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Development, Testing, and Qualification of Space-Rated Robotic Manipulators

Sean Dougherty, Thomas Debus, MDA-US ICRA 2015, May 26, 2015

The  data/informa/on  contained  in  this  document  has  been  reviewed  and  approved  for  release  by  SSL  Export-­‐Import  Administra/on  on  the  basis  that  this  document  contains  no  export-­‐controlled  informa/on.  

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Space Manipulator Heritage

Planetary Exploration

Robotic Servicing

Human Spaceflight

And Beyond…

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Design Challenge

Task, Environment

RA

Perf

orm

ance

R

A D

esig

n Sp

ace

Tracking / Positioning Accuracy

Control Bandwidth Dexterity / Reachability

Temperature Limits

1g Operability

Launch Survivability Radiation / Life

Range of Motion Natural Frequency (Mass/Stiffness)

Sensor Selection

Kinematics

Launch Lock

Material/Part Manufacturability Packaging

Power

Design Methodology 1.  Customer Requirements

§  Task Definition §  Environment §  Arm Performance

2.  RA Design Space

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Aerospace Process

•  Not necessarily unique but very rigorously followed §  Usually little can be done to repair a system after launch – one chance to get it right §  Generally can’t afford to fail – Launch and mission costs in the 100’s of millions

•  Different from production environment and lab environment §  This unique environment drives a unique solution

•  Large, complex system §  True systems engineering required §  Interface definition and control §  Revision control §  Traceability & extensive documentation §  Verification and Validation

•  Requirements flow down §  Clear link to mission goals §  Helps maintain cost and schedule

•  Innovation is very focused §  Risk reduction §  Heritage is often primary

•  Testing, V&V §  A large part of the development process

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Analysis Tools

Iteration is important. Tools needed to do so quickly and efficiently

MDA Structural Analysis “Dashboard” MDA Workspace Analysis Tools

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Simulation Tools

Complex/capable system provides unlimited options and flexibility but how do you bound and study the problem? •  Infinite poses, infinite solutions •  7DOF, redundant degree of freedom •  Reachable workspace vs. dexterous/

capable workspace §  Tip velocities/forces in all directions

or just specific direction…

MDA Workspace Explorer Software

MDA Workspace Analyzer Toolbox

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Hardware Development Challenge

§  Complex Mechanical system •  Multiple DOF •  400+ primary mechanical parts

–  Some with very high geometric precision (1/10000”)

–  Complex match machining operations (errors can be very costly)

–  2000+ fasteners, washers, pins, jackscrews, jackposts

–  Each part must be analyzed –  Each bolt must be analyzed

•  Cabling –  70m+ of cabling –  700+ pins

•  Mix of high current, sensitive sensor signal, high speed data

–  Little packaging tolerance

FREND Robotic Arm

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Assembly, Integration, and Test: Increasingly Significant Aspect

Actuator Run-in

1. Component Acceptance Test

Gearmotor

2. Actuator Assembly

F/T Sensor and Electronics

Output Sensor and Electronics

4. Arm Assembly

Stiffness Characterization Joint Tuning

PRTs

Dyno Friction Characterization

Functional CheckoutSafe to Mate

Force/Torque Sensor Signal

Checkout

Natural Frequency

Characterization

Single Joint ROM and

Inductosyn Zero

5. Arm Functional Test

6. Arm Performance Testing

3. Actuator Testing

Geometric Calibration

High Level Trajectory Testing

Tip Bandwidth Characterization

Command Characterization

RA V&V Compliance

Accuracy Characterization

Flex Cable

Robotic Arm Tuning

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Component - Assembly and Test Flow

Actuator Mechanical Assembly

Actuator Electrical Assembly

Dyno Testing

Components Integration (gear train, sensors)

Gearmotor Acceptance Test

Gearmotor Integration

Harness Acceptance Test

Controller

Dyno Testing Actuator Tuning

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Component - Thermal & Life

Component level testing done to: •  Characterize subsystems •  Reduce Risk •  Demonstrate requirements (V&V)

Actuator in thermal chamber

Flex Harness Spool Life Test

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Arm Assembly

Flex Integration

FTS Integration

Tube Integration

Actuator Integration

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Arm Testing – Functional

•  Safe to mate •  Range of Motion •  Sensor Checkout •  Natural frequency characterization •  Robotic arm tuning

Range of Motion Testing at NRL

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•  Geometric Calibration •  High level trajectory testing •  Tip bandwidth characterization •  Command characterization •  V&V compliance

Arm Testing - Performance

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Arm – EMI/EMC, Vibration and Thermal

“Test what you fly, fly what you test” •  Challenge is to replicate the space

environment here on earth

MER IDD Vibration Testing MER IDD Thermal Vacuum Testing

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Another Challenge: 1g Testing

Canadarm – MDA air bearing floor

Ranger – University of Maryland NBRF

SUMO/FREND – NRL High Bay

Photo Curtesy NRL

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Conclusions •  Space-rated manipulators are getting increasingly more capable and complex

§  Growing design space => needs for design tools §  Growing performance requirements significantly impact testing phase

•  V&V, Documentation, and Tractability are key drivers in the development of space-rated hardware - and now more than ever