[Top][All Lists]
[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]
[Paparazzi-devel] Re: Paparazzi UAV Project
From: |
antoine . drouin |
Subject: |
[Paparazzi-devel] Re: Paparazzi UAV Project |
Date: |
Fri, 16 Apr 2004 11:45:09 +0200 |
User-agent: |
Internet Messaging Program (IMP) 3.2.1 |
Hi Hugo
We are still using infrared sensors.
When we have the cerfboard flying, we will try again with inertial ones.
Regards
Antoine
Selon Hugo Vincent <address@hidden>:
> Hello again Antoine,
>
> I forgot to ask you what your main flight sensors are now, with the
> CerfBoard configuration? Are you still using the Infrared sensors, or
> have you moved across to the inertial type, gyros and accelerometers?
>
> On 16/04/2004, at 7:42 PM, address@hidden wrote:
>
> > Selon Hugo Vincent <address@hidden>:
> >
> > Hi Hugo
> >
> >> Hi Antoine,
> >>
> >> Thanks for your prompt reply. I will check the CVS again in a week or
> >> two, and look forward to seeing what you have been up to.
> >>
> >> Would it be fair to say that you are moving more to the AUTOPILOT
> >> topology - I mean with the Linux board and so on?
> >>
> >> Do you think there is still a need for two AVRs when you have a
> >> CerfBoard? What sort of interface are you using to talk to the AVR
> >> from
> >> the ARM CPU. (BTW, XScale == (ARM + extensions))
> >
> > I Like the idea of having two avrs:
> >
> > - For robustness : the code in the small avr is short, well tested
> > and frozen.
> > If you put a bug in the big avr where the code is bigger and more
> > complicated, you will still get manual control, health supervision and
> > failsafe.
> >
> > - the parameters of the small MCU are tuned during the first test
> > flight of an
> > airframe and never changed after that. So, no risk of trashing these
> > vital
> > settings when playing with autopilot gains and flashing the big MCU
> >
> > - another advantage is that it gives alot of spare "power" in the
> > small avr to
> > implement PCM decoding ( I think we really need that ) and lets you be
> > less
> > "realtime" in the big avr.
> >
> > - we want to keep developing the avr-only system because is is
> > simple, cheap,
> > light and has a low power comsumption. It is very well suited for the
> > smallest
> > aircraft. We intend to fit one in a 300g airframe.
>
> wow, 300g!!
> Like i said, i am new to RC, so: what is the advantage of PCM? just
> better range and signal quality? or something more subtle...
>
> >
> > We are using RS232 to talk between the big avr and the cerfboard.
> >
> >>
> >> I am going to buy a cheap airframe real soon -- do you recommend the
> >> Twin Star? I am kind of put off by the twin motors.
> >
> > The twinstar is a good airframe. It flies well and is very "heavy
> > duty". The
> > "high wing - twin engine" configuration has advantages and drawbacks.
> >
> > advantages : it leaves space in the fuselage - namely in the nose of
> > the
> > aircraft - it is very handy to put the camera and the video
> > transmitter.
> > it protects the motors and propeller during belly landings.
> > it's easy to hand launch
> >
> > drawbacks : if you want to use high end motor, you'll have to buy
> > two...
> > if you want to use brushless motors you'll need two controllers.
> > Generally
> > speaking, one big motor has a better efficiency than two small.
> >
> >> Approximately what
> >> is the payload weight capacity of that airframe?
> >
> > well... it depends. With a 8*2400mAh nicd, it weights about 1300g. We
> > have flow
> > one up to 1600g.
> > I would say payload is between 200g and 500g depending on battery
> > weight.
>
> ok, how much of the 1300g is batteries?
>
> >> Also, what
> >> approximately is the battery life like?
> >
> > What do you mean life ? for flight duration, with the stock electric
> > motor, we
> > get 17 minutes with a 8x2400mAh nicd packs. We also have a 8x3300 nimh
> > (same
> > weight as previous pack) which give 25 minutes flight.
