Helicopter UAV based on a Raptor 30
Hello everyone!
Just got my board manufactured a few weeks ago, so it's time to post a little description of my ongoing project here, so this is it:
Here is what's embedded onboard:
Processing elements:
- CPU: Microchip dsPIC33F256 at 40Mhz, allowing a processing power of 40MIPS and with 12bit resolution ADC for better accuracy in measuring the values of analog sensors.
- FPGA: Will take care of converting PWM data from receiver (12 channels supported) and reencode PWM data to servos (12 channels). This way the board is able to support any receiver available, including thoses using PCM encoding.
Sensors:
- 3 axis accelerometer with 4 sensitivity scale (from Freescale)
- 1 axis gyro on the Z axis, with a 150°/s max sensitivity, and integrated temperature sensor
- 2 axis geomagnetic compas
- Barometric pressure sensor
- 2 hall effect sensor, for rotor ans motor RPM monitoring
- Thermocouple, for engine temp. sensing
- Electric field imaging device with 3 antennas (one for monitoring fuel level)
- Ultrasonic range finder, up to 8 meter (driven by the FPGA)
- 12 channels WAAS GPS receiver, outputing NMEA or proprietary 5Hz protocol
Communication:
- Embedded audio/video transmitter with 2km range
- Modem (integrated in FPGA) for sending live flight data to ground on the audio channel of the transmitter
- Orders can be sent by dedicating one of the remote control channel
Imaging:
- An embedded sony 7.2Mpix still digital camera with video mode. All controls (zoom, focus, shooting mode, trigger) are operated remotely
- Tilt rig from 0 to 90°, for pointing the camera remotely
Misc:
- An embedded 4 elements LiPO battery charger, and intelligent battery fuel gauge embedded in the battery pack
- Pushbuttons, buzzer and LEDs
- Serial port for ground debug
The board is still in testing stage, and most of the passive components need to be ordered, but it is comming. The real challenge will come with programming!
On this aspect, I have only 4DOF on the inertial unit...
this raise the same questions that Harrison Jones have in his dual axis accelerometer project, as far as how much will be enough for hovering. I still have an easy way to upgrade my board to 6DOF if I need it but I would rather avoid it if possible.
I understand that gyro on the yaw axis is absolutely mandatory to keep the heading (plus the compas will help), but any displacement of the helicopter should generate an acceleration. I understand then that there's lot of issues as to what created the acceleration and how to process it, as well as drift due to noise and the minute measurements necessary. However, I don't understand how gyros can help if the helicopter is in constant velocity translation: the accelerometer won't register the displacement of course, but the gyros shouldn't as well as there's no angular velocity involved in translation.
Just got my board manufactured a few weeks ago, so it's time to post a little description of my ongoing project here, so this is it:
Here is what's embedded onboard:
Processing elements:
- CPU: Microchip dsPIC33F256 at 40Mhz, allowing a processing power of 40MIPS and with 12bit resolution ADC for better accuracy in measuring the values of analog sensors.
- FPGA: Will take care of converting PWM data from receiver (12 channels supported) and reencode PWM data to servos (12 channels). This way the board is able to support any receiver available, including thoses using PCM encoding.
Sensors:
- 3 axis accelerometer with 4 sensitivity scale (from Freescale)
- 1 axis gyro on the Z axis, with a 150°/s max sensitivity, and integrated temperature sensor
- 2 axis geomagnetic compas
- Barometric pressure sensor
- 2 hall effect sensor, for rotor ans motor RPM monitoring
- Thermocouple, for engine temp. sensing
- Electric field imaging device with 3 antennas (one for monitoring fuel level)
- Ultrasonic range finder, up to 8 meter (driven by the FPGA)
- 12 channels WAAS GPS receiver, outputing NMEA or proprietary 5Hz protocol
Communication:
- Embedded audio/video transmitter with 2km range
- Modem (integrated in FPGA) for sending live flight data to ground on the audio channel of the transmitter
- Orders can be sent by dedicating one of the remote control channel
Imaging:
- An embedded sony 7.2Mpix still digital camera with video mode. All controls (zoom, focus, shooting mode, trigger) are operated remotely
- Tilt rig from 0 to 90°, for pointing the camera remotely
Misc:
- An embedded 4 elements LiPO battery charger, and intelligent battery fuel gauge embedded in the battery pack
- Pushbuttons, buzzer and LEDs
- Serial port for ground debug
The board is still in testing stage, and most of the passive components need to be ordered, but it is comming. The real challenge will come with programming!
On this aspect, I have only 4DOF on the inertial unit...
this raise the same questions that Harrison Jones have in his dual axis accelerometer project, as far as how much will be enough for hovering. I still have an easy way to upgrade my board to 6DOF if I need it but I would rather avoid it if possible.
I understand that gyro on the yaw axis is absolutely mandatory to keep the heading (plus the compas will help), but any displacement of the helicopter should generate an acceleration. I understand then that there's lot of issues as to what created the acceleration and how to process it, as well as drift due to noise and the minute measurements necessary. However, I don't understand how gyros can help if the helicopter is in constant velocity translation: the accelerometer won't register the displacement of course, but the gyros shouldn't as well as there's no angular velocity involved in translation.
