PDF - University of Maryland

test.col.pp4 

University of Maryland 

Concepts and Technologies 

for Robotic Servicing of 

Hubble Space Telescope 

David Akin, Brian Roberts, 

Walt Smith, and Brook Sullivan 

Space Systems Laboratory 

University of Maryland, 

College Park 


University of Maryland

test.col.pp4 

Presentation Overview 

• Space Systems Laboratory background 

• Relevant SSL technologies 

• Ranger: system and experiences 

• Recent HST studies 

• Mission concepts 

• Conclusions 



test.col.pp4 

ARAMIS Telerobotics Study 

Survey of five NASA “Great Observatories” to 

assess impacts and benefits of telerobotic 

servicing - major results: 

• Ground-controlled telerobotics is a pivotal 

technology for future space operations 

• Robotic system should be designed to perform 

EVA-equivalent tasks using EVA interfaces 

– Maximum market penetration for robot 

– Maximum operational reliability 

– Designing to EVA standards well understood 

• Fully capable robotic system needs to be able to 

do rendezvous and proximity operations, 

grapple, dexterous manipulation 



test.col.pp4 

Fundamental Concept of Robotic Servicing 

Human Workload 

Issues? 

Control Station 

Design? 

Manipulator 

Design? 

Ground Control? 

Flexible Connections 

to Work Site? 

Multi-arm Control and 

Operations? 

Interaction with Nonrobot 

Compatible 

Interfaces? 

Utility of 

Interchangeable 

End Effectors? 

Ground-based 

Simulation 

Technologies? 

Capabilities and 

Limitations? 

Hazard Detection and 

Avoidance? 

Development, 

Production, and 

Operating Costs? 

Effects and Mitigation 

of Time Delays? 



test.col.pp4 

Beam Assembly Teleoperator 



test.col.pp4 

SSL Relevant Experience Timeline (1) 

‘80 ‘81 ‘82 ‘83 ‘84 ‘85 ‘86 ‘87 ‘88 ‘89 

SSL studies applications 

of automation, robotics, 

and machine intelligence 

for servicing Hubble and 

other Great Observatories 

for NASA MSFC 

Initial operational 

tests of Beam 

Assembly 

Teleoperator 

Experimental 

Assembly of 

Structures in EVA 

flies on STS 61-B 

BAT used for 

extensive 

servicing tests on 

HST training 

mockup 

SSL develops 

ParaShield 

flight test 

vehicle for 

suborbital 

mission 



test.col.pp4 

Ranger Telerobotic Flight Experiment 



test.col.pp4 


‘90 ‘91 ‘92 ‘93 ‘94 ‘95 ‘96 ‘97 ‘98 ‘99 

SSL 

designs 

Ranger 

based on 

experience 

with HST 

servicing 

UMd NBRF opens 

NASA 

selects 

Ranger TFX 

as low-cost 

robotic flight 

experiment 

Ranger NBV 

operational 

Ranger performs 

end-to-end HST 

servicing simulations 

SSL directed to 

redesign 

Ranger for 

shuttle mission: 

Ranger TSX 

Phase 0 

PSRP 

RTSX 

PDR 



RTSX 

CDR 

Phase 1 

PSRP 

Phase 2 

PSRP 

Environmental 

testing at JSC

test.col.pp4 

Ranger Neutral Buoyancy Vehicle I 



test.col.pp4 

Ranger Telerobotic Shuttle Experiment 



test.col.pp4 


2000 2001 2002 2003 2004 

PXL in NB 

testing 

Development of ECU 

operations timeline 

All-up mockup for public 

outreach 

Ranger TSX 

program 

cancelled 

Dual-arm system in 

active test 

Modular 

miniature 

servicer 

development 

for DARPA 



test.col.pp4 

Robotic HST Servicing - Batteries 

BAT (1987) 

RANGER (2003) 



test.col.pp4 

Robotic HST Servicing - Instruments 

FGS 

ECU 

WFPC 



test.col.pp4 

Ranger Flight Dexterous Arms 



test.col.pp4 

Dexterous Arm Design Objectives 

• Approximately EVA-glove-sized end effectors with 30 

lbf capability and 30 lb-ft torque capability in any 

direction, and 45° per second joint velocities 

• Allow safe surface contact despite communications 

time delays requires active compliance-control loop 

closed onboard 

• Sufficient arm articulation for a wide range of tasks in 

a cluttered workspace 

• Allow exchange of specialized end effectors 

• Two mechanical tool drives to each end effector 

• For cooperative tasks, two arms with intersecting 

workspaces mounted on narrow base 

• Where feasible, additional sensors as alignment aids 



test.col.pp4 

Dexterous Manipulator System Design 

Objectives Design Consequences 

Performance goals --- # of sensors, actuators --- # of wires 

Envelope requirements 

Reliability --- No external wiring 

Internal temperature monitoring 

Force/Torque sensing requirement 

Component temperature limits --- thermal analysis 

results 

Reliability, low maintenance 

Performance, low friction 

Thermal environment 

Component temperature limits --- thermal analysis 

results 

Serial communications, 

constant-length wiring 

through joint axes 

Short wiring runs 

for analog signals 

Brushless DC 

motors for arm 

actuation 

Internal heat sinks 

Aluminum and 

copper 

circumferential 

conductive paths 

Local 

processors for 

inner control 

loops 



test.col.pp4 

Dexterous Manip System Design (cont.) 

Electrical Power 

limitations 

Thermal variation 

Thermal environment 

Objectives Design Consequences 

45-day nominal active design life without 

access for recalibration 

Control bandwidth goals 

Friction rejection 

Compliance Loop performance requirements --- stiff drive, no 

backlash 

Envelope 

requirements 

Unregulated Bus for 

high efficiency 

Joint-level control loops based on 

digital sensors to avoid analog drift 

and noise 

Co-located position 

sensors for high-gain inner 

joint loops 

Large 

harmonic 

drives 

Compliance Loop performance requirements --- high outer loop rate --- simple 

kinematics 

Contact stability requirements 

Task requirements --- ≥7 DOF (w/elbow pose) 

Envelope requirements 

Workspace requirements 

Current driver 

circuits rather 

than Voltage 

drivers 

Motors inside 

harmonic drives 

3 DOF intersecting 

axis shoulder 

4 DOF intersecting 

axis wrist 

1 elbow pitch w/ 

offset 



test.col.pp4 

4-Axis Skew Wrist Design 



test.col.pp4 

Wrist Roll 

Drive (aft) 

Why a Skew Axis? 

