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About Low Cost Automation
Copyright © IFAC Low Cost Automation 1996 Valencia. Spain. 19X6
KEYNOTE ADDRESS
ABOUT LOW COST AUTOMATION G. A. Ferrate, President of CEA-IFAC, Spain Working Group of CEA-IFAC
Abstract: As a result of a one day meeting held by working Group of the Spanish NXO of IFAC (CEA-IFAC) a brainstorming session was dedicated to the analysis of the main topics related with Low Cost Automation. Three cathegories of factors have been pOinted out: the control equipment aspects, the process characteristics and the system exploitation. INTRODUCTION
LOW COST CONCEPT
In the past, the concept of low cost automation was associated to simple devices, with rather low of the control performances, adequate for non-sophisticated plants or processes which do not reqUire very stringent specifications .
The concept of Low Cost has been traditionally associated with simplicity, but simplicity is an evasive and ambiguous concept. If we consider, for example a PID controller made up of mechanical parts including levers, bellows, springs, dumpers, etc . and we compare it with a device performing electronically a similar function,and making use of LSI circuits, the question arises us to which one is simpler.
Nowadays, the fast evolution of the theory and applications of Automatic Control, as well as the development of highly performant non expensive changed the traditional computing decives has concept of low cost automation, incorporating new aspects such as, for instance, the easiness of the flexibility, the design and installation, friendly operation and the maintenablli ty, thus concept of Low Cost giving rise to the new Automation (LCA). These considerations have lead us to present some brief reflexions concerning the evolving concept of LCA and its possible interpretation at the present time. First of all we propose a possible definition of LCA, and we analyse some of the factors that are associate to it. LCA is not a general solution and its applicability is directly related to the kind of process to be controlled and to the existence of some special specifications to be fulfilled. It is clear, for instance, that LCA does not seams, in principle, the adequate approach to automate a nuclear power station, a car factory or a railway traffic network. LCA concept is still and open subject, rapidly evolving along with the development of computer techniques and the availability of cheap components and modular or standardized units wich result frOD the increasing application of control techniques to many new fields .
The electronic device is manufactured simply assembling, into a printed circuit board, a few readily available components which conceal a great internal complexity and which require the access to very sophisticated and advanced technologies for their production. The mechanical controller, on the other hand, can be manufactured making use of much mare simple and well known technologies, and needs the careful fixing and adjustment of many precision engineered parts, specially designed and produced for the purpose. Which one is simpler? The answer is not easy if additional considerations concerning other factors such as ease of maintenance, reliability and many other, are not made. Generally speaking, it can be affirmed that simplicity is nowadays much mar related to the easiness of design, assembly and adjustment of systems, making use of readily available components, modules and units, than to the intrinsic complexity of the system as a whole. Up to now, we have referred ourselves to the cost of the control eqUipment itself, which is strongly related to its simplicity, whatever this may be. However, a more general perspective, taking into account other aspects of the whole system leads to the concept of LCA. To the cost of the equipment must be added other factors mainly concerning the context, the operation, the maintenance and the replacement, as well as the norms or regulations to be fulfilled .
2
G. A. Ferrate
LCA is not an absolute figure but rather a relative concept, as a consequence of the variety and fuzziness of the involved aspects. From the previous considerations and comments we could establish that the aim of LCA is to accomplish the control of machines, plants or processes, trying to minimize a cost function while achieving a sufficiently good performance. The cost func tion should take into account factors concerning the c ontrol equipment, the system to be controlled and the global operation. Strictu sensu, LCA requires that the value of each of the cost function terms, as well as the total value of this function, should be below some preestablished limits. The above limits should be set according to current market situation and to the relative economical parameters of the plant to be controlled and of the row materials being handled. The general technological level is also to be considered .
LOW COST FACTORS As previously mentioned, the factors to be considered as forming part of the cost function in order to evaluate the degree of fulfillment of the LCA conditions can be grouped into three c athegories refering to: - the control equipment aspects - the process characteristics - the system exploitation In the first cathegory we must consider related to the equipment itself like: -
design acquisition or manufacture programming installation tuning or adjustment of parameters other
as well as those which AlTDng these: -
aspects
refer to
-
environmental conditions operation cost row material cost continuous or non continuous operation failure cost reliability and safety requirements legal regulations other
Besides the three cathegories just mentioned, attention should be payed to some features of the equipment to be used that may have an important role in evaluating the function c ost: the flexibility or capacity of the equipment to be easely adapted to perform different tasks, or, for instance, the possibility of re-using it, in another system, opportunity, or context. It is obvious that equipment modularity and standardization may positively influence the solution given to an a'Jtomation problem, even if does not represent the simplest one. Modularity can be a decisive factor to achieve the desired flexibility and re-usability of the equipment . Standardization may not only reduce the cost of the equipment, due to mass-production, but also facilitate and make easier to find qualified personel for operation and maintenance . This is another cost reducing component in view of LCA.
