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Infusing Human Factors in Ground System DesignsProject Management Challenge 2010
Pat Simpkins, NASA/KSC EngineeringTim Barth, NASA Engineering and Safety Center
Used with permission
Outline Background Ground Crew Factors Ground Systems and Ground Support Equipment
Pathfinder Activities Human Factors Overview Design Team Sessions Sample Results and Feedback Recommendations and Lessons Learned
Current Status Discussion
Why are Ground Crew Factors Important?
RangeSystems
PayloadProcessing
Systems
Launch, Landing & Recovery
Systems
Flight &Ground Crew
TrainingSystems
VehicleProcessing
Systems
Space transportation systems involve many ground and flight systems. A concurrent engineering, “system of systems” development approach is required to optimize life-cycle performance. Apollo and Shuttle lessons learned
Exploration systems must be safe, sustainable, and affordable NASA safety stakeholders: public,
flight crews, workforce (including ground crews), and high-value capital assets (including spacecraft)
Majority of life-cycle cost is typically in operations, including ground crew operations
People are the critical elements of the system of
Exploration systems: flight crews and ground crews
FlightVehicle
Systems
“Ground systems represent the largest overall cost for most space programs. However, testing of ground systems does not always get the same visibility as vehicle testing, for example.
This is a major concern because problems with ground systems are just as likely to cause a mission failure as are vehicle problems. Also, ground systems tests are more prone to human error…”Excerpts from “Ground Systems Testing” by Norm Strang, Aerospace Corp.
Ground Crew Functions
Ground Crew Human-System Integration Challenges
Flight systems Launch vehicles, spacecraft, payloads
Flight/ground system interfaces Mechanical, fluid, and electrical connectors
Ground systems Ground support equipment, ground crew training systems,
launch control workstations, facility systems, personnel protective equipment (PPE), ground crew work instruction systems, repair/refurbishment workstations, and more
Flight System Example: Waste Collection System Removal and
Re-Installation
Flight/Ground System Interface ExamplesQuick Disconnects (QDs), Fluid and Electrical Umbilicals:
- Flexhose connections inside the spacecraft introduce risk of collateral damage, additional work content- Human error potential (QD mismates)
Spacecraft Handling Mechanisms
Personnel Protective Equipment ExampleSelf-Contained Atmosphere Protective Ensemble (SCAPE) Suit HSI Challenges:
- Dexterity/agility/flexibility- Weight/bulkiness- Heat stress/fatigue - Negative pressure relief valve- Electrostatic discharge- Sizing/suit dimensions- Visibility- Communication
Similar Issues in Ground and Flight Systems
PREVIOUS
NEW
Comm boxes near crew module ladder
ISS
Results of Human Factors Engineering Pathfinder Activity for
Ground Systems
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Human Factors Pathfinder Core Team
KSC Engineering KSC Constellation Ground Ops Project Office KSC S&MA KSC Spacecraft/Payload Processing Ames Human System Integration NASA Engineering and Safety Center
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Pathfinder Goals Improve KSC designs by improving ground and flight
crew interfaces with ground systems and GSE Tremendous opportunity to influence designs early Apply lessons learned from current ground ops to Constellation
Demonstrate value of effectively using HFE capabilities in GSE design teams
The expected outcomes are: Ground systems/GSE that are safer and easier (and therefore
cheaper) for ground crews to operate and maintain during 20+ years of Constellation launch operations
Fewer mishaps during ground processing where ground system/GSE designs are cited as contributing factors or causes
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Shuttle Ground Operations Mishap DataMajor Category Comparison
1254 Cause/Contributor Findings in 335 Mishaps 11-08-1996 to 09-30-2007
23%
20%
10%8%
5%
5%
4%
4%
4%
17% Design IssuesTeam BehaviorsProceduresDecision ProcessTraining IssuesIndividual Attitude/MoodsTask Specific ExperienceSupervisory ControlsCultures and PoliciesOther
Courtesy of USA Industrial and Human Engineering
Design Issues(flight & ground systems)
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Mishaps in Ground Operations
For 11 NASA/KSC mishap investigation boards in FY06 and FY07: Several million dollars in direct costs (includes civil
service board member labor and travel, board procurement costs, and estimated hardware damage costs) Plus additional direct costs such as contractor labor
for amelioration, contractor labor for investigation boards, corrective actions (new procedures, training, etc.) Plus indirect costs Plus schedule impacts Plus personnel injuries
Let’s Design it Right the First Time!