• Lower interference of the tool with the 

forearm extends pitch travel 

• Single-sided support of the inner wrist 

allows for greater yaw range 

• Frontal area of the wrist reduced by 

skew layback of pitch actuator 

Orthogonal 4-axis 

Yaw Drive 

Pitch Drive 

Hand Roll & 

Tool Drives 

Wrist Roll 

Drive (aft) 

Skew 4-axis 

Pitch Drive 

Yaw Drive 

Wrist Roll & 

Tool Drives 



Pitch 

test.col.pp4 

180° 

135° 

90° 

45° 

0° 

-45° 

-90° 

-135° 

-180° 

Wrist Workspace Evolution 

3-DOF Wrist 

-180° -135° -90° -45° 0° 45° 90° 135° 180° 

Yaw 

Yaw, Wrist Roll, Hand Roll 

Pitch 

180° 

135° 

90° 

45° 

0° 

-45° 

-90° 

-135° 

-180° 

-180° -135° -90° -45° 0° 45° 90° 135° 180° 

- Workspace 

Orthogonal 4-DOF Wrist 

Yaw 

- Tool aligned with second link 

Yaw, Wrist Roll 

Yaw 

- Single singularity: redundancy lost in one or more axis; 

constrained axes are indicated 

- Double singularity; wrist drops to 2-DOF 

Hand Roll, Pitch 

Hand Roll, Pitch 

Pitch 

180° 

135° 

90° 

45° 

0° 

-45° 

-90° 

-135° 

-180° 

Skew 4-DOF Wrist 

-180° -135° -90° -45° 0° 45° 90° 135° 180° 

Yaw 

Yaw, Wrist Roll 

Hand Roll 

Pitch 

Yaw 

Hand Roll 



test.col.pp4 

φ (deg) 

1080 

720 

(deg) 

φ 

360 

0 

Toolspace Comparison 

skew RPYR 

orthogonal RPYR 

RPR 

0 45 90 135 180 

θ (deg) 



test.col.pp4 

Wrist Yaw Axis 

Hand Roll Axis 

Slow Tool Axis 

Fast Tool Axis 

Dexterous Arm Cross-Section 

Wrist Camera 

Wrist Pitch Axis 

Elbow Roll Axis 

Force/Torque Sensor 

Wrist Roll Axis 

Elbow Pitch Axis 

Shoulder Pitch Axis 

Shoulder Roll Axis 



test.col.pp4 

Inner Wrist (Exploded View) 



test.col.pp4 

Bearing/Housing Design 

• Problem: Steel (α = 7 µin/in°F) bearing 

installed in Aluminum (α = 13.1 µin/in°F) 

housing. Over a wide temperature range 

the mismatch can cause the bearing to 

spin in housing or seize. 

• Solution: Install appropriately-sized Invar 

(α = 0.7 µin/in°F) sleeve between bearing 

and housing. Sleeve size is chosen taking 

into account elastic deformation of 

bearing race, sleeve, and housing. 

Preload is provided by interference 

(shrink) fit of sleeve in housing. 



Bearing Installed 

Directly in Housing 

test.col.pp4 

Bearing Design Example 

.250" 

Ø6.250" 

Aluminum 6061-T6 

Housing 

Invar Sleeve 

Kaydon KC055BD6C 

Ball Bearing 

.250" 

.082" 

Sleeve Installed 

Between Bearing 

and Housing 

Effect of Invar sleeve is to make bearing preload invariate with temperature 



test.col.pp4 

Actuator Performance Summary 

Wrist Yaw 

Wrist Pitch 

Shoulder Roll Elbow Roll Hand Roll 

Shoulder Pitch Elbow Pitch Wrist Roll Slow Tool Fast Tool 

Motor RBE-02112A RBE-01812A RBE-01812A BMS-3302A RBE-01512B 

Ratio 101 101 61 120 1 

Torque (ft lb) 201 118 71 52 1 

No-load Vel (°/s) 56 101 168 139 15675 

Motor rpm (max) 948 1707 1708 2797 5225 



test.col.pp4 

Dexterous Arm Parameters 

• Modular arm with co-located electronics 

– Embedded 386EX rad-tolerant processors 

– Only power and 1553 data passed along arm 

• 53 inch reach mounting plate-tool interface plate 

• 8 DOF with two additional tool drives (10 

actuators) 

• Interchangeable end effectors with secure tool 

exchange 

• 30 pounds tip force, full extension 

• 150 pounds (could be significantly reduced) 

• 250 W (average 1G ops) 



test.col.pp4 

Design Loads 

• Nominal Operations; Structural Load Path 

– Fx, Fy, Fz: 300 lbf 

– Mx, My, Mz: 200 lb-ft 

• Actuator Input-side Loads (pure moment) 

– Shoulder Actuators: 650 oz-in 

– Elbow, Wrist Roll Actuators: 400 oz-in 

– Wrist Pitch, Yaw, Hand Roll, Slow Tool Actuators: 230 oz-in 

– Fast Tool Actuator: 240 oz-in 

• Actuator Output-side Loads (pure moment) 

– Shoulder Actuators: 200 lb-ft 

– Elbow Actuators: 120 lb-ft 

– Wrist Roll Actuator: 70 lb-ft 

– Wrist Pitch, Yaw, Hand Roll, Slow Tool Actuators: 50 lb-ft 



test.col.pp4 

Design Loads (continued) 

• Collision Loads; External Housings 

– Maximal collision: 10 Joules (equivalent to 20 kg @ 1 meter/sec) 

– Method: assume kinetic energy converted to strain energy; find 

stresses for concentrated loading of component that produces 

the same strain energy 

• Launch and Landing Loads 

– Assume Stowed Configuration 

– Accelerations: 

– X: ± 7.9 G 

– Y: ± 4.9 G 

– Z: + 8.3 G, - 6.3 G 

– Subject to refinement with coupled-loads analysis 

• Consider additional loads in some cases: 

– Thermal ambient operational limits: -60° to +100° C 

– Assembly 



test.col.pp4 

Generalized Inverse Kinematics 

WRIST JOINT 

ANGLES 

WRIST 

FORWARD 

KINEMATICS 

WRIST 

JACOBIAN 

MANIPULABILITY, 

JOINT LIMIT INDEX 

0 

RT J W 

ROTATIONAL 

CHANGE 

WRIST 

PSEUDOINVERSE 

JACOBIAN 

WRIST 

NULLSPACE 

JACOBIAN 

NULLSPACE 

VELOCITY 

0 

RT des 

Δr 

† 

J W 

0/ 

JW r 0/ 

HAND 

CONTROLLER 

φ,θ,ψ 

DESIRED 

TOOL 

ORIENATION 

Δθ p 

Δθ 0/ 

+ 

Δθ 

+ 

W 



test.col.pp4 

Singularity Avoidance (Experiment) 

Forearm rolls to avoid singularity 

0:13 



test.col.pp4 

Interchangeable End Effector Mech. 

• 3 Mechanical Interfaces 

– Hand Roll Drive 

– Fast Tool Drive 

– Slow Tool Drive 

• No power or data 

interface 

Each IEEM is 

approximately 

2.75” Ø by 2”. 

