Robot Arm

discuss both original and modern hardware for the bbc micro/electron
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nOmArch
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Robot Arm

Post by nOmArch » Sun Jul 31, 2011 6:19 pm

http://www.ebay.co.uk/itm/Robot-Arm-Mec ... 43a428e5a1

£30 on ebay, just wondering what the likelihood of building an interface to control this from a Beeb.

I remember at school we had a BBC connected up to big orange metal box which in turn was connected to a Robot Arm and could control it very well.

EDIT: Found a USB version, maybe hook it up via a Datacentre and then write a driver for it?
Alex

Back up to 1 Beeb again. \o/

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harrymatic
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Re: Robot Arm

Post by harrymatic » Mon Aug 01, 2011 8:30 pm

I've been building a robotic arm according to a very old book. It's designed with the Beeb in mind, although it can be modified to work with a C64 as well. It has all the templates and a control circuit along with a BASIC controller program. So far I haven't got very far with the robot, but I've built the circuit and typed in the program, which needless to say took about a thousand retries because it's a type-in. :roll:
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nOmArch
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Re: Robot Arm

Post by nOmArch » Mon Aug 01, 2011 8:59 pm

Usborne guides, that's a trip down memory lane right there.

Oh nice found a copy on ebay for 99p,

If it's the choice of building one from scratch or pre-made, I think it's gotta be the former if at all possible.

How long is the program? Might just have to cheat and OCR it somehow :lol:

Beeb Robot Wars in a couple of months time then? 8)
Alex

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Re: Robot Arm

Post by harrymatic » Mon Aug 01, 2011 9:25 pm

104 lines to be precise. You're in luck, I already typed it in.
10 ?&FE62=31:OP=&FE60
20 GOSUB 830:GOSUB 920:GOSUB 990
30 MODE7:CLS
40 PRINT CHR$(132)CHR$(132)CHR$(132)CHR$(141)"Robot Control Program":PRINT CHR$(132)CHR$(132)CHR$(132)CHR$(141)"Robot Control Program"
50 SOUND 1,-10,6,3:PRINT
60 PRINT "1 - Enter Commands"
70 PRINT "2 - Display Commands":PRINT "3 - Run Program"
80 PRINT
90 INPUT A:IF A<1 OR A>3 THEN GOTO 90
100 ON A GOSUB 330,230,120
110 GOTO 30
120 LET PC=1:LET PF=0
130 LET Q=M(PC)
140 IF Q=17 THEN GOSUB 830:RETURN
150 IF Q=0 THEN GOTO 210
160 IF Q>11 THEN GOTO 190
170 ON Q GOSUB 480,480,480,480,480,480,480,500,540,620,640
180 GOTO 200
190 ON Q-11 GOSUB 680,690,710,730,750
200 IF PF=1 THEN RETURN
210 LET PC=PC+1:IF PC>40 THEN GOSUB 830:RETURN
220 GOTO 130
230 CLS
240 PRINT "From which step?":INPUT S
250 LET EL=S+15:IF EL>40 THEN LET EL=40
260 FOR I=S TO EL
270 PRINT " ";I;". ";V$(M(I));
280 IF D(I)>0 THEN PRINT TAB(15);D(I);
290 PRINT
300 NEXT I
310 PRINT "Press RETURN for menu."
320 INPUT Q$:RETURN
330 CLS
340 PRINT:PRINT "Step number...":INPUT N
350 IF N=0 OR N>40 THEN RETURN
360 PRINT "Command...":INPUT C$
370 LET V=0
380 FOR I=1 TO 17
390 IF C$=V$(I) THEN LET V=I
400 NEXT I
410 IF V=0 THEN PRINT "Invalid command":GOTO 360
420 LET M(N)=V
430 IF V=10 OR V=11 OR V=16 OR V=17 THEN LET D(N)=0:GOTO 470
440 IF V<10 OR V=15 THEN PRINT "Duration...":GOTO 460
450 PRINT "To which step?"
460 INPUT D(N)
470 GOTO 340
480 LET G=P(Q):LET N=D(PC):LET TF=0
490 GOSUB 770:RETURN
500 IF A$="UP" THEN RETURN
510 GOSUB 580
520 IF SF=1 THEN LET A$="UP"
530 RETURN
540 IF A$="DO" THEN RETURN
550 GOSUB 580
560 IF SF=1 THEN LET A$="DO"
570 RETURN
580 LET TN=128
590 GOSUB 880:LET N=D(PC):LET TF=1
600 GOSUB 770:LET A$=""
610 RETURN
620 IF G$="OP" THEN RETURN
630 GOSUB 660:LET G$="OP":RETURN
640 IF G$="CL" THEN RETURN
650 GOSUB 660:LET G$="CL":RETURN
660 LET TN=64:GOSUB 880:LET N=1E5
670 LET TF=1:GOSUB 770:RETURN
680 LET PC=D(PC)-1:RETURN
690 LET TN=32:GOSUB 850:IF SF=0 THEN GOSUB 680
700 RETURN
710 LET TN=32:GOSUB 850:IF SF=1 THEN GOSUB 680
720 RETURN
730 LET R=PC:LET E=D(PC)
740 LET C=0:RETURN
750 LET C=C+1:IF C<E THEN LET PC=R
760 RETURN
770 GOSUB 840:LET T=0
780 IF TF=0 THEN GOTO 800
790 GOSUB 850:IF SF=1 THEN GOSUB 830:RETURN
800 IF INKEY$(0)<>"" THEN GOSUB 830:PF=1:RETURN
810 LET T=T+1:IF T<N THEN GOTO 780
820 RETURN
830 ?&FE60=0:RETURN
840 ?&FE60=G:RETURN
850 LET SF=0
860 IF (?OP AND TN)=0 THEN LET SF=1
870 RETURN
880 LET G=P(Q):GOSUB 840
890 GOSUB 850:IF SF=1 THEN GOTO 890
900 FOR T=1 TO 500:NEXT
910 RETURN
920 DIM M(40):DIM D(40):DIM P(11):DIM V$(17)
930 FOR I=1 TO 17:READ V$(I):NEXT I
940 FOR I=1 TO 11:READ P(I):NEXT I
950 RETURN
960 DATA "F","B","FR","FL","BR","BL","STOP","UP","DOWN","OPEN","CLOSE"
970 DATA "GOTO","IFON","IFOFF","REPEAT","END","HALT"
980 DATA 6,7,4,2,5,3,0,16,17,9,8
990 CLS:PRINT "Is the gripper fully open? (Y/N)":INPUT I$
1000 IF I$="N" THEN LET Q=10:GOSUB 630
1010 PRINT:PRINT "Is the arm fully down? (Y/N)":INPUT I$
1020 IF I$="N" THEN LET Q=9:LET PC=1:LET D(1)=1E5:GOSUB 550
1030 LET G$="OP":LET A$="DO"
1040 RETURN