APPLI CABILITY Not all the fields that may be subject for automation are suited to LCA. Among the factors that have been mentioned in the previus paragraph, some of those included in the two last cathegories are of special relevance in order to determine the applicability of LCA in a specific case. With respect to process characteristics, the number and nature of variables as well as the accuracy requirements could be incompatible with Low Cost solutions while, where system exploitation is considered, aspects like environmental conditions, failure cost, reliability and safety requirements and legal regulations might also be the most important to that end.
the utilization.
operation maintenance wor k1 ng lif e energy and environmental reqUirements other
a The process characteristics is normally determining factor to take a decision ahout the applicability of a LCA system. The following are important:
"Groso ){odo", three main groups of applications can be considered: those applications where the factors just mentioned discourage from using LCA methods, situations where LCA is clearly the best suited approach, and those cases in which the applicability of LCA depends on many other factors, thus making the decision much more c omplex.
About Low Cost Automation It is easy to find examples of application fields where LCA is obviously discarded : avionics and space, nuclear power stations, railway systems, and electric power dispatching. . . and, generally speaking, the military area . The main common factor to these examples is the strong requirements on reliability. All of them exhibit complex dynamic behaviour and, moreover, the cost of the control system is not a decisive factor, taking into account the hign cost of the syste. as a whole, and the crucial importance of its function . Fortunately, the areas where LCA is clearly applicable are rather wide. Many of them refer to industrial manufacturing processes and consumer equipments . It is difficult to define precisely the limits of this group, but we can mention as examples all those where temperature or position control is necessary, sequencial systems, speed controllers, and, generally speaking, all those where the system dynamics is relatively simple and the safety and legal requirements are not very demanding. Many of the micro-processor controlled systems are also progressively falling into this cathegory.
REFERElCES Beaty, R. T. "Evolution Towards Automation". lEE Proc., Part A, V. 133, pt . A, n. 6, Sep. 1986, p.332. Anon."High Productivity - Low Cost Automation in Industry" . Certif . Eng., V. 54, n. 3, Mar. 1981, pp . 864-872. Ca Idwe 11 , Laura 11 . "LoW-Cost Factory SystellS Integration" . CIK Reev., v. 1, n . 4, Summer 1985, pp. 27-35. Sogo,Marllyn R. "Closing The Loop" . lIech . Eng., v. 107, n. 10, Oct . 1985, pp . 50-52. Dzieyk, Bruno. "Low Cost - Automatisierung Von Fertigungsablaeufen". lIess . Pruef, n. 12, Dec . 1973, pp . 769-773. Allan-Inglis VG . "Where to Start in Low Cost Automation". Engineering Design Show Conf. Mar . 2-6 1970, Brighton . Engl . Leung , LP .; Chick, V.K . "lIicro-Computer Control For Low Cost Automation" . lIeas . Control, v. 15, n . 2, Feb . 1982, pp . 67-71 . Hodgson, T. " Automation, with Particular Reference to the feed for Low Cost Automation in South Africa" . S. Afr . !(echo Eng., v. 27, n. 3, Mar. 1977, pp . 71-79. Jickols, lan. "Hydraulic Developments in Low Cost Automation" FlUid Power Int., V. 37, n. 435, Jun. 1972, pp. 85-86 . Arnd,G . "On the Implementation of Flexible Manufacturing Systems for Efficient Small-Scale Production". Xech. Eng. Trans. Inst . Eng . Aust., v . !(e-3, 1978, pp. 10-15 . Anon. "Low-Cost Autoll/ltion Output" . Mach . Prod . Eng., V . 126, n. 3248, Mar. 5 1975, pp . 222-223.
