Robots and Systems
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BARG Newsletter #2 pages 8 - 13
[Letters continued] Thank you for sending the membership package and first BARG Newsletter. Obviously one feels there is a substantial road ahead in seeking to develop the group from such early days but a start has been made and as a member I wish you every success with the development of the Group. It is sad perhaps that the current evidence on the micro explosion of the last two years is not appearing to lead to worthwhile developments, real applications - robotics and communications being perhaps the obvious and logical direction, but seems to have got bogged down as a machine to emulate the sophisticated cultural pursuits of the amusement arcade (see Sunday Times 20 Jan 1985 p.61). One wonders if the invention of the wheel and fire were trivlalised in their early development to quite the extent of the equally monumental importance of the computer. However, BARG should not exist as a platform for me to knock those that want that sort of thing, [ Why not? - we said wa wanted controversy - Ed] If you keep a database of such things as members equipment to let people with similar hardware and problems be put in touch with each other, I would advise you I have the following hardware: 512K IBM PC (Colour) 48K Spectrum Genesis P101 hydraulic robotic arm (Powertran Cybernetics Ltd) This immediately suggests l might be able to help anyone with interfacing the arm to the IBM PC, who might otherwise experience the same difficulties I had. I was advised prior to the purchase of the arm (which at 1,700 is hardly a toy) that linking to the IBM PC was no problem - just plug in and go... This proved, of course, not to be the case, and I was subsequently advised that an interface was available in the US, or would be, and the price would be around 60 - no delivery dates. If anyone is in the same boat, the SMART CABLE model SC817 from IQ Technologies Inc (available in the UK from most dealers at about the same price) is a flexible answer that works immediately and can be used for other things. Whilst the Genesis P10l comes complete with a sophisticated control box, one does need direct computer control to build the Library of repeatable application files and should anyone require a programs for the IBM PC in BASIC, I should be only too pleased to pass it on (gratis of course). Good luck with the competitions, and if any help is required for the national conference - please don't hesitate to ask. Well done for starting the Group and best wishes for a long and hectic life for you all... John Delieu, Chichester.
Thank you for your letter and encouragement, as well as the offers of help. If any members want to avail themselves of your assistance, we'll be glad to pass on their letters. The Smart Cable, by the way, is an intelligent RS232 cable which sorts out most of the differences between different implementations automatically.
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I am studying for my A levels, and am trying to find a University/Polytechnic doing robotics. After a brief look, it seems that I will have to do most robotic study outside any courses and do self-study from books. At present, I am trying to devise a turtle for an O-level electronics project (without much success). My problem is, I have the ideas but- I cannot implement them. I think that the Zylatron robot is my basic concept of a robot - mobile and self- contained. I feel that such robots should not be thought- of as just menial servants, doing the jobs that their owner does not want to do. This may, in the long term, 1imit their uses by reducing the opportunities available, because the robot would be too well developed for just one task. I would like to join as many robotics clubs as possible and would appreciate addresses of any other clubs. Neville Ward, Bournemouth. 8ARG has members all over the UK and Eire, and several even further abroad, so someone surely can offer suggestions with regard to your first problem Neville. As for the Turtle, our experience is that team work is a good way for the beginner as there are so many aspects of robot building. We will be publishing circuits and suggestions, so watch this space. We will send on any advice received from members about study possibilities and contacts for clubs etc.
Note: Darlington is the term now used to refer to two transistors connected so that the gains of each are effectively multiplied, giving very high current ampl- ification. The only real disadvantages are that the voltage drop across the combined bases is around 1.2 volts, and the saturated collector-emitter voltage is also not much better than 1 volt. Darlington pairs can be obtained built into one transistor case, or several may be integrated into a dip package, such as the ULN2003. This chip has 7 darlington devices, each with a protective diode and a base input resistor. It can be connected directly to TTL level outputs and used to drive small motors or relays without additions! components.
