I'm partial to the STM32 (ARM CORTEX-M3 based uController) line of uControllers, not only for their hardware mul/div instructions, but also for their ability to have the ADC converter continually scanning and pushing to memory its conversion results from a series of analog devices.
Now, it looks like STMicro has a gamer development board, complete with five ST sensors – a 2-axis roll-and-pitch gyroscope (LPR430AL), a single-axis yaw[3] gyroscope (LY330ALH), a 6-axis geomagnetic module (LSM303DLH),a pressure sensor (LPS001DL) and a temperature sensor (STLM75). All the sensors and the AHRS algorithm are managed by an on-board STM32 microcontroller. The module, which comprises a 4x4cm evaluation board and all the necessary firmware and software, will be available for volume orders in Q2 2010.
It also runs a sophisticated sensor fusion algorithm(Attitude Heading Reference System) to provide static and dynamic orientation and inertial measurements.
In an article entitled "The Rise of the Robo-Fighters", Britain's Daily Mail newspaper discusses us:
"The website DIY Drones is a thriving community of do-it-yourself drone builders and operators, building drones that look eerily similar to - or are copies of - the weapons employed currently by the West. For a terrorist, or a lone psychopath, the idea of a vehicle that could launch, find targets and attack autonomously must seem like the ultimate risk-free weapon - a suicide bomb without a suicide bomber."
What's troubling about this is the notion that "drones = weapons". But until the regulators open up national airspace to more civilian/commercial use that shows more peaceful use cases, I suppose this is going to be something we're going to continue to have to fight/educate against.
[Thanks to Gary Mortimer for the find. Photo taken from the article]
APM 2 is an open source, Arduino-compatible, pro-quality autopilot. It is the most advanced IMU-based open source autopilot available today, and provides an entire UAV control system with scriptable missions with 3D waypoints, in-flight uploading of commands and powerful ground station software.
APM 2 supports any kind of of vehicle with a one-click change of code. Available code include ArduPlane (fixed wing), ArduCopter (rotary wing), ArduRover (ground vehicles) and more.
You'll also need a at least a five-channel RC radio setup, a soldering iron, a mini USB cable and of course something that flies! (We're partial to the SkyFun delta wing (right) and Bixlee 2 powered glider (left) or its equivalents ourselves).
Note: ArduPilot Mega requires no programming, but it's open source and you're welcome to modify it if you'd like. If you are going to play with the code, you can use the free Arduino IDE to edit and upload the code to the ArduPilot board.
Some more progress on the GCS. I integrated a line builder and line manager. The line builder contains the editor to edit GPS coordinates of the line, as well as options for line thickness and color. The line manager imports these coordinates as a set, and given a name. This clears up the line builder, allowing multiple lines to co-exist.
The Line builder can import a list of GPS coordinates from a text file with the format: lat lon lat lon ...
I plan on adding a 3rd dimension, but i don't yet have a barometric pressure sensor.
This is zoomed in to show the Open Street map layer.
The line appears shifted from the road, but it is really aligned. The line right now is at an elevation of 2500 km, so the shifting is due to the perspective distortion. Any lower, the line disappears into the ground (the globe has elevation data). I need to figure out how to have the line at ground level.
10A @11.5V for a speed of 5.6 km/h is lousy. The same speed with 5.0A would be OK. This benchmark was set by the Firebrigade-ship, but the catamarane had a much better straight-line behaviour.
OK, let´s improve the catamarane...
In the long winter evenings i googled a lot about catamaranes. Somebody had posted a comparison between different hull shapes / cross-sections. The one with the triangular cross-section as i was using, proved to be the worst in terms of drag. But it was the best in terms of straight-line behaviour and ease of construction. The best in terms of drag was an elliptic shape. Now i knew, where i was.
There are also dxf-files available. A colleage of mine is a specialist for 3D CAD design. I gave him the dxf-files and he made a 3D model of the hull out of the DXF-files. (Thanks Matthias)
But how getting a hull from the plans with the least effort?
diy-store -> Styrofoam with 100mm thickness --> some cardboard --> 14 cross-sections of the hull printed on paper --> some double sided sticky tape --> a hotwire styro-cutting assembly and three evenings when my wife had to watch TV lonely.
One of the hull-segments is the solution to the "guess-what" picture of the last episode.
This are the middle segments, stacked up.
All 14 segments (each with a thickness of 100mm) were glued together with styro-glue. A little bit sanding and the hull was nearly finished.
