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10x Cheaper/lighter Airspeed Indicator

Posted by bGatti on December 10, 2008 at 12:55pm
Given that an Airspeed Sensor costs about $12, I though it worth proposing an alternative: 2 temperature sensors and a resistor. Couple the resistor to one temperature sensor, and induce a voltage to generate heat. Place the coupled part in the airstream, now compare the temp of the one sensor against the ambient temperature; the difference is relative to airspeed. Cost $1.20; Weight nearly zilch. Downsides, not as quick to respond, might use more energy, but given the cost and the relative unimportance of airspeed as it input, it might qualify as a reasonable DIY alternative.
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3D Robotics

Buy bare boards and components for a DIY ArduPilot

Posted by Chris Anderson on December 8, 2008 at 1:00pm

You'll soon be able to buy ArduPilot already made, but for those of you who would rather build their own, here are the necessary parts:

You can buy the boards here.

Eagle (PCB and schematic) files are here.

A pdf of the schematic is here.

Once you've made the board, instructions on setting the fuses and loading the bootloader are here.

A few notes on building the board: Aside from all the surface-mount components below, the only through-hole components you need to solder on are a 5-pin breakaway connector for the FTDI port (first five pins next to the GPS connector), the two 2x3 ICSP connectors, two 3-pin connectors for channel 1 & 2 output, one 3-pin connector for the power select and three pigtails (female-to-female servo connectors cut in half) for CTRL and channel 1 & 2 in. The other two channels (3&4) are not currently used. IMPORTANT: the power selector pins must have a jumper cap placed on two of the pins. Use the two closest to the servo-out ports if you're going to power the board from the RC receiver via the RC-in cables (that's what I've done in the picture above), or use the other two if you want to power the board with a separate regulated 5v power source. If you don't put the jumper cap on these pins, the board will have no power!

Components: ICs:

Capacitors: Diodes: Resistors: Other: Others things you'll need if you don't already have them:
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Status of Project

Posted by Daniel Morgan on December 8, 2008 at 9:00am
Team OSAM just finished surveying a couple thousand feet of road with our high resolution camera in very narrow canyon. We also recently did a multiple uav formation flight (my baby). In addition to this austin recently wrote some new functions for the paparazzi navagtion scheme. The two function are bungee takeoff which will automatically turn on the throttle after the bungee stake has been cleared along with the bungee detaching and also a flower function which makes the plane fly continuously in a pattern that resembles a flower.We are currently working on flying a 5 miles sqaure section of area using a high resolution camera to geo-reference the photos in RGB and NIR. In addition to that we are working on a navigation function which will survey a polygon (sector) in a much more precise manner than before and that has the ability to know when it is finished. This is all using paparazzi of course.Our Team Project Site is http://www.engr.usu.edu/wiki/index.php/OSAM
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3D Robotics

A small fleet of BlimpDuinos going out to the beta testers

Posted by Chris Anderson on December 7, 2008 at 10:42pm

We're still hand-assembling these--it's a lot of work! But if they pass the beta tests, we can have the boards pre-made and just package the other parts in a bag for user assembly (it takes about an evening). Right now we're sourcing the parts to keep the price under $100. Not sure what volume we'll need, but we'll start with a couple hundred kits and see where it goes. A single BlimpDuino kits will have all the parts to create the following (the bag is the envelope and the little disc is the ground beacon):

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3D Robotics

Build your own BlimpDuino platform

Posted by Chris Anderson on December 7, 2008 at 10:30pm

Here are the instructions to build your own BlimpDuino platform. All the parts, with links and prices, are at the bottom:

Step 1: If you're buying a pre-made BlimpDuino board (not available yet), you're done! If you're doing it yourself, order the parts and assemble a BlimpDuino board. You'll need to also download the Eagle files from that post to see which components go where. Don't forget to check the polarity of the two big capacitors and the LEDs when soldering. Use the female machine pin connectors for the two motor outputs, and the male machine pin connectors for the 7-pin ultrasonic sensor connector. Once you've got the board assembled, set the fuses and load the firmware as per these instructions. Then you can load the BlimpDuino code with the Arduino IDE (remember to select "Arduino Pro" as the board. The latest code can always be found on the BlimpDuino home page.