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BOOK REVIEW David Buckley Microprocessor Based Robotics by Mark J Robillard Howard W Sams & Co Inc (13.50) Those of you who have come across Robotics Age, the main American hobby robotics magazine, will already be familiar with Mark Robillard as one of its contributors. In this book, Mark has taken some of the topics from his Robotics Age articles and presented them with mouch new material. His main expertise is in microcomputers but this is left to the end of the book after he has introduced the mechanical aspects of robots He rightly says that the most important part of a robot arm is the gripper or hand and, although many discussions of robot arms skip over the design of grippers, Mark chooses this as the first chapter in his book followed by Arms and Legs and Mobile bases. In these introductory chapters are many photographs and diagrams of simple "kitchen table" mechanisms built by the author. Simple sensors are covered in the first- few chapters including Ultrasonics and a camera made from a converted 4116 Dynamic RAM IC. This first half of the book is fairly light reading and should serve to emphasise "If he can build it then so can I", In the second half all the "nasty" mechanical stuff is left behind, and he gets down to a discussion of single-chip micro- controllers as an introduction to his conversion of Big Trak with an on-board Z8671 Tiny BASIC microcontroller. Almost in passing the addition of bump sensors to Big Irak is mentioned, but the one photograph of a Big Irak bump sensor is totally unintelligible unless one remembers his Robotics Age article. There now follows the longest chapter in the book, where the reader is led through the design of a robot subsystem controller based on the 8748 single chip micro- controller. Robot control languages are briefly discussed, followed by a BASIC program for the Color Computer to control his modified Biq Trak using high level commands. The last part of the book deals with remote control links with emphasis on the Motorola MC14457/14458 chip set and voice activation of robots. It is unfortunate that this is an American book, because a lot of the electronic components mentioned are not easily available to the hobbyist in Britain and the parts suppliers list is also for America. Micoprocessor Based Robotics is probably a good book to get from a library unless you are particularly interested in single chip microcontrollers. The Robotics Revolution by Peter B Scott Blackwell Peter Scott is a roboticist at the Centre for Robotics and Automated Systems at the Imperial College of Science and Technology, University of London. His book is primarily about industrial robots and their implications, rather than the personal robots which we might own, but, even so, it should be on the reading list of everyone interested in robotics. Page 10
The book is subtitled "The Coiplete Guide for Managers and Engineers" and is written so that virtually no technical knowledge is needed to understand it. Each specialist subject, generates its own jargon to convey specialist meaning and robotics is no exception, in fact it is probably worse than other subjects, spreading as it does across many fields. To alleviate this, there is a glossary of about 500 technical terms at the end of the book, and throughout the text these are printed in bold type. Starting from the origins of robots and the various configurations, he leads the reader through their development into how they work by discussing drive systems, feedback, software, sensors and grippers. Following this, the ways robots are used in industry are covered, moving into possible future uses. One of the main worries regarding industrial robots seems to be what will happen to jobs and on this he examines the pattern of events in the relatively short- history of industrial robotics, with reference back to earlier technological revolutions. Just because robots are available is no reason for automatically assuming that any particular industrial task is suitable for a robot to do, similarly even when a task is suitable there may be many reasons for not adopting robots and these are discussed before dealing with safety aspects of robotic installations. One thing about robots is certain, and that is they cost money, but what is their real cost over the years? Here there are some guidelines that may be used to estimate potential costs and savings. To round off the book, the final section is devoted to current- prospects for robots in various fields together with potential developments extending into the future. This book is very manch a guided tour of industrial robots rather than a hard technical treatise and, as I said earlier, should be on the reading list of those interested in robotics, even if this interest only extends to Turtles and Logo. Advanced Robot Systems by Mark Robillard This book follows on from where Mark Robillard's earlier book, "Microprocessor Based Robotics" left off and considers robot systems as distinct from robot con- struction. This usefully allows the author to leave all the mechanical stuff to somebody else and concentrate on the design of electronic systems for hypothetical robot devices, including a robot truck for a factory, a security robot and a mail delivery robot for offices. Rotbillard's style, common in quite a few American books, is to select an inte- grated circuit, explain how it works and then go on to consider how it might be used in a particular application. He describes some very useful IC's, that (were they easily available in the UK) would make construction of electronics systems for robot control Much easier. Nevertheless, the systems he describes provide much food for thought with many circuit diagrams for various sensor circuits, such as a line follower and lots of Page 11