3
Mills Use programmable Vachter, Henry G. "U .S. Pap . Controllers For Low-Cost Automat ion" . Trade. J. , V . 169, n. 10, Oct. 1985, pp. 55-56. Yamanaka, Kunio; Kera, Kazuo; Osako, Kazuyoshi . Hitachi "Recent Advanced fa Controllers". Rev ., V. 35, n . 1, Feb. 1986, pp . 33-36. Riker, Vllliam J . "GK s Manufacturing Automation Protocol". Iron Stell Eng., V. 63, n.1., Jan . 1986, pp . 68-70 . Sullivan, John L. "Xonitor X: A Low-Cost Answer to Automation in Physical Testing" . Pima lIag., V . 68, n.2, Feb. 1986, pp . 38-40 . Anon . "Low-Cost Kodular System of Machine-to-Computer Communication For a Flexible machining Cell". Int. J . Adv . Manu!. Technol., v.1, n. 1, Sep . 1985 , pp. 55-71. Josef . Verkzeuginnendruck Schinmele, "Mi t optimieren und Rationalisieren: Gemeinsamer Nenner Fuer praezision und Kostenguenstige Fert igung" . Plast verarbe iter, v, 35, n. 5 May . 1984, pp. 82-85 . Vatson, E. "Low-Cost Automation in Pilkington Bros . Ind . Robot., v .3 , n . 1, Kar. Using Robots". 1976, pp . 23-27. Fisher, Herbert, Kostensenkende Kombinierte Bohr-Und Gewinde-bohr-Einheiten" . Verkstatt Betr., v . 108, n. 4, Apr . 1975, pp . 205-206. Freeman Ag. "Fluid logic systems for the control of Low Cost Automation machine tools". Hydraul. Pheum. Power, V. 16, n. 187, July 1970, pp . 388-94. Poll A; Ray DJ. "One digital controller for 16 DDC loops" . Contr. Eng . , V. 17, n.4, Apr. 1970, pp. 75-8 . Sidders PA. "Low-Cost Automation at works of Bellows-Valvair" Machy (Lond ) , V. 115, n. 2963, 2966, Aug. 27 . 1969, pp. 322-7. Sept. 17., pp . 460-4 Barker AJ. "Low-cost Automation Transfer IIachine" . IIachy (Lond) ,v. 114, n. 2947, 2949, May 7 1969, pp. 738-41, lIay . 21, pp. 810-13. Herridge FV . "Low-Cost Automation at Works of Fry ' s Diecastings". Machy. (Lond), V . 113, n . 2905, July 17 . 1968, pp . 180-4.
KEYNOTE ADDRESS
ABOUT LOW COST AUTOMATION G. A. Ferrate, President of CEA-IFAC, Spain Working Group of CEA-IFAC
Abstract: As a result of a one day meeting held by working Group of the Spanish NXO of IFAC (CEA-IFAC) a brainstorming session was dedicated to the analysis of the main topics related with Low Cost Automation. Three cathegories of factors have been pOinted out: the control equipment aspects, the process characteristics and the system exploitation. INTRODUCTION
LOW COST CONCEPT
In the past, the concept of low cost automation was associated to simple devices, with rather low of the control performances, adequate for non-sophisticated plants or processes which do not reqUire very stringent specifications .
The concept of Low Cost has been traditionally associated with simplicity, but simplicity is an evasive and ambiguous concept. If we consider, for example a PID controller made up of mechanical parts including levers, bellows, springs, dumpers, etc . and we compare it with a device performing electronically a similar function,and making use of LSI circuits, the question arises us to which one is simpler.
Nowadays, the fast evolution of the theory and applications of Automatic Control, as well as the development of highly performant non expensive changed the traditional computing decives has concept of low cost automation, incorporating new aspects such as, for instance, the easiness of the flexibility, the design and installation, friendly operation and the maintenablli ty, thus concept of Low Cost giving rise to the new Automation (LCA). These considerations have lead us to present some brief reflexions concerning the evolving concept of LCA and its possible interpretation at the present time. First of all we propose a possible definition of LCA, and we analyse some of the factors that are associate to it. LCA is not a general solution and its applicability is directly related to the kind of process to be controlled and to the existence of some special specifications to be fulfilled. It is clear, for instance, that LCA does not seams, in principle, the adequate approach to automate a nuclear power station, a car factory or a railway traffic network. LCA concept is still and open subject, rapidly evolving along with the development of computer techniques and the availability of cheap components and modular or standardized units wich result frOD the increasing application of control techniques to many new fields .
