Anyone in the so Cal area?

[bikerfreak]

Hi, I was curious if there's anyone in the So Cal area that may be interested in getting together and work on building a low cost UAV? I have some EE and programming skills, but am not very knowledgable in general plane design. It would be great if people in the same area can all get together and share information.

If anyone is interested, please let me know.

Thanks,
David

[Medve]

Too bad you're not in the Nor Cal area.

[ElectroLawndart]

I'm in the San Fernando Valley. About 3 miles away from the Woodley R/C Airfield. I don't fly there because the few times I did, I got some attitude about my parkflyer taking up channel time that should be used for "real" model aircraft. Huh!?!

Where in SoCal are you Bikerfreak?

Dart

[bikerfreak]

ElectroLawndart, I'm by the Whittier Narrows Airfield off the 60 freeway. I'm not sure why ppl were giving you attitude, most of the ppl I see at the Airfield are quite nice and polite. If you're ever in my area, let me know.

David

[aviationmodeler]

I am interested in building a RC Predator B UA V if any body has the plans or designs for this

[danstrider]

avaitonmodeler, try www.littlebirdz.com for a Predator B kit. It's too small for carrying electronics, but if you pester the owner, he might cut you a double sized kit (he owns the laser)

You actually may have better luck going with something standard like a Telemaster or other large trainer. Building a UAV is a lot more than just having a sleek airframe (I'm learning this lesson too). It's alllllll about the avionics and what payload capacity you have. The Predator is purpose-built for long endurance missions and might not be the best choice for a UAV testbed...

Just my two cents.

Dan

[ElectroLawndart]

Bikerfreak,

I'm sure that the attitude I got was actually the minority. But its that minority that makes me drive 15 minutes more to fly at a Little League Baseball field. I'll have to take a trip out to Whittier in couple of weekends.

Dart

[MrLift]

I am in the So Cal forsure, I am thinking of building a UAV for law enforcement purposes since that is what I do oink oink. I have methodically thought out alot of what would make a UAV work in a law enforcment application and how it could succeed. I am definetally looking for skilled partners in this area to collaborate and build a prototype aircraft. Oh yeah I am in the Riverside area. People out of the area could still collaboorate on lots of things that is what makes the internet great. Please anyone drop me a line about the topic and David did your UAv have a specific purpose?

[bikerfreak]

ElectroLawndart, yeah visit Whittier when you get the chance, it's a great field.

MrLift, I was actually looking to build an UAV for surveillance as well. Basically, I want something with long endurance, has a few cameras on board that takes high res photos (and possibly IR for night surveillance), collects telemetry data, and is able to both store locally and send back all of this information in realtime. I don't mind if the UAV is a bit large. Actually I would prefer it if it was a bit large so it'll be easier to fit all the instruments in there. But not knowing enough about plane designs, I don't even know if I can squeeze all of this in there.

I"m drawing up the electronics now. All the parts will be modular. Everything will connect into a central collector so you can add/remove sensors that you don't need to adjust weight.

Riverside is not too far from me. I'm definitely interested in working on something like this.

[Lost In OC]

I'm in the orange county are and currently building a uav....a collaboration would be awesome!

[raptor22]

I am in SD and could help out.

[Nethole]

Likely there are some EX- LABIKERs that could help out

[rocky79]

I'm in the San Fernando Valley. About 3 miles away from the Woodley R/C Airfield. I don't fly there because the few times I did, I got some attitude about my parkflyer taking up channel time that should be used for "real" model aircraft. Huh!?!

Where in SoCal are you Bikerfreak?

Dart

I live in westwood 15 min from woodley flying field. I have a project at hand. It's basicaly getting a wireless data to ground using a telemetry system. I want to do this as cheap as possible any idea?. What's your area of expertise?

Thanks

[vpatron]

Hi guys,

This is an old thread but I'm also interested in teaming up. My interests more lean toward building an AP plane for commercial use, but want some short-range basic autonomous capabilities so it can do things like circle in place so I can compose the photo or keep a camera trained on a bad guy (police surveillance) using a continuously rotatable pan/tilt mechanism, fly a grid to take mapping photos or for search and rescue, etc.

I'm in San Diego/Mira Mesa area (near Miramar base).

rocky79, a cheap telemetry system I'm thinking about modulates simple 1200 baud FSK onto the audio channel of an inexpensive wireless video transmitter (as low as $80 for RX/TX pair). There are several designs for a small PIC microcontroller to take GPS data and general FSK audio for amateur radio APRS. See <http://www.tapr.org/kits_pic-e.html>. The FSK-to-RS232 decoder is a bit more involved but not that difficult.

