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Author Topic: Computer WiFi Control of model boat  (Read 2622 times)

banjo

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Computer WiFi Control of model boat
« on: January 12, 2007, 09:51:24 AM »

Hi people,

Am I being sold a pup?

My son says he can fit my boat with the following to enable control from my laptop/Joystick:-
A mini EPIA motherboard
a servo control board ( can control up to 16 servos)
and also lights audio web cam etc

Comments please?
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DickyD

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Re: Computer WiFi Control of model boat
« Reply #1 on: January 12, 2007, 09:59:34 AM »

If he's younger than 15 he can probably do it.

Richard ;)
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Re: Computer WiFi Control of model boat
« Reply #2 on: January 12, 2007, 03:24:33 PM »

How long will your laptop run for on internal battery. Couple of hours ?

Something to consider maybe.
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Peterm

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Re: Computer WiFi Control of model boat
« Reply #3 on: January 12, 2007, 03:33:17 PM »

Range?  Pete M
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johno 52-11

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Re: Computer WiFi Control of model boat
« Reply #4 on: January 12, 2007, 04:07:38 PM »

This should be possible as long as you can get the right input and output at each end. all you are doing is getting one computer (your laptop) to control and pass data to another computer which is in the boat. all the WiFi is doing is replacing a physical connection a cable with a radio signal.
The advantage is that a data network is two way so you can get data back from your model webcams etc.

A good modern laptop should be able to run for 3 to 4 hours off a battery and WiFi range can be increased by directional antenna. (Google Cantenna)

The downside would be the cost and you may have a problem with interferace from other WiFi Networks if there are any near where you sail.

John
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banjo

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Re: Computer WiFi Control of model boat
« Reply #5 on: January 12, 2007, 04:26:21 PM »

Hi,
The Laptop I have,
The servo card is about 29 from some outfit called PARALLAX.com
He has spare WiFi gear loafing about his room.
I will keep you posted if it is of intrest

alan
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grasshopper

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Re: Computer WiFi Control of model boat
« Reply #6 on: January 12, 2007, 09:54:29 PM »

This is definitely of interest, with two way communication you could have remote vision via your screen from onboard cameras - just think of the advantage on a steering course....good thing that I've got a teenager to help sort this one out...please keep us informed.
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Scottie

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Re: Computer WiFi Control of model boat
« Reply #7 on: January 13, 2007, 12:28:34 PM »

Spektrum do a system (designed primarily for cars) that has an option for telemetry.
Have a look here if it's of interest -
http://www.rchobbies.org/spektrum-telemetry.htm

Scottie
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johno 52-11

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Re: Computer WiFi Control of model boat
« Reply #8 on: January 13, 2007, 06:12:54 PM »

This is definitely of interest, with two way communication you could have remote vision via your screen from onboard cameras - just think of the advantage on a steering course....good thing that I've got a teenager to help sort this one out...please keep us informed.

You can get video back from a boat with wireless cctv kit the works in the same frequency range as WiFi As I have fitted it to my Friends Severn Class Lifeboat http://www.lifeboatmodels.co.uk/severnvideoclips.htm see the "Video From the Wheelhouse" about Half way down the page.

John

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malcolmfrary

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Re: Computer WiFi Control of model boat
« Reply #9 on: January 14, 2007, 06:17:50 PM »

I had a look on
http://www.theregister.co.uk/2003/09/15/atheros_triples_wifi_range/
which is a site for a company claiming to"extend wi-fi beyond 100 yards"
Reading the page implies that data transmission speed drops off as range increases.  This could be a problem if there is an adverse effect on, say, speed of responce to steering.
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Re: Computer WiFi Control of model boat
« Reply #10 on: January 14, 2007, 07:10:20 PM »

I looked into this a while ago, and while feasible, requires a certain amount of work......

For a start, if you are using PC at the recieving end you need to make sufficient amount of space. A MicroITX board (e.g. the EPIA boards) is 17cm square. Add onto that the power supply. You will need to provide 5V +/-10% - it cannot be driven striaght off the battery, you will need a suitable regulator. You will need to provide sufficient cooling. A fanless unit will make this easier, but still there are issues to be addressed.

To store the code you will need to either organise a suitable cushioned hard drive or you will need to have a solid state drive - these are not cheap. Then there is the problem of the operating system for the PC - you will need a suitable base to run the code on. This will involve compromise - a windows based system will require boot-up time. There is also the problem of what happens if you get a BSOD while out on the pond. Also if the battery does go, the processor will go into  reboot cycle - there will be no graceful degradation of control. You therefore need some battery monitoring or to guarantee sufficient AH capacity for the time you want to run for.

IIUC, there is not an off-the-peg solution to this sort of application, so you will have to code up the top and bottom end software. This will require someone with a reasonable knowledge of how to correctly implement TCP/IP comms. Also there is the issue of how to get the control information into the laptop - buttons and sliders on the screen are OK for auxiliary controls, but the input for the steering and throttle(s) probably requires a bit more finesse.

