interface design improvement in supervisory control

Interface Design Improvement in Supervisory

Control

Pere Ponsa1, Ramon Vilanova2, Marta Diaz3, Anton Goma4

1 Automatic Control Department, Technical University of CataloniaAv. Victor Balaguer s/n, 08800 Vilanova i la Geltru, Spain

Pedro.Ponsa AT upc.edu

2 Telecomunication and Systems Engineering Department, UniversitatAutonoma de Barcelona

ETSE, 08913 Bellaterra, SpainRamon.Vilanova AT uab.cat

3 4all-L@b Usability Laboratory, Technical University of Catalonia,Av. Victor Balaguer s/n, 08800, Vilanova i la Geltru, Spain

Marta.Diaz AT upc.edu

4 S.A.F. Sports Service Area, Universitat Autonoma de Barcelona08913 Bellaterra, Spain

Anton.Goma AT uab.cat

Abstract In tasks of human supervision in industrial controlroom several generic disciplines such as the software engineeringfor the design of the computing interface and the human factorsfor the design of the control room layout come into application.From the point of view of the human computer interaction, tothese disciplines it is necessary to add the usability engineeringand the cognitive ergonomics since they contribute rules for theuser centered design. The main goal of this work is the appli-cation of a guideline for supervisory control interface design inorder to improve the efficiency of the human machine systems inautomation. This communication presents the work developedto improve the Sports Service Area interface of the UniversitatAutonoma de Barcelona.

1 Introduction

In recent years, control systems and the role of control room human opera-tors have changed dramatically [13]. Human operator activity has evolvedfrom manually performing the process, to control system supervision. To-day, the human operator requires an in-depth knowledge of the processthat he/she is overseeing and the ability to make effective decisions withindemanding constraints.

The increased complexity of industrial process control systems callsfor a new methodological approach (for research and design purposes),

Pere Ponsa, Ramon Vilanova, Marta Diaz, Anton Goma “Interface DesignImprovement in Supervisory Control” Vol. I No. 3 (Dec. 2007). ISSN: 1697-9613

(print) - 1887-3022 (online). www.eminds.uniovi.es

Pere Ponsa, Ramon Vilanova, Marta Diaz, Anton Goma

which reproduces the essential components of current control systems:the environment, the task at hand and human operator activity [19].

The complexity of industrial process supervision makes it necessaryto supplement the Human Factors approach and the Human-ComputerInteraction approach with a cross-disciplinary cooperation in order to in-tegrate knowledge and methods from other fields, especially CognitiveErgonomics, Automation and Artificial Intelligence [1] [2] [6], [7] [9]. Ourview is that complete control systems engineering must encompass allthese approaches.

Ergonomics is concerned with the adaptation of technology to suithuman operator needs and ability so as to achieve effectiveness, efficiencyand user/worker satisfaction and comfort [3].

Supervisory control is conceived as the set of activities and techniquesdeveloped over a set of controllers (programmable logic controllers andindustrial regulators) which ensures the fulfilling of control goals. One ofthe main goals is to prevent possible plant malfunctions that can lead toeconomical lose and/or result in damage [16]. For this reason, other fieldsof knowledge concerned with manufacturing systems performance - suchas maintenance and industrial security - are complementary in the studyand application of supervision systems.

In this paper a methodology for the creation of a human factor guide-line for supervisory control interface design is proposed. In section 2 achecklist of indicators of the guideline called ’ergonomic guideline for su-pervisory control interface design’ (GEDIS) is presented. The frameworkfor the application of the presented guideline is the Sports Service Areaproject is described in section 3. The purpose is not to cover with detailthe entire project but to give an idea of the different kind of topics thathave been covered. In section 4, transition from the GEDIS model toSports Service Area interface in control room is evaluated. In this sec-tion a usability framework to improve control room design and a set ofrecommendations about graphical interface improvement are presented.Finally, conclusions and future research lines are outlined.

