Potton Pi & Pints Social

Just back from the Raspberry Pi piss up social in Potton, Bedfordshire, arranged by Mike & Tim who normally organize the Cambridge Jams.   This social event was informal, held upstairs in their local watering hole - The Rising Sun

As you can see, a few familiar faces in attendance from previous Jams:

Pictured - Ben Nuttel (Raspberry Pi Foundation), Ryan Walmsley (RyanTeck), Nevile Hunt (Seven Segments of Pi), and more....

This is PJ Evans demonstrating the Raspberry Pi enabled Enigma machine which I saw last year at Bletchley Park.  PJ also brought along a newly released FUZE machine featuring a variant of BBC Basic, developed by Gordon Henderson of WiringPi fame, and if you recall, I met Gordon during December's Cam Jam :

John Evans pictured here demonstrating XBMS, and how to receive Live TV on a Raspberry Pi in full High Definition using a USB dongle :

....should be a good picture, the TV transmitter station at Sandy Heath is visible from the window :

I decided not to bring the Armdroid along as I thought it was a bit bulky, but it was nice to hear from a few people who attended my presentation in Peterborough asking how things are currently going....     Well.... the Windows LEARN software is currently in progress, and hopefully will be released soon.

A fantastic afternoon, and another great opportunity to catch up with everybody.

Jammin' at UCP

Saturday, 15 March  Raspberry Jam - University Centre Peterborough (UCP)

UCP is a small, modern university campus of Peterborough Regional College, and venue for the very first Raspberry Jam to be held in Peterborough organized by Mike Mills.

Arriving early to setup the Armdroid in the Show & Tell display section:

The tea-tray was borrowed because in the afternoon I was to give a short presentation and needed a way of carrying everything upstairs to the conference room.

All reduction gears lucubrated with oil, and my original 12V power supply was chosen in favor of the 15V supply to put less stress on the motors, as these will be mostly powered all day.   I don't yet have any control in my Arduino firmware to enable/disable Holding Torque which would have allowed me to cool down the stepper motors by de-energizing the coils during long periods of standby.

Whilst the opening presentations were being held, the show & tell area was quite, so I had time to experiment further with different speed settings.  The Armdroid performs really well at 200RPM, but excessive vibrations seem to occur at speeds lower than 100RPM.  This is especially notable with base rotations, and additional lubrication applied to the bearings didn't seem to help matters.

I eventually pushed the speed right up to approx 600RPM and at this point, things started to go unpredictably wrong, so 500RPM would appear to be the safest maximum top-speed.   Switching off, and re-positioning the arm back to a predefined home position recovered everything nicely.

Unfortunately I didn't have time to write any sequencing software before the show, so all movements had to be instructed by commands entered manually on the Raspberry Pi.

The show & tell became very busy, and in the afternoon gave a 30-min presentation to an over-subscribed class room, and despite having not preparing any material, went surprisingly well.   It was pleasing to hear from people who previously saw the Armdroid at Cambridge saying how much smoother everything is running these days.

I would like to congratulate Mike and all helpers for putting on a great show.  It was also fantastic to catch up with familiar faces from previous Milton Keynes (Bletchley Park) and Cambridge Jams.

As before, I've come away with a list of things/issues to address:

• Gripper - the precision of fingers closing is not as accurate as I would like and makes picking up objects unreliable
• Sequencing software for the Raspberry Pi
• Pre-designed sequences to really demonstrate & show off capabilities
• Motion limiters - add protection from operating outside working envelope
• Sensors - must install original reed-switches and update the Arduino to accept the bi-directional interface on the digital I/O pins
• Torque control
• Investigate use of PIGPIO for low-level driving from the Pi instead of slaving out to an Arduino

As hinted in my presentation I'll also be looking to design "applications" which will use the robotic arm to solve some real-world problems, so hopefully, in time we'll have something really interesting and impressive to show....

Photographs used with permission - John Evans

Cambridge Raspberry Jam - 7th December

Yesterday, was the 4th Cambridge Jam (CamJam) of 2013 at the Institute of Astronomy, Cambridge University.

We arrived early to set up the Armdroid display, and before we could finish unpacking everything we had a small crowd hovering around the desk.....

Above, Matthew (The Raspberry Pi Guy) was really taken by the Robotic arm, and wanted one!   Ryan Walmsley was demonstrating his RTK-000-001 motor controller board & buggy, and some of the other demonstrations was equally as impressive!