The glued segments, before the coating...
To add stability, the hulls were coated with a thin layer of fiberglass and epoxy.
The coating - and sticky fingers...
To connect the two hulls with a styrofoam-board that serves as a platform for the superstructures i used styrofoam screw-anchors and M5 Screws, that were epoxied and glued into the top of the hulls prior to coating.
The styro screw-anchor
To give it a real good finish there had to be much more sanding, priming and painting, but as already mentioned earlier, patience is not one of my strenghts, and so i decided to bring that provisional assembly into the water as fast as possible.
This construction is far from being perfect, but to prove the concept it was OK.
The first launch...
The first launch:
Yipee! I have invented the catamarane-oscillator!
The cat oscillated, but found its waypoints. On the first run...
The second one with decreased P ended up in my first swimming exercise in this year. It was still oscillating, but it did not manage to find anything. The problem seemed to be the lateral stability of the ship´s aft. The new hull had problems with his butt! Back at home i added fins on the backside of the hulls. The size had a triangular shape and went about 100mm below the waterline.
Back to the lake...
The lateral stability was much better, when manually testing it by shifting the ship left and right.
Launch...
Swim!
This was too much of the good thing. The ship went off with absolutely no oscillations, it seemed that it sits on on rails. Finally it crashed to the shoreline after having drawn a very wide circle. The crashpoint was 2 meters away from a russian-immigrant fisherman, who is always there when i had unlucky experiences. I like his comments. "Ahh, new ship ey!", "Ahh, better ship now (grin)". The propeller managed to wrap the end of a small branch around its shaft two meters away from the shoreline. I took off my trousers and waded into the swamp to get it out of the water. Must have been a curious looking picture, because i went to the lake on my way back from the office: A man standing in his undertrousers in a lake with shirt and tie, holding a catamarane in his hands, discussing with a russian-based fisherman about fishing spots.
As a next step, i stripped the fins to one third of their original size. And now it was perfect.
No oscillations, straight line...
The two fin sizes together ( i re-glued the cutted segment to see the difference)
What a difference some square-centimeters make!
The new Data:
current: 5.2A @ 11.5V
speed: up to 8 km/h
Thats all till now, time-lapse is over, with episode 11 we have reached the real-time.
Let´s see what the future will bring!
What about starting a colaborating project for UAVs (Unmanned Aquatic Vehicles) on this site?
(The start will be the finding of a better abbreviation...)
Here's an excerpt froman articlein Willamette Week, a Portland weekly. It's a mix of well reported details about the founders and clashes within the company, plus some clueless stuff about how drones are evil and kill people (Insitu UAVs are actually unarmed, something the reporter seems not to understand). Read the comments, too.
"With a successful 1998 flight from Newfoundland to Scotland on a gallon and a half of gas, Aerosonde became the first unmanned plane ever to cross the Atlantic.
The publicity stunt captured headlines. But McGeer never managed to sell more than a handful of the drones—despite some enthusiastic support from within the bureaucracies of national weather services around the world, they could not be swayed into buying.
“That was life,” von Flotow says. “When you’re running a little garage business—and there’s many such businesses—you’re always chasing the dream, and the dream never quite makes it into your grasp.”
The next opportunity at McGeer’s door came from the tuna industry, of all places.
Tuna companies track schools of the fish using helicopters. It’s expensive and dangerous work, and McGeer was told the industry would pay for a plane that could launch from a boat with a camera to do the job.
McGeer set to work designing a new unmanned plane he called the SeaScan.
Again with help from von Flotow, McGeer and five employees worked at a dizzying rate of invention to master the biggest technical hurdle—launching and retrieving the plane from the deck of a ship.
They came up with a 14-foot catapult that slingshots the plane into the air at more than 50 mph, then spent years perfecting and eventually patenting the so-called “sky hook” landing system, which lets the plane fly into a rope suspended from a pole.
With a maximum speed of about 90 mph, the SeaScan was the first unmanned plane able to deliver high-quality video footage. Like the Aerosonde, however, the SeaScan never found a successful market.
This time, it was terrorists who got in the way.
Just as the SeaScan prototype was being completed, the 9/11 attacks came. McGeer had already been in contact with Boeing and others in the defense industry for the better part of a year about possible military uses for SeaScan.
Now they left the tuna industry behind and went into high gear. But not without reservations.
“There were plenty of people who weren’t comfortable. But we went along with it,” McGeer says. “I took an ends-justify-the-means argument—that taking this money would allow me to get into the civilian market. But I was wrong. That never happened.”