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nOmArch
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Re: Robot Arm

Post by nOmArch » Mon Aug 01, 2011 9:34 pm

Ahhhh outstanding sir, thanks =D>

Now I just have to wait for the bloody book to arrive :lol:
Alex

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harrymatic
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Re: Robot Arm

Post by harrymatic » Mon Aug 01, 2011 9:39 pm

What's always baffled me is how the book is written in a way to explain the things to children, but in reality, there's no bloody way in hell any child would ever be able to actually build it.

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nOmArch
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Re: Robot Arm

Post by nOmArch » Mon Aug 01, 2011 10:43 pm

Kids were more resourceful back then :) I remember I used to take apart nearly every new device I got my hands on. Annoyed the parents no end but gave me a lifelong interest in all things technical.
Alex

Back up to 1 Beeb again. \o/

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Re: Robot Arm

Post by Darren Grant » Tue Aug 02, 2011 3:33 pm

Usborne guides were brilliant. I understood it enough to build an IO interface and a buggy while still at school. Along with a pocket radio with one of their electronics books.

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Re: Robot Arm

Post by 1024MAK » Fri Aug 05, 2011 6:07 pm

nOmArch wrote:http://www.ebay.co.uk/itm/Robot-Arm-Mec ... 43a428e5a1

£30 on ebay, just wondering what the likelihood of building an interface to control this from a Beeb.

I remember at school we had a BBC connected up to big orange metal box which in turn was connected to a Robot Arm and could control it very well.
I've just received the one that I ordered :D .
I got mine from http://myworld.ebay.co.uk/ladz-stuff-that-you-want/
http://cgi.ebay.co.uk/ws/eBayISAPI.dll? ... 0359626455
Looking at the supplied PCB's and then at the English instruction booklet (well its mainly diagrams, but the words are in English) it includes a circuit diagram.
The motors are all 3V types and are fed via switches from a battery pack that is made up of four 1.5V cells in two banks of two (so two 3V batteries) giving +3V, 0V and -3V.
To control it from a Beeb you will need some electronics. If you use the printer port and the user port, 11 resistors, 11 transistors and 10 diodes are needed.
If you only want to use either just the printer port, or just the user port, two IC's (chips) will also be needed.