Subject: CLV Mobile Launcher and access platforms with stairs and their impact to Ops
We just finished our ML PMR last week and I have attached a few of the slides that were briefed. My concern is these show quite a few stairs that are now planned for access from the ML to the Ares I vehicle once out of the VAB. I am concerned that this will adversely affect the Operations for 20+ years and just might be a big impact. I would like to get your take on how much of an impact this is. This will have a large impact on the ML and the design, schedule, cost, etc., but I don’t want to look back and say we should have stopped the design and fixed this regardless.
I am sure folks in my LX group are going to want some hard requirements that show why the stairs will not work or why they may present an unsafe condition. So if you could, please respond with specifics as to why these stairs will impact specific operations. We plan to receive the 90% design on the ML structure on 11/14/07 and 90% design review on 11/29/07 with the final design due in December so this is getting very late in the game but we will need this system for 20+ years. Better to do it right the first time!
• Systems engineering requires a system lifecycle perspective• Designing to requirements is necessary but not sufficient
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Pathfinder Activities
Day 1 Two-hour Human Factors Overview for GS/GSE
Designers
Days 2-4 Working Sessions with Design Teams Wrap-Up Session with Design Team Leads
Human Factors Overview Two-hour panel discussion designed to
familiarize designers with basic HF principles before their working sessions First HF course developed specifically for ground
system/GSE designers Target audience: fluid and mechanical systems Included KSC mishap data and examples Topics:
Goals and BackgroundHistorical PerspectiveDesign Topics and ExamplesShop Floor Perspective
Approximately 100 participants Sponsored by KSC Engineering Academy Prerequisite for the working sessions
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Human Factors Engineering
“The design of tasks, tools, systems and (work) environments that enhance the abilities and accommodate the limitations of people to produce safe and effective systems.”
- Human Factors and Ergonomics Society (one of many definitions)
Human Factors Concepts:A Systems Perspective
Human-system interfaces include assemblers, maintainers, operators, inspectors, and engineers
F-22 Example"You've got to be kidding me....there must be a handle in here somewhere!"
Robust Designs Help Prevent Human Errors and Collateral Damage
Unintentional human errors and collateral damage can occur in the design, development, operation, and maintenance of any system
A poorly designed (vulnerable) system enables workers to make errors and/or damage systems
A well designed (robust or resistant) system enables workers to avoid errors and collateral damage
vulnerable
average
resistant
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Common Areas for Improvement in Ground Crew/Ground System Integration
Workspace and work envelope Tool clearances Functional work areas Visual access Displays within field of view Lifting, pushing, and pulling Damage/error prevention, detection, and recovery Connectors Interface controls and information displays Labels and communications Consistent work practices Personal Protective Equipment (PPE) Work environment
WorkspaceSome workspace positions may be difficult to reach.
In picture: Forward Reaction Control System (FRCS) work that requires an awkward reach.
Damage/Error Prevention, Detection and Recovery
Before
After
Orbiter flex hoses and fluid lines may get damaged during ground operations, which can lead to schedule delays and technical issues.
Human Factors Design:
• Protect hardware during inspection and processing
• Location, design of temporary covers
Lifting, Work Envelope, Damage PreventionSSME Dome Heat Shield Removal & Installation
Lifting, Work Envelope, Damage PreventionSSME Dome Heat Shield Removal & Installation
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Additional Modeling and Simulation Tools
Posture, static strength, reach, clearance analyses
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Human Factors (HF) Overview:Survey Feedback
Things that were most liked: Specific design examples Application of HF principles to GSE designs Varied perspectives of speakers Looking at life cycle and integrated product teams User input to designs, designing with users in mind HF specialist as part of the design team Ground system/GSE Design Evaluation Worksheet
Additional topics to address: How to force HF issues to be addressed in design
approvals/reviews HF specs and standards HF for software, human-computer interaction (HCI)
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GSE Design Team Sessions 9 design team sessions conducted 7 mechanical systems 1 fluid system 1 electrical system
All teams completed the evaluation worksheet in advance Most teams were able to access current design packages/files
during their working session Human factors workbook and reference guide provided Worked with team leads to identify the most significant HF issues
that need to be addressed by the design teams Potential HF issues were documented
Observation: different/overlapping perspectives were valuable SMA Professional Technician (end users) Operations Engineers Systems Engineers Human Factors Engineer
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GSE Design Teams
Mobile Launcher Physical Data Interface Crew Access Arm Emergency Egress System Mobile Launcher Hypergol Servicing System Upper Stage T-0 Tilt Up Umbilical Arms Upper Stage Umbilical Plates Mobile Launcher Access Platforms SRB Forward Skirt Umbilical First Stage Aft Skirt Umbilical
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Mobile Launcher Physical Data Interface (MPDI)
Human Factor Challenges (Examples) Recommendations & Potential Design SolutionsWork envelope – cable congestion. Increase spacing between connectors within a panel and between panels.