2 GEDIS Guideline

The previous research on human interface design guidelines includes, forexample, the standard ISO 11064 that establishes ergonomic principles forthe evaluation of control centers [8], the Human Factors Design Standards(HFDS) of the Federal Aviation Administration of the United States [5] ,the Human Interface Design Review Guidelines NUREG 0700 in nuclearpower plants [21], the I-002 Safety and Automation Systems NORSOKabout Norwegian petroleum industry [15] and the Man Systems Integra-tion Standard NASA-STD-3000 about manned space programs [11]. Ta-ble (1) provides a comprehensive summary of the different approaches andcorresponding application domains:

22

Interface Design Improvement in Supervisory Control

Table 1: User Interface Design GuidelinesStandard -Guide

Description Domain

HDFS Human factors practices and prin-ciples integral to the procurement,design, development, and testingof Federal Aviation Administration(FAA) systems, facilities, and equip-ment of the United States

Aviation

NUREG700 Human factors engineering (HFE)aspects of nuclear power plants inaccordance with the Standard Re-view Plan of the U.S.

NuclearPower Plant

NORSOK-SAS

This standard of the Norweginapetroleum industry covers func-tional and technical requirementsand establishes a basis for engineer-ing related to Safety and Automa-tion System Design.

Petroleumindustry

MSIS This document provides specificuser information to ensure properintegration of the man-system in-terface requirements with those ofother aerospace disciplines

Aerospace

GEDIS is not a Standard, is a guideline and can be used in oil andgas industry, for example. It is necessary to stablish a Standard in theindustrial domain. The GEDIS guideline is a first approach.

In order to introduce the GEDIS guide it is necessary to define therelationship between the designer, the human supervisor and the controlroom operator. There are a variety of expert-review methods [20]:

- Heuristic evaluation (the eight golden rules of interface design

- Guidelines review (organizing the display, getting the user’s atten-tion)

- Consistency inspection (the experts verify consistency of terminol-ogy, color, layout, etc.)

- Cognitive walkthrough (the experts simulate users walking throughthe interface to carry out typical tasks)

- Formal usability inspection

An example of cognitive modelling in human computer interactionis the GOMS guideline, about goals, operators, methods and selection

23


rules in usability analysis [4]. In combination with Keystroke-Level Model(KLM) an interface can be studied, also task execution time and humanefficiency can be studied too.

Table 2: Characterization of Human Computer Interaction guidelinesMethod-Characteristic

GEDIS GOMS HeuristicEvaluation

Reach Total anddetailed

partial Total butnot detailed

Include Human Su-pervisory ControlElements?

Yes No No

Include SoftwareToolbox?

No Yes No

Include NumericEvaluation?

Yes No No

Evaluation Guide Minimum Complex Extensive

The GEDIS guide is a method that seeks to cover all the aspectsof the interface design [18]. From the initial point of view of strategiesfor effective human-computer interaction applied to supervision tasks inindustrial control room [14], [20].

The GEDIS guide can provide design recommendations at interfacecreation time as well as recommendations for improvement of already cre-ated interfaces. The GEDIS guide is composed of two parts: descriptionof ten indicators and measure of ten indicators. The indicators have beendefined from extracted concepts of other generic human factors guidelines,and for aspects of human interface design in human computer interaction.

The method for the application of the GEDIS guide is: analyze theindicator, measure the indicator, obtain the global evaluation index andfinally offer recommendations of improvement.

For the correct use of the GEDIS guide it is necessary the collabo-ration between the control room technical team and the human factortechnician, since in some cases to analyze the indicator is necessary theexpert’s opinion.

2.1 Indicators List

The GEDIS guide consists of ten indicators that seek to cover all theaspects of the interface design in the supervisory control domain. The in-dicators are: architecture, distribution, navigation, color, text font, statusof the devices, process values, graphs and tables, data-entry commandsand, finally, alarms. For example, the relationship between architectureand navigation indicators is illustrated in Fig. 1. The physical plant canbe structured in area, subarea, and team. In the same way, the interface

24


presents four navigation levels. Fig. 1 shows a possible layout to locate allthe connections between screens. The connection among screens is com-plex in a supervisory control interface. From the point of view of humancomputer interaction, is a typical example of cyclic network menu.

