MultiWii Plugged In

Just a quick pair of photos to prove I have the Multi Wii controller plugged in.

Note the lack of props!  I still don’t trust this thing to fly around the way I expect it to. There’s a problem with the minimum throttle setting which means the motors are always spun up when the controller is armed. It’s possible to change this, but you need to flash new software onto the board and I’m not sure I’m brave enough to do that yet.

Mounted the board with double-sided tape and a chunk of firm packing foam (my XBox was packed in it).

I managed to get all the channels wired up and working in the correct direction and confirm that the motors spin up an down in the way I’d expect them to. Weirdly this involved reversing the aileron channel on my DX6i.  I also had to max out the travel of all the channels and jump through some hoops to make the “gear” switch drive channel 6.

Even though I managed to get two switches on my Tx to send signals through to the Multi-Wii, it weirdly won’t read anything from AUX2, AUX3 or AUX4. I confirmed it’s not the Tx by swapping channels.  Not sure if this is another setting that needs to be enabled in the Config.h file and flashed onto the board – I can see some logic in not reading more inputs than you need to on a real-time controller [UPDATE:  Turns out this is true!]. Will have to investigate as I’d like to have separate switches to enable/disable the various different sensors as I get used to them.

The Java GUI for the Multi Wii is really starting to annoy me.  It’s slow and clunky and very hard to use.  Today I found that you need to click in the top left hand corner of the 10×10 pixel grey/white squares that act a bit like checkboxes. If you click round the bottom right edge it just ignores you.  It’s also impossible to know whether it’s accepted a click onto buttons like “Write” or “ACC Calibrate”, which is frustrating and also a little scary.

Anyway, I am still positive so far.  Maybe I need to take this thing out and get to know it in the flesh rather than watching bar graphs jump up and down on my PC screen…

Starting out with MultiWii

Last night I unpacked my new MultiWii controller and plugged it into my PC.  I bought it from Hobby King and it comes ready to fly out of the box – configured for an X-quad, which is perfect for my carbon H-copter.

The Multi-Wii board attracted me because it comes with so many sensors out of the box.  Barometric pressure, compass, gyros and accelerometers as well as the option to add GPS in future.  That’s compared to just gyros on the KK board.  I love the KK board to bits – it’s a great board for line-of sight flying, allowing a fair amount of acrobatics and some nimble and fast flight.  It’s scary flying FPV with the KK though.  I managed a good FPV flight at the weekend (see video later) but it would be great to push more of the stability control onto the ‘copter for less stressful remote piloting.

I didn’t get the board hooked up to the quad or the receiver last night, just plugged it into the PC and fired up the Java tool.

I have to say I was very impressed with the board and the UI tool.  The tool shows a live trace from all of the on-board sensors and a 3D model of the ‘copter which moves in real-time.  Every single setting is configurable, including the PID terms, throttle travel, behaviour of the auxiliary “switch” channels and so on.

Hardware wise, the barometric pressure sensor was the star – it responds to changes in height of about 10cm, which is spookily accurate!  The only worry I have is the effect of wind on this sensor – I am wondering whether a wind shield is going to be needed for breezy days.

Down sides so far:  The GUI is a bit painful to use.  About 25% of mouse clicks are ignored or lost (I think because the refresh loop for the graph is running and the app is polling for user input).  Also, the numeric values are editted using very very very small sliders.  It would be much simpler to just enter the text!  Maybe these things annoy me more because I do that sort of thing for a living…

Expect more soon!  In the mean time, here’s an FPV video from this weekend…

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Saturday Morning Lanes and FPV

This weekend Dr J, My Assistant and I were allowed out to play in the Land Rovers for a few hours.  We made it up to some of the Lanes north of Newbury and had fun with axes, sand ladders and ‘copters.

Dr J takes a swing at a pesky tree that had fallen on the track

We’re being followed!

The Patriot

Through a water hazard

Stopped for FPV and coffee

A ‘drover within a ‘drover

Whoops!  Maybe we should have done this somewhere more open?

When Blogs Collide

Today, logicalgenetics.com and danandtheduke.co.uk merged to make one Super-Blog!  It seemed daft having two websites and two blogs, so I’ve pulled all the Land Rover posts into the Logical Genetics blog and pointed both addresses right here.  You don’t need to change your bookmarks or format your brain – both logicalgenetics.com and danandtheduke.co.uk still work fine.