> >
> > We have buit a new fuselage with 2P3S 2000mAh lipo. It shoud give much
> > longer
> > flight time. We are also working on a new wing with brushless motors
> > to further
> > improve flight time.
> >
> > For how the battery behave in time. Nicd tend to be robust and last
> > long. NiMh
> > tend to be more fragile (last less than a year, maybe 100 cycles). We
> > have very
> > little experience with lipo cells.
>
> I did a project at work with Lithium Ion cells on a handheld computer
> design we were working on -- a charger and power supply unit. At least
> with the cells we were using, they prefer constant, lower current draw,
> i.e. not 30A, and not on-and-off, but if they had to, they can supply
> fairly the high currents. I am not 100% sure about the differences
> between LiIon and LiPo, but have heard LiPo have a shorter life cycle
> (# of charges) but have a better energy density. I have heard that
> after around 1000 charges for LiIon or 500 charges for LiPo, the total
> capacity is about 1/2 of what it was new. I would guess that high
> discharge rates would decrease them somewhat.
>
> For comparison, the RCtoys Predator
> (http://www.rctoys.com/predator.php) apparently runs 1 hr 30 min on
> LiPo, and 16-20 min with the NiCad. There battery pack is 7.4V,
> 4200mAh, for US$139. A quick look at www.jelu.se which sells (among
> other things), surplus Nokia LiIon cells of 3.6V and 1200mAh capacity
> for about US$13. So 6 of them for about US$80 would give 10.8V and
> 4400mAh!!! Maybe too heavy though.
>
> The charging is a lot more complicated for Lithium, than for Nickel
> cells. But you can get nice single chip solutions to do it (we used the
> MAX1649 + an ATtiny micro).
>
> >> I am definitely keen on getting
> >> started with an electric model.
> >>
> >> Would I really need a test pilot? Can I just teach myself to fly it :)
> >
> > It's you to see, but it may take a little time before you are
> > confortable with
> > flying.
> > I think an experienced pilote will better handle the emergency
> > situations that
> > might occur during initial test flights. Furthermore, it is very handy
> > to be
> > two. One will keep his eyes on the airplane, the second one on the
> > laptop screen.
> >
> > If i were you, i would buy two aircraft. A small one like a multiplex
> > pico cub
> > to teach you flying and a second one like a twinstar to test flight
> > your autopilot.
> Are there any other airframes that you have been eyeing up, thinking,
> "that would be perfect for this project"?
> > I'm sure you will be less stressed when you learn to fly if you don't
> > risk your
> > precious electronic toys (GPS camera cerfboard).
> >
> > Anyway, I think it's a good idea to have contacts with a modele
> > aircraft club.
> > People there know well how to build/fly model airplanes and it will
> > save you
> > time and money.
> I agree. I am working on it...
> >
> >> If you are offering, I would really appreciate a blank PCB -- they are
> >> unreasonably expensive to get made over here in NZ.
> >
> > I will send you one when its done, in a couple of week. It will be a
> > panel with
> > several PCBs (ground_modem, programmer, ir_sensor, ctl_board,
> > power_supply, GPS).
> >
> > Maybe you'll want to review the routing/design before i send it to fab.
> >
> >
> > Maybe we could continue this discussion on the mailling list so that
> > other can
> > participate
> >
> > Regards
> >
> > Antoine
> >
> >>
> >> Regards,
> >> Hugo Vincent
> >> address@hidden
> >>
> >> On 15/04/2004, at 7:49 PM, address@hidden wrote:
> >>
> >>> Hi Hugo
> >>>
> >>> Selon Hugo Vincent <address@hidden>:
> >>>
> >>>> Hi Antoine,
> >>>>
> >>>> I am a university student in New Zealand, currently in third year
> >>>> Electrical/Computer Engineering. I am planning a UAV project as a
> >>>> hobby
> >>>> project, and part of it would be my thesis. I have been writing a
> >>>> document describing some of the aspects of it, that I have attached.