Figure 1: A typical cyclic network menu in supervisory control interfaceassociated to navigation indicator (the user can jump around the branchesof the tree, go back to the previous menu, or to go to the beginning)

Figure 2: An example of object’s layout inside the screen for the distri-bution indicator. The display must be simple because the limitation ofhuman information processing in short-term memory

Distribution indicator of Fig. 2 shows a possible layout to locate all theobjects inside the screen. The objects homogeneous distribution allowsus to maintain the interface coherence when user changes from one screento another. The secondary objects are located in screen areas that don’trequire the user’s attention (enterprise logo, and date/hour information).

25


The user should recognize the screen title and the general navigation toolto move among screens. The main objects are located in visible screenareas (alarms, data-entry commands, subnavigation tool, and synopticobjects). The user can surveillance the process evolution without acting(human out of the loop), or he can decide to introduce changes in theset point or in the controller’s parameters (human in the loop) inside afaceplate window in the data-entry command object. The user shouldpay special attention to the alarm indicators, which should be located ina clear position in the screen so that the user can recognize the situation(situation awareness).

3 SAF Project

This section presents the development of the supervisory control system,with special emphasis on the interface features, for the Sports ServiceArea (SAF in Catalan version) of the Universitat Autonoma of Barcelona(UAB). This supervisory control system has been developed by a team ofComputer Sciences Engineers with common design guidelines [22].

Figure 3: Main window of the developed monitoring system with a globalview of the Sports Service Area

First of all, it is worth to know that the UAB is a campus baseduniversity with more than 40.000 inhabitants (students, academics, staff,etc.). In fact, this makes the University campus to behave like a citywith some sort of facilities offered for their inhabitants. Among them, theSports Service Area (SAF) is one of the largest and with more complexinstallations. It encompasses indoor as well as outdoor activities that runfor more than 12 hours each day. Just to give an idea of the diversity ofinstallations that give support to the offered activities, we can find there:

26


Figure 4: ISA-PID used to close the loops

covered swimming pool, boulders, outdoor facilities for tennis, football,athletics, etc., indoor installations for fitness, basketball, aerobic, gym,etc.

Therefore, large complexes build up from different subsystems. Eachone of these subsystems has to assure a quality of service each day. Thisfact introduces the need for good monitoring tools to help on this task.In addition, there is a huge number of automation and control problems(automated watering, temperature controls for water and indoor areas,lightning systems, ozone controlled system for water cleaning in coveredswimming pools, etc.).

The SAF project has different automation levels: from field instru-mentation and data collection, Programable Logic Controller (PLC) pro-gramming and feedback loop configuration, to information integration ona SCADA system. The SAF project use PLC from different manufacturers(SIEMENS, GE-FANUC, Landys, and Mitsubishi). All the data has beenintegrated through implementing the corresponding supervisory controlinterface with Wonderware suite called In TOUCH. The basic communi-cations use specific drivers to connect PLC with PC based control; theadvanced communications use the standard OPC protocol. How identifyoperator problems with tasks and technology?

An example: for indoor activities temperature control of both the SAFbuilding and the water for the gym showers has been implemented. Thismeans the control room operator has to close some loops by using theISA-PID present either in the PLC or in the software (see Fig. 4).

One important aspect of a monitoring system is how it deals withalarms. As this feature is a common feature, it should be incorporated inevery part of the system according to the same rules. This way, in every

27


SCADA window and alarm indicator has to be included that shows thehuman operator if an alarm is currently fired and can let you go directlyto the main alarm window to process it.

Finally, design implementation and configuration of the In TOUCHbased SCADA system has been done starting from zero. This allowedto think of a distributed application where from the different computerslocated either at the main SAF office or at the technical staff room theoverall system can be accessed. In addition a special access, using terminalservices, for the technical staff has been enabled so remote operation canalso be done from outside the SAF installations.