Mark K.

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nOmArch
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Re: Robot Arm

Post by nOmArch » Fri Aug 05, 2011 7:37 pm

Isn't that the non USB version? I was thinking use the Datacentre to connect it up then all you would need to do is write the software.

Are you intending to have a go at connecting yours up?
Alex

Back up to 1 Beeb again. \o/

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Re: Robot Arm

Post by 1024MAK » Fri Aug 05, 2011 8:43 pm

Yes, its the non-USB version.
And yes once I've found the time to build it, i do intend to connect it up to a Beeb :mrgreen:

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Re: Robot Arm

Post by station240 » Thu Aug 11, 2011 8:37 am

Collection of books and games on ebay at the moment, thought I'd mention.

http://www.ebay.co.uk/itm/BBC-Micro-boo ... 20bbd8636f
Books include:
DIY robotics and sensors with the BBC computer
Interfacing projects for the BBC Micro

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Re: Robot Arm

Post by nOmArch » Thu Aug 11, 2011 11:08 am

Thanks dude, added to my watch list.

btw if anyone is interested in one of those robot arms, Maplin are selling one with the USB kit for £29.99 on ebay

http://cgi.ebay.co.uk/ws/eBayISAPI.dll? ... K:MEWNX:IT
Alex

Back up to 1 Beeb again. \o/

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Re: Robot Arm

Post by CanonMan » Thu Aug 11, 2011 1:15 pm

Sadly, if it's from Maplin then it's probably complete crap :(

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Re: Robot Arm

Post by nOmArch » Thu Aug 11, 2011 3:53 pm

No it's the same arm as all the other sellers have but this one includes the USB kit and is cheaper than most of the others without the kit.
Alex

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Re: Robot Arm

Post by nOmArch » Sun Aug 14, 2011 7:03 pm

Built the Maplin Arm today, took about 3 hours from start to finish working at a steady pace. Instructions were pretty good although there was one small problem with one of the gripper arms not having a little nub of plastic to allow me to attach the screw to it as per the instructions but was able to use the one other extra part to DIY it.

Box
Image

Parts
Image

Motors
Image

Base
Image

First motor attached
Image

Main arm part
Image

About to attach to base
Image

Attached to base
Image

Gripper motor gearbox
Image

Gripper motor
Image

Finished gripper
Image

Done apart from USB PCB & wire tidying.
Image

Arm in action
http://www.youtube.com/watch?v=szD12LaaZlQ
Alex

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Re: Robot Arm

Post by MartinB » Sun Aug 14, 2011 9:31 pm

Brilliant job - I love stuff like that =D>

I'd be looking to add resolvers and touch sensors next - you could do wonders with a spot of feedback :wink:

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Re: Robot Arm

Post by nOmArch » Sun Aug 14, 2011 10:16 pm

Unfortunately it's a little bit small to really do anything interesting with it, which is why I have a plan B!

I've been talking to a really nice guy called David Buckley from the Beebcontrol group and I may have the chance to build his now discontinued TecArm (see site).

Image

That would be an arm to modify!
Alex

Back up to 1 Beeb again. \o/

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Re: Robot Arm

Post by nOmArch » Tue Aug 16, 2011 8:20 pm

MartinB wrote: I'd be looking to add resolvers and touch sensors next - you could do wonders with a spot of feedback :wink:
nOmArch wrote:Unfortunately it's a little bit small to really do anything interesting with it
Oh me of little faith...

I was mooching around Instructables and found this

http://www.instructables.com/id/Modific ... er-Feedba/

Video of the same arm but built using potentiometers instead of optos.

http://www.youtube.com/watch?v=ArEjPsYxM4A
Alex

Back up to 1 Beeb again. \o/

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Re: Robot Arm

Post by MartinB » Thu Aug 18, 2011 10:53 pm

Interesting :wink:

Yeah, for the Beeb I was actually thinking along the lines of high quality linear pots connected to the analogue port with touch/proximity/limit sensors to the User or 1MHz ports.