I already have an AP slowstick with video downlink. I'm working on a simple mid-size EPP foam glider that is a very stable flier, very crashable and durable, yet can pack into a 2 foot long box for airline travel.

My background is ex-E.E. (quit last year) with 10 years in industry, analog and RF design, and some PIC and older microcontrollers on the side. I'd also like to start commercial AP work (a good plane, not crappy AP Slow Stick) before year-end to fund the UAV development.

If anyone in San Diego wants to collaborate, let me know. I can build electronics hardware but looking for someone to lead the firmware development. Thanks,

-Vince

[ElectroLawndart]

vpatron
Thanks for reviving this thread.

rocky79
Sorry for not replying.

My background is also in EE. Gave it up about 15 yrs ago when I couldn't fiind a decent job in the field. :rolleyes:
Currently I'm trying to get an airspeed/AOA sensor going during my brief periods of spare time. I'm also interested in a video camera/horizon sensor. Any chance I can combine a couple of functions in one unit I'm interested. Space and weight being my concern in UAV's.
I'm also trying to build a CNC foam cutter as I'm expecting to have to rebuild ALOT during development. :eek:

Dart

[vpatron]

Hi Dart,

>My background is also in EE. Gave it up about 15 yrs ago when I couldn't fiind a decent job in the field. :rolleyes:

Yeah, I think that was a tough time when eng jobs weren't aplenty. I've been playing with electronics since I was a kid so I kind of got burned out, but it's fun when done as a hobby... :)

>Currently I'm trying to get an airspeed/AOA sensor going during my brief periods of spare time.

Can't you just use an electronic pressure transducer on a pitot tube? I've never tried but seems easy enough. I'll be looking into pressure transducers soon: need it for altitude hold to keep the plane's pitch level. I'm tired of rotating crooked pictures.

>I'm also interested in a video camera/horizon sensor. Any chance I can combine a couple of functions in one unit I'm interested. Space and weight being my concern in UAV's.

I thought about this, too, and think a camera takes too much CPU power to analyze the image for a cheap UAV.

I thought the simplest would be to use a barometric pressure transducer to do altitude hold and simply use a stable polyhedral glider airplane so that it naturally flies right-side up! Then do GPS for navigation. Also thought about using a gyro to do yaw correction and maybe a 2nd unit to do roll correction to help out the GPS nav against wind turbulence since GPS is only once per second.

>I'm also trying to build a CNC foam cutter as I'm expecting to have to rebuild ALOT during development. :eek:

I found a guy locally who built his own CNC foam cutter to design his own wings who'll help me out. I figure I have to collaborate with others for some of the portions of the project or else it will take a lifetime to do everything myself!

Have you seen the stuff at www.u-nav.com? The PICO-THRT might interest you, either to buy or to emulate. I'll probably just buy his GPS autopilot; don't want to spend hundreds of hours of development to reinvent the wheel.

See ya,

-Vince

[ElectroLawndart]

Hi vpatron,

By the time I got my EE degree NOBODY was hiring. I ended up repairing CD player as a bench tech making $6.50/Hr with a couple of laidoff engineers. Decided it was time for a career change before my career even started.

"Can't you just use an electronic pressure transducer on a pitot tube?"

I'm looking to use one or two of the Freescale pressure transducers. Maybe a differential transducer for the AOA sensor/Airspeed and a absolute pressure for altitude.

"I thought about this, too, and think a camera takes too much CPU power to analyze the image for a cheap UAV."

I was thinking that since I'll have a video camera onboard I might as well make it do double duty. The CMUcam uses a SX microcontroller and it does onboard vision processing.

"Have you seen the stuff at www.u-nav.com? The PICO-THRT might interest you, either to buy or to emulate."

I'm trying for a distributed system where subsystems have their own microcontroller for control and communication and a PIC18 microcontroller as a main controller.

Dart

[vpatron]

Hi Dart,

Thanks for the info re: Freescale Semi. I found their AN1979 has the design for an altimeter and barometer. Definitely useful, I'll just copy the analog interface as-is.

The CMUcam looks neat, too.

Yes, same idea, here, too: distributed PICs with a PIC18 for main control... :) Simple serial network for communicating between modules.