Weight is 2 lbs. 



test.col.pp4 

Interchangeable End-Effector Mechanism (IEEM) 

• Objectives 

– Permit teleoperated and possible autonomous tool changeout 

– Allow a rigid connection of Hand Roll DOF to tool structure 

– Allow a connection of two, Tool Drive actuators 

– Avoid introducing extra actuators or sensors 

– Minimize risk of tool detaching from DX Manipulator 

– Minimize risk of tool detaching from Tool Post 

– Package mechanism compactly 

» Minimize Tool/Wrist-center distance 

» Maintain clear Wrist Camera field of view 

» Maintain center shaft clear for boresight laser 

• Design Consequences: 5-State Mechanism 

– IEEM locked to Tool Post, back-driving blocked 

– DX Manipulator “Soft-Docked” to IEEM, IEEM locked to Tool Post 

– IEEM locked to both DX Manipulator and Tool Post 

– IEEM locked to DX Manipulator, “Soft-Docked” with Tool Post 

– IEEM locked to DX Manipulator, free from Tool Post, back-driving blocked 



test.col.pp4 

IEEM Attached to Tool Post 

6 inches 

5 

4 

3 

2 

4 

0 



test.col.pp4 

IEEM Exploded View 



test.col.pp4 

State 1: IEEM Locked to Tool Post 

Tool Post 

Slotted Ring 

Blocking Latch 

Ball-Locks 

• Slotted Ring retains mushroom end of Tool Post 

• Two Ball-locks prevent ring rotation 



test.col.pp4 

State 2: Manipulator Engages IEEM 

Manipulator teeth engaging 

Slotted Ring 

• Three teeth on Manipulator engage Slotted Ring 

• Two Ball-locks are released, permitting Ring rotation 

• Tool drives self-align and engage 

Ball-lock (Released) 



test.col.pp4 

States 3, 4: Manipulator Rotates 60° 

Three Manipulator flanges 

engage IEEM flanges 

60° 

• State 3: Three flanges on Manipulator engage flanges on IEEM at 

beginning of rotation, locking Manipulator axially to IEEM 

• State 4: At end of rotation, mushroom end of Tool Post is free to 

disengage from IEEM 



test.col.pp4 

State 5: Disengage Tool Post 

Blocking Latch 

(rotated) 

• Outward radial motion of Tool Post rotates Blocking Latch, 

preventing reverse rotation of Slotted Ring 

• When Tool Post is free, spring plunger in detent prevents 

back-rotation of Blocking Latch 



test.col.pp4 

IEEM Bearing Design 

• Problem: Locking Collar has poor thermal 

contact with IEEM inner structure, since it 

is supported on ball bearings. If a large 

temperature difference develops, the 

bearings could seize. 

• Solution: Design contact angle of 

bearings such that contact cones intersect 

on centerline of IEEM. Then any 

differential expansion of Locking Collar 

w.r.t. center structure occurs parallel to 

bearing contact, not affecting clearance or 

preload. 



test.col.pp4 

Schematic of IEEM Bearings 

As Installed, Homogeneous 

Temperature 

Bearing Contact Cones 

Intersect on Centerline 

Locking Collar Contracted 2% 

(4000°F ΔT) 

No change in clearance 



test.col.pp4 

Arm Side 

Wrist Camera View 

IEEM 

Tool Side 



test.col.pp4 

Tool Drives 

• Tool Drive Motor Controllers are primary method 

for commanding / sensing EE gripping force or 

output torque 

• Tool Drive Motor Specifications 

– Hand Roll Drive (High Torque, Low Speed) 

– Slow Tool Drive (High Torque, Low Speed) 

– 52 ft-lbs, 139 °/s no load 

– Fast Tool Drive (Low Torque, High Speed) 

– 1 ft-lb, 15,675 °/s no load 

– Must add gearing to use 



test.col.pp4 

End Effector Design Drivers 

• Structural / Mechanical Requirements 

– Grasp must be non-back-driveable 

– Factor of safety of 1.4 (Test) or 2.0 ( Analysis) 

– Withstand 300 lbs Force Along All Axes 

– Withstand 200 ft-lbs Moment About All Axes 

– Survive 6.75J Impact 

– Withstand Launch & Landing Loads 

– Meet NASA EVA contact spec 

– Meet RTSX Thermal Range 

• Operational 

– Visual Turn Indicators 

– Tool Color Should Contrast With Task Equipment (Not Black) 

– Visual Access for Grasp Verification 

– Neutral Buoyancy Compatible 



test.col.pp4 

Bare Bolt Drive 

RTSX End Effectors 

Right Angle Drive 

Microconical 

End Effector 

Tether Loop 

Gripper 

EVA Handrail 

SPAR Gripper 

Gripper 



test.col.pp4 

• Interfaces 

– 7/16” Hex Head Bolts 

– ECU Keyway Slot Bolts 

– APFR Latch Bolts 

• Characteristics 

• 5 lbs. 

• 12” x 3”ø 

• Status 

– NBV version in use 

Bare Bolt Drive (BBD) 

IEEM 

NBV 

Prototype 



test.col.pp4 

Microconical End Effector (MEE) 


– RPCM Microconical Interface 


• 12 lbs. est. 

• 8” x 3”ø 

• Status 

– Drawings and Stress Analysis for EVA 

version received from OSS 

– IDEAS models completed 

– Not currently fabricated 

IEEM 

Microconical 

Interface 



test.col.pp4 


– 7/16” Hex Head Bolts 

– ECU Connector Drive 


• 6 lbs. 

• 8” x 6” x 3” 

• Status 

– NBV version in use 

Right Angle Drive (RAD) 

IEEM 

NBV 

Prototype 



test.col.pp4 


APFR Paddle Gripper (APG) 

– APFR Locking Collar 

– APFR Paddles 

– APFR Detent Levers 


– 9 Lbs. 

– 14” X 11” X 3” 

– PJM Based 

• Typical of parallel 

jaw mechanism 

flexibility for 

specialized 

interfaces 

IEEM 

Levers 

Paddles 

Collar 



Tether 

Loop 

Gripper 

test.col.pp4 

Bare 

Bolt 

Drive 

Right 

Angle 

Drive 

Task Interfaces - ECU 

Electronic Controller Unit 



test.col.pp4 

Task Interfaces - APFR 

Yoke 

Interfaces Include: 

1. Quarter Turn Rings (2) 

2. Latch Bolts (2) 

3. Lock Knob 

4. Yoke 

5. Detent Levers 

6. Locking Collar 

7. Paddles 

AQP 

BBD 

AQP 

TLG 

APG 

APG 

APG 

Plus use BBD to rotate APFR probe 



test.col.pp4 

Ranger PXL System Requirements 

• Device to supply full 6 DOF mobility within a limited work 

volume 

• Force max: 25 lbf Torque max: 200 ft-lbf 

• Stiffness: 250 Klbf/rad Angular Speed max: 12º/sec 

• End point accuracy +/-.12”, precision .01” 

• Provide means to react loads generated by Ranger 

performing task duties while minimizing overall deflection 

• Design to maximize natural frequency of device with a target 

minimum of 10 Hz 

• Capable of reacting 580 ft-lbf torque due to Primary 

Reaction Control System firings (PRCS) 