The project is not a trivial one - it does offer possibilities for larger models with a large number of options, though unless an off-the-shelf solution definately does not meet you requirements, I would say that the project is not economical and should only be undertaken as a project in its own right.

Tim the Wombat
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johno 52-11

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Re: Computer WiFi Control of model boat
« Reply #11 on: January 14, 2007, 07:22:09 PM »

I had a look on
http://www.theregister.co.uk/2003/09/15/atheros_triples_wifi_range/
which is a site for a company claiming to"extend wi-fi beyond 100 yards"
Reading the page implies that data transmission speed drops off as range increases.  This could be a problem if there is an adverse effect on, say, speed of responce to steering.

If you need to know how to extend the range on WiFi lans have a look here http://www.wirelesspro.co.uk If your doing line of sight which you are with a model then you could probable get a range in excess of 2Km. I have seen some point to point WiFi kit that quotes range of 4 Km but thats static line of Sight.

John
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wombat

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Re: Computer WiFi Control of model boat
« Reply #12 on: January 14, 2007, 07:35:26 PM »

I would say that range is not an issue on WiFi - if you are prepared to pay the dosh for the long-range antennae, you can exceed line-of-sight

Wom
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SonofBanjo

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Re: Computer WiFi Control of model boat
« Reply #13 on: January 18, 2007, 04:35:06 PM »

I come to this from a background in Car PCs so I have faced a few of these problems.

You are absolutely correct on the size of the motherboard however the PSU I would use is tiny and is designed to cope with an input range of 6-26v.  http://www.mini-itx.com/store/?c=10#p1835  Also as you will see there is no problem with it cutting out when the battery runs out.  If you have more money to spend you could get a Nano-ITX which is 12x12cm.

Heat should not be a problem.  Our puposes are not at all power hungry.  We can get the slowest, cheapest EPIA motherboard and without maxing out the CPU it will not give off much heat.  A bit of airflow is an advantage but not totally required.  If you were to put this in very cramped area with no air intake I would advise to use the versions with a fan as this will stir around what little air there is.

For a harddrive you can use either a laptop one or a compact flash card.  There are no special mounting options required, laptop drives are a lot studier than their desktop counterparts.  Compact flash has the advantages of size, speed, even more robustness and using a lot less power.  The price has fallen dramatically due to the popularity of digital cameras and you can get a 1GB card for 14 or a 2GB for 18.  With compact flash you must use the EWF, it is optional for a laptop hardrive.

Running windows XP and using some optimisations it is easy to get the boot time down to 20s or less if you are more skilled.  There are a number of things to do including disabling hardware we are not using, running from compact flash, use tinyxp or nlite to strip down xp to what we basically need, borrow minlogon and the EWF from windows embedded, store a hibernation file so that each time we start we are returning from hibernation instead of loading everything up again.

EWF is the Enhanced Write Filter.  What this does is store any changes we make to the disk to ram instead and then we can decide to merge them back in or forget them entirely.  It is required for compact flash because CF only has a set number of writes and with windows we would use this up in a matter of days.  In this application we can store a hibernation file on drive/CF to start from.  The applications never write to disk, they simply communicate over WiFi so when the power is cut off all changes are lost and we start again with our hibernation file at next boot.  This way we don't have to worry about corrupt files and need no shutdown control.

WiFi range is from 100m-400m with standard antennae depending on whether you have a/b or the latest g.  With a directional antenna you could get a range of several km but you won't be able to see the boat by then. :)

Software you would have to code, but I will probably make mine in such a way that it is quite configurable and share it with whoever is interested.

For control, there are a number of options, you could use a PDA or PSP or a laptop with a standard joystick or steering wheel.  You could even control it with Bluetooth from your mobile phone.  I was planning to use a Playstation controller with a usb adapter (connected to a laptop) as this is most like a normal RC controller.

A lot of this kit is quite expensive, my estimate puts it at around 125-175 if you buy it all brand new.  But the good thing is that because they are all standard components, some you may have lying around already or otherwise there are a lot for sale on ebay.
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wombat

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Re: Computer WiFi Control of model boat
« Reply #14 on: January 18, 2007, 06:47:59 PM »

Hi SonOfBanjo,

I would still want to put a bit of care inot the power supply - gl;itches can have all sorts of odd effects (been there - done that). I haven't any experience with Nano-ITX because the EPIA chipsets aren't quite powerful enough for me. I tend to use EBX format. A less powerful processor will ease the problem - but in a fibreglass hull there could still be an issue. The heat can build up as the hull is fairly well insulated. Of course this will be less of a problem.

XPE will boot quickly with the newer modes, though I have no experience with stripping XP. If you use Win95, you can get the footprint down to about 12MB. I haven't use EWF outside of the Embedded workbench so cannot comment. I would suspect that with care you can set Flash to avoid too many writes, but then again if you have a smart flash, it will automatically correct for failing bits of the filesystem.

I wouldn't underestimate the coding time - been there and done that. Not a non-starter, but something I would say to be undertaken as a medium term project in itself.

Tim
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