Even some basic principles on ergonomics and interface design weretaken into account; the GEDIS analysis will show existing weakness.

4 SAF Evaluation

The connection between the SAF interface and GEDIS guideline designersis necessary to define a global evaluation of the SAF interface and providea set of recommendations about graphical screen improvement (see Fig.5). This is the first step in the definition of a usability framework toimprove control room design. The Control Engineering students havethe role of control room operators. Each student uses the SAF Interfaceand applies the GEDIS guideline. Finally, from the point of view of usercentered design, the GEDIS designer assess the results and propose aglobal evaluation index and interface improvement to the SAF designer.

Figure 5: SAF interface evalutation with GEDIS guide method

28


4.1 Evaluation

The evaluation expressed in quantitative numeric form or in qualitativeformat seeks to promote the user’s reflection that stuffs the GEDIS guideby way of a questionnaire, so that it picks up the user experience thatdoesn’t end up being verbalized in many occasions.

Each one of the indicators of tables (3) and (4) are in diverse subindi-cators. For example, the indicator Color can be detailed in: absence ofnon appropriate combinations (5), number of colors (5), blink absence (noalarm situation) (5), contrast screen versus graphical objects (3), relation-ship with text (3). For each subindicator numerical punctuation in a scalefrom 1 to 5 is recommended. In this example the number of subindicatorsof the indicator Color is J = 5 (see formula (1)). To calculate the numericvalue of each indicator formula (1) is defined, where, Subindj is the valueassociated to each subindicator and wj the corresponding weight.

Indicator =

∑J

j=1wjSubindj

∑J

j=1wj

(1)

The mean value that one obtains by formula (1) with these numericvalues is, say, 4,2 . If it is rounded, the value is 4, so that to the indicatorColor is finally assigned a value of 4 in this example, considering that eachone of the subindicators has the same weight (w1 = w2 = ... = wJ = 1).1

Each one of the indicators of table (3) is measured in a scale from1 to 5. The human expert operator prepares in this point of concreteinformation on the indicator, so that it can already evaluate the necessitiesof improvement. The values of the indicators can be grouped so that theGEDIS guide offers the global evaluation of the interface as a whole andit can be compared with others interfaces. The formula necessary tocalculate the GEDIS guide global evalutation index is formula (2), whereindi is the indicator evaluation and pi the corresponding weight.

GlobalEvaluation =

∑10

i=1piindi

∑10

i=1pi

(2)

In a first approach it has been considered the mean value among indi-cators expressed in the formula (2). That is to say, to each indicator anidentical weight (p1 = p2 = ... = p10 = 1) is assigned. Although it willallow, it in future studies, to evaluate the importance of some indicatorswith respect to others. The global evaluation is expressed in a scale from1 to 5. Assisting to the complexity of the systems of industrial supervisionand the fact that an ineffective interface design can cause human error,the global evaluation of a supervision interface it should be located in

1Obviously, this situation may seem unrealistic. In any case, interviews with controlexperts should help in establishing the appropriate weights

29


Table 3: GEDIS Guide indicators (part one)

an initial value of 3-4 and with the aid of GEDIS guide it is possible topropose measures of improvement to come closer to 5.

4.2 Experimental study

The experimental study is the evaluation of SAF interface with the col-laboration of control engineering students from the Technical Universityof Catalonia, Vilanova i la Geltru, Twenty five students were monitoringthe SAF interface for around three weeks. The students define a numericvalue for each indicator and propose interface improvement.

The SAF interface global evaluation resulted to be 3,4. The globalevaluation is expressed in a scale from 1 to 5, so a set of important rec-ommendations are forwarded to the SAF designer:

– revise the relationship between structure, distribution and naviga-tion indicators because the numeric values are low. It is recom-mended to create a map to improve the understanding of the S.A.F.

30


Table 4: GEDIS Guide indicators (part two)

interface; arrange some objects inside the screens to maintain thecoherence of the S.A.F. interface; improve the location of the nav-igation switches in order to maintain the coherence of the S.A.F.interface.