• Brakes engage when no power is supplied 

• Brakes must have manual (EVA) over-ride 

• EVA interfaces to be at least 24” away from SLP end 



Design Requirements 

• Control electronics same as in the DX & VM 

• Co-located at actuator operated by serial command 

1553 

• Main power 48VDC 10A max, control power 28VDC 

• No changing form factors on cards from DX design 

• Pass through hole to be integrated in spine of mechanism 

approximately 1” diameter 

• Drive system to use DC brush-less motors 

• Each actuator to have triple redundant position feedback. One 

feedback system gives absolute position information that 

maintains position after power loss 

• Actuator drive system back drive-able under zero power 

conditions 

• Actuators connected using aerospace standard V-couplings to 

facilitate assembly 

test.col.pp4 



test.col.pp4 

~19” 

Ø 9.5” 

~75” 

Design:PXL Assembly 

Pitch 

Joints 

Electronics’ Housing 

Roll 

Joints 



EVA 

Interface

Inner 

Housing 

Absolute Encoder 

test.col.pp4 

Design: Roll Joint 

Outer Housing Main Drive Gear Motor 

Driveshaft 

Flexspline 

Wave 

Generator 

Incremental 

Encoder 

Brake 

EVA Interface 

Pass Through 

Tube (Ø .80”) 

Brake 

Release 



test.col.pp4 

PXL in Stowed Configuration 

Side View 



test.col.pp4 

Components: Harmonic Drive 

• Double the torsional 

stiffness 

• Double the peak torque 

ratings 

• Double the life 

• No reduction in efficiency 



Components: Brake 

• Electroid Model MRFSB-150-16 

test.col.pp4 

– Release mechanism will need 

augmentation to penetrate 

housing 

– Drive shaft hub through hole can 

be enlarged up to Ø1.25” with any 

keyed or spline profile 

– Supply voltage can be changed to 

48VDC 

– Release has detent which releases 

when power is supplied 

– Brake material Kinel 5504 

» Polyimide material 

» Mfg Thermech Eng. Crop 

» Per MSFC 82496 



test.col.pp4 

Components: Incremental Encoder 

Stegmann model HG900E 

• Reader supported by 

bearings in respect to disk 

• Clamps directly to shaft and 

uses torque reaction bar to 

stabilize 

• No external housing reduces 

bending moment load on 

drive 

• Through hole size 30mm 

(1.18”) 

• Company has space 

experience with lower quality 

version of same model (K15) 

on space station 



test.col.pp4 

Back Up: Components,Absolute Encoder 



test.col.pp4 

Components: Absolute Encoder 

BEI Model µS14/40L Absolute Through Hole 

Encoder 

– Ø1” through hole 

– Reader supported by bearings in respect to disk 

– Robust design with much space history 



test.col.pp4 

Components: Motor 

Kollmorgen Model RBE-03010A-00 

• Brushless design with integrated Hall effect sensors 

• Frameless design permits for efficient packaging with 

other components such as harmonic drive, brake and 

encoders 

• Company has much space and flight experience 



test.col.pp4 

Components: V-Clamp 

40º V-Clamp System to Aerospace standard AS1895 

• History of accessory mounting applications 

• Very high preload 

• Approximately 17,000 lbf depending on clamp material 

• Keeps joint rigid preventing stressing internal components 

• Pilot feature ensures proper alignment 

• Failsafe latch device protects against bolt failure 

• Joint can be disassembled without removing nut 

• Available in A286, Titanium, Aluminum or Inconel 

• Multiple vendors including Voss Aerospace and local EG&G Pressure 

Science 



test.col.pp4 

PXL Assembly and Testing 



test.col.pp4 

PXL Underwater Operations 



test.col.pp4 

Ranger Control Station 



test.col.pp4 

Ground Control Station 

Video Rack Operator Console #1 

Operator Console #2 



test.col.pp4 

Control Stations Overview 

• Ranger was designed from the outset to be 

controlled from the ground 

• Ground Control Station Functions 

– Real-time ground team control of robot 

– On-ground monitoring of FCS operations 

– Command, telemetry, and video recording 

– Video distribution to Payload Officer 

– Recording of RTSX related audio loops 

• Same control station is used to control identical 

underwater robot in neutral buoyancy simulation 

– Preflight training 

– Inflight contingency workarounds 

– Automated sequence development 



test.col.pp4 

Flight 

Control 

Station 

Orbiter 

Ku Ch.2 (Data&Cmd)) 

RS-422 

(128kbps/2 Mbps) 

Ku Ch.3 (Digital Video) 

RS-422 (10 Mbps) 

RTSX Telemetry Distribution 

OCA 

Router 

Video 

DeMUX and 

Dist. 

MUX 

Note: No DeMUX 

T1/T3 Modem 

To 

UMD 

NOTE: 

10 BaseT 

Video Distribution is shown 

on a separate diagram for 

clarity 

10 BaseT 

PCC 

Ethernet 

Hub 

10 BaseT 

10 BaseT 

10 BaseT 

10 BaseT 

10 BaseT 

10 BaseT 

RTSX 

Operator 

Position 

#1 

RTSX 

Operator 

Position 

#2 

RTSX 

Graphics 

Engine 

RTSX 

Data 

Archiver 

MCC/FCR 

Payload 

Officer 

Console 

CSR 

RTSX 

Telemetry 

Display 

RTSX Equipment 

JSC Equipment 



To 

Rest 

Of 

NASA/ 

PAO

test.col.pp4 

Flight 

Control 

Station 

Orbiter 

GCS Audio / Video Distribution 

Ku Ch.2 (Data/Cmd)) 

RS-422 

(128kbps/2 Mbps) 

Ku Ch.3 (Digital Video) 

RS-422 (10 Mbps) 

RTSX 

Telemetry 

Dist. 

Video 

DeMUX and 

Decoder 

MUX 

Note: No DeMUX 

T1/T3 Modem 

To 

UMD 

NOTE: 

Telemetry Distribution is 

shown on a separate diagram 

for clarity 

NTSC Composite 

PCC 

Video 

Distribution 

Amplifiers 

and 

Matrix 

Switcher 

NTSC 

Composite 

NTSC 

Composite 


RTSX 

Operator 

Consoles 

RTSX 

Video 

Recorders 

DVIS 


To 

NASA Video Dist. 

(FCR, PAO, etc.) 

