Systems and Lifecycles

Chris Wallace

7 ‘Systems’

• S1, S1’ Context System• S2 Intervention System• S3 Realization System• S4 Deployed System• S5 Collaborating System• S6 Sustainment System• S7 Competing System• P1 Initial Problem • P2 Consequential Problem

S2

P1

S4P2

S5

S7

S6

S1

S3

S1’

P1 - Problems

• Hard and Soft– ‘Hard’ problems – problem is simply identified, stated

and agreed by all parties– Soft problems - Problem identification is problematic,

hard to state and seen differently by different parties• ‘wicked’ problems (Horst Rittel)

• Methods to address soft problems– P1 is often ‘lack of fitness’ of an existing system – Recognition of multiple viewpoints - CORE– Peter Checkland’s Soft Systems Methodology >>

S1 - Context

• Bounding – Bounded rationality ( Simon)

• We can never hope to understand the entire context • We must limit our attention to things which matter most• Satisficing not Optimising• Is this just another cognitive limitation?

• Dynamic– S1->S1’->S1’’…how the Context is expected to

evolve

System and Context

• System– “A recognisable whole which consists of a set of inter-dependent

parts. More specifically:• A system is an assembly of components connected together in an

organised way• The components are affected by being in the system and the

behaviour of the system is changed if they leave it• This organised assembly of components does something• This assembly as a whole has been identified by someone who

is interested in it i.e. the agent, the client, or the problem owner

– From Carter, et al, ‘Systems, Management and Change’ : textbook for OU module T301

• The concept of a system is a thinking tool.• To be useful ‘system’ can’t just mean ‘stuff’

S3 – the Realisation System

• Much of the attention of Systems Engineering is on S3 – Engineers build planes– System Engineers build plane-making systems

• S3 is a Human Activity system – a ‘meat’ system– People, roles, organisational structures, procedures, documents,

training programs…– Emphasis on

• Knowledge management• Information & communication• Decision making and tracking

• Re-use– Of people, procedures, design and analysis tools, manufacturing

processes– Assemblage of often inflexible resources

Smart Acquisition

• A whole-life approach – through life costing - Through Life Management Plan (TLMP)

• Integrated Project Teams (IPT)• More investment during early project phases• Effective trade-offs between systems

performance, through life costs and time• Two process models

– CADMID for new equipment– CADMIT for procurement

CADMIDA Mandated Approach

• Concept– URD – User Requirements Document– Initial Gate

• Assessment – SRD – Systems Requirements Document– Main Gate

• Demonstration• Manufacture• In-service• Disposal

ISO 15288 A Contingent Approach

• Defines Multiple Processes in the systems lifecycle.

• “Each life cycle Process can be invoked, as required, at any time throughout the life cycle and there is no definitive order in their use.” Draft

S3 (Realisation) <> S1 (Context)

• Knowledge acquisition– Gathering of understanding of the context and the

problem >>• Description

– Of the context and problem– Then of the proposed S2 in stages of reduction in

solution space (set of possible S2’s)• Idea• KPI (Key Performance indicators)• Brief• URD (User Requirements Document)• SRD (Systems Requirements Documents)• Architectural Design• Detailed Design

Trade-offs

• ‘Nothing we design or make ever really works. We can always say what it ought to do, but that it never does. The aircraft falls out of the sky, or rams the earth full tilt and kills people. It has to be tended like a new-born babe. It drinks like a fish. Its life is measured in hours.’– David Pye , The Nature of design,1964

Descriptions

• Multiple languages of description– Text

• Requirements– Diagrammatic

• 22 kinds in 12 papers in INCOSE conference• Martin uses a form of ER model – structure

– We also need to describe dynamics, interactions, interface– SysML is a modification of UML (Unified Modelling Language)

for SE >>– UML has 13 kinds of model

• Most descriptions are of S2 (the form), not S1 (the problem)– Michael A. Jackson argues system engineering requires a

greater focus on the problem and context – we leap into the solution space too quickly >>

S2 - The Intervention System

• The ‘system’ being developed– A400M, Beagle 2, NHS Information System– But also

• The GCSE /A level examinations in schools• Daylight saving• The law ‘no smoking in pubs and clubs’

– Are these all systems?