Insitu underwent other rapid changes in 2001. McGeer called in Steve Sliwa, a friend he knew from their undergrad days at Princeton, to turn Insitu around. And coincidentally, the day before 9/11, the Boeing Co. first agreed to invest in Insitu."
For a class project, we built a quadrotor using the Sparkfun Razor IMU and a Atmega32U4 running the PID controls. After about a month of work, we successfully flew it with great results (alright, it wasn't super stable, but it stayed up!). Check it out at www.wyvernupenn.blogspot.com.
The 1st flag to be lifted autonomously suffered an acidic fate...
when our field battery fell over & leaked acid on it. Lead acid batteries do pour when they fall over. It was never much use since crashes would always end a campaign before the batteries ran out.
Rather than fly the melted nylon & cause a hole to form, decided to put it down. All cleaned off, tried to give it to the Air Force, whose answer was yet another FUGGEDABOUTIT.
Marcy 1 & 2 examine the melted masterpiece.
MARCY 1 RPM INCREASE
Marcy 1 began a campaign to increase RPM, abandon thermopile attitude sensing, & become passively stable. Thermopiles & active stability may return in a large scale copter.
It's been disasterous. The fatter wing seems to require too much balance beam inertia to stabilize. May have to go to with a long, thinner wing.
Have a flight over Livermore.
Never got Major Marcy but still got some emotional support in the end.
The best explanation for why Major Marcy never wanted to see us in real life was if a heroine knows someone's attracted to her image online yet has no confidence in her beauty, she may be afraid of losing the illusion. It's been very consistent for years.
She only talked to alpha males but demonstration of lower value, overwhelming surplus of men in Silicon Valley, & our crazy gender views didn't explain everything.
Now a still photo movie.
MARCY 2
Been a few weeks & still stumped over why Marcy 2's radio won't initialize on the golf course but will initialize in the apartment. It's very common for circuits to fail on the golf course because of the harsh environment, nothing specific to Marcy class vehicles. Focusing on weak solder joints & floating solder balls. Sux using custom electronics for Mar vehicles in a sea of off the shelf parts.
Marcy-2 radio test.
It's heading towards just insulating the board & keeping it warm. The traces are probably too long & close together for the environment.
PCB Boards are Cool, but the Holy Grail for robotics are the Kapton Flex Circuits which are both wire and circuit in one.
Using This Material, I was able to CNC a single-sided SMD circuit which is thin and flexible - though not quite Kapton :-(
For lightweight circuits that fit into odd shapes (like fuselages), etc, this is a process that can't be beat. You could probably use a chemical etch, but the CNC does the routing and cutout with the same tool.
First Design in Eagle then export in PCB-GCODE. I used 20mil spacing in eagle and a 16mil tool in gcode with a 3mil default (offset). I glued the scissor-cut material to a thicker PCB with spray glue, then held it down with clamps. It is critical to get the working surface flat (which took time and error).
Take a look at this crasy simulation. This is an openloop designed for mission testing. Of course I got virtual permission and the whole airspace was NOTAMed to the ground. An UAV has 'flown' over Cote d'Azur.
Simulation time around 2h. In the previous run I saw mission aborts due to exceeded safety distances etc (due to protective config variables from real-life photomissions).
In short this is a 2h+ mission, over the range of EasyUAV/Easyglider,Cularis but technically barely flyable with Pteryx loaded with a small camera and some 20Ah of lipos.
In practice taking flight permission from there would be impossible (close to one of France's busiest airports).
Log content: LOG_POINTS=26274
Flight statistics: Max altitude above takeoff point AGL=206.0[m] Cumulative climb=205.97[m] Max distance to takeoff=9.591[km] Max VLOS distance to takeoff=9.593[km] Total travel (groundtrip)=67.950[km] Takeoff: 2010-04-28 16:30:31.799 Last event: 2010-04-28 18:20:00.046 Total log time=6568.50[s] Total flight time=6567.00[s] 100.0% of log time Autonomous flight time=0.00[s] 0.0% of flight time Average groundspeed=37.2[km/h] 10.3[m/s] Min air temperature=30.24[C] Max air temperature=31.51[C]
[UPDATE: Hooks has, er, hooked us up with a 10% discount at FPVFlying.com, for this and anything else they sell. Just use the discount code "diydrones". Awesome! Thanks Hooks!]