Consider location of connectors on panels to be compatible with procedural sequence (start with inside connectors and work out to edge of panels). Make the most frequently used connections the most accessible.
Functional work areas – high or low connections.
Consider using a horizontal configuration of smaller panels to reduce above-the-head or below-the-waist connections.
Damage/error prevention and detection –mismates, misalignments.
Color code and label cables with large, bold fonts. Consider built-in lights for the MLP, possibly LED. Reduce/eliminate blind connections. Use keyed connectors. Provide visual feedback (color rings) and/or audible feedback for good connections.
Damage/error prevention and detection –fiber optic cables.
Separate more delicate fiber optic cables from the other cables.
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Crew Access Arm (CAA)
Human Factor Challenges (Examples) Recommendations & Potential Design Solutions
Work envelope and access – actuator, energy chain, blast doors, access arm.
For actuator area (motor/pulleys/cables): consider locating equipment on platforms with maintenance/inspection access for at least two workers. For energy chain: provide catwalk for access. Ensure blast doors can be accessed for inspection/maintenance via mobile platforms. Ensure there is access for maintenance/inspection underneath the crew access arm. Ensure adequate connection points for fall protection equipment in all areas.
Lifting – actuator motor, ALAS hatch (potential requirement).
Provide overhead attach point for motor (150-175 lbs) removal for maintenance. Allow at least two people access to motor for positioning of hoist for removal. Possibility of ALAS hatch removal requirement (approx. 175 lbs in a confined space).
Damage/error prevention – actuator. Provide guards on actuator motor and cables to limit cable wear & tear. Install a machine guard around motor for personnel safety.
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Emergency Egress System (EES)
Human Factor Challenges (Examples) Recommendations & Potential Design Solutions
Controls – rail car brake release. Ensure brake release in car requires intentional activation (like ejection seats in aircraft).
Personal protective equipment (PPE) – suited personnel. Levers/handles should accommodate personnel in flight suits, SCAPE suits, and fire/rescue suits.
Functional work areas – track maintenance. Ensure easy access is provided for inspection/maintenance of track. Minimize inspection/maintenance tasks that require work overhead or below the waist.
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Hypergol Servicing Systems
Human Factor Challenges (Examples) Recommendations & Potential Design Solutions
Work envelope – access arm at vehicle interface needs to accommodate at least two SCAPE personnel and the control panel.
Provide adequate space on access arm to allow SCAPE personnel maneuverability. Include SCAPE technicians on the design team.
Lifting, pushing, and pulling – weight/size of servicing equipment and effort required to move/maneuver the equipment.
Consider hoist or rail crane to assist with equipment lifts. Include lift points. Minimize number of cables and hoses in higher traffic areas on the platform.
Connectors – quick disconnects vs. B-nuts. Perform a formal usability analysis in the SCAPE lab as part of the connector trade study.
Damage/error prevention – fundamentally different hypergol servicing approach without the level of redundancy and controls used by the Shuttle system.
Perform an in-depth task analysis of hypergol servicing (HF-PFMEA, ST- PRA, or other method). Proactively identify and mitigate potential process escapes, process catches, and human errors.
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Upper Stage T-0 Tilt-Up Umbilical Arms (TUUAs)
Human Factor Challenges (Examples) Recommendations & Potential Design SolutionsDamage/error prevention – need reliable system feedback when technician lowers arm and mates the umbilicals.
Have one technician run the motor to lower umbilical to a marked position. Use lock- out pins so umbilical can’t go below horizontal position and so the umbilical end does not over-extend and damage the vehicle.
Work envelope – ground plate to flight plate interface is only accessible by platforms in VAB (no on-pad access). Potentially limited platform area during mating operation.
Coordinate platforms used for vehicle access so they can also be used for maintenance and inspection of umbilical components and subsystem replacement items in nominal and vertical positions. Consider designing custom access platforms.
Lifting, pushing, and pulling - ground plate movement into mating position may require heavy exertion from technicians.
