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Re: [Paparazzi-devel] HW


From: Pardeep Athwal
Subject: Re: [Paparazzi-devel] HW
Date: Tue, 8 Jun 2004 00:14:22 -0700 (PDT)

Hi Chris,
I do agree with most of your points regarding
increasing the budget of the UAV.  If we can achieve
considerable improvements in design and functionality
with a reasonable cost increase then so be it.  

My concern is that many of us have fairly busy lives
with work and family etc.. The thought of one crash
forcing us to be grounded because we must re fabricate
custom components does not sound appealing.

I would hope that we do set standards for hardware so
that all of us are working together to improve one
system.  As with any project there will be divergence,
is it possible to build it in components so that those
of us who would like to spend a little extra can.

While those who do not wish to do so can use the basic
system.  I will let Antoine speak with respect to base
cost and how we should proceed.

I for one would also like to know if there is an off
the shelf or kit available for the infrared sensor. 
If those amongst us who are talented with a soldering
iron could produce units for a modest fee, it would be
much appreciated.  This way we can get more people up
and running and contributing to the project.

I'm not sure if any of you have seen this website yet 
http://www.cyber-flyer.com/
but if you click on the telemetry part you will see an
antenna that tracks the guys RC plane.  He can
actually track his plane while driving.  Very
interesting, maybe he can provide us with the software
and setup he used.  I will e-mail him.

cheers,
Pardeep. 

--- address@hidden wrote:
> Hi to all.
> I will raise a little discussion or hear you'r
> feeling about
> price/functionality of a UAV similar to paparazzi.
> 
> All the price discussion leaves out the RC TX/RX and
> laptop equipment 
> required to operate the uav.
> 
> It's possible to build a full featured UAV
> (paparazzi) for 500$ having TV
> quality live images with options to carry minimal
> other payload.
> 
> With more then the double price, 1000 Euro, it's
> possible to build a
> advanced UAV with spread spectrum RF modems, higher
> imaging quality,
> possibility to add visual processing, having
> redundand sensors.
> 
> With 1500 Euro, it's possible to have better sensor
> resolution, real gyros
> + accelerometers and so one.
> 
> Using LIPO batterys, 40 minutes flight is not a
> problem. 
> This gives a theoretical 10-15 Km range.
> Only this fact is amazing, having real time video.
> 
> I know, that if building some components itself, the
> 1000 Euro UAV can be
> made at 700 Euro. It's the question, if one should
> use COTS parts or 
> developing the subsystem itself. 
> Hacking a CDROM motor to a brushless motor gives big
> cost savings,
> for other thing, the story can be different. One
> example can be the air
> frame.
> 
> Dont misunderstand me, i'm not telling, building a
> low cost UAV
> with `limited' functionality is wrong. Building UAV
> is funny. I 
> seriously ask myself and you, if it's better to
> build a 400 Euro UAV
> , than building one for 1000 Euro with many more
> possibilitys.
> I'm not interrest in building a UAV bussiness for
> lowest cost UAV.
> Building a low cost UAV, expanding it later to
> higher capability, better
> sensor processing involves developing the UAV two or
> tree times.
> The hard part is sensor fusing and controlling the
> UAV.
> 
> Annother thing is, there is a high risk, that this
> project spin off like
> the autopilote one. Ok, the open source autopilot
> project don't work
> reliable, the paparazzi make the job a lot better.
> 
> As example, adding pressure sensors will increase
> the stability noticable.
> Using the usual motorola part, means a price
> addition of 20%.
> The stability is not only in the Z axis. The
> atmospheric pressure can be
> used to evaluate the overall gps precision. If there
> is a noticable
> error on the Z axis, it's highly probable, that the
> x and y axis are not
> accurate. As a result, with more gps error, a minor
> weight can be added
> to the error value. CA grade GPS updates the Z axis
> only at 1HZ interval.
> Additionally, this gives stability, if the GPS
> signal is absent for some
> time, and simple failsafe, in order to don't go down
> at to high speed.
>  
> Using the pressure sensor have influence to the
> altitude software.
> In order to recover the UAV, if less than 4 GPS
> satellite are in field,
> using 10 degree apogee instead of the default 5
> degree for higer precision,
> the altitude must be measured relative to the start
> altitude, in order to
> land without GPS altitude information.
> The simple approach of storing the start altitude
> don't work, because the
> pressure is not absolute and must recalibrate during
> flight at certain 
> intervals. If the uav, after one hour return and
> must land using the 
> pressure sensor, the software is never able to
> recalculate the pressure
> from the stored height value. Storing the initial
> pressure don't takes
> in account the recalibrations.
> 
> Depending on the planned usage, each of the list
> member has other
> constraints and needs. It's nice, if the base UAV
> can handle most of the
> features wanted. 
> 
> As example of different features for the same goal.
> You want higher GPS update rates in order to improve
> the overall GPS
> performance . On higher update rates, it's possible
> to apply better filter
> in order to get good coordinates.
> I want better precision from gps unit with minor
> update rate.
> The same goal, better GPS precision, opposite
> features wanted resulting
> in different firmware. What solution is better ? i
> don't know the response.
> 
> chris
> 
> 
> 
> 
> 
> 
> currently i review my uav.
> I have found 19k2. full approved bidirectional RF
> Radios for 100$ each ( 40$
> in 1K quantity). The range is more than 14Km.
> Low cost 1Hz GPS with code for areal mode that go
> into 2D mode, if only 2-3
> GPS satellites are visible and capable of generating
> DGPS infos. 100$ /
> each. It's capable of giving 3D velocity values.
> 3D compass, pressure sensors, little MCU , IR
> sensors 100 Eur
> bigger cpu 100-200 Euro
> high resolution camera with webcam function 100-150
> Eur
> 
> communication: 200
> position       200
> sensor+MCU     200
> Imagery        200
>                ----
>                800
> 
> building two, one without imagery acting as RF relay
> for short range RF
> modem = 1100
> 
> 600 Euro / UAV
> 200 Euro / Control station + laptop/computer.
> 200 Euro / more processing power.
> 
> I can build one for 1000, two for 1500
> 
> No DGPS, 200+200+400+200=1000 Euro.
> 
> UAV:
> 100 GPS
> 100 Sensor
> 120 2Mb USB camera
> 140 200MH Xscale CPU
> 200 Model + servos
> 100 Modem
> 60  Battery
> -----
> 800 Euro
> 
> Base:
> 100 Modem
> 100 Support logic + Joystick or RC interface for
> manual flight
>     Computer
> -----
> 200
> 
> Optional:
> +50 400Mh Xscale CP
> +100 DGPS
> +100 3M camera
> +160 4M camera with triple optical zoom.
> 
> 
> This is twice the target price.
> Removing the higer resolution camera and higher
> processing power, 800 Euro
> remain.
> 
> Plain paparazzi solution:
> UAV:
> 200 Frame + servo
> 100 GPS
> 100 Sensors+MCU
> 150 TV trasmitter/receiver
> 
=== message truncated ===



        
                
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