– improve the feedback between interface and human operator in data-entry commands, in order to make easier the transition of the humanoperator modes (human in the loop, human out of the loop).

– improve the location of the alarm indicator from the point of viewof the distribution indicator example of the Figure 2. It is necessaryto extend the size of alarm’s object to increase the visibility.

With the GEDIS guide it is also possible to indicate the SAF designera set of important recommendations about graphical screen improvement.For example, the Piscina ACS screen can improve with a set of changesin color and text font indicators. Fig. (6) shows the original Piscina ACSscreen and Fig. (7) shows revisited Piscina ACS screen.

A second example, the Fronton and Rocodrom screen can improvewith a set of changes in distribution indicator. Fig. (8) shows the originalFronton and Rocodrom screen and Fig. (9) shows revisited Fronton andRocodrom screen.

31


Figure 6: Original Piscina ACS screen

Figure 7: Piscina ACS revisited with changes in color indicator

Finally, the authors assess the necessity to apply the cognitive walk-through method [23]. The usability expert can simulate users walkingthrough the SAF interface to carry out typical tasks. The collaborationbetween the general manager, the interface designer, the operators, theengineering students and the GEDIS designer are necessary to create andusability framework.

5 Conclusions

In tasks of human supervision in industrial control room is habitual thatan external engineer, - by means of commercial SCADA Software sys-tems -, take charge of designing the supervision interfaces on the basis ofthe knowledge on the physical plant and the group of physical-chemicalprocesses contributed by the process engineers.

32


Figure 8: Original Fronto and Rocodrom screen

Figure 9: Fronto and Rocodrom revisited with changes in distributionindicator.

Although standards exist about security in the human machine sys-tems that impact in aspects of physical ergonomics, interface design bymeans of rules of style, it is remarkable the absence of the design of inter-active systems centered in the user where the engineering usability andthe cognitive ergonomics can contribute significant improvements [12].

The GEDIS guide is an approach that tries to fill a methodological gapthat joins the efforts of the systems engineering and the human factorsfor the improvement of the effectiveness of the human-machine system inindustrial control room.

The application of the GEDIS guide to the study of cases contributes,among other details, to the measure in form of indicators of aspects ofinterface design, the recommendation of changes for the improvement ofthe interface, and a global evaluation index that allows to quantify thecurrent state of the interface regarding the future state after applying thecorrect measures.

33


The studied case presented shows an academic application, but withthe same characteristics of an industrial project. With the GEDIS guideapproach it’s possible to perceive diverse anomalies and to propose im-provements in the interface design.

Another current study with the GEDIS guide is the analysis of a sugarmill interface [17]. At the Sugar Technology Center (CTA), located in Val-ladolid (Spain), there has been developed a training simulator for mod-eling and simulation of the production process and the human operators’supervisory tasks. The simulator developed in this center is an exampleof a full scale simulator, a type of simulator that reproduces the wholeoperating environment [10]. This simulator emulates the control room ofa sugar mill. A series of object oriented modelling library tools are usedto create each part of the sugar mill: diffusion, evaporation, purification,sugar room, boilers, dryer, and liquor storage.

In these moments the 4all-L@b Usability Laboratory of the TechnicalUniversity of Catalonia is analyzing the GEDIS guide to simplify thenumber of indicators of the guide, to improve the evaluation method, andto promote the use of the guide inside the software engineering life-cycle,in this case in the early phases of the supervisory control interface design.

6 Acknowledgements

Participation of the second author is supported in part by the SpanishCICYT program under contract DPI2004-06393.

34

Bibliography

[1] Antsaklis Panos, Basar Tamer, DeCarlo Ray, McClamroch N.Harris,Spong Mark, Yurkovich Stephen, 1999. Report on the NSF/CSSworkshop on new directions in control engineering education. IEEEControl Systems Magazine, (10), pp 53-58.

[2] Astrom, Karl Johan, 1999. Automatic control: the hidden technology.P.M. Frank ed.. Advances in Control: Highlights of ECC-99, pp. 1-28.