Tags: Pro
Replies to This Discussion
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3D RoboticsPermalink Reply by Chris Anderson on -
Wow! That's a great-looking board. Now for the fun work of programming--in my experience software takes about ten times as long as hardware, but perhaps you can build on the work of others here and fast-track that.
As for constant velocity, you're right that neither gyros or accelerometers can help you there. We use GPS (coarse data) or pitot tubes/pressure sensors (fine data, best for altitude hold with throttle) for that.
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Permalink Reply by Howard Gordon on -
According to other posts on that thread, the 2-axis accelerometer is not sufficient. I'm not convinced, but I am starting to understand the issues - the accelerometers are very sensitive to vibration and other movement (e.g. the servo action), and if the roll or pitch angle is small, the effect of gravity on the planar accelerometers is small, so a fair amount of data smoothing may be required to extract a useful error signal for the control loop. I'm in the middle of trying to make this work, and I am already seeing the vibration issues. Next step is to add the signal processing to see if I can smooth things out. My original assumptions may prove to have been overly optimistic, but I need to prove this to myself one way of the other ...
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Permalink Reply by James Hall on -
Outstanding! I have Raptor 30 as well and I am working on mine little by little. Board looks great! How much did it set you back for the PCB work?
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Permalink Reply by Antoine Bercovici on -
They indeed did a terrific work on the PCB. It is a 4 layer board, and it has some unique edge cutting that very few PCB manufacturer would do!
I always had a good experience with "sinfopbc" in china. they have some very reasonable price and they are very professionnal and communicative. Set up fee for a 4 layer board is a fixed 99$, then the price per square inch is very low. I ordered 10 boards and it costed me around 300$ which is not really bad for the work they provided (especially with the very unusual layout I wanted!).
I think it will take age to program this! But I'm confident, there are lots of code examples and goodies on kalmann filtering, and friends doing others UAV helis project, so this should help a lot as well.
But first of all hardware needs to be finished and fully tested
What about your project for your raptor?
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Permalink Reply by Antoine Bercovici on
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Just did more soldering work on my board since I got the dsPIC. I think I'm gonna add the 2 missing gyros on small riser boards later on. Most of the work has been done on 6DOF inertial units and it will be easier to use that as a stepping stone.
Here it is in place in the head of the raptor 30:
And here it fits perfectly inside the standard canopy
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Permalink Reply by Jack Crossfire on -
So how's the software coming? Have found in an IMU using gyros & accelerometers the result has to be 0.998 * gyro angle + 0.002 * accelerometer angle otherwise the translational acceleration becomes too much. People using larger than a 450 seem to get more stability.
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Permalink Reply by Antoine Bercovici on
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Software is planned when the hardware will be done, it will take a little while. I hope to get that started as soon as possible, however I still have a lot to learn
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Permalink Reply by Georgios on -
Hi,
This is great work.
Have you designed the hole board yourself? Do you supply them with ready CAD files or do they CAD the board? Is the price only for PCB or does it include mounted components. In that case is great.
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Permalink Reply by Antoine Bercovici on
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I have designed the board myself. You just supply the gerber source file to them. Price is for PCB only, but they can also provide component mounting services as well I think (they can even provide the components). However no one would have accepted to do the round edge cutting and some oval drilled holes. I can only praise what they did for me so far, and I tried other companies before (one in France and one in the US). Of course regular 2 layer boards are much cheaper!
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Permalink Reply by Alexandre on -
I'm still trying to digest your project. Damn good looks. My project is to build instrumentation for an autonomous car first, master movement in 2 axes with maybe artificial vision and artificial inteligence, and later on, evolve into 3 axes. Some problems come to hand, financial limitations being the hardest. Anyway, I must look into your project with care, since you so gracefully show us your progress. Maybe your solutions can give me some kind of breaktrough. Do you have it published anywere else, or is it just a matter of looking at your posts and building the information as I go along?
Thanks again, it's always great to see such professional work. Makes me want to follow your foot steps.
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Permalink Reply by Antoine Bercovici on
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Thanks for your support! however it is far from working yet... I haven't done much lately, as I was busy finishing other projects, but will probably carry on in the following months. There's too little done yet to publish detailed information, but when the time will come, I will do it.
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Permalink Reply by Alexandre on
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I would like to check out some of your hardware solutions, is it possible? Right now time is getting scarce, and althought I have a project that might need some bug fixing, it has grown insuficient in time. Like you, other projects come first sometimes, and after a long time dedicating just to my own projects, i've come to the biggest project of my life so far... a family. I still haven't found a balance point, and the time I have left is still not enough. That led me to have a great respect for the people that have many realities. We are so many diferent people in the course of the day: Man, husband, father, friend, worker, hobbyst, saint, sinner... And sometimes other dreams are not easy to find when you have bigger projects, like the love of your life :)
I don't mean to copy your work, just take a look and perhaps discover some hardware solutions that I don't know of yet. After all, if you want to copy other peoples work, you might as well buy a commercial kit or an already assembled solution.
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