Vehicle System Design Process

M. SquairPrincipal Engineer – Systems Assurance

Architectural Design

• Currently we have little that defines a process for architectural design

• Start out with a set of ‘system’ requirements & end up with production drawings

• And in the middle?

• Reality is that design proceeds concurrently at

• System level• Subsystem (functional design)• Detailed physical design of the vehicle

• Traditional response to concurrency is to adopt a first pass (primitive modelling) then second pass (detailed) modelling

• Nor forgetting the need to make advance parts buys to make schedule (lock in solution at piece part before system/subsystem design)

Design WBS Ambiguity

• A problem with the current engineering WBS is the concept of ‘areas’ in design

• Used to represent the design principal of an integrated 3D model

• Designers work in areas to develop a model then from the model 2D drawings are generated for manufacture/procurement

• Input design of procured components & adjust vehicle design e.g. bracket design, move components around, reroute cables & ducts

• Represents a integrating (vehicle system) level design element

• Problem: A Model is not a deliverable of itself, so a ‘physical area’ as a WBS element makes no sense unless it is tied to specific deliverables.

• End result. Modelling becomes an end in itself à OSCAR Design Blow-out

Proposed Total Vehicle Design Process

Major modules/cabsMajor equipmentMajor pipe-workMajor cablewaysVentilation ductsLifting pointsRemoval routesPersonnel access routesMaintenance envelopesInstallation EnvelopesMajor seatsShock mounted equipmentMinor bulkheadsWalkways(LOD 1,2)

Subsystem designEqpt SpecificationsEqpt Physical DataCommissioning support

Systems EngineeringStructural DesignFunctional definition/alloc.Subsystem specificationsSafety caseWeight managementIntegration supportCommissioning supportDesign Strategy Integrated detail design (LOD3) Create Dwgs/EBOMs

Create IGES Files (LOD4)

Vehicle Design Process

Inputs:• Modelling strategy• BUILD/OUTFIT CONCEPT• Supply (Procurement) lead times, suppliers• Modularisation• Production Output Reqmts• Detailed design (foreign)• Support

PrimitiveModelling

Subsystem X Design Area Detail

Design

VehicleDesign

Inputs:• Strategies/plans for:

- Architectural design & Build strategy- Implementation- Supply (Procurement) - Integration & Verification etc

• Production & Commissioning Support Needs

Spatial (area)Integration

Create ProductOutputs

ModellingStrategy

Level of DetailRequired

Outputs

Required

Vehicle Prelim Design WBS

Vehicle SystemDesign WBS

Subsystem X WBSDesign

Make/Buy Items

Commission

Test

Area X Prod’nDrawings WBSDesign Area X

(Detailed Production)Make/Buy Area X

Assemble Area XInstall Subsystems

in Area X

Area X DetailedDesign WBSDesign Area X

(Detailed Spatial)

Subsystem Design

• What About Subsystem Design?

• How does a phased design approach integrate efforts

• Remember the V Model

• Are system (Vehicle) & subsystem design in parallel?

• If so does subsystem prelim design leads/lag ßà Vehicle prelim design?

VehicleDesign

PrimitiveModelling

Spatial AreaIntegration

CreateOutputs

PreliminaryDesign

DetailDesign

Interface to vehicle design? Completion of subsystem design phase = Entry Criteria for Vehicle Phase End Control Gate?

FuelSubsystem

Design Process

DetailedDesign

PreliminaryDesign

Example: Fuel Subsystem Design

Commisioning

Inputs:• Required Fuel service functions

Verification

Detail design of componentsFinal 3D CAD layoutFinal InstallationDetailed production drawings??

Type test procedures--Equipment type testsPrelim Component analysesDetail Component Analyses(fatigue, thermal, clearances)---Prelim Subsystem analysesDetail Subsystem analyses(flow, press loss/safety)Clearance checks (piping)Subsystem type testsSafety functions verification

Installation ProceduresCommisioning (Routine) test support

Redundancy analysisSystem schematicsPreliminary 3D CAD layoutPreliminary Installation

Component sizingDerived functions(fault tolerance)Actuator flow/shutoff controlServicer reqmts tableDesign service eqmtEquipment SpecificationsVerification PlanTest Plan

Field Feedback

Test & analysis Results

Results

Interface to vehicle design? Completion of subsystem design phase = Entry Criteria for Vehicle Phase End Control Gate?

Design Process & WBS

• The original design WBS reflected an attempt to address the subsystem design versus area integration problem

• Model ‘areas’ are not an end in themselves, need to identify the deliverables

• Some elements of the modelling task = vehicle design• Intermediate product (Primitive to detail modelling)• Some elements of the modelling task = detailed design

• To successfully integrate engineering effort to manufacturing effort a common framework for manufacture, assemble & commissioning of the product needs to be established

• Bottom line – Physical area WBS (in Design WBS) needs to be merged with actual manufacturing WBS Areas• Shipbuilding has been doing this for years

Design Management

• Level of work at each preceding step defined by required outputs to next

• Production drawing needs (end user) defines detailed area modelling• Detailed modelling strategy defines level of primitive modelling required

• Question, where are these requirements defined currently?

• Subsystem design (equipment) is an intermediate design input

• Require delivery iteratively e.g.

• envelope & mounts to primitive modelling• then detailed interface to detailed spatial modelling

Distributed Subsystems

• Design distributed subsystems (lighting, power, pneumatic etc) functionally

• But, we build by module/zone/area

• Result is production ‘cherry picks’ information from various source documents, time consuming and error prone – especially for spaghetti (wiring & piping)

• Cure: Integrate area /modular outfit into distributed subsystems

• Wiring, piping, paint schemes, ducting design by area• Easy to mate interfaces between areas• Integrated drawings package for areas• Carry back partitioning into system schematics

• Ideally integrate (wiring tests & checks) by area, then integrate areas as part of commissioning of subsystem – Mileage may vary

• Allows for off vehicle test & checkout then plug in and play

Product Line Management

• By definition• New product variant should not change the fundamental product line design

• Review for impact• But where is this captured, how can it be reviewed?

• Changes to some system, subsystem design (for example ECP)

• More change at model level (assuming a detailed model has been created)

• New elements step through LOD refinement 1à3,4

• Do/Don’t revisit primitive modelling? – How do we capture installation & access routes in detailed models?

Other Benefits: Outsourcing Design

• Modularisation allows us to efficiently outsource design

• Defined and lock down interface• Subsystem design needs to be managed ‘through’ the module design

• A vehicle design process gives us the methodology ‘who’, ‘what’ & ‘when’

• Outsource primitive modelling (we fill in the detail), OR• Outsource the detail (they fill in the detail), OR• Completely outsource design ( to an agreed interface)*

*Toilet Modules on OSC and HRC

Reference

• People who use this process, or a variant thereof:

• Electric Boat (Submarines)• BAE Systems & Alenia Marconi (Shipbuilding)• General Dynamics & Lockheed Martin (Shipbuilding)

Recommendations

• Accept that we have a ‘chicken & egg’ concurrent design process• Define lead/lag relationship between subsystem and vehicle design• Merge physical manufacturing areas with design areas using WBS• Establish how we manage zone/area design interfaces• Define subsystem design inputs and sequence to modelling• Integrate area/modularisation into distributed subsystem design

process• Define scope of engineering WBS in the WBS dictionary

• Revise the Design Process Procedure