Month: January 2016

Simulators and Micro Quads

There’s a very light misty rain falling this morning, which isn’t going to clear any time soon, so no flying this week. I might have given it a go, apart from it being really dark, impossible to see an aeroplane if you wear glasses (think windscreen wipers) and the forecast is for strong winds by lunchtime.

Actually, I’m really annoyed because I spent most of yesterday on the electronics for my 110 size quadcopter, only to find that the flight controller had packed up.

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My 110 size micro quad made out of Depron and four HubSan motors.

As you can see from the picture, I built the frame out of Depron, which was originally from an old pizza box base that I saved. It’s surprisingly strong, considering that it’s only a push fit and there is no glue used at all. The flight controller is a Flip32+, which should sit on the brown sticky pad in the centre. Everything was going really well until I connected it up last night and I think the micro USB connection broke. It detects that something is connected to the USB, but I suddenly started getting “unrecognised USB device” errors from Windows 10 when it had all been working perfectly before. It’s annoying because I was just about to connect up the motors and run them using Cleanflight for the first time to see if it had enough thrust to fly. It’s a bit heavy for this class of quad, so the flight controller and radio are going to be switched for smaller and lighter versions. It appeared to be working up to that point as I had test run one motor, then added the other three and suddenly the flight controller won’t talk to me. There’s a lot of wiring there for something this small, and the connectors are the pins from a Futaba servo connector, crimped onto the wires and then covered in heat shrink tubing. It works surprisingly well, but an integrated PCB with tracks running out to the motors would probably be better.

So, I spent the rest of my time on the quadcopter simulator. I’ve worked out how to set the textures on models imported from Blender into Unity. You have to create a folder called “Textures”, put the images in there, open the Blender model from Unity, point at the textures you just copied to the Unity Assets “Textures” folder and then set the albedo on the Unity material to use the correct one which now appears as an Asset. UV mapping in Blender is a completely different problem though. I can’t say I’m really impressed by any of this as, having worked in computer graphics for quite a number of years, it seems to me that their model import chain is just rubbish. There’s no reason why Unity couldn’t do all that for you, but as long as you know about the albedo hack, most people can probably work it out for themselves.

Anyway, here are some of the screenshots so far:

 

I really need to get this playable by the end of the day, as we’re running a Royal Institution coding for kids session in about a month and this forms the central theme. All that is left to do is some of the housekeeping code and then I’ll have an alpha release.

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Two Weeks Running

I can’t remember the last time I managed to go flying two weeks running, but it was quite a while ago. This week wasn’t exactly good weather, but the rain held off (just) and it started out as a very dull grey morning that gradually turned sunny. It’s just a pity about the wind, which was really strong.

I was on my own in the bleak conditions to start with. My first flight was with clear glasses, something I don’t do very often, so it must really have been bad. Almost immediately after launch the Sun came out, so I ended up getting blinded.

Soon after that a young boy turned up with a 3D Robotics Iris quadcopter. I haven’t seen one of these before, so I had to ask him what it was. It flew really well considering the gale that was blowing, which is almost certainly due to the fact that it was flying with GPS assistance. The thing I didn’t like was that it sat on the ground for ages before it was able to get a GPS fix. During all this time the controller and a tablet computer were being fiddled with to try to rectify the issue. Personally, I just want to power it up and fly, but it won’t let you without the GPS.

After that we had the EFlite Advance 25E, a family with a DJI Phantom 3 and the guy from last week with the FPV foam flying wing. He broke something on his first flight, possibly due to the extra weight of the FPV camera, which is mounted high up, and the really seriously windy conditions. He then went away to get some hot melt glue to fix it back together and then come back again in the afternoon. The Phantom flew really well and he teased the little ones by flying their teddy bear away. It’s not great when they try and chase after it though. We also noticed that there was another Phantom flying down in the woods at the extreme corner of the field. I wonder if he was the same guy from last week, but he seemed intent on trying to crash into the trees? As for me, I had 4 flights with the RS352, trying and failing to do a harrier. The conditions were against it really, but for some strange reason, all our landings were really good. Because of the wind we were all able to hover down to the ground with almost no forward speed. Other than that, I nearly had a mid air with the Advance 25E, but I doubt it was actually that close. He’s a lot bigger than me and I think I was well underneath him, but it’s closer than I like to get.

The only building I’ve been doing for the week is to put together a micro quadcopter which we need for a project in March. The problem I’m having is that I need a brushed motor controller and the only suitable source seems to be the “Ready to Fly Quads” brushed motor driver which is only available in the US: http://www.readytoflyquads.com/brushed-motor-driver. I’ve been looking at building my own as you only need a diode, MSOFET and resistor, but I’m going to have to put in an RS order as I don’t have any suitable MOSFETS. You need a low threshold voltage due to the 1S LiPo power source, plus a low gate drain resistance. My current experiment is with a BJT, so I’m going to try putting it all together later this evening and see if it will lift the weight of the radio gear. Every gram counts on something this small.

