in line with the shaft. Any deviation from centre will result in a skewed motor or even worse, drilling through the outside of the shaft. Cut some 1/4" ply with some 3mm ply glued on top to make up space between the blade grip arms. The replacement servo is a cheapy HXT900 and seems to be doing a good job so far.
This configuration has had about 10 flights put through it. The only problem was the linkage arm popped off after a particularly bouncy landing. Although thats probably a better result to the alternative of probably stripping the servo gears that a traditional push-rod link may have caused.
OLD YAW MOUNT
NEW & IMPROVED SUPER SIMPLE TRICOPTER YAW MOUNT
Tricopter: Anti Vibration mount
Mounting the cameras directly to the ply base didn't yield great results in image quality due to all the vibration. To try and reduce it, I did a rough balance of the props using music wire as a 'balance beam'. I think this improved it a bit until a proper balance can be done.
The first mount was made with fuel tubing screwed onto nylon bolts. I probably should have made the tube length a bit shorter because it was too flexible for the weight of the camera. I'm not sure it made a big difference to countering vibrations and mounting the camera on the foam to get the right angle was difficult. The first bounce on landing and the camera would shift.
Version two uses rubber mounts taken from inside an old PC CD-ROM drive. A 1/4" nylon bolt holds the camera firmly in place while cable ties with the head cut off hold it all in place. I think this mount reduced the vibration getting to the camera but still not entirely. Until I properly balance the props and motors I can't tell if it's good enough.
I'm still impressed with the video quality I get out of the keychain cameras considering their small size and weight compared to that of the IXUS 100IS. Next test I reckon I'll velcro the keychain cam to the version two mount and see what I get.
Mount 1
Mount 2
TriCopter LED Strip Lights
These photos show the strip LEDs controlled via the HK Turnigy Receiver Controlled Switch. The Blue LEDs only face forward where the white LEDs is on both sides of the rear boom. The idea is to help with orientation such that if I can't directly see the blue, it's facing away from me. Ideally I would have used more distinct colours but it's what I had on hand at the time.
I'm thinking I might tripod mount the Canon DSLR, at night, and use the remote switch to do a long exposure with the Tricopter lights on and see if I can't paint the sky.