schematic diagrams of microcomputer systems. This is a book on robot systems, so software to run the electronics is also considered, mainly in the form of flow diagrams and tables of instructions for the various IC's discussed. One section of the book examines the hardware and software of Hero 1 as a prelude to considering the design of a more advanced control system using IC's invest- igated in earlier chapters. Don't expect Robillard to tell you how to design a complete robot system down to the last detail. He doesn't set out to do that. What he does give you, though, are various ideas which you can consider and incorporate into your design as appropriate. Practical Robotics & Interfacing for the Spectrum by Dr A A Berk Robotics is definitely an "in" word at the moment for book titles, plain old "interfacing" is passe. Unfortunately, having "Robotics" in the title doesn't guarantee that the book will actually be about robotics. I imagine this book was written about 12 months or so ago and because every other book was about interfacing for the You Name It computer, this one didn't get published, Now, with a quick revamp and a chapter on robot arms, we have a book on robotics, or do we? A robot is essentially an amalgam of mechanics, electrics, electronics and software; this book, however, deals only with electrics and electronics, leaving the reader to cope with any mechanical bits. Of course, because it's about the Spectrum, there are short programs showing how to turn various bits on or off. However all is not lost, for this is a really good introductory book on how the Spectrum works, what ASCII Binary and Hexadeciaal mean and, above all. it's the best guide I have read on practical circuit building. The section on Electronics, Components and Soldering starts off by introducing electricity and electronics, tells you what tools you will need, describes all the general components and goes on to describe how actually to solder them onto circuit boards. To use the simple interface circuits in the book requires opening the Spectrum and soldering two wires inside. Whilst this is easy to do, it will invalidate the guarantee. The more complex interface circuits described need building into boards that plug into the bus expansion slot at the back of the computer, but he doesn't actually tell you how to do this. On the whole, the book is a strange mixture of very good parts and others that show a lack of awareness in certain fields. Besides several surprising errors, at one stage the reader is advised to use an "escapement" as used in single-channel radio control, but I haven't seen adverts for escapements or single-channel radio control for nearly twenty years! Radiospares is mentioned as a supplier of comp- onents, but deals only with the trade, and most of the information on robot arms you could easily get from the manufacturers' advertising literature. However, as I said, it is a good introductory book on the workings of the Spectrum and practical circuit building. Page 12
Basic Robotic Concepts by John M Holland Howard W Sams & Co Inc (15.95) In his introduction to the book John Holland makes the important point that "virtually all the great civilisations of the past were based in part on slavery. The ancient Romans, Greeks and Egyptians all used slaves to free their citizens from the trivial and monotonous work of daily existence. Unfortunately, the enslaving of other peoples brings with it a high moral price. Now there is a way for people to have slaves without injustice". These modern-day slaves are of course robots, but without an understanding of what robotics is all about and the jargon that goes with it, it is all too easy to see them as something threatening. This book should serve to dispel such visions. Most aspects of robotics are covered, from the different types of electric motor to problems with image recognition. The non-technical reader will not be faced with pages of hieroglyphics, since all the formulae, technical notes, program listings etc are in the appendices. In the main body of the book all the explanations are in words with many diagrams and photographs. This book should be beside the bed of everyone interested in robotics.
That's it for this issue. The Spring 85 Newsletter, out next month, will include the Polaroid article, constructional details for a Spectrum I/O port and a review of a new Commercial turtle, costing about 100, and of course, your letters. Page 13
BARG Newsletter Issue 3/4 Spring/Summer 1985