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Lots of bits and equipment in the process of building a micro quadcopter

Snow!

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The RS352 sitting on a thin layer of overnight snow

It’s the first flight of 2016 and my first fixed wing flight since before the Drone Show in early December and we’ve had a light dusting of snow overnight. It’s been years since I’ve flown in snow and I really hope we get a bit more just so I can fix skis to the RS352. It was actually quite warm to begin with, but it seemed to get much colder as the morning went on, to the point where I was beginning to think that my boots were letting in water. The cold seemed to be freezing my feet and my fingers weren’t doing much better on the three flights that I managed with the RS352. The real problem with snow is that you seem to get water in everywhere and it must really have been cold as I found that condensation had formed on the screen of my smartphone. I’ve never seen that happen before.

When I arrived there was already one person there with a small red and white Monocoupe from the inter-war period. After that I was joined by a guy with a DJI Inspire, someone else with an EFlite Advance and near the end a father and son with a foamy Cessna arrived. Somewhere in the middle we also saw a DJI Phantom being flown, but they were being anti-social and keeping away from us. They were also flying a long way out of the confines of the field which isn’t allowed. Then, right when most of us were leaving, somebody with a foam flying wing equipped with FPV turned up. We saw the first flight (and the crash before it), then left him alone in the cold. Most of the snow had gone by this point, but we were absolutely freezing.

As you can probably guess, I haven’t done much on the ATOM Autogyro this week, apart from glue in the mast. The rudders work, so aileron and elevator are next. This project got bumped down the priority list by an urgent requirement for a micro quadcopter that we need for work. I’ll add some more details about this later, but for the moment I need to get back to making a Flip32+ board control some brushed motors on a single LiPo cell. This is going to be my replacement for my own HubSan X4 which hasn’t been working right for a while now.

More Annoying Weather

Today is one of those days when it started off overcast, then ended up as a bright, crisp sunny morning, making me think I should have gone flying after all. Like I said, it’s just annoying. We had some really extreme weather yesterday and this morning is just a bit of a lull in the weather until the serious stuff arrives later on, so the timing and flying window was always going to be limited. Yesterday there were gale force winds, rain and then a hail storm to finish off. When I look outside this morning, I can see a small anemometer which belongs to a house over the back. It’s definitely windy because I can see it spinning around at about 90 miles per hour, then it slows to a stop and everything is calm, then it spins up again. Annoying.

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An Adafruit BNO 055 gyro sensor (left) and an Arduino Nano on a breadboard.

Anyway, I can’t post any pictures of the ATOM autogyro at the moment as I’ve just glued the mast on and I’m waiting for it to set. All the tail bits with the rudders and bell crank should be working now, although I haven’t actually tried the servo yet. The closed loop links are all in place and I’ve moved on to the aileron and elevator controls.

The picture above is what I’m planning to experiment with for the rest of the day. A while ago I got a gyro sensor which I can connect to an Arduino board and try out some micro quadcopter code. The idea is to take four motors and props from a HubSan X4, build some motor control circuitry for the Arduino and see if I can make a quadcopter fly. In addition to this I need to do some work on the quadcopter simulator if I get time later this evening.

New Year, Same Weather

Well, I would have gone flying today, apart from the fact that it’s been raining all day so far. Not just light rain either, it’s been absolutely chucking it down. Anyway, last night’s weather forecast told me this was going to be a building day, so I’ve made good use of my time and almost got the waggly bits to waggle on the back end of the autogyro.

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The back end of the ATOM autogyro showing the linkages connected up (almost).

At the moment I’m still waiting for the epoxy on the fibreglass control horns to fully set before bending the wire to fit the hole in the right rudder horn. I’ve used a piece of PCB to form the bell crank in the middle, you can still see the copper coating. I couldn’t bend the wire before putting it through the locking point in the bell crank because the wire won’t fit round the 90 degree corner. I’m also going to add some tubing to the wire as stop points as I don’t trust that screw in the middle to hold. I thought that a couple of bits of silicon tube either side of the centre screw would maintain some rudder control in the event of the stop screw failing. I’m also putting a nylon lock nut underneath to hold everything onto the bell crank nice and secure. It’s not that I’m paranoid, I just don’t like bits falling off in flight.

Once the back end is done, I just need to glue the mast and screw in the aileron and elevator rods, which should be an easy job. I think that’s it apart from some final installation, fixing the canopy and covering, so it’s almost ready to fly. I guess that’s my first New Year’s resolution then.