USB Robotic Arm

[Jaseman]

I found this £45 robotic arm kit:

http://www.maplin.co.uk/roboti.....8;t=module

I wonder if it is possible to control this kit from within Python on a Raspberry Pi?

I think a lot of beginners might prefer this as an intro to hardware education, before trying to attempt soldering a GPIO header onto their Raspberry Pi so that they can dive into 'Gertboard' - If that even becomes commercially available as product that you can buy.

If they can just plug in to the USB port, it would get them started a lot quicker.

[RaTTuS]

Probably not [easliy] as the drivers are Win32 stuff

[greypower]

I'm afraid this does not get a good write-up on the Maplins forum. See:

http://forum.maplin.co.uk/view.....c.php?t=33

See contribution from a "Joe Doe" on this topic. Looks like a "no-no" from several points of view.

[Prometheus]

Though the device as-is is restricted by its drivers to Microsoft Windows only, the robotic arm has been made to work with Linux. More information is available at the links below;

http://www.linuxquestions.org/.....rm-851033/

http://code.google.com/p/mapli.....for-linux/

[Jaseman]

greypower said:


I'm afraid this does not get a good write-up on the Maplins forum. See:

http://forum.maplin.co.uk/view.....c.php?t=33

See contribution from a "Joe Doe" on this topic. Looks like a "no-no" from several points of view.



Well he did say that 'Its cool and works realy well' providing that he used his own software, and other reviews looked quite positive.  Hopefully there is enough talent amongst the Raspberry Pi community to come up with something.

Nobody is expecting this robot arm to be fantastic at that price, but it might be of interest to some.  You always get some people that will complain about any product.  I suppose it depends upon your expectations.

[JonB]

I haven't followed the link but I assume you are talking about the cute littel yellow and black number that costs about £30.

If so, is is actually an OWI EDGE 535 arm, and there is quite a fair bit of info on it on the net. The most interesting of which is the Instructables article that explains how to get reasonably accurate joint position information by hacking the servos (which are, sadly, normal electric motors, not proper servos). Now, given the whole thiong is driven my motors, and the board itself has a couple of bog standard motor driver ICs on it (I know, i've seen them), I think it would be fairly easy to, say, wire the GPIO pins on the Pi directly to the inputs of the driver ICs on the arm's PCB, bypassing the USB port.

Suddenly, you don't need a USB driver.... and I actually bought an Arduino for this purpose, but have not had the time yet to do it.

[morphy_richards]

I think I might get one before they suddenly sell out. I've got a set of Arduinos and am experimenting with them before we develop a scheme of work for them. So far I've made as kind of flatulant theremin using an LDR on the analogue input.

A robotic arm would be much more fun!

Could it be feasibly be mounted on a motorized trolly and the whole ting controlled by arduino to make something like a skutter?

[morphy_richards]

I meant controlled by raspi, not arduino. (Brain, hand interface malfunction.) Could make it fully autonomous.

[morphy_richards]

... Imagine if you could mount some sort of sonar transducer thingy to guide it, a few fig for it to build up an internimage recognitional map and some kind of cam with image recognition. Now imagine if there was two in opposite rooms at either end of a corridor and they were going to play a game of capture the flag ... Oooh...

[morphy_richards]

So many typos! But you get what I mean hopefully.

[Jaseman]

Raspberry Powered Skutter!  I love it.

[morphy_richards]

Wonder if the whole thing could be combined with something like this for machine vision...
http://www.tina-vision.net/

[morphy_richards]

There is also this http://www.societyofrobots.com.....onar.shtml which looks like it would be quite straightforward to implement.

If you could have something like a skutter and something either like this sonar idea, IR rangefinder or image recognition as hardware "modules" and with software components that deliver some sort of standardised output then students could learn a lot about programming by designing a kind of skutter 'concisousness' - they wouldn't need to worry so much about programming the really hard core stuff straight away but could have a lot of fun creating a kind of 'mind' that would direct the skutter to go running off in all sorts of competitions or pursuits etc...