[3] Canas, Juan Jose, 2004. Personas y maquinas. Editorial Piramide,Coleccion Psicologıa

[4] Card, Stuart K., Moran, Thomas P., Newell, Allen, 1983. The psy-chology of human computer interaction. Lawrence Erlbaum Asso-ciates, Inc.

[5] Federal Aviation Administration, 1996. Human factors designguide for acquisition of commercial-off-the-shelf subsystems, non-developmental items, and developmental systems (DOT/FAA/CT-96/01). Atlantic City International Airport, DOT/FAA TechnicalCenter

[6] Granollers, Toni, Lores, Jesus, Canas, Juan Jose 2005. Diseno de sis-temas interactivos centrados en el usuario. Editorial UOC, ColeccionInformatica, No 43

[7] Holstom, Conny O., 2000. Human factors and control centre issues.What lessons we have learned. Institute for Energy Tecnology, OECDHalden Reactor Project

[8] ISO International Organization for Standarization, 2004. Er-gonomic design of control centres, parts I, II, III, IV. In URL:http://www.iso.org

[9] Kheir, N.A., Astrom, K.J., Auslander, D., Cheok, K.C., Franklin.G.F., Masten, M., Rabins, M., 1996. Control systems engineeringeducation. Automatica 32 (2), pp. 147-166.

[10] Merino, Alejandro, Alves, Raul, Acebes. Luis Felipe, 2005. A trainingSimulator fot the evaporation section of a beet sugar production.European Simulation Multiconference, ESM-05, Oporto, Portugal.

[11] NASA, 1995. Man system integration standards. NASA-STD-3000,In

[12] Nielsen, Jacob, 1993. Usability engineering. Academic Press, Boston.


[13] Noyes, Jan, Bransby, Mathew 2007. People in conrol: human factorsin control room design. The Institution of Engineering and Technol-ogy.

[14] Nimmo, Ian, 2004. Designing control rooms for humans. ControlMagazine

[15] Norsok Standard, 2006. I-002 Safety automation system. NorwegianTechnology Centre Oscarsgt. 20, Postbox 7072 Majorstua N-0306Oslo. In

[16] Petersen, Johannes, May, Michael, 2006. Scale transformations andinformation presentation in supervisory control. International Jour-nal of Human-Computer Studies, Vol 64, 5, May, pp. 405-419.

[17] Ponsa, Pere, Dıaz, Marta 2007. Application of an ergonomic guidelinefor sugar mill control room interface design. FAIM 2007, 17 th In-ternational Conference on Factory Automation and Intelligent Man-ufacturing, Philadelphia, USA

[18] Ponsa, Pere, Dıaz, Marta, 2007. Creation of an ergonomic guidelinefor supervisory control interface design. Engineering Psychology andCognitive Ergonomics, Don Harris (Editor), Lecture Notes ArtificialIntelligence 4562

[19] Samad, Tariq, Weyrauch, John, 2000. Automation, control and com-plexity: an integrated approach. John Wiley and Sons

[20] Schneiderman, Ben, 1997. Designing the user interface. Strategies foreffective human-computer interaction. Addison-Wesley, third edition

[21] U.S. Nuclear Regulatory Commission, 2002. NUREG-0700, Human-system interface design review guidelines. Office of NuclearRegulatory Research, Washington DC 20555-0001. In URL:http://www.nrc.gov/reading-rm/doc-

[22] Vilanova, Ramon, Goma, Anton, 2006. A collaborative experienceto show how the University can play the industrial role. 7th IFACSymposium on Advances in Control Education, June, Madrid, Spain.URL: http:www.dia.uned/ace2006

[23] Wharton, Cathleen, Rieman, John, Lewis, Clayton, Polson, Peter,1994. The cognitive walkthrough method: A practitioner’s guide. InNielsen, J. and Mack, R. (Editors), Usability Inspection Methods,John Wiley and Sons, new York

36

interface design improvement in supervisory control

Documents