Unfortunately, my Raspberry Pi was randomly rebooting itself, so out came the manual controller to the rescue !

Eventually the Pi started behaving itself....   Perhaps there was a shift in wind direction ?

I recompiled some of the test programs with shorter delay statements to speed things up, this made the arm appear a lot more responsive when controlled by the Pi.

Daniel Bull was back with the mighty AstroBlaster arcade console...  We spent most of the day talking (fantasying) about 3D Printing technologies.   The question being... can we print replacement Armdroid components with enough precision not to require further machining ?   We will have to wait and see...

Later in the afternoon I had the pleasure of meeting Gordon Henderson, author of Wiring Pi.  This is the GPIO access library I've been using to write my Armdroid software.

I met lots of interesting people and wished I had taken more photographs.

I've been invited to the forthcoming Peterborough Raspberry Jam starting in March which I'm really looking forward to attend.

Final picture of the day....  Yulia and myself, ready for a well deserved Beer at a local pub !   It was after all a long and very successful day.

We suffered a breakage in the afternoon....

The tension equaliser had been playing up all day, and eventually lead to failure of the fingers.  I suspect one of the retaining grub screws wasn't as tight as it should, this must have slipped.   If you look closely at the Kevlar which didn't snap, literately tore itself free.

Actually, I couldn't have asked for a better proving ground - the kids absolutely loved playing with the Armdroid, and really gave it a good hammering...   I've come away with a lengthy list of problems which need to be addressed & resolved for next time.

A full write up can be found at http://www.recantha.co.uk/blog/?p=7219 with an additional update http://www.recantha.co.uk/blog/?p=7290

Finally....   Big thanks to Michael and Tim, and all the Jam Makers for their superb organisation and dedication put into running such a good show.   Next jam will be Saturday, 8 February.

Raspberry Jam @ Bletchley Park

This morning I arrived at Bletchley Park

The National Museum of Computing was holding their 14th, and one year's anniversary Raspberry Jam.  Special guest was Eben Upton, and for those who don't know - he's the guy who invented Raspberry Pi

The morning started with introductions, followed by an informative presentation by Eben :

It was great to hear about what's happening in the Raspberry Pi Eco-system, and achievements made in terms of shipment volumes over the past year...  A few hints was made about what to expect in future, and hopefully we'll be seeing more add-on modules to follow.

I personally liked hearing about how the Education world is starting to find these devices into class rooms, and what the teachers are doing with them.

During the break-out session, I managed to spend around 15mins chatting to Eben about how the projected all started, and why Raspberry Pi as the name was chosen...  Seems the computer industry just likes fruity names!

He was originally a software engineer at IBM Warwick... What a small world this is !!


People brought their Raspberry Pi based projects along...

 

Believe it or not... This is a Raspberry Pi internet enabled Enigma machine.  It's a faithful rendition of the original, expect encoded messages are transmitted over the internet for decoding elsewhere

Based on German Naval Enigma with 4 rotors - one of Bletchely Park's own working rebuilt Bombe machines has previously been used to crack a coded message produced from this machine.

This is one project that particularly interested me...

Sure did taste great, and compliments to the chef !

Next, we have an internet enabled environmental monitoring station - includes a bunch of digital and analog sensors to measure things like temperature, humidity, UV and light levels, which is then published onto a website...

Daniel brought along his Astro Blaster arcade machine restoration / conversion to table top form - seen here standing on side showing the internals through observation windows in the base:

A Raspberry Pi hidden inside is running MAME (multiple arcade machine emulation) which means he'll have literally hundreds of games at hand to choose from.

I was having Berry IO demonstrated here - a browser based GPIO controller for the Raspberry Pi.   Actually, this has given me an idea to try this out when the Armdroid is ready to be hooked up.


The arcade was connected to a large monitor in the room, and proved to be very popular with everybody... 

Space Invaders... You can't beat the old ones!

The Raspberry Pies certainly was going down well...

I didn't eat them all, honestly !

Enjoyed meeting everybody, and hopefully will see again sometime...  Discussing my project with the experts, was soon pointed out I might have some challenges generating those clock pulses reliably on these little devices...

Information on Milton Keynes Raspberry Jams can be found at their Forum

This inspired me to go home, and get on with my Armdroid project...  Hopefully,  we'll have something to demonstrate soon!  The house redecorating is nearly finished, so more time will soon be allocated to getting things sorted here.

Enjoy the rest of your Bank Holiday....