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Jan 06, 2009, 12:58 PM
Chris Anderson
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ArduPilot, an open source autopilot, now available ($24.95!)


Our open source autopilot project at DIY Drones has now delivered its first commerical product: ArduPilot, an Ardunio-compatible autopilot board. You can buy it here for $24.95 (you'll also need a GPS module and a FMA co-pilot for all but the most stable aircraft.)


Features:
  • Based on a 16MHz Atmega168 processor. Total onboard processing power aprox 24 MIPS.
  • Built-in hardware failsafe that uses a separate circuit (multiplexer chip and ATTiny processor) to transfer control from the RC system to the autopilot and back again. Includes ability to reboot the main processor in mid-flight.
  • Multiple waypoints (limited only by available memory)
  • Comes with a 6-pin GPS connector for the 1Hz EM406 GPS module. Faster 5Hz GPS module, such as the Locosys 200031, are supported via an optional 3.3V daughterboard
  • Has six spare analog inputs (with ADC on each) and six spare digital input/outputs to add additional sensors
  • Supports addition of wireless downlink module for telemetry.
  • Can be powered by either the RC receiver or a separate battery
  • High-speed ASCII NMEA parser for compatibility with standard GPS modules at any baud rate.
  • Hardware-driven servo control, which means less processor overhead, tighter response and no jitters.
  • Four RC-in channels (plus the autopilot on/off channel) can be processed by the autopilot. This allows the autopilot to read the initial throttle and rudder position when you switch to autonomous mode, so it can maintain speed and heading. The other two channels can be used for whatever you want, such as triggering a camera sequence or dropping an object. (Remember that the aileron and elevator channels are separately controlled by the FMA Co-Pilot)
  • Status LEDs for power, failsafe (on/off) and GPS (satellite lock)
Dimensions: 30mm x 47mm
Last edited by zlite; Apr 11, 2009 at 08:39 PM.
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Jan 06, 2009, 04:06 PM
Gaftopher
Gary Mortimer's Avatar
Chris and Jordi and and and have done a top job on this one, very exciting. Bring on the Pro!
Jan 06, 2009, 10:21 PM
Expert plane crasher
AXI Motor Models's Avatar
It is great that it's so cheap!
Can it provide RTL function without having to do any programming at all?
Jan 06, 2009, 10:45 PM
Registered User
wallaguest1's Avatar
AXI Motor Models looks like you need to spend 13 extra dollars in the FTDI board to load the ardupilot code...

i read the manual and its all very easy,
Jan 06, 2009, 11:23 PM
Chris Anderson
Quote:
Originally Posted by AXI Motor Models
Can it provide RTL function without having to do any programming at all?
Yes, the code defaults to RTL, no modification or programming required. But you do need to load the code the first time, using the FTDI cable and the Arduino software. It's really easy.
Jan 06, 2009, 11:24 PM
How do I change this text?
Darth_Elevator's Avatar
This looks awesome. I just ordered the kit, the GPS module, and the programming board. One question, though, can waypoints be set to different altitudes or do they all have to be the same altitude?
Jan 06, 2009, 11:40 PM
Registered User
wallaguest1's Avatar
zlite in fact there should be done a modification in the code to make it work as RTL, just change a 0 to an 1.
that line:

#define RTL 0 //0 = waypoint mode, 1 = Return home mode

Darth_Elevator yes you can set any diff altituds to each waypoint

Jan 06, 2009, 11:42 PM
How do I change this text?
Darth_Elevator's Avatar
Thanks, walla!
Jan 06, 2009, 11:43 PM
Chris Anderson
Quote:
Originally Posted by wallaguest1
zlite in fact there should be done a modification in the code to make it work as RTL, just change a 0 to an 1.
Yes, I just did that. You beat me to the upload ;-)

Suggestions and advice very welcome! We're now working on the ground station and thermopile version of ArduPilot, so there's plenty of work to go around...
Jan 07, 2009, 12:36 AM
7000mw of raw power!
rich smith's Avatar
Amazing accomplishment! And open source to boot. This is what an RC autopilot should be like. Got to get one ASAP.