• The ‘Form’ designed to fit the ‘Context’

S2 -> S4 – Deployed System

• Processes– Manufacture– Training– Field and Customer Adaptation– Installation

• Cases– 3-day Car – NPfIT (NHS national programme for IT)

• £2.3bn initial funding• Risen to £6.2bn procurement costs• Total implementation costs £12bn to £24bn• Life-cycle costs 1.5 times Channel tunnel

S1’ + S4• We have to understand the context so well that

when we implement our solution it fits perfectly.• A Simple situation

– Context is bar magnet– Form is the arrangement of iron filings– Objective is perfect fit of the form when its placed in

the context

• Two extremes:– Traditional approach – trial and error– Design approach – model and predict solution fitness

before build • Requirements are a surrogate for S1’

S3 <> S1’

• Fit is not enough– Usually we want to change the context in some desirable

direction– Others are trying to compete with or destroy our system (S7)– S1 and S4 change throughout the lifetime of S4

• We use models and theories to attempt to predict the behaviour of S4 in S1’ – Models and theories to predict how the system will behave under

different circumstances• General systems theory• Causal diagrams • Systems thinking >>

– Analysis to predict all the possible ways in which the system can fail and counter them

• Genesis failure • Failure analysis >>

Genesis failure“Investigators may have discovered what caused the Genesis spacecraft to

crash into the Utah desert this September. Some crucial switches were installed backwards, because of an error in the instructions.

The problem stems from the craft's design drawings, made by Lockheed Martin in 2001. They showed that some tiny cylindrical plungers, designed to detect the gravity of an incoming planet and deploy a parachute, were installed the wrong way.

There were four such switches - two as a backup in case the first two failed. But all of them had been installed backwards. As a result the parachute didn't open, and the capsule plummeted to Earth.

None of NASA's review processes picked up the mistake. "It would be very easy to mix this up," says Michael Ryschkewitsch, chair of NASA's mishap investigation board at the Goddard Space Flight Center in Greenbelt, Maryland. Investigators had to X-ray the crashed craft to confirm that the devices were the wrong way round.”

S5 Collaborating Systems

• Multiple existing systems into which the deployed system has to fit.

• If already existing, they must be part of S1 and thus need to be understood and described.

• Collaborating system vary in their degree of co-operation– Regulatory authorities – little co-operation– Partners – much co-operation

S6 Sustainment System(s)

• Systems which need to be developed alongside S2– Documentation– Training– Maintenance– Spares

• Difference between Sustainment and Collaboration is a matter of degree or control

P2 – Consequential Problems

• Does the engineer have an ethical responsibility for the consequences of her systems?

• Are unanticipated consequences simply the result of poor analysis?

• Are consequential problems good for business?

“Every problem we solveCreates 10 problems more” Piet Hein

Poem – The centipedeby Mrs Edmund Craster (d. 1874)

A centipede was happy quite,

Until a toad in fun

Said ‘Pray which leg moves after which ? “

This raised her doubts to such a pitch

She fell exhausted in a ditch,

Not knowing how to run.

While lying in this plight,A ray of sunshine caught her sight ;She dwelt upon its beauties long,Till breaking into happy song,Unthinking she began to run,And quite forgot the croakers fun.

Agile development - Bedoll paper

Workshop

• Apply the Martin Framework to the following situations

– a) S2 is the A400M – b) S4 is a KLM-owned Boeing 747 PH-BLF – c) P1 is Sadaam's Weapons of Mass Destruction – d) S2 is the proposal to retain daylight saving all year.– e) S2 is Martin's paper, 'the Seven Samurai'