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morphy_richards
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Re: Skutter v0.1

Sat Mar 31, 2012 5:50 am

In the command dev.ctrl_transfer
"The first four parameters are the bmRequestType,bmRequest,wValue and wIndex fields of the standard control transfer structure" ( http://pyusb.sourceforge.net/d.....orial.html)

All these args are explained in this page
http://www.beyondlogic.org/usb.....usb6.shtml

…USB in a nutshell! Love it!

It's also worth mentioning here that another requirement for usb programming in python is to also install libusb (core usb functions written in c) or openUSB(which itself is based in libusb). You need to install either of these before you try to use pyusb as pyusb is a backend.

Jaseman
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Re: Skutter v0.1

Sat Mar 31, 2012 8:46 pm

It all sounds awesome to me.  When you have figured it all out, please document exactly what needs to be done.  I'm sure others will try to do this.

Do you have any more photos of the arm built?  Or maybe you could do a Gert-style video?

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morphy_richards
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Re: Skutter v0.1

Mon Apr 02, 2012 8:23 am

Here's a photo of the arm - it's not entirely finished but everything works. (Well except I think I mounted the base gears backwards and it cant rotate properly, will fix that in due course but for testing programming purposes it's fine). As I'm going to add some sensor modules I haven't bothered putting the cover over the electronics or tidied the wiring up yet. (I sort of prefer it looking that way anyway)



Annoyingly I got in this morning and found that the virtual disk image of Debian / virtual raspberry pi has been wiped off my computer in my office. I don't know how but it might have been my fiddling around with cloning on Friday that did it. I'm currently marking coursework with a re-install going on in the background once it's finished I'll upload a vid of it working

Jaseman
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Re: Skutter v0.1

Mon Apr 02, 2012 8:43 am

Thanks very much for the picture.  I want one!

I wonder if you would be interested in writing an article about this for The MagPi magazine?

Even without the added sensors, it would be very interesting to a lot of people.

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morphy_richards
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Re: Skutter v0.1

Mon Apr 02, 2012 8:58 am

I'm toying with the idea of an article. In the meantime I'm kind of using this thread as a sort of jotter / notebook. I can refer back to it if neccessary (like I will need to this morning to help me reconstruct my pyUSB1.0 enabled virtual Raspberry Pi computer and the code I'd figured out) and in the meantime if anyone's interested they can follow it and perhaps apply it themselves.

I used to read 'Everyday with Practical Electronics' magazine and there was a regular column by someone writing under the pseudonym "Max Fiddling" and he wrote funny little anecdotal stories about electronics projects in his garden shed (and his amusing pet cat) - the stories were detailed enough to allow you to try the projects yourself but were also quite a good read and quite educational even if you didnt try the project out.

I may have to come up with a similar pseudonym and have a go at that kind of thing

Ravenous
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Re: Skutter v0.1

Mon Apr 02, 2012 9:18 am

I just noticed you have a Kinect camera thing at the side... apparenty there are people using those on Linux robots too you know...

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morphy_richards
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Re: Skutter v0.1

Mon Apr 02, 2012 9:46 am

Yes I"ve been fiddling with that as well. A drawback is that it demands quite intensive hardware from it"s host computer. Mainly it"s part of the "reboot" being planned for next year – I want to be able to offer the option of programming gesture driven computer games. RM security over Windows 7 makes things a bit tricky but I"ve decided I"m going to buy a really good laptop (and use most of my budget in one go) which I will keep away from RM and leave as "standalone" and allow students to develop on it.

It"s also got some uses for "inclusion" whereby students from our Resources area who have "PMLD" (profound multiple learning difficulties) will be able to do activities in a new and interesting way.

I should really make a separate thread for this idea. (But really I want to make a big robot like Johnny 5 from Short Circuit and want to use the Kinect as it"s eyes / head.)

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morphy_richards
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Re: Skutter v0.1

Mon Apr 02, 2012 1:44 pm

OK - so here is a little vid of the arm in action (sort of)

I'm still figuring out the command codes at the minute - what I do doesn't quite seem to tally with what's been published. I suspect it may because I am sending command codes to the USB as literal strings and characters and the interface is interpreting the byte values - ie instead of receiving "1" it's getting "49" (or the ascii value) but I may well be barking up the wrong tree.



Apologies for the video quality - I wanted to show the step by step code changes I was making on screen but the camera isn't good enough. (Typing and clicking with one hand and filming with another isn't particularly great either)

Jaseman
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Re: Skutter v0.1

Wed Apr 04, 2012 9:09 pm

A perfect plastic dinosaur removal tool.

Was the robotic arm easy to assemble?  I mean could a real novice like me manage it or do you need a certain amount of electronic skills?

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morphy_richards
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Re: Skutter v0.1

Fri Apr 06, 2012 5:21 am

It"s really easy. A bit like building an airfix model using screws instead of glue. All you need is scissors and screwdriver.
The electronics are preassembled so all you need to worry about is plugging the right wire into the right plug (and if you get that wrong the worst thing that happens is left becomes right or the shoulder activates the gripper)
It took me about 2 hours to put together.

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morphy_richards
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Re: Skutter v0.1

Fri Apr 06, 2012 4:42 pm

I"m going to sign off this version of the scutter. Scutter v0.2 will involve trying to create some simple positional feedback modules. Will keep you posted

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morphy_richards
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Re: Skutter v0.1

Tue Apr 17, 2012 11:28 am

Just for fun ....


rob+pi
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Re: Skutter v0.1

Mon Apr 22, 2013 9:42 pm

and here is the link to the Skutter v0.2 thread.
FYI it should be "scutter"(according to google), though plenty of people still refer to them as skutters.

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