The electronic device is manufactured simply assembling, into a printed circuit board, a few readily available components which conceal a great internal complexity and which require the access to very sophisticated and advanced technologies for their production. The mechanical controller, on the other hand, can be manufactured making use of much mare simple and well known technologies, and needs the careful fixing and adjustment of many precision engineered parts, specially designed and produced for the purpose. Which one is simpler? The answer is not easy if additional considerations concerning other factors such as ease of maintenance, reliability and many other, are not made. Generally speaking, it can be affirmed that simplicity is nowadays much mar related to the easiness of design, assembly and adjustment of systems, making use of readily available components, modules and units, than to the intrinsic complexity of the system as a whole. Up to now, we have referred ourselves to the cost of the control eqUipment itself, which is strongly related to its simplicity, whatever this may be. However, a more general perspective, taking into account other aspects of the whole system leads to the concept of LCA. To the cost of the equipment must be added other factors mainly concerning the context, the operation, the maintenance and the replacement, as well as the norms or regulations to be fulfilled .
2
G. A. Ferrate
LCA is not an absolute figure but rather a relative concept, as a consequence of the variety and fuzziness of the involved aspects. From the previous considerations and comments we could establish that the aim of LCA is to accomplish the control of machines, plants or processes, trying to minimize a cost function while achieving a sufficiently good performance. The cost func tion should take into account factors concerning the c ontrol equipment, the system to be controlled and the global operation. Strictu sensu, LCA requires that the value of each of the cost function terms, as well as the total value of this function, should be below some preestablished limits. The above limits should be set according to current market situation and to the relative economical parameters of the plant to be controlled and of the row materials being handled. The general technological level is also to be considered .
LOW COST FACTORS As previously mentioned, the factors to be considered as forming part of the cost function in order to evaluate the degree of fulfillment of the LCA conditions can be grouped into three c athegories refering to: - the control equipment aspects - the process characteristics - the system exploitation In the first cathegory we must consider related to the equipment itself like: -
design acquisition or manufacture programming installation tuning or adjustment of parameters other
as well as those which AlTDng these: -
aspects
refer to
-
environmental conditions operation cost row material cost continuous or non continuous operation failure cost reliability and safety requirements legal regulations other
Besides the three cathegories just mentioned, attention should be payed to some features of the equipment to be used that may have an important role in evaluating the function c ost: the flexibility or capacity of the equipment to be easely adapted to perform different tasks, or, for instance, the possibility of re-using it, in another system, opportunity, or context. It is obvious that equipment modularity and standardization may positively influence the solution given to an a'Jtomation problem, even if does not represent the simplest one. Modularity can be a decisive factor to achieve the desired flexibility and re-usability of the equipment . Standardization may not only reduce the cost of the equipment, due to mass-production, but also facilitate and make easier to find qualified personel for operation and maintenance . This is another cost reducing component in view of LCA.
APPLI CABILITY Not all the fields that may be subject for automation are suited to LCA. Among the factors that have been mentioned in the previus paragraph, some of those included in the two last cathegories are of special relevance in order to determine the applicability of LCA in a specific case. With respect to process characteristics, the number and nature of variables as well as the accuracy requirements could be incompatible with Low Cost solutions while, where system exploitation is considered, aspects like environmental conditions, failure cost, reliability and safety requirements and legal regulations might also be the most important to that end.
the utilization.
operation maintenance wor k1 ng lif e energy and environmental reqUirements other
a The process characteristics is normally determining factor to take a decision ahout the applicability of a LCA system. The following are important:
"Groso ){odo", three main groups of applications can be considered: those applications where the factors just mentioned discourage from using LCA methods, situations where LCA is clearly the best suited approach, and those cases in which the applicability of LCA depends on many other factors, thus making the decision much more c omplex.
About Low Cost Automation It is easy to find examples of application fields where LCA is obviously discarded : avionics and space, nuclear power stations, railway systems, and electric power dispatching. . . and, generally speaking, the military area . The main common factor to these examples is the strong requirements on reliability. All of them exhibit complex dynamic behaviour and, moreover, the cost of the control system is not a decisive factor, taking into account the hign cost of the syste. as a whole, and the crucial importance of its function . Fortunately, the areas where LCA is clearly applicable are rather wide. Many of them refer to industrial manufacturing processes and consumer equipments . It is difficult to define precisely the limits of this group, but we can mention as examples all those where temperature or position control is necessary, sequencial systems, speed controllers, and, generally speaking, all those where the system dynamics is relatively simple and the safety and legal requirements are not very demanding. Many of the micro-processor controlled systems are also progressively falling into this cathegory.