CSR 

RTSX 

Video 

Display 

RTSX Equipment 

JSC Equipment 



test.col.pp4 

• Power 

GCS Services / Interfaces 

– GCS is powered from 110 VAC standard wall outlets 

– Total power consumption: 5200 W 

• Floor Space 

– Operator Consoles: approx 60 ft2 

– Video Rack: approx 20 ft2 

• Ethernet comm to spacecraft via TDRSS 

(equivalent to OCA bent-pipe to orbiter) 



• Video Rack Functions 

– Decodes / demutiplexes the Ku 

Ch.3 downlinked video 

– Records 5 video feeds (4 

downlinked, one ground 

generated) 

– Amplifies and distributes video 

to rest of GCS and Payload 

Officer 

– Provides constant video 

“preview” of downlinked 

channels 

– Records RTSX voice loops on 

VCRs 

test.col.pp4 

GCS Components: Video Rack 

Item Manufacturer Part Number Quantity 

VCRs Sony EV-C200 5 

4” Quadruple 

Mono 

Monititors 

Sony PVM-411 2 

VDA Chassis Grass Valley 8900T2 1 

VDAs Grass Valley 8801 4 

Video Switcher 

(32x32) 

Autopatch 4YDM.3232.V1 1 

Video Decoder Enerdyne DEC1000R10 1 

CrystalEyes 

View/Record 

Unit 

Sterographics VW (NTSC) 1 



test.col.pp4 

GCS Components: Ops Console #1 

• Operator Console #1 

Functions 

– Provides real-time control of 

Ranger 

– Displays telemetry of operator’s 

choice on SGI display 

– Interfaces with the translational and 

rotation hand controllers as primary 

mode of robot control (see Control 

Station Software section for more 

info) 

– Interfaces with 3D advanced input 

device -- Specific device TBD 

– Displays video of operator’s choice 

on video displays 



test.col.pp4 

GCS Components: Ops Console #2 

• Operator Console #2 Functions 

– Provides real-time control of 

Ranger 

– Displays telemetry of operator’s 

choice on SGI display 

– Interfaces with the translational and 

rotation hand controllers as primary 

mode of Robot control (see Control 

Station Software section for more 

info) 

– Interfaces with 3D advanced input 

device 

– Displays video of operator’s choice 

on video displays 



test.col.pp4 

Predictive and Commanded Displays 

Predictive Display 

• Predictive displays run a simulation 

to forecast what the actual system 

will do 

• Only as good as the model of the 

simulation and its error calibration 

technique 

• Dynamic simulation can require a 

large amount of processing 

• Simulation typically runs faster and 

is updated by actual sensor data to 

calibrate any errors 

• Can show dynamics and transient 

motion of the system 

• Useful for handling force and 

contact operations 

Commanded Display 

• Commanded displays use supervisory 

control methods and display the 

command sent to the actual system 

• The display is integral in the control of 

the system 

• Requires on board processing to close 

the loop about the displayed command 

• Commanded simulation can be simple 

requiring little processing, processing 

load is placed on board 

• Does not show dynamics, only the 

steady state solution 

• Can be used to control the vehicle in 

real time, or can be used off-line to 

develop a script of actions 



test.col.pp4 

Time Delay and Sampling Rate 

50 6 

40 

3 

6P 

30 

3P 

20 

1.5 

6C 

10 

3C 

0 

1.5C 

2.5 5 10 20 

0 

50 

40 

30 

20 

10 

Sampling Rate Across Time 

Delay and Display Method 

0 

Unmitigated Time 

Delay Effects 

3 1.5 0 0 

6 in/s 

1.3 in/s 

• The Modified Fitts’ Law task was used 

to determine the effects on performance 

due to time delay, the usage of 

commanded and predictive displays, and 

command sampling rate 

• Time delay increased completion time, 

at 0.01 statistical significance 

• The effects of unmitigated time delay 

caused a linear increase in completion 

time 

• Decreasing sampling rate degraded 

performance, at 0.01 statistical 

significance for each level of reduction 

• A knee in performance occurred at a 

sampling rate of 5 Hz, below that a 

substantial effect on completion time 

existed 

• Unmitigated time delay was more 

affected by reduced sampling rate, even 

at rates above 5 Hz 



test.col.pp4 

Commanded and Predictive Displays 

Time Delay and Display Method Effects 

• The commanded display severely reduced the performance degradation 

with 0.01 statistical significance 

• The commanded display reduced time delay effects on completion time up 

to 91% at 1.5-second delay 

– Subjects controlled the manipulator more accurately with the commanded display 

– Impacts were detected and compensated faster 

60 

50 

40 

30 

20 

10 

0 

6 3 6P 3P 1.5 6C 3C 1.5C 0 

Time Delay and Display Method 

• The predictive display also had better performance than time delay alone, 

at 0.01 statistical significance 

• The minor calibration errors caused the predictive displays to be about 

half as effective as the commanded display, a 0.01 statistical significant 

difference 



test.col.pp4 

Impact Comparison 

Commanded Display’s Reduction of Impacts 

0.07 

0.06 

0.05 

0.04 

0.03 

0.02 

0.01 

0.00 

6 3 6P 3P 1.5 6C 3C 1.5C 0 

Time Delay and Display Method 

• Time delay and predictive display usage had no statistical significant 

effects on number of impacts 

• Use of the commanded display dramatically reduced errors, at 0.01 

significant level, even when compared to no time delay 

• Only 3 errors were made with a commanded display over 4 hours of 

testing including 4 subjects testing a total of 1440 trials. 

• 20 times more errors were made without a commanded display 

• This reduction was due to subjects carefully positioning the 

commanded display to avoid an impact 



45 

35 

25 

15 

5 

-5 

test.col.pp4 

Erroneous Commanded Displays 

Fixed Offset Error/Varying Time Delay Random Error/Varying Time Delay 

0 0.5 1 1.5 3 

NoCmd 

1.0o 

0.5o 

0.25o 

0.1o 

Cmd* 

0 0.5 1 1.5 3 

• The peg-in-hole task was used to determine the usefulness of erroneous 

commanded displays in ameliorating time delay effects 

• As error increased performance decreased, however the erroneous display 

still performed better than when no commanded display existed 

• The above performance curves are statistically significant at the 0.01 level, 

except between the 0.1 random error and the error free actual display only. 

• The increase in completion time at 0.5 second time delay may be due to the 

small delay or to the commanded display occluding the actual display 

• Number of impacts increased as the random error increased 

• Fixed error had a significant effect that didn’t scale with increased error 

45 

35 

25 

15 

5 

-5 



Truncated Speed Limit Comparison 

test.col.pp4 

60 

50 

40 

30 

20 

10 

0 

Scaled Speed Limit Comparison 

60 

50 

40 

30 

20 

10 

0 

1 2 3 4 5 7.5 9 

Truncated Manipulator Speed [in/s] 

1 2 3 4 5 7.5 9 

Scaled Manipulator Speed [in/s] 