> >>>> Lots of things in it are wrong or incomplete or subject to change,
> >>>> but
> >>>> you'll get the general idea. I am looking at using an AVR and an ARM
> >>>> processor, with a similar topology to your paparazzi system (AVR for
> >>>> real-time stuff- RC reception, servos, etc., and the ARM for
> >>>> navigation
> >>>> and stabilization). I am new to RC aircraft and don't really know
> >>>> where
> >>>> to look, but I have experience with the electronics and software
> >>>> sides
> >>>> of things.
> >>>
> >>> That is a very good news. I have some experience with RC aircraft but
> >>> less with
> >>> electronics :)
> >>>
> >>> If you are new to RC aircraft, you will need a test pilot for your
> >>> project.
> >>> Maybe you should look for a local RC aircraft club.
> >>>
> >>> Regarding the topology of our project, we use a 3 levels/processors
> >>> architecture.
> >>>
> >>> We have a small avr mega8 mcu which is responsible for radio control
> >>> decoding,
> >>> servos actuating and low level monitoring (like battery). With this
> >>> MCU alone,
> >>> you are able to fly the model in manual mode.
> >>>
> >>> We then have a second MCU, an avr mega128, wich is responsible for
> >>> measurments
> >>> (ADCs, compass etc...), low level control loop, telemetry
> >>> transmition,
> >>> etc...
> >>> With both MCU's our aircraft if capable of fully autonomous
> >>> navigation.
> >>>
> >>> We intend to expend the system with a third high level processor
> >>> which
> >>> would
> >>> allow intensive computation and network communication. We have an arm
> >>> cerfboards running Linux that is almost ready to test flight. We
> >>> intend to
> >>> connect it to a 800MHz radio modem (coronis wavecard
> >>> http://www.coronis-systems.com/produits/PageProduit.php?
> >>> IdCategorieProduit=21)
> >>> and to our real time controller board.
> >>>
> >>>>
> >>>> I just found about your project today, and have been reading the
> >>>> mailing list archives etc. It seems you project might be headed
> >>>> where
> >>>> my one wants to begin, at least in terms of electronics and
> >>>> processors... I am more interested in a longer duration (therefore
> >>>> gas
> >>>> powered) airframe, but an electric drive is so appealing for
> >>>> convenience reasons...
> >>>
> >>> The airframe is not really important at first. Use something cheap
> >>> and
> >>> realiable
> >>> to devellop your autopilot. When it's done, you can then mount it on
> >>> a
> >>> sophisticated airframe.
> >>> We use the twinstar because it flies well, is cheap, can fit in the
> >>> car, doesn't
> >>> need a runway etc... Someday, when i have time, i will mount a
> >>> paparazzi
> >>> autopilot in one of my gas aircraft.
> >>>
> >>>>
> >>>> I would be most interested in your views and opinions about my
> >>>> ideas,
> >>>
> >>> I think your project is heading in the good direction.
> >>>
> >>>> and maybe the possibility of working together. I look forward to
> >>>> hearing back.
> >>>
> >>> Working together would be great!
> >>> We have spend past weeks writting documentation, reorganizing code
> >>> and
> >>> writting
> >>> user interface. I will update savannah in the following days and
> >>> announce it on
> >>> the mailing list.
> >>>
> >>> I am now designing a new version of the controller board. I intend to
> >>> have PCBs
> >>> build by eurocircuits. I could send you one of these when they are
> >>> done.
> >>>
> >>>
> >>> Regards
> >>>
> >>> Antoine
> >>>
> >>>>
> >>>> Regards,
> >>>>
> >>>> Hugo Vincent
> >>>> address@hidden
> >>>>
> >>>>
> >>>
> >>>
> >>
> >>
> >
> >
>
>