Step 2: Cut out the gondola platform from the 1/16th plywood. Here are the dimensions:

Step 3: Assemble the Lego vectoring motor shaft with the parts listed below. The following view, with the assembled shaft on top and the exploded view below, should show you what goes where:

Step 4: CA glue on to the plywood the two Lego blocks that hold the motor shaft so the little gear spins freely at the front end of the slot in the wood. Snip the studs off the two little Lego blocks without the center hole. CA glue them to the other side of plywood according to the following photo. Make sure the two Lego blocks are a little bit more than the width of the LiPo apart, as shown:

Step 5: Enlarge the hole in the big Lego gear with a 5/32 drill. CA glue it to the shaft of the servo (try not to get glue in the servo!). Snip the mounting flanges off the servo. Plug the servo into a RC receiver and turn it and the transmitter channel one to center the servo. With the RC system still on, place the servo in the position shown below and ensure that the gears are meshed so the motor mounts at each end are more-or-less horizontal and pointing away from the board (depending on the servo, it may be impossible to get them perfectly horizontal. Don't worry; the software will correct for this). You can also check that a RC receiver and the battery can fit where shown:

Step 6: Cut four 20cm lengths of very thin wire and strip and solder the ends to the motor terminals on one side, and male machine pins on the other (it doesn't matter which terminals go to which pins, since we'll just reverse them at the plug if the motors are going in the wrong direction). Make sure you put short lengths of heat-shrink tubing on the wires before you solder them on the connector. Once you're done, shrink the tubing over the connector solder joints. CA glue the motors on to the Lego motor mounts. Press the props onto each motor.

Step 7: Double-stick tape the BlimpDuino board to the two Lego blocks, with the switch closest to the motor shaft. Wrap the motor wires around the shaft until you've taken up most of the slack, and then plug them into the two connectors on either side of the motor driver chip. Plug the servo into the connector closest to the reset switch, black wire furthest out. Here's a diagram showing the connections:

Step 8: Depending on what batteries you're using for BlimpDuino and the ground beacon, make connector wires that match the two-pin power connectors on both the board and the beacon. Make sure you've the polarity right! Power on beacon and BlimpDuino. After BlimpDuino goes through its start-up self-check process (green LEDs flash in a circle, then servos go max down, center and max up), you should see stuff start to happen. BlimpDuino should light up the green LED in the direction of the beacon, and the servos should move up and down depending on what the ultrasonic sensor is seeing. The motors should turn in the opposition direction as the lit LEDs. The props should be blowing air back (away from the board). If they're blowing the wrong direction, just reverse the connector into the BlimpDuino board. Step 9: If everything works, you're ready to go! Inflate the envelope and tape the BlimpDuino gondola on the bottom and trim it all so it's neutrally buoyant, or as close as possible. Put the beacon on a chair in the middle of the room and power it on. Holding the blimp at the desired height, power it on and wait until the servos go up and down (that's a sign that ultrasonic sensor has recorded the distance to the floor). Let it go. The blimp should maintain height and circle the beacon. Looks simple, but that's the beginning of full autonomy! Step 10 (optional): If you want to fly in RC mode, connect a RC receiver to the other two connectors next to where the servo goes, and plug the servo into the receiver's channel 2 (elevator) position. Our code should autosense that a receiver has been connected and place you in RC mode, where the aileron controls the differential thrust of the motors, the elevator controls the vectoring servo and the throttle controls the speed of forward motion. Here's how to connect everything in RC mode:

Here's everything you need (prices shown are approximate price of all the components if you buy from the retailers linked. In the case of multiple units, the price reflects the total price of all the units required):

Lego parts: (All but the last can be found by going to Lego's "Pick a Brick" store and entering in the name in search box)

  • 4x "Cross Axle 8M" ($0.64)
  • 2x "Angle Element, 180 Degrees" ($0.32)
  • 1x "Cross Axle, Extension, 2M" ($0.06)
  • 1x "Double Conical Wheel Z12 1M" ($0.22)
  • 4x "Technic Lever 3M" ($0.52)
  • 4x "Technic Brick 1X2, Ø4.9" ($0.16)
  • 1x large gear (only available from this third-party store right now; I'm working to get it in the Lego store) ($0.29)
(For RC mode, you'll also need a transmitter and receiver. Any one will work--you only need three channels)

Total: $158.32 (without helium)

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Developer

New DIY Open-Source MUX...