Manipulator Speed 

• The peg-in-hole task was used to compare various 

maximum allowable manipulator speeds 

• 1 and 2 inches/second speeds were slower than 

other speeds with 0.1 statistical significance or 

better 

• No preferred speed was found for the truncated 

speed limit 

• Only 10% time reduction separated the fastest 

from the slowest completion time between 2 and 9 

inches/second truncated manipulator speeds 

• A preferred speed of 7.5 inches/second was found 

when compared to all other scaled speeds at the 

0.1 significance level or better 

• Subject’s previous experience concentrated at 7.5 

inches/second speed, which may have influenced 

the results 

• Only 5% difference separated the times between 5 

and 9 inches/second scaled speeds 

• Number of impacts increased when operating at 9 

inches/second 



test.col.pp4 

Summary Control Scheme Study 

• The peg-in-hole task was used to reinvestigate the effects of time delay, 

commanded display usage, error, manipulator speed, and output method 

– As with most previous studies, time delay was revisited to quantify its 

performance degradation 

– The amelioration effect of the commanded display was retested as well 

– One of the larger random error treatments was tested with zero error; it was 

expected that the error would degrade performance 

– The level of random error was high enough to create a meaningful effect 

without overwhelming the subject 

– The random error was tested with all other treatments not just the 

commanded display treatments, this simulated a malfunction in the system 

that the subject would compensate for 

– The two manipulator speeds evaluated, 3 and 6 inches/second, showed a small 

difference in the manipulator speed study that could be enhanced by 

interaction effects 

– Stereo and monoscopic displays were tested using the CrystalEyes LCD 

glasses; subjects were also tested on a 2-D monitor 

– It was believed that stereo would enhance performance, and that the use of 

CrystalEyes would increase simulator sickness 

– All output methods had the same screen resolution and frame rate 

• This study also focused on any interaction between the above listed 

effects 



test.col.pp4 

Time Delay and Commanded Display 

60 

50 

40 

30 

20 

10 

0 

Completion Time 

Comparison 

0 

1.5C 

1.5 

3 NoE 3 Err 6 NoE 6 Err 

Manipulator Speed and 

Random Error 

Impacts Comparison 

• Results found that differences between the monitor, CrystalEyes without 

stereo, and stereo CrystalEyes were negligible 

• Previous results were confirmed, all completion time comparisons 

between zero time delay, 1.5 second delay with commanded display, and 

1.5 second delay with no commanded display were statistically significant 

at the 0.01 level 

• With no induced error, the commanded displays had statistically 

significant reduction of impacts 

0.8 

0.7 

0.6 

0.5 

0.4 

0.3 

0.2 

0.1 

0 

0 

1.5C 

1.5 

3 NoE 3 Err 6 NoE 6 Err 

Manipulator Speed and Random 

Error 



test.col.pp4 

60 

50 

40 

30 

20 

10 

0 

No Error 

Error 

Completion Time 

Comparison 

0TD 3 0TD 6 1.5C 3 1.5C 6 1.5TD 3 1.5TD 6 

Time Delay, Display Method, and Manipluator Speed 

All Error Comparisons are Significant at the 0.01 level 

Effects of Error 


• Error within the system degraded performance (statistically significant at 

the 0.01 level) 

• The effects of error were more dramatic with the commanded display, 

averaging a 60% increase in completion time when using the commanded 

display compared to 17% increase without a commanded display 

• Even with the error, the command display was still effective relieving the 

effects of time delay 

• Due to the random error algorithm, the effect on impacts was greater for 

the 3 inches/second manipulator speed increasing impacts by 450% 

• 6 inches/second manipulator speed was also affected with 77% increase 

in number of impacts 

0.8 

0.7 

0.6 

0.5 

0.4 

0.3 

0.2 

0.1 

0 

No Error 

Error 

0TD 3 0TD 6 1.5C 3 1.5C 6 1.5TD 3 1.5TD 6 

Time Delay, Display Method, Manipulator Speed 

All Error Comparisons are Significant at the 0.01 level 



test.col.pp4 

60 

50 

40 

30 

20 

10 

VII:Manipulator Speed Comparison 

3 in/s 

6 in/s 

Completion Time Comparison 

0 

0TD 0TD 1.5C 1.5C 1.5TD 1.5TD 

NoE Err NoE* Err NoE Err 

Time Delay, Display Method, Random Error 

* Not Statistically Significant 

• The error and speed interaction was reaffirmed, 

error caused greater degradation with the slower 

3 inches/second manipulator speed 

– With no error, less impacts occurred with the slower 

manipulator speed 

– The addition of error flipped the results, impacts 

increased with the slower speed with 0.01 statistical 

significance or better. 

0.8 

0.7 

0.6 

0.5 

0.4 

0.3 

0.2 

0.1 

0 

3 in/s 

6 in/s 


0TD 0TD 1.5C 1.5C 1.5TD 1.5TD 

NoE Err NoE* Err NoE Err 

Time Delay, Display Method, Random Error 

* Not Statistically Significant 



test.col.pp4 

Overall Ranking of Effects 

Completion Time Comparison 

1.5TD 3 Err 

1.5TD 3 NoE* 

1.5TD 6 Err* 

1.5TD 6 NoE 

1.5C 3 Err 

1.5C 6 Err 

0TD 3 Err* 

1.5C 6 NoE* 

1.5C 3 NoE* 

0TD 6 Err 

0TD 3 NoE 

OTD 6 NoE 

* These Cells are 

not Statistically 

0 10 20 30 40 50 60 

Significant to Eachother Average Completion Time 

1.5TD 3 Err 

1.5C 3 Err 

0TD 3 Err 

1.5TD 6 Err 

0TD 6 Err 

1.5C 6 Err 

1.5TD 6 NoE 

OTD 6 NoE 

1.5TD 3 NoE 

0TD 3 NoE 

1.5C 6 NoE 

1.5C 3 NoE 


0 0.2 0.4 0.6 0.8 

Average Number of Impacts 

• The ranking of effects for completion time from most to least important 

was the following: time delay, command display usage, error, 

manipulator speed, and output method 

• For impacts the ranking of effects were the following: error, 

commanded display usage, manipulator speed, time delay and output 

method 



test.col.pp4 

250 

200 

150 

100 

50 

0 

Learning Effects 

Initial Learning Curve Hand Controller Usage with Experience 

Naïve Subject 

Experienced Subject 

Power (Naïve Subject) 

Power (Experienced Subject) 

0 50 100 150 

Trial Number 

y = 201.18x -0.269 

R 2 = 0.4637 

y = 41.642x -0.1095 

R 2 = 0.1121 

1.02 

1.00 

0.98 

0.96 

0.94 

0.92 

0.90 

0.88 

0.86 

0.84 

0.82 

Naïve 1st Test 

Naïve 2nd Test 

Naïve 3rd Test 

Naïve 4th Test 

Experienced 1st Test 

Experienced 2nd Test 

Experienced 3rd Test 

Experienced 4th Test 

0 1 2 3 4 5 6 7 

Commanded Manipulator Velocity [in/s] 

• Two subjects performed four test sessions with the peg-in-hole task, using stereo 

vision, 1.5 second delay and a commanded display with random error at 6 inches/ 

second manipulator speed 

• A completely naïve subject exhibited 83% learning, while a subject with extensive 

robotic experience who had never performed the experimental task had 93% 

learning 

• Hand controller usage showed that with increased experience, subjects spent less 

time waiting 

• Using 93% learning as a gauge, one experiment needed 10 hours of training which 

would cut completion times in half, and an additional 20 hours of experimental 

testing results in 8% reduction of completion time 

• This could cause a bias for test cells taken at the end of the experiment 



test.col.pp4 

Conclusions (1 of 2) 

• Time delay increased completion time linearly; this linear relationship 

occurred for both commanded display and unmitigated treatments 

• Commanded displays without error alleviated the majority of time delay 

effects, up to a 91% reduction 

– Even with no delay the commanded display reduced completion time by 22% 

– Impacts were faster to detect and compensate for using the commanded display 

– The commanded display facilitated more accurate control even when compared to 

no time delay, for the Modified Fitts’ Law Study: 

– Only 3 errors were made with a commanded display over 4 hours of testing 

including 4 subjects testing a total of 1440 trials. 