REFERElCES Beaty, R. T. "Evolution Towards Automation". lEE Proc., Part A, V. 133, pt . A, n. 6, Sep. 1986, p.332. Anon."High Productivity - Low Cost Automation in Industry" . Certif . Eng., V. 54, n. 3, Mar. 1981, pp . 864-872. Ca Idwe 11 , Laura 11 . "LoW-Cost Factory SystellS Integration" . CIK Reev., v. 1, n . 4, Summer 1985, pp. 27-35. Sogo,Marllyn R. "Closing The Loop" . lIech . Eng., v. 107, n. 10, Oct . 1985, pp . 50-52. Dzieyk, Bruno. "Low Cost - Automatisierung Von Fertigungsablaeufen". lIess . Pruef, n. 12, Dec . 1973, pp . 769-773. Allan-Inglis VG . "Where to Start in Low Cost Automation". Engineering Design Show Conf. Mar . 2-6 1970, Brighton . Engl . Leung , LP .; Chick, V.K . "lIicro-Computer Control For Low Cost Automation" . lIeas . Control, v. 15, n . 2, Feb . 1982, pp . 67-71 . Hodgson, T. " Automation, with Particular Reference to the feed for Low Cost Automation in South Africa" . S. Afr . !(echo Eng., v. 27, n. 3, Mar. 1977, pp . 71-79. Jickols, lan. "Hydraulic Developments in Low Cost Automation" FlUid Power Int., V. 37, n. 435, Jun. 1972, pp. 85-86 . Arnd,G . "On the Implementation of Flexible Manufacturing Systems for Efficient Small-Scale Production". Xech. Eng. Trans. Inst . Eng . Aust., v . !(e-3, 1978, pp. 10-15 . Anon. "Low-Cost Autoll/ltion Output" . Mach . Prod . Eng., V . 126, n. 3248, Mar. 5 1975, pp . 222-223.
3
Mills Use programmable Vachter, Henry G. "U .S. Pap . Controllers For Low-Cost Automat ion" . Trade. J. , V . 169, n. 10, Oct. 1985, pp. 55-56. Yamanaka, Kunio; Kera, Kazuo; Osako, Kazuyoshi . Hitachi "Recent Advanced fa Controllers". Rev ., V. 35, n . 1, Feb. 1986, pp . 33-36. Riker, Vllliam J . "GK s Manufacturing Automation Protocol". Iron Stell Eng., V. 63, n.1., Jan . 1986, pp . 68-70 . Sullivan, John L. "Xonitor X: A Low-Cost Answer to Automation in Physical Testing" . Pima lIag., V . 68, n.2, Feb. 1986, pp . 38-40 . Anon . "Low-Cost Kodular System of Machine-to-Computer Communication For a Flexible machining Cell". Int. J . Adv . Manu!. Technol., v.1, n. 1, Sep . 1985 , pp. 55-71. Josef . Verkzeuginnendruck Schinmele, "Mi t optimieren und Rationalisieren: Gemeinsamer Nenner Fuer praezision und Kostenguenstige Fert igung" . Plast verarbe iter, v, 35, n. 5 May . 1984, pp. 82-85 . Vatson, E. "Low-Cost Automation in Pilkington Bros . Ind . Robot., v .3 , n . 1, Kar. Using Robots". 1976, pp . 23-27. Fisher, Herbert, Kostensenkende Kombinierte Bohr-Und Gewinde-bohr-Einheiten" . Verkstatt Betr., v . 108, n. 4, Apr . 1975, pp . 205-206. Freeman Ag. "Fluid logic systems for the control of Low Cost Automation machine tools". Hydraul. Pheum. Power, V. 16, n. 187, July 1970, pp . 388-94. Poll A; Ray DJ. "One digital controller for 16 DDC loops" . Contr. Eng . , V. 17, n.4, Apr. 1970, pp. 75-8 . Sidders PA. "Low-Cost Automation at works of Bellows-Valvair" Machy (Lond ) , V. 115, n. 2963, 2966, Aug. 27 . 1969, pp. 322-7. Sept. 17., pp . 460-4 Barker AJ. "Low-cost Automation Transfer IIachine" . IIachy (Lond) ,v. 114, n. 2947, 2949, May 7 1969, pp. 738-41, lIay . 21, pp. 810-13. Herridge FV . "Low-Cost Automation at Works of Fry ' s Diecastings". Machy. (Lond), V . 113, n . 2905, July 17 . 1968, pp . 180-4.