-Vince

[LukeZ]

I'm looking to use one or two of the Freescale pressure transducers. Maybe a differential transducer for the AOA sensor/Airspeed and a absolute pressure for altitude.
Dart, I've just recently built an altimeter/airspeed sensor using Freescale products myself. It is in the final tweaking stages now, but it seems to work well. I used the MPX4115A absolute sensor for altitude (can measure up to about 45,000 feet) and the MPX5010 differential for airspeed. They have pretty user friendly output voltages. I ran them through a buffer op-amp (Texas Instruments TLV2472) for the heck of it, then into a Linear Technology LTC1291 (http://www.linear.com/pc/downloadDocument.do?navId=H0,C1,C1155,C1001,C1158, P1446,D1075) 12-bit, 2 channel A/D converter. The 1291 spits out serial data on an SPI port so it's easy to read with your micro.

With a 12 bit A/D the altitude resolution ranges from about 7 feet at sea level and widens to approximately 40 feet resolution at an altitude of 45,000. The airspeed sensor resolution is finer than you'd probably ever need, and the MPX5010 can measure close to around 300 mph at sea level. Again, however, the resolution decreases somewhat at higher altitudes as the air gets thinner, but it's not a big deal in the case of the airspeed sensor.

Nevertheless, I may try a 14 bit A/D to get better resolution on the altitude, or, as soon as I get a few more brain cells, try what Bill recommended to me in this thread (http://www.rcgroups.com/forums/showthread.php?t=372869).

Anyways, I think you know most of this stuff already but I'm just posting it fwiw.


I'm trying for a distributed system where subsystems have their own microcontroller for control and communication and a PIC18 microcontroller as a main controller.This is precisely what I'm trying to do as well. Currently I'm feeding my alt/airspeed info into a PIC18F452. I also have it reading several temperatures (DS18S20 sensors from TI), voltages, humidity, and next I'm working on current. What I'd like to do is get all this miniaturized a bit and have it be its own stand-alone sensor package with a standard serial port for output. Then I could forget about it and move on to the next component of my autopilot. When the main computer/microcontroller wanted to know anything about altitude/airspeed/temp, etc..., it would simply communicate with this sensor computer who would have all those values ready to go.


Maybe a differential transducer for the AOA sensor/Airspeed ...I'm getting pretty off topic now, but I'm curious how you would use the sensor for AOA? Could you use the same sensor for both AOA and airspeed, just by design of the pitot tube somehow?


Luke

[ElectroLawndart]

LukeZ,

Glad to hear your Alt/AS sensor is comming along. Makes me feel better that I am on the right track.

The AOA sensor is just like two altimeter sensors placed in a verticle plane with something inbetween to split the airflow. When the sensors AOA increases the lower sensor will see a rise in pressure while the pressure on the upper sensor will drop. Some people talked about placing the sensor taps on the upper and lower leading edge of the wing. I will be placing my taps out on a probe about 15 - 20% of chord in front of the leading edge (about an inch and a half). The airspeed data comes for the average pressure of both. I miss spoke on my previous post. I need two differential transducers for this to work.

Dart

[LukeZ]

Dart,
I see: if you have two differential transducers, the static port of both will be common, and the "pitot" or dynamic pressure ports of both will go to the upper or lower taps of your AOA/airspeed sensor, is that right?

Does this in any way degrade the accuracy of the airspeed measurement? Especially perhaps at extreme angles of attack? (I guess even a traditional airspeed pitot tube would give erroneous readings at extreme AOA though...)

I had not thought of this approach before - though I have been weighing the utility of an AOA sensor. In my mind I figured I would just use a vane; this way, however, sounds more elegant and eliminates moving parts. Hmm...


Luke

[vpatron]

Dart, sounds like it should work and is a pretty nifty idea.

I also thought about using gyros. Now I don't know much about them and never used them, but can we use a gyro to monitor the angle of attack and keep the plane flying level? If it needs to be calibrated to a flat position, can it be computed from GPS altitude data?

LukeZ, if I just want a system to hold the altitude (fly the plane flat so I can focus on picture taking), can I just use the PICs internal 10-bit A/D converter? My thought was to get the 14-bit or better accuracy cheaply by using a simple D/A converter (e.g. R2R ladder) to feed a variable reference voltage into the PIC's A/D block to set the conversion range (Vref- and Vref+). The PIC would simply seek the range that sets the A/D input about midrange. This system is only for holding the altitude while GPS provides the absolute altitude.