Use lift assisting devices and guides to keep physical forces within recommended weight limits and protect from inadvertent, sudden arm movements. Provide carts to transport and maneuver air tuggers if VAB shop air is used.
Umbilical placement and mating operation is a precision operation requiring 2 technicians; a mistake during the mating operation could cause incapacitating damage to the vehicle.
Include a systematic analysis of VAB processing tasks for potential process escapes/catches (using HF-PFMEA or a similar method) and usability testing/evaluation using the prototype in the LETF to satisfy the requirement for a human factors assessment in the 60% design review package.
(Includes updates after 30% design review)
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Upper Stage Umbilical Plates
Human Factor Challenges (Examples) Recommendations & Potential Design SolutionsConnectors – if not connected properly, requires roll-back to VAB. Limited space is available on the plate to access connectors.
Consider a trade study on number of guide pins or a custom alignment tool. Extend crows feet to reduce the mating angle and use a centering feature. Consider self-alignment approaches, a laser alignment system, and/or a linear mating system (vs angled mating system).Note: in the Feb 08 baseline, a “linear engagement after angular mate” design with centering feet is used. The alignment pins were eliminated. Consider a full design mockup and thorough usability testing to predict/demonstrate human reliability of aligning the plates and ensuring a correct mate.
Lifting, pushing, and pulling - manual alignment of pivot feet is required.
Consider hand grips (machined into plate or attached) or temporary handles so there is an easy way to hold/manipulate the plate without grabbing cables.
Damage/error prevention and detection. Provide a visual indication on the collet engagement so that it is not overrun but fully connected. Need verification that feet are properly seated.
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Tilt-Up Umbilical Arm Visualization
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Recommendations Utilize experience and expertise of KSC technicians, as appropriate Continue soliciting design inputs from SMA and Ops Engineers
Integrate human factors engineering into the systems engineering process Establish a KSC Engineering Human Factors POC to integrate HF
support for GSE design teams Track and help resolve significant HF issues, including those identified during
the pathfinder activity Lead development of HF tools, guidance, and additional resources
Acquire additional HF expertise to provide embedded support to design teams, including completion of HF assessments and requirement verifications
Determine criteria for a complete, valid human factors assessment HF assessment methods and approaches vary with GSE complexity,
criticality/hazards, frequency of ground crew/GSE interfaces, etc. Address need for adequate consideration/evaluation of human
factors in software and computer system designs Increase use of KSC modeling and simulation capabilities for
evaluating designs from a HF perspective
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Current Status Pathfinder core team members supported ongoing GSE design reviews Human factors worksheet and workbook were widely distributed KSC Engineering Directorate has obtained new contractor and NASA
human factors engineering capabilities Formal human factors assessments are required products in the KSC
Technical Review Process (KDP-P-2713) Human factors section in the KSC Engineering Design Handbook Also infusing human factors in Ground Operations Planning
Task designs to complement hardware designs Operability enhancements
HFE improvements to the NASA GSE design standard (NASA STD 5005) and the KSC design standard for Ground Systems (KSC STD 512)
New section in the NASA Space Flight Human System Standard (NASA STD 3001) and Human Integration Design Handbook (HIDH) devoted to ground support activities
Upper Stage mockup and simulations at MSFC to evaluate human-system integration issues with temporary GSE installed inside the vehicle
Spreadsheet-based Human Factors Engineering Assessment Tool (HFEAT) developed to assist human factors engineers in verification of GSE design requirements
Human Factors Engineering Assessment Tool
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Primary Lessons Learned Proactive consideration of ground crew factors enhances the designs of
ground and flight systems by: Reducing the risks of undetected ground crew errors and collateral damage that
compromise vehicle reliability and flight/ground crew safety Ensuring compatibility of specific vehicle to ground system/GSE interfaces Optimizing the safety of ground systems/GSE Optimizing the operability of ground systems/GSE (reducing error potential, task
complexity, task timelines, and total labor hour requirements) Improving task designs for ground operations that use the ground systems/GSE Reducing future re-design costs, such as system upgrades as a result of mishap
investigations
Many human-system integration challenges associated with flight systems/flight crews also exist with ground systems/ground crews
HFE expertise is most effective when embedded in ground system design teams
HFE methods, processes, and tools need to be part of the systems engineering process over the entire system life-cycle
HFE concepts need to be infused as early as possible during the design phases and reinforced during all milestone reviews