– 20 times more errors were made without a commanded display 

• A correlation was found between hand controller usage and completion 

time: the longer the subjects did not move the controllers the more time a 

task took 

– The move and wait strategy was evidence, at larger delay subjects spent more 

time waiting 

– The commanded display enabled the subjects to effectively use the hand 

controllers during time delay, resulting in lower completion times 

– Moderate levels of random error caused subjects to ignore the commanded 

display for fine maneuvering and revert to a move and wait strategy; however, the 

commanded display still saved time during coarse movements 



test.col.pp4 

Conclusions (2 of 2) 

• A commanded display was shown to be useful even with large 

amounts of error 

• Evidence indicated that subjects pulsed hand controllers 

during time delay operations 

• Although manipulator speed was a factor in lowering task 

completion time, no specific speed presented itself as 

superior 

• The ability to move the viewpoint was more powerful than 

stereo vision at improving the subject depth perception 

• The use of LCD shutter glasses outperformed the HMD tested 

for stereo viewing; its greater resolution and more natural 

optics may outweigh the greater head tracking provided by 

the HMD for a given application 

• Simulator sickness symptoms occurred most with the HMD, 

next the LCD shutter glasses, and least with the monitor 



Future Research 

• Reevaluate stereo viewing using different output devices: newer HMDs, LCD 

glasses, ‘cave’ technology, and prism screen monitors 

• Concentrate on the effects of display resolution, field of view, and frame rate 

on performing a task with a commanded display 

• Look at using a variety of ways to control the manipulator speeds, moving 

faster when accuracy is less important 

• Investigate different methods to control the manipulator and the view inside 

the virtual environment: head tracking, hand controllers, 6 DOF mice, 

forceballs, touchscreens, and mechanical master arms 

• Determine how to build the best commanded display using transparency, 

wireframes, flashing, and color to create an overlay that is helpful without 

occluding the actual display 

• Compare the effectiveness of the commanded display against the predictive 

display with dynamic systems and contact operations 

• Research should be directed to how best to use commanded displays for 

different applications, including using the command display with other 

advanced supervisory control methods 

test.col.pp4 

– Using commanded displays to control multiple systems 

– Use the commanded display to plan, simulate, and alter scripts which are then run 

autonomously by the remote system 

– Using a commanded display to overlay on live video 



test.col.pp4 

Ranger Spacecraft Servicing System 



test.col.pp4 

How the Robot Interacts with the Worksite 

Ranger’s Place in Space Robotics 

How the Operator Interacts with the Robot 



test.col.pp4 

Missions Enabled by Space Robotics 

How the Robot Interacts with the Worksite 

Specialized 

Robotic 

Interfaces 

Any EVA- 

Compatible 

Interface 

Any Human- 

Compatible 

Interface 

How the Operator Interacts with the Robot 

Locally 

Teleoperated 

• Payload 

Positioning 

• ISS Planned 

Robotic Servicing 

• Free-flying 

Cameras 

• All ISS Servicing 

• NGST 

Ass’y/Servicing* 

• Aerobrake Ass’y 

• LEO Contingency 

Repairs 

• Telepresence 

Remote 

(Ground) 

Teleoperated 

• Lunar Long- 

Distance Surveying 

• Future ISS 

Servicing 

• Lunar Nearside 

Infrastructure 

• “Grand 

Observatories” 

Ass’y/Servicing 

• Mars EVA Robotic 

Assistant 

• Lunar/HEO 

Contingency 

Repairs 

• Dexterous 

Science Teleops 

* Feasibility Study Currently Underway for NASA Goddard 

Supervisory/ 

Autonomous 

Control 

• Planetary Rovers 

• Deep Space 

Visual Inspection 

• Mars Base 

Construction 

• Mars ISRU 

Servicing 

• Mars Geology/ 

Life Sciences 

• Deep Space 

Contingency 

Repairs 

• Dexterous 

Science Ops 

Missions 

Supported 

by Ranger 

Flight 



Engineering Arm Performing HST ECU Task 

2:00 Bare bolt drive (BBD) on arm 

0:55 Arm (with BBD) moves to ECU 

0:51 BBD on lower left bolt 

0:48 BBD turns lower left bolt 6 times 

0:51 Arm moves from lower left bolt to upper left bolt 

0:48 BBD turns upper left bolt 6 times 

1:13 Arm moves from upper left bolt to upper right bolt 

0:48 BBD turns upper right bolt 6 times 

0:59 Arm moves from upper right bolt to lower right bolt 

0:48 BBD turns lower right bolt 6 times 

1:10 Arm moves from lower right bolt to tool post 

2:00 Right angle drive (RAD) on arm 

2:00 (Tether loop gripper on other arm) 

0:57 Arm (with RAD) moves to connector drive mechanism 

0:39 RAD on connector drive mechanism 

0:28 Tether loop gripper closes on tether loop 

0:20 RAD turns connector drive mechanism to lift ECU 

0:12 Tether loop gripper opens from tether loop 

17:47 Total time 

test.col.pp4 



test.col.pp4 

Time (hrs) 

0.75 18:00 

15:00 0.63 

12:00 0.50 

9:00 0.38 

6:00 0.25 

3:00 0.13 

0:000 

Ranger Application to HST SM1 

EVA Daily Average from SM1 

EVA Day 1 EVA Day 2 EVA Day 3 EVA Day 4 EVA Day 5 

Ranger (pre-EVA) 

Ranger (post-EVA) 

EV1 - with Ranger Ranger (during EVA) EV2 - with Ranger 



test.col.pp4 

Impact of Ranger-class Robot on SM3A 



test.col.pp4 

325 

76 

52 

Grasp Analysis of SM-3B 

250 

1,157 

1DOF tasks 

2DOF tasks 

Modified tasks 

Dexterous tasks 

Not yet categorized 

Numbers refer to instances of grasp type over five EVAs 

Total discrete end effector types required ~8-10 



test.col.pp4 

Results of Robot Dexterity Analysis 

• Broke 63 crew-hrs of EVA activity on SM 

-3B into 1860 task primitives 

• 13.4% not yet categorized 

• Of categorized task primitives, 95.3% are 

viable candidates for 2DOF robotic end 

effectors 

– 71.8% 1DOF tasks 

– 3.2% 2DOF tasks 

– 20.2% tasks performed differently by robot than EVA 

(e.g., torque settings) 