Posted by Jordi Muñoz on December 6, 2008 at 4:00am
This an Open-Source multiplexor that will allow you switch between manual or auto mode using only one channel of your remote control, also include a "build-in" picoswitch with three states (down, middle and up) + reset mode, and all through one channel.This MUX is intended to be use in low power and simple autopilot systems. In case your uController do not have enough timers to control servos, you should try the pololu servo controller and interface it with the DIY MUX.The attiny firmware is also Open-Source and you can modify it as you wish, you will need winavr+avrstudio4 and of course an ISCP programmer, like this one.To buy a PCB click here.Part list from DigiKey:3 x 1k SMD(0805) resistor P1.00KCCT-ND1 x 10k SMD resistor P10.0KCCT-ND1 x .1uf capacitor PCC1828CT-ND2 x LEDs SMD(0603), the color is optional:Red: 160-1181-1-NDGreen: 160-1183-1-NDBlue: 160-1646-1-ND1 x Attiny 85, ATTINY85V-10SU-ND1 x Mux 74LS157 296-14884-1-NDThere is also an optional component (D1), (in the top of PSEL label on the schematics), this is just a protection diode, if you are not planning to use it you should make a solder bridge between the pads..Eagle files:ardumux4_v1.zipAttiny firmware:antifail_system.rarJust to remember, when i used to have no idea of basic PCB design rules:

Now i try to fallow some rules, for example NEVER use the autorouter. 100% by hand..
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3D Robotics

Jack Crossfire's quadcopter now doing autonomous takeoff and landing

Posted by Chris Anderson on December 5, 2008 at 7:49pm

For those of you who follow "Jack Crossfire"'s entertaining diaries of his autonomous helicopter projects. He struggled for more than a year to get a conventional helicopter to reliably fly autonomously, then switched to a quadcopter in hopes of a smoother path. Seems like it worked like a charm. In just a month, he's designed and built a platform and got it not just flying autonomously, but taking off and landing autonomously, too! Here's his latest post with details.
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3D Robotics

New board to allow use of 5Hz GPS modules with ArduPilot

Posted by Chris Anderson on December 5, 2008 at 12:30pm

(Shown at left above, with a Locosys LS20033 GPS module for size comparison) ArduPilot is designed to use the solid and reliable EM406 GPS module, which is a 5v, 1Hz device that works well under most conditions. But if you want more precise navigation, you may want to upgrade to the 5Hz Locosys module that Dean Goedde is using with AttoPilot. That's a 3.3v module, so you can't just plug it into the ArduPilot board. Instead, Jordi has designed a special daughterboard that does the following: --Converts ArduPilot's 5v power to 3.3v power --Provides a EM406 connector, so it's a direct plug-in replacement for the EM406 --Provides a break-out connector so you can add a wireless modem, such as a Zigbee. --Power LED We may release this as a pre-made product, but in the meantime you can make your own. Buy the board from BatchPCB here. Components:

Eagle files (schematic and PCB) are here.

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3D Robotics

Review: Multiplex EasyGlider Pro for UAV use

Posted by Chris Anderson on December 4, 2008 at 7:43pm

We all love the Multiplex EasyStar, but for autopilots that separate stabilization and navigation, its lack of ailerons is a limitation. (Stabalization--FMA Co-Pilot in our case--uses ailerons and elevator; navigation uses rudder and throttle). The next plane up in the Multiplex family is the EasyGlider, recently upgraded for brushless power with the EasyGlider Pro. It's bigger (71" wingspan vs the EasyStar's 54"), has ailerons and can lift more weight. But it's also a lot more expensive ($256 with power package, as opposed to just $66 for the EasyStar), and the front-mounted motor takes up a lot of interior room. How suitable is it for a UAV? I got one and tested it out last weekend. Here's my report:

As with all Multiplex kits, the build quality is excellent and the Elastopor foam goes together nicely with CA glue. If you get the optional power kit, all you need is four servos (2x HS55 and 2x HS81), a Deans connector, and a LiPo battery, along with your RC kit. You can put it together in one evening. I of course added a FMA Co-Pilot, and mounted the sensor above the wing. The plane is slightly nose-heavy in this configuration, but nothing a bolt or two in the tail can't cure. But when you put in all the equipment, you'll spot the first big disadvantage of the EasyGlider Pro: it's got less room inside than the smaller EasyStar! That's not just because the motor and the ESC are in the cockpit. It's also because the servo and pushrods are, too. In the EasyStar, they're all on the outside, leaving the cockpit entirely open for radio and camera equipment, but in the EasyGlider you have to share a narrower (albeit longer) space with everything else. You can see the two side-by-side in this picture:

The EasyStar is closest to us (it's the beat-up one!) and the EasyGlider is behind it. Even though I've added a camera-trigger servo on the EasyStar it still has more unused space than the EasyGlider. The only way to add more space to the EasyGlider would be to create a second "floor" layer above the servos and put autopilot equipment on that, under the foam canopy. Otherwise, anything you stuff in there risks tangling up with the servos, pushrods and other wires. Obviously, the other problem with the EasyGlider is that it's hard to put a forward-looking camera in it, since the prop is in the way, something which isn't a problem for the EasyStar with its pusher prop. There are people who have modded the Easy Glider to put the prop in a pusher configuration with a pylon, but that's too much work for me ;-) As for flight, the EasyGlider flies really well and the ailerons give more precise control than the EasyStar's rudder. But it's also a bit harder to fly for beginners, and if you crash nose-in, you're going to damage the prop and maybe the motor, which isn't a problem with the indestructable EasyStar. I found that the FMA Co-pilot had a hard time maintaining level flight at high gain settings, but that may be due to calibration problems. I'll have to test a bit more to see what the problem is. Bottom line: I prefer the EasyStar, but since I need the ailerons I'm going to continue working with the EasyGlider and create an autopilot layer for the cockpit as mentioned above. What I love about these foam powered gliders is that you can fly them anywhere and they can land on any surface without damage. So as an autopilot test platform, they're great for quick trials and experiments. But I wouldn't recommend the EasyGlider as the optimal UAV platform for serious use. For that, you'll want the usual high-wing trainer, even if that means having to take off and land from a proper runway.
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Octopilot -- Open source propeller-based autopilot

Posted by Ben Levitt on December 3, 2008 at 11:24pm
small.jpgOctopilot is open source autopilot hardware and software for radio controlled planes. It is based on the Parallax Propeller microcontroller, and uses a 5-degrees-of-freedom IMU plus a GPS and proximity sensor to stabilize and navigate your plane.It can be enabled/disabled through an extra channel/switch on your transmitter, and when switched on, stabilizes the plane and navigates it back to the starting location, where it will circle. It can also optionally trigger external actions, like taking a photo or dropping an item, when it reaches a waypoint.Coming soon: multiple waypoints, stabilization of inverted flight, on-board TV-out, and more.If you're interested in helping out, there's lots to be done! Swing on over to the project page and join the octopilot group.http://code.google.com/p/octopilot/
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New (Possibly useful) PIC

Posted by Tyler Nighswander on December 2, 2008 at 8:48pm
SparkFun has a new PIC that seems to have some very nice stats.It's not quite as useful now that the ArduPilotPro is almost ready, but it does look to have much better performance.The datasheet shows the most power hungry mode at 75mA max, and 80MHz, which might make processing GPS data in a UAV a whole lot easier, and a 32 bit processor and a ton of IOs are always nice to have.
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3D Robotics

Final ArduPilot production candidate

Posted by Chris Anderson on December 1, 2008 at 6:02pm

Third time's the charm! This is the ArduPilot board that's now going through the production process. If it passes QA, we're good to go! No big functional changes, but we added the option to use external power or RC receiver power, and we've broken out unused Atmega pins so you can use them if you want. Some other wiring changes, so you'll want to use the latest code. Eagle files here.
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3D Robotics

Awesome simulation setup for ArduPilot!

Posted by Chris Anderson on November 30, 2008 at 12:00pm

Jordi's really outdone himself this time! He created a amazing full-featured simulator for ArduPilot that does the following:

  • Uses the servo output from the autopilot or RC controller (depending on which one is selected by the MUX) to "fly" a plane in the X-Plane flight simulator, via a custom interface he's designed around this ARM board.
  • Also flies the plane in manual RC mode with RC controller output going through the MUX and then into the ARM board.
  • Displays the plane's attitude and other flight telemetry with a custom Ground Station built in LabView.
  • Uses LabView to simulate the FMA Co-Pilot, stabilizing the plane in flight using PID loops.
  • Display the plane's position in a moving map using Google Maps, which also shows waypoints.
As you'll observe in the videos here, you can see the plane's: 1) Flight in X-Plane 2) Glass cockpit with full telemetry and debug data in the Ground Station 3) Overhead position and path in Google Maps Here's a diagram that shows how everything is connected:

You'd note that he's using using the ArduPilot Pro board with just one atmega installed for this. (the other atmega does stabilization, which we're doing in the LabView Ground Station for this demo.) It's the board we use for development, since it's easy to replace atmega chips. It's best to have at least two computers and three screens for this, as you'll see in the video. Video 1 (above) just shows the setup Video 2 (below) shows the plane taking off in manual mode, switching to autonomous and flying to first two waypoints Video 3 (below) shows the plane flying to the last two waypoints, and switching back to manual mode and landing. Video 2 Video 3 Full code and instructions on how to create this simulation setup coming soon.

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3D Robotics

Autonomous blimp art shows

Posted by Chris Anderson on November 28, 2008 at 10:05am

Jed Berk's original Blubberbot was the inspiration for BlimpDuino. It isn't programmable and the sensors don't work predictably, so it just sort of bumbles around, bouncing off walls and floors. But it's lovely to have around and taught us a lot about what to do (use N20 motors and a 54" envelope) and what not to do (complicated and fiddly plastic gondola). We used it as the original prototype platform for BlimpDuino before we moved to modded toys and then our own custom vectoring servo platform. Anyway, Jed, who is an artist, continues to run art installations with Blubberbot, and they're always cool to see. Make has a full roundup .
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3D Robotics

Using the 5Hz Locosys GPS with Arduino/ArduPilot

Posted by Chris Anderson on November 27, 2008 at 2:00pm

Sparkfun is now selling the excellent 5Hz Locosys (Mediatek chipset) GPS that Dean Goedde uses in ArduPilot. We're developing a daughterboard that will allow this 3.3v module to be a plug-and-play replacement for the 5v, 1Hz EM406 GPS that we're currently using for ArduPilot. In the meantime, if you want to start playing with a 5Hz GPS with Arduino here's some code and instructions to get you started.
The code is Jordi's new NMEA parser for the Locosys GPS. It's checksum verified, rocksolid, continuous, no delays, loop rate is about 32000hz. It uses pointers, so it's efficient.

You have to configure the Locosys for the first time you use it. It's very easy, you just need an FTDI cable. Be sure to connect the GPS to a 3.3 volt source. (We'll do this setup for you in the commercial version)


Instructions (please use the picture above as reference):

1-Run Realterminal and open the port @4800bps, you should see all the NMEA stuff, is not check the connections..
2-Now make sure you have checked the options marked with the green arrow... +CR +LF
3-Copy and paste this code: $PMTK251,38400*27 to the box indicated with the red arrow.
4-Then click the "Send ASCII" button indicated with the blue arrow..
5-Then the NMEA should disappear, and starting showing strange values. Go back to the "Port tab" (yellow arrow),
close the port, and choose the Baud "38400", and open the port again. You should the NMEA data again... =)
6- Then go back to the "Send" tab, and copy&paste this code: $PMTK314,0,1,0,1,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0*28 then click Send, this should turn Off all sentences except GGA and RMC
7-Copy&paste now this code: $PMTK220,200*2C This should increase the updates to 5hz... (WOW!!!)..
8- Now you are able to connect the GPS module to Arduino, (only connect the RX pin to the TX of the GPS)
9-Then upload the code above, and open the port monitor, you should see Lat, Lon, Course, Speed, Altitude, Fix Position... like this:
46024504 8050998 312 0 519 1 (and yes you now know the exact position of my Swiss Chalet =P)...

If you want other setup codes for this GPS, you can find them in this datasheet.

Code explanation

If you'd like to understand the NMEA parser code a bit better, here are some of the library functions that it calls (all from the standard C++ library):

  • First of all pointers, which are very easy. They just give you the memory address where a variable is allocated in the ram: info
  • Then the strncmp(), better know as String Comparator. We use it to compare the header of the NMEA string "$GPGGA": info
  • Then strtl(), which means String to Long Variable. It converts a string number into a long variable: info
  • Then the strtok(). This is the string tokens, which looks for tokens in a string, for example commas ",", the ones used to separate values in the NMEA sentence: info
  • The atoi() will convert strings to integers: info
  • If you want to know all the available functions, see the library called "strings.h", "stdlib.h": info and info
(All these libraries are already installed in the Arduino IDE.)
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