I always wanted to get a Beeb robot arm to learn to control itself by being able to press keys on the keyboard - hard to get your head round but a fascinating concept :D

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Re: Robot Arm

Post by jonb » Sat Aug 20, 2011 8:03 am

I've just got me one of those Maplin arms too. It's actually an OWI 535 "Edge" arm, Maplin are just reselling them. It's not the usual crap you get from Maplin - for the money it's a great educational toy. There are a number of articles scattered around the web that explain all about it and there's a few hacking guides too (including a guide to the protocol the USB interface is using). One of the most interesting is an entry on Instructables that shows you how to use optical sensors to implement positional feedback for the four main servos (and it retains its neatness as everything fits inside the gearbox. Also, a ideo on YouTube showing another feedback mod made with potentiometers - this would suit the Beeb as you could just plug them into the analogue port. In fact it's a piece of cake to do, and use the user port to control the motors.

Looking at the potentiometer based feedback mod video, it appears you can get it to be quite dextrous and accurate and this is pretty neat for a £30 toy!

Links:

Opto mod : http://www.instructables.com/id/Modific ... er-Feedba/
Potentiometer demo : http://www.youtube.com/watch?v=32uCAyxKCbI

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Re: Robot Arm

Post by nOmArch » Sat Aug 20, 2011 10:43 am

Those links look familiar :lol:
Alex

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Re: Robot Arm

Post by jonb » Sun Aug 21, 2011 8:42 am

nOmArch wrote:Those links look familiar :lol:

D'oh!


:D

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Re: Robot Arm

Post by Anobium » Wed Aug 24, 2011 10:26 am

See http://www.zen21667.zen.co.uk/ I have just completed a modification program.

We can easily port to this platform! I had some experience with this platform...

I was part of the team that created the networking solution many, many years ago and I wrote for Acorn a specialised communications protocol for RS232. The memories....

Anobium

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Re: Robot Arm

Post by nOmArch » Wed Aug 24, 2011 11:02 am

Excellant stuff there Anobium. I have the USB version of the arm, will I still be able to use your mod?
Alex

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Re: Robot Arm

Post by Anobium » Wed Aug 24, 2011 11:12 am

In my modification I did not use the USB kit. I did try but this simply uses 'time' to locate the position of the arm axis(s).

I did try to use the USB, I even got the IC provider to send me additional ICs!! But, after a few hours of struggling with the USB PC driver I gave up.

The solution now uses a number of microcontrollers with the master computer controlling these microcontrollers. It would be relatively simple to port to this platform.

Anobium

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Re: Robot Arm

Post by jonb » Wed Aug 24, 2011 8:21 pm

I've ordered an Arduino Uno and I plan to directly interface it to the arm, with potentiometers to sense joint angles, and a pressure gauge for the claw. This would replace the USB board entirely and I'd need some DC motor controllers (like this : http://www.arduino.cc/playground/Main/DCMotorControl)...

I did look closely at the Instructables opto mod but this isn't going to give an absolute position, just a relative one from the last known position. Given we're dealing with DC motors, not steppers or servos, the last known position is only a guess, so absolute arm positioning feedback has to be the way forward..

Of course, using pots means the arm doesn't look as neat, unless.... unless something could be contrived that fits inside the gearboxes. Hmmm.....

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Re: Robot Arm

Post by Anobium » Wed Aug 24, 2011 8:49 pm

The mods I can have give about 0.5mm accurancy across the whole range of movement.

I used the Opto Mod then added a QRD114 sensor also within the gearbox. I did try the pots approach but gave up. With only a little effort I got all the sensors into the gearbox.

So, the QRD114 gives a reference point - this is very, very accurate. From the reference point I move - or + in terms of movement. All movement is relative to the reference hence the accuracy. I do have some positional algoriths but this are simple but my experience may help. :-)

I have no pots. I use the opto and the reference point for position.

Re the gripper. I use back EMF work very, very well. It can pick hard and very soft objects. I use back EMF to locate the fully open position and then all commands are relative to this position.

have a lot at http://www.zen21667.zen.co.uk/photos/bu ... G_0753.JPG & http://www.zen21667.zen.co.uk/photos/bu ... G_0748.JPG

I agree totally with the uController approach. I not sure about the pots and gripper.

Hope this helps.
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Re: Robot Arm

Post by Anobium » Wed Aug 24, 2011 8:55 pm

I can webcast the robot and explain if you wish.

One evening (UK time) or the weekend?

Anobium

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Re: Robot Arm

Post by nOmArch » Wed Aug 24, 2011 9:21 pm

=D> =D> =D>

Have you removed 2 of the 4 gears to get that to fit?
Alex

Back up to 1 Beeb again. \o/

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