Thanks to Hooks for turning us on to the new Skywalker foam UAV platform. Mine just arrived and based on a quick inspection, I'm pretty sure this is the one for me! Everything about is totally optimized for a UAV, from the payload capacity to transportability. I'm blown away by how thoughtfully designed this one is.
It's got it all:
The durability of foam with all the interior room of balsa
Payload area right under the CG, so you don't have to worry about balance issues
Hand launchable, but still can carry pounds of payload
Breaks down easily for transport
Ailerons and optional flaps
Pusher, high-wing configuration, with servos outside to save room inside
Super tough EPO material
Easy to get to equipment with big bay doors on both sides
External mounting spots on rear fuselage for wireless transmitters (keeps them away from other electronics)
At $144, I think it's very fairly priced. I think this is one of the best made foam ARFs that I've seen, right up there with the Multiplex line. Don't forget to order the power pack at the same time.
Here's a shot of a prototype being flown by the creators:
Rather than give it a full review (I haven't flow it yet), I'll just give first impressions in pictures.
I'm still working on the next installment on my SAGAR drone, however my progress has slowed, as I suddenly find myself in Boston for 7 weeks. Life can be very exciting when you work for the Department of Defense.
In the mean time, I have been asked by a few people over at SocietyofRobots.com on how SAGAR's micro-controller (an Axon) communicates with LabView. Instead of a bland answer, I spent s little time writting about the different problems hobbyist can run into when they try to have to computer systems communicate with each other.
So we're going into the Outback UAV challenge and I've been brainstorming ideas about a backup communication system as it's not really desirable to lose primary communication at all. So I know the Aerosonde guys use satellite data packets for their backup telemetry (namely iridium), but having looked at their prices and latency I don't think it's a good option. Enter the GE864. I'm currently working with it at my day job and it's a fantastic little unit with so much functionality it's almost silly. It has an in-built python interpreter with 1MB of program memory which is pretty good. It also has a slew of GPIO and emulated bus protocols such as SPI, I2C, etc that can be multiplexed onto the pins.
If they wanted to, I'm sure someone could make an Autopilot out of it, but I am more interested in it as a backup communication method. With a suitable antenna, at the altitudes and speeds which we fly at, we should be able to get GPRS reception in most areas. Would it be viable as a platform for sending intermittent telemetry to a internet-connected ground station?
If so, one could write a python application that accepted a serial input (such as the one you would normally send to a radio) and send it to a specific IP address.
And cool home page promo on the Sparkfun site here.
Here's a quick FAQ for people just now coming to the site, or hearing about ArduPilot Mega for the first time:
It is designed to work with an IMU "shield" (board that fits on top) that contains all the sensors. That board will be available by the end of May. The latest info on the shield is here.
The ArduPilot Mega code will build on ArduPilot 2.6 and be available in about a month.
We recommend this board just for people who want to beta test or tinker. For regular users who want a plug-and-play (ish) experience, it's best to wait a few weeks for us to release the IMU shield, code and documentation. (The Sparkfun board will also be tweaked a bit, with mostly cosmetic changes to make some pin labeling clearer, in the next batch.)
I have lightened the Quad and made the cargo bay bigger. Still need to do landing gear and put the ArduIMU in to control it. The electronics bay screws on the top. Here is some pics. Earl
Very soon for pan and tilt camera. Lots of room.
The electronics bay. It unscrews from the main body.Holds the batteries also.
Clear dome over camera. Now to design a landing gear !
I now have a compass module and i wrote some better code. The compass module is just a life saver. It is really accurate and just makes programming easier. You use i2c to communicate with it and just a snippet of code. Just make sure you mount it level and away from the electronics.
My new code has improved steering. I guess its proportional but i do not know if it is definition proportional drive. I came up with this little formula of delay=degree error / 180 *3000. It takes about 3 secs to turn 180 degrees so 3000 was my number i could tweak. Of course it is out of 180 because that is the most i will be turning either left or right. Our degree of error is how much we are off from our current heading to the heading we need to be at. Simply subtract the current heading from the desired heading and take the absolute value and presto! This code seems to work really well. I tested this in a parking lot plus i had 2 waypoints this time. (see video). You can see the results. the waypoints were given a radius of 2 meters but it normally gets closer than that. I will reduce the radius next time. The AGV is programmed to stop when it reaches its last GPS point. I ordered a l298 motor driver and will update this post when i have that on the AGV and i will have a more complicated path of waypoints.