BTW how to get unlimited waypoints into less than 16k flash? 8th dimension trick proprietary to Banzai Institute or can you tell us?
Jan 07, 2009, 01:10 AM
Chris Anderson
Quote:
Originally Posted by rich smith
BTW how to get unlimited waypoints into less than 16k flash? 8th dimension trick proprietary to Banzai Institute or can you tell us?
Touche! Replace "unlimited" with "more than we've ever bothered to test". Scores? Hundreds? At 16 bytes each, they don't take up much room. We're planning to move them to EEPROM with our groundstation/waypoint generator, and if you enter them that way there's a limit of 32 waypoints. But if you're willing to enter them into the code, it's a lot more.

Tell me how many you need and we'll see what we can do ;-)
Jan 07, 2009, 02:55 AM
7000mw of raw power!
rich smith's Avatar
Just my way of hinting it's not best business practice to exaggerate specs. Makes prospectives wonder about rest of the info. Inflight update would be virtually infinte but I gather this is not capable (nor desirable considering complexity/cost of 2-way link).

One of the few drawbacks to my Mega8 version was limited to a little over 850 points which proved inadequate. The plane has about 200 mile capability and due to short range of Xbee Pro and other issues the waypoints need to "hug" the chase car route. About 1100 would keep the plane in sight.

Maybe you haven't tested but what is theoretical limit (or latest code size)?

Quote:
Originally Posted by zlite
Touche! Replace "unlimited" with "more than we've ever bothered to test". Scores? Hundreds? At 16 bytes each, they don't take up much room. We're planning to move them to EEPROM with our groundstation/waypoint generator, and if you enter them that way there's a limit of 32 waypoints. But if you're willing to enter them into the code, it's a lot more.

Tell me how many you need and we'll see what we can do ;-)
Jan 07, 2009, 10:57 AM
Registered User
dmgoedde's Avatar
Quote:
Originally Posted by rich smith
One of the few drawbacks to my Mega8 version was limited to a little over 850 points which proved inadequate. The plane has about 200 mile capability and due to short range of Xbee Pro and other issues the waypoints need to "hug" the chase car route. About 1100 would keep the plane in sight.
Rich - there are methods to have the plane hug a line between two waypoints, thus eliminating the need for gobs and gobs of waypoints to keep it on a path. I'm willing to provide hints how I did it, and given the open nature of Arduino autopilot, I bet the ArduPilot community can implement something.

It comes down to needing to accurately know distance between plane and spot perpindicular on the line between last and current waypoint target. Using right triangles and arcSine type trig won't cut it when plane is close to the line, because the angles are smaller than normal lookup table resolution. If you do have some floating point method to handle the trig of arc-second size angles then great and it will be a lot easier. Now that you know distance to the line from plane, if distance is greater than some upper limit (say 50 meters) plane will need a target vector that veers it onto the line at say 30 degrees... you take vector from last to current waypoint and add or subtract 30 degrees from that vector depending what side of the line the plane is on. Now that plane is nearing the line and is within say 50 meters, the target heading vector for plane starts to grade gradully to be parallel to the vector between last and current waypoint targets. That's all there is to it. Implementation could be a biyatch depending on your computing resources, but that's more than enough detail to get someone pointed in the right direction for the algorithm.

Dean
Jan 07, 2009, 11:03 AM
Chris Anderson
Quote:
Originally Posted by rich smith
Maybe you haven't tested but what is theoretical limit (or latest code size)?
Thanks for the good advice. I've changed the description to "Multiple waypoints (limited only by memory)". We haven't tested the maximum. I imagine it in the hundreds now, but as our code size changes that will change too.

PS: The distinction we were trying to draw is that in open source autopilots, the number of waypoints is not preset as it is most closed-source ones. The user can add as many as they want until they run out of memory, because they're dynamically allocating that memory at compile time.
Last edited by zlite; Jan 07, 2009 at 12:07 PM.
Jan 07, 2009, 11:16 AM
Full disclosure, not sponsored
JONBOYLEMON's Avatar
Since I dont have a clue what any of you are talking about answer me this. Supposing I had the Co pilot, gps, etc like in the recomended setup, and a plane that could travel the distance desired, could I takeoff from my local park @ 4600' in elevation and fly to the 12,000' mtn summit 2 miles away and back.

Supposing I knew the gps of starting and ending points could I just plug in the start point at the park and add 500' elevation from takeoff point and 500' elevation above summit. Could it be that easy to go a very long ways??? This is supposing plane could sustain that climb angle needed and sufficient batteries for the task.

Or if plane could not climb in a straight line that steep could you do switchbacks to & from same waypoints but at different altitudes???

I live in an area full of mountains and do alot of flying in them so this is an important consideration for this system.


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