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1 OF 23NASA 2009 Project Management Challenge EC5/D. Gohmert/281-483-9350
CEV Seat Concept Design
The CEV Seat: Seeking a Custom Fit
in an Off-the-Rack World
Dustin GohmertCREW AND THERMAL SYSTEMS DIVISION
NASA Project Management Challenge24 Feb. 2009
EC5/D.Gohmert281-483-9350
2 OF 23NASA 2009 Project Management Challenge EC5/D. Gohmert/281-483-9350
CEV Seat Concept DesignMotivation
• Seat design does not fully support the occupant for off-nominal landings.– Lack of lateral support– Lack of full leg support for all occupants
• Race-car seat concepts are supportive—but require customization to fit occupant.– Do not provide leg supports– Do not allow for feasible egress in emergency scenario
• No design exists that meets implicit and explicit needs of a CEV seat system.• I needed something to do over the holidays…
OBJECTIVE• To design a simple seat concept that provides full occupant support in all axes for
the full range of occupant sizes without fully custom components for each person.
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CEV Seat Concept DesignSeat Design Basic Requirements and Needs1. Occupant Protection
1. Conformal support2. Hip bolsters3. Shoulder bolsters4. Head bolsters5. Load-distributing harness
2. Adjustable Fit for All Sizes1. Seated height (shoulder height)2. Shoulder breadth3. Buttocks to popliteal4. Popliteal height5. Hip breadth
3. Stowable1. Reconfigurable for on-orbit maximization of volume
4. Multipurpose1. Operator seats2. Non-operator seats
5. Reliable1. Technologies and materials proven for spaceflight2. Minimal failure modes
6. Lightweight
Seat Layout Views
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CEV Seat Concept DesignBaseline Seat Concept• 90/90 hip/thigh angles • Non-operator legs must be raised toward chest to fit in vehicle spacing• Minimal lateral support• Stowable• Lightweight• HOWEVER, IT DID MEET THE MINIMAL REQUIREMENTS WE HAD SET FORTH
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CEV Seat Concept DesignWhat Can We Learn from Industry?
• Highly conformal, custom-fit seats save lives and improve performance
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CEV Seat Concept DesignBut…
• You can’t get out of them when you are on your back or in a space-suit…
• And they only fit the person they were designed for.
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CEV Seat Concept DesignChallenge - Leg Curvature
• Problem: Flat seats are flat, humans are not.– Models cannot adequately convey the conformity of a human.– In a +Z impact the body is going to find those empty spaces and fill them.
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CEV Seat Concept DesignChallenge Leg Length Differences
• Problem: We have to accommodate varying thigh and lower leg lengths—but the seat and Orion inner mold line (the walls) do not move.
– Means that legs of persons with longer lower legs must have thighs pulled farther toward chest.
IML
Spac
ing
Line
Seat
Bot
tom
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CEV Seat Concept DesignSeat Concept
• Pulls together the best features of the designs that we examined, and modified the features to work in a recumbent posture with a space suit.
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CEV Seat Concept DesignSmall Female vs. Large Male Fit
• Spacer pads added at shoulders and hips to provide semi-custom, conformal lateral fit
• Maximum shoulder spacer app. 3.5” each side
Conformal Spacer Pads
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CEV Seat Concept DesignLateral Support
• Full lateral support at primary load paths of pelvis and shoulders– Exact principles applied in race-car seat designs.
• Additional lateral support at knees, head, and feet.
Areas of Lateral Support
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CEV Seat Concept DesignThigh Panel Extension Assembly
• Curved thigh extension • Mates to curved groove of hip panel—curve
is essential to maintain path of motion• As thigh panel is lengthened, knee pivot is
moved up in the Z axis automatically.
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CEV Seat Concept DesignShoulder and Head Support Assembly
• Single assembly that provides:– Headrest – lateral support wings with fabric “hammock” for head support
sized to helmet diameterNOTE: lateral wings should nominally be taller and the hammock should be deeper than in prototype. I estimated wrong in my first stab at it…
– Lateral shoulder supports pads added to decrease span for smaller occupants
– Shoulder belt anchor points– Anti-elongation support
Provides support to keep occupant from elongating in a –Z impact
• Adjusts as single unit to occupants seated mid-shoulder height
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CEV Seat Concept DesignHand Controller Mounts• Hands naturally fall at knees when seated recumbently.• Seat structure is near hand area, so why not use it as a mounting point?• Eliminated need for separate armrest
– Eliminates egress obstruction– Eliminates stability issues associated with cantilevered armrest
• May rotate out of the way for egress• Hand controller mounts must be extendable down toward pallet to accommodate varying
forearm lengths.
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CEV Seat Concept DesignAdjustability
Small Occupant ConfigurationLarge Occupant Configuration
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CEV Seat Concept DesignACES Suited Fit
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CEV Seat Concept DesignTips that Helped in the Process
• Keep an Open Mind– It is easy to become close-minded with a singular focus just because the status quo is comfortable.– Challenge yourself to step past that comfort zone to question if what you are doing can be improved.
• Listen to the ideas of others – even if you think the idea is not sound– The conformal seat was a very good idea, but we knew it would not work so we discounted it for a while and
settled into a comfort zone with what we had.– Had we not given the work of others a fair and fresh look, the current concept would have never emerged.
• Don’t Fall into a Computer-Designed Trap– Computer tools like CAD and FEA are nice, but not without some good old-fashioned common sense
behind them. They should not be the only tool in the toolbox. – Sometimes pure hands-on creativity and gruntwork allows you to find the hidden pitfalls that are buried
behind the pixels.
• Understand What You are Trying to Do– Fundamentally and in self-actualizing detail, not just the “lawyered-up” requirements language that is given
to you.– Were we building a seat or was a seat the design solution to keeping the crew safe in a landing? Once the
latter was understood, then the seat became something so much more than just a perch for a posterior.
• Don’t Be Afraid to Take a Chance on Your Own to Make a Change– The squeaky wheel gets the grease, so sometimes it is okay to cause a ruckus.– But that wheel is still only part of the greater vehicle – don’t alienate others in the process, since you are
still part of something greater than just you.
• Have Fun!
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CEV Seat Concept DesignConcept Testing
• High G Sled Testing at Wright Patterson AFB
Zoom Zoom!
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CEV Seat Concept DesignConcept Testing
• 0 Gravity Testing
Seat Functionality Evaluations
0g Spinal Growth Evaluations
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CEV Seat Concept Design3D Human Scanning:
• I know I said I hated computer models, but…– This was more accurate than tracing my rear-end on cardboard
• Used to refine shape of seatpan to fit full crew complement
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CEV Seat Concept DesignWhere We Have Gone From There
Lockheed Martin Export Controlled
Lockheed Martin/NASA Orion Seat Design Evolution
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CEV Seat Concept DesignExamples of Design Concept Exploration
• Currently searching for a way to integrate auxiliary breathing air onto a person seated in a semi-conformal seat.
Legacy designs prevent proper integration to conformal fitting seats.
Firetruck seat with integrated mounts for Self Contained Breathing Apparatus (SCBA)
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CEV Seat Concept DesignExamples of Design Concept Exploration
• Heel Mounting Design Concept Exploration– Cycling Shoes and Clipless Pedals
If all else fails I can now seek work as a cobbler…