Anyway, those are 3 ideas for keeping the plane flying perfectly flat: 1) AOA sensor like Darts, 2) Gyro with GPS calibration, 3) barometric pressure using internal A/D.

Will these work and which one is best (simple and effective)? Seems like 3 is the lightest/smallest and easiest to install.


Also, what do you guys do with the airspeed info? Do you fly the plane at some fixed airspeed to keep from stalling yet keep it flying at a slow enough speed for surveillance?

Thanks,

-Vince

[LukeZ]

if I just want a system to hold the altitude (fly the plane flat so I can focus on picture taking), can I just use the PICs internal 10-bit A/D converter? My thought was to get the 14-bit or better accuracy cheaply by using a simple D/A converter (e.g. R2R ladder) to feed a variable reference voltage into the PIC's A/D block to set the conversion range (Vref- and Vref+). The PIC would simply seek the range that sets the A/D input about midrange.
Vince, I think you certainly could do just that. In fact, one reason why my resolution is so poor is that I'm not amplifying my sensor output before I read it on the A/D converter. The reason is that I wanted to be able to use the full range up to 45,000 feet (mostly because it sounds cool, not that I think I'll be flying that high). Although I did mention an op-amp in my design, I use it only as a buffer so no amplification is taking place.

If you don't need to measure altitudes that high, you could amplify the sensor output so your A/D only sees a small portion of your sensor's voltage output range. For example, the MPX4115 puts out approximately 0.2 to 4.8 volts, from 15 kPa to around 110 kPa respectively (here, the higher the kPa and voltage, the lower the altitude). So let's say you amplify and shift the output so that the range of 90 to 110 kPa from the sensor is read as a full shift from 0 to 5 volts on your A/D. Then you'll have much higher resolution for that range.

I'm probably not explaining that very well, but perhaps you already know what I'm talking about.

The variable voltage into the PIC to set the A/D reference sounds like a pretty neat trick - you could use it to adjust the altitude at which the airplane would fly, as you point out. Alternatively, depending on what PIC you're using, you could just read a straight PWM feed from a channel on your R/C receiver. You could turn that into some numeric range by which you could scale your reference altitude. Say you used the throttle stick: full up stick would be read as the number +500 and full down stick as -500, and zero would be in the middle. Then, you could set up your PIC to default to holding steady at 500 feet altitude, plus or minus whatever your adjustment factor was from the RX reading. Moving your throttle stick up or down would move the aircraft to an altitude higher or lower than the default 500 feet. I'm mostly just thinking out loud - of course it would take some work to implement.

As for which of your three aproaches might be best for an altitude hold, I'd agree that the use of barometric pressure will probably be the easiest and I suspect the most effective. Others can feel free to chime in what they think...

Also, what do you guys do with the airspeed info? Do you fly the plane at some fixed airspeed to keep from stalling yet keep it flying at a slow enough speed for surveillance?
Ha! Right now I use it to check the speedometer on my car.:D I'm nowhere near to having a flight-worthy UAV yet. When I do, airspeed is probably not going to be entirely critical - as far as the more interesting groundspeed, GPS is a better instrument. Still, airspeed could be useful in helping measure wind speed and direction, which I will want to know for landing. And I think it will be useful for the purpose of determining the most optimum glide angle (indirect AOA).


I say: might all this not make a decent new thread?

Luke

[ElectroLawndart]

Time to continue this in a properly named thread...

Dart

[sesat]

I'm moving to the Bay Area this fall. Is that considered SoCal or NorCal?

Thanks,
Ram.

[vpatron]

SPlit into two: AOA Sensor by Dart and Altitude Hold by me.

-Vince

[ElectroLawndart]

sesat

That's considered NoCal which means BIG sports rivalries. Dodgers vs Giants, Lakers vs Sacramento, Kings vs San Jose and to this day, to a lesser degree, Rams vs 49'ers even though the Rams left Los Angeles (Anaheim really) 10 years ago.

Dart

[soccercisco]

I'm trying to post this question here and there, to see if anybody is familiar with this frame grabber... If that is the case I have a couple of question regarding Image Acquisition and Processing...

Thanks for your help.

P.S. I am in the SoCAl area if you're still looking for help. I live in Fullerton, but i wouldn't mind driving to work on an UAV project. I can gain experience for my current Senior Project (Vision-based stabilization).

I am an EE student at Cal State Fullerton.

Best wishes.