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