The old Land Rover blog won’t see any more action – I’ll be posting everything here.  You’ll still get all the mission reports and photos of mechanicals.  You’ll also get weird posts about Software, Machine Tools, Multi-Rotors and model flight and, well, just about anything else I can dream up.

If you just want to read about Land Rovers or Adventures, use the “Blog Posts” menu at the top to choose your poison.

Enjoy!

Repairs and FPV Setup

While repairing the crash damage to the Carbon-Copter I decided to do a more scientific investigation into the differences between carbon and aluminium…

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10mm x 10mm Carbon square tube weighs about 0.5g/cm while aluminium bar of the same dimensions (purchased from B&Q) is just slightly under 1g/cm.  That makes the maths easy – 150cm of bar needed for the carbon quad means a 75g difference between carbon and aluminium – which isn’t that bad.

Aluminium is cheaper and seems to be more crash-resistant too, plus I can pop over the road at lunchtime to buy some as opposed to ordering it from China.  So, I made up a complete set of parts using each material.

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With the ‘copter repaired I concentrated on setting up the FPV gear.  Sadly, I broke my little FPV camera – I think I caught a screwdriver on some of the components and shorted something.  It was only a tenner but I am still quite cross with myself for not taking enough care.

Anyway, I have the GoPro which can also output video for FPV use.  There’s a slight lag (less than half a second probably) in the video feed which makes it a bit weird and since I’m not willing to drill the waterproof case the camera has to fly “naked” which is a little riskier.  On the plus side, many people report success with exactly the setup pictured below:

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The garden isn’t the ideal place for testing with fences and walls in every direction, but my darling wife was kind enough to snaps some pics of the video feed on the garage telly while I had a nose over the neighbour’s fence flying line-of-sight.

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The feed was a little noisy but a lot of that is going to be due to the fact that the signal had to get through the garage roof.  Penetration is not good on 5.8GHz signals.  Need to sort out something a bit more portable and pop over to Dr J’s house for more testing this week.  Watch this space!

Christening, Cruising then Crashing the Carbon-Copter

I watched the BBC weather report with a growing sense of foreboding this morning.  A huge band of rain sweeping inexorably towards Newbury from the south coast, set to smother the whole of Berkshire under a blanket of liquid misery until Saturday lunchtime.  Nothing unusual, but particularly inopportune as I had a completed carbon copter and a suitcase full of batteries in the back seat of the car.

Luckily, the rain held off and Dr Johnson and I met up on the green to fly some multi-rotors in the blustery wind.  The Carbon-Copter performed stunningly…

Make sure you stick with the video (or hit fast-forward) as there’s some cool shots of the FireGoat from the air towards the end.

A tiny bit of transmitter tinkering was required: un-reversing the rudder direction, lowering the expo on the pitch and roll axes and so on.  After that it was just a case of whacking the throttle up and grinning like a fool as the quad danced around the skies.

In the end I got too cocky – of course.  Started with some backwards and forwards stuff, then progressed to attempting some lazy 8’s at increasing speeds.  Eventually I lost it and hit the ground.  Initially I thought everything was OK with the frame but on closer inspection I found that both legs and one of the front-back braces was cracked.

Amazingly though, it still flew.  There was a noticeable twist in the frame as I lifted off, but it continued to fly brilliantly.  Of course, now that the legs were broken and my money effectively spent I had nothing to lose – the lazy eights became less and less lazy until they became simply “eights” then “vigorous eights” and finally “broken quad eights”.

Hit the floor pretty hard and the carbon rods shattered into a thousand useless shards.  Time to go home and make some more!  The carbon sheet remains intact, so the repair will just involve cutting and drilling some new legs and braces.  £5 total cost, which isn’t a million miles from the cost of fixing the aluminium copter after similar crashes.

So I had fun and I perhaps went a bit too far with the aerobatics.  The carbon quad is an unmitigated success and I have a big smile on my face.  It’s also worth remembering that I built the carbon quad for slow moving videography and FPV, so maybe “mental eights” won’t be happening again too soon!