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More Wanging of Wellies

Well, I don’t really want to give too much away about the design, but our welly wanger for the Scrapheap Challenge Roadshow is now coming along – Ian has been really busy with building a motorised chassis to move the whole contraption around on, and has even built the rotor arms, however the hub was mounted a little too low, so the wellies kept hitting the chassis, so I set about it with the angle grinder and welder and raised the height of the hub buy about 8 inches, providing more than enough clearance.

Our decision to use paired wellies to balance each other looks to be a good one, as when we ran the rotor with only one welly on it, there was a certain amount of bouncing induced into the whole machine.

We also ran the machine with 2 wellies which was a lot more stable, and succeeded in chucking one (unintentionally) a reasonable distance, even though it was released near vertical.

20060806BuildDay/DSC_1381.jpg

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Fun with ballistics

I’m writing some software to control the welly wanger, and am having to do some nasty ballistic calculations.
I’ve got some code that implements some of the equations, but not everything is straightforward. I need to determine a pair of variables (rpm and launch angle) from the desired distance – the competition is not just about throwing it as far as you can, but hitting targets, so being able to calculate desired parameters is vital. Of course, solving this way will not result in a single pair, but in multiple value pairs, so my initial guess is to fix the RPM as close as possible to the maximum, so we don’t have to control the motor directly, and just alter the release angle.
We do intend to have some form of PWM control of the motor driving the rotor, but I’m not sure how well the starter motor will react to rapid switching from the microcontroller.

The other issue that I have is solving for release angle, as the release angle determines the release height, as well as the trajectory, which confuses the issue somewhat, and is making my head hurt somewhat. I’m going to have to consult a proper mathematician to help me with the algebra.

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Scrapheap challenge roadshow again

I had a phone call from RDF media last week, informing me that our team for the second scrapheap challenge roadshow had been accepted, and that we could start building our welly wanger.

20060619Welly/DSC_1077.jpg

This is a different team that entered the Sofa Speedway, and I’m the team captain this time, together with Andy Shaw and Ian Izett, we are building a computer controlled welly chucker, that will have an on-board microcontroller, witha USB interface to a laptop that will perform all the complex calculations that are required to be able to control the distance that the welly will be thrown.

It’s all taking place at The Great Dorset Steam Fair on the 30th August, so we’ve got to get busy with the building and programming, so that we can have enough time to train the artificial intelligence in the control software to the physical aspects of the machine.

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Power outages in Mid Wales

This server is likely to suffer a little of the yo-yo mode because:

The power outages at the University today have been caused by a
problem with Manweb overhead equipment and has affected a large part
of west Wales (SY23, SY24 and parts of LL35 and LL36 postcode areas).
They currently have no information on how long it will take to resolve
the problem and until they do there is the likelihood of further power
cuts.

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Crossing borders with laptops

Next time you cross a border with your laptop, don’t be suprised if they want to examine the data on it.
Ars Technica have just posted an article about examination of data in the US at international airports and borders. Don’t think that you’re safe in the UK either – they’ve been doing it since at least 1998 as reported by the BBC

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Nikon customer service are stars.

I sent the D70 off about two weeks ago to Nikon, and it took them a week or so to check it into the system. They told me that it would be probably five or six weeks before I would see it again. True I wasn’t being charged for the repair, even though the camera is out of warranty, but six weeks seemed to be an inordinately long time to be without my DSLR. :’-(

So how suprised was I when the neighbours came over tonight with a parcel conaining my Nikon, completely repaired. 😀
A quick couple of shots, and it turns on again, and responds to the controls again instantly, and the shots that I took are perfectly exposed.

Off to look at a boat with Dad tomorrow – so I’ll be able to take some photos. (P)

Happy 🙂

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Fun with Google Earth

I got my GPS reciever back today, and in the car on the way home I thought that I’d put it to use, so a bit of wardriving with Kismac was in order. It appears to have been seriously updated since I last used it – you can now save the points directly to a file to load into Google Earth. Just with the PowerBook sat on the passenger seat, no external aerial it still managed to pick up a lot of access points, so I’ll take a different route through town tomorrow, and extend the survey – maybe when it’s a bit more complete I’ll actually upload it and share it with all of you out there in Aberystwyth.

I’ve also been mapping some of the places I visited in France, mainly where I took photos and such, and I’ll upload those when I’m done with them – I’m not sure if I can be bothered to map the whole route, but I’ve got all the overnight stops and that gives you a pretty good idea of how far I travelled.

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France Photos

Well, I have finally got up all of the photos that I managed to take whilst in France. 2006france/DSC_1241.jpg (Click on the picture and it takes you to one of the photos in the album – there are about 90 photos there.)

Some are badly exposed because of the problems with the exposure mechanism in the D70, which is about to be posted off to Nikon UK for free repair.
I will write more about the trip later.