[SN]

my initial enthusiasm to splash cash on this is tempered by the fact this has no feedback sensors of any kind – so there's no easy way to know/guess where the pivots are without a "general reset all pivots back to an endstop condition"

still tempted though…

footnote: SWMBO has seen latest credit card bill – having to explain random collection of small paypal payments for "bits"

[morphy_richards]

I think it should be possible to add other sensors to provide feedback ... The original Red Dwarf scutter had "eyes" mounted in the gripper. Not a bad idea because doing that would provide some if not all the required feedback .

[morphy_richards]

Or perhaps one of these on each arm section
http://uk.rs-online.com/web/p/.....r/7190995/

(no solutions for SWMBO though)

[alimorgana]

Hi,

I'm a complete novice at any of this so forgive my ignorance. I understand that there are two versions of the robotic arm, one which relies on a PC interface and another which is simply connected to a 'joypad' controller. Would it be possible to mimic the signals outputted by the joypad to control the robot? I'm not really sure how these signals are being sent but if we could 'read' and replicate them then would that work?

Thanks,

Alex

[morphy_richards]

AFAIK you can upgrade the joypad version to a USB controller with an extra module so I would imagine that it would be possible. Sounds like a GPIO job.

[SN]

the maplin robotic arm with USB is on offer at 30 quid in store and internet/ebay at the moment so I just had to buy one.  I think stock is running down though so get one quick if you want one

bit of a nightmare building the darn thing and the win drivers don"t work with 64 bit win7 which is a shame as I"ve just been "upgraded", so using SWMBO"s older HP G60 to play.

need to go and chase down the Linux x86 drivers for my older laptop before moving on to the raspi when it comes.

incidentally my dog is fascinated with it, especially as I"m delivering dog biscuits to him with it

EDIT – found some C code using libusb to drive it with

See http://notbrainsurgery.livejou.....38622.html

DOUBLE EDIT - and some PYTHON code too!

http://python-poly.blogspot.co.uk/

http://dl.dropbox.com/u/941820.....control.py http://dl.dropbox.com/u/941820.....arm_gui.py

[Dapa]

Thanks for the info – I think I'll be looking to pick one up tomorrow… and seeing what the dog makes of it

By the way, I recall reading on the Maplin FAQs that you can use the robotic arm with 64-bit Windows, but that you need to disable driver signing.

Oh - it's said you can use Ruby to control the arm too, which is what I'll likely be doing.

I'm Looking forward to seeing how folks get on with running the arm via the Pi!

[SN]

Dog training!



I'm thinking an internet connected raspi could be used as a remote dog feeder (I know its been done before but nowhere near as cool IMHO)

I've also had a webcam trapped in the jaws too which is quite cool – but I really need to make a mount for webcam to sit behind the jaws so the jaws can be used (and seen too) – possibilities are endless with this one

FOOTNOTE - might buy a second one of these ....

[morphy_richards]

Have you seen my thread "Skutter v0.1" ? I would be really glad to have a collaborator in this project if you are up for it.

[SN]

morphy_richards said:


Have you seen my thread "Skutter v0.1" ? I would be really glad to have a collaborator in this project if you are up for it.


Yes, but couldn't remember the name of it - I have already take some C code off one of the sites above and hacked it around so I can drive the Arm in shell script now - even without the feedback loop, having seen the python examples that 'record' where the arm has been to 'remember where it is in relation to a reference point' I'm going to expand it to use that approach.

Anyone want to see the C code so far?

[SN]

lightbulb moment (well actually a special LED moment).

The arm comes with a nice led which you can turn on and off.

Here goes...

1. Replace arm's standard LED with infrared LED

2. Plug in bluetooth USB adaptor into raspi with driver

3. Connect a Wiimote via bluetooth to raspi

4. Track Infrared LED movement with Wiimote

5. Use multiple LED's to improve accuracy

Anyone who's seen Johnny Chung Lee's Wiimote magic will know what I'm talking about

I've already used his magic (and some bits) to turn my laptop into a touchscreen one

[Jaseman]

You'll be glad to hear that I had time to squeeze your article into The MagPi.