• 4.7% require additional dexterity 

• All SM-3B robotic tasks can be performed 

by suite of 8-10 different end effectors 



test.col.pp4 

Baseline SM4 Task Allocations 

• RSUs (3) 3:00 

• Battery Modules (2) 2:50 

• COS 3:10 

• WFC3 2:55 

• ASCS/CPL 3:30 

• FGS3 3:35 

• NOBLs (3) 1:50 

• ASCS/STIK 1:55 

• DSC 1:00 

• Setup & Closeout 5:00 



test.col.pp4 

HERCULES (Single Arm; Stowed) 



test.col.pp4 

HERCULES (Dual Arm; non-EVA Ops) 



HERCULES (Dual Arm; EVA Operations) 

test.col.pp4 



test.col.pp4 

Approaches to Ranger Operations 

• All scenarios assume Ranger dexterous 

manipulator(s) mounted on RMS throughout 

SM4 

• Case 1: Single dexterous arm on modified MFR 

– Case 1A: Operates only during EVA in support of crew (“third 

hand”) 

– Case 1B: Operates only when EVA is not underway (conservative 

mode) 

– Case 1C: Operates with and without EVA crew 

• Case 2: Dual dexterous arms on RMS 

– Case 2A: Mounted on MFR; used only for EVA support 

– Case 2B: Mounted on MFR; used only outside of EVA 

– Case 2C: Mounted on MFR; used with and without EVA 

– Case 2D: Dedicated RMS mount; both EVA crew free-floating 

– Only Case 2C has been considered to date in any detail 



test.col.pp4 

Estimates of Relative Time Savings 

SM4 Task Case 1A Case 1B Case 1C Case 2C 

RSUs – – – 10% 

Batteries 10% 20% 30% 90% 

COS 10% 10% 20% 35% 

WFC3 10% 10% 20% 35% 

ASCS/CPL 5% 5% 10% 30% 

FGS3 – 5% 5% 10% 

NOBLs 10% 20% 30% 80% 

ASCS/STIK 5% 5% 10% 30% 

DSC – – – 10% 

Setup & 

Closeout 

10% 60% 70% 90% 



HERCULES/EVA Team in SM4 Operations 

test.col.pp4 



test.col.pp4 

HERCULES Proof-of-Concept Testing 



test.col.pp4 

SM4 Time Savings with Ranger Arm(s) 

SM4 Task Case 1A Case 1B Case 1C Case 2C 

RSUs – – – 0:18 

Batteries 0:17 0:34 0:51 2:33 

COS 0:19 0:19 0:38 1:06 

WFC3 0:17 0:17 0:35 1:01 

ASCS/CPL 0:10 0:10 0:21 1:03 

FGS3 – 0:11 0:11 0:21 

NOBLs 0:11 0:22 0:33 1:22 

ASCS/STIK 0:06 0:06 0:11 0:34 

DSC – – – 0:06 

Setup & 

Closeout 

0:30 3:00 3:30 4:30 

Totals 1:50 4:59 6:50 12:54 



test.col.pp4 

SM4R(obotic) Concept Overview 

Ranger Telerobotic Servicing System 


Interim Control Module 

Naval Research Laboratory 

HST SM4 Servicing Hardware 

NASA Goddard 



test.col.pp4 

Maneuvering Spacecraft Bus - ICM 

• Developed by Naval 

Research Laboratory for 

NASA ISS 

• Sufficient payload on EELV 

for Ranger robotics, SM-4 

servicing hardware, HST 

flight support hardware 

• Sufficient maneuvering 

capability for extensive 

coorbital operations, 

followed by HST deorbit or 

boost to disposal altitude 

• Currently in bonded 

storage at NRL 



test.col.pp4 

Dexterous Robotics - Ranger 

• Developed by University of 

Maryland for NASA as low-cost 

flight demonstration of 

dexterous telerobotics 

• Designed to be capable of 

using EVA interfaces and 

performing EVA tasks 

• System passed through NASA 

Phase 0/1/2 PSRP safety 

reviews for shuttle flight 

• High-fidelity qualification arms 

in extended tests at UMd SSL 

• 70% of flight dexterous 

manipulator components in 

bonded storage at UMd 



test.col.pp4 

Servicing Option 1 

• Limited to critical 

servicing options 

– Batteries 

– Rate sensor 

units 

– Battery carrier 

plates, SOPE, 

COPE 

• HST payload 

mass 3194 lbs 

• Total ICM payload 

4454 lbs 

• Servicer empty 

mass 11,065 lb 



test.col.pp4 


• Limited to 

critical servicing 

options 

– Batteries 

– Rate sensor 

units 

– Battery 

carrier plates, 

SOPE, COPE 


mass 3194 lbs 

• Total ICM 

payload 4454 lbs 





test.col.pp4 


• All SM4 ORUs 

and launch 

protective 

enclosures 


mass 9574 lbs 

• Total ICM 

payload 10,834 

lbs 





test.col.pp4 

Modifications to Existing Hardware 

• ICM 

– Addition of TDRSS Ku-band command data links 

– Mounting interfaces for robotic hardware, HST servicing 

hardware, MMS berthing ring 

– Attachment to EELV payload adapter 

• Ranger 

– Addition of longer strut elements to provide needed reach for 

positioning leg 

– Completion of flight manipulator units 

– Development of required end effectors for servicing tasks 

– Implementation of launch restraints for robot on ICM deck 

– Development of control station for teleoperated/supervisory 

control 

• HST servicing hardware 

– Modification of shuttle launch restraints to ICM deck 

– Verification of thermal environment for ORUs 



test.col.pp4 

SM4R Mission Scenario 

• Launch on EELV, rendezvous and dock to HST at aft 

bulkhead MMS fittings (high level supervisory control) 

• Perform high-priority servicing (batteries/gyros), other 

targets of opportunity (e.g., SM4 instrument 

changeouts), boost HST to multi-decade stable altitude 

• Separate ICM and move into coorbital location to allow 

HST to perform nominal science data collection (no 

impact to HST pointing or stability) - ICM can be used as 

robotics testbed during this time 

• ICM can redock and service multiple times if needed 

(e.g., periodic gyro replacements) 

• ICM is based on design with proven flight duration of 6 

years on-station 

• At end of HST science mission, ICM redocks and 

performs deorbit/disposal boost mission 



test.col.pp4 

Launch Vehicle Considerations 

• Due to size of ICM and servicing hardware, an 

EELV with a 5-meter payload fairing is required 

– Delta IV Medium+ (5,2) 

– Atlas V 501 

• Also considered next larger size EELV for 

heavier mission cases 

– Delta IV Medium+ (5,4) 

– Atlas V 521 



test.col.pp4 

ICM Propellant Loads 

Delta IV M+(5,2) 

Atlas V 501 

Delta IV M+(5,4) 

Atlas V 521 

Option 1 Option 2 Option 3 

11,700 11,040 7,515 

11,700 11,700 11,700 

Propellant Mass in lbs 



test.col.pp4 

Assumptions: 

• 300 m/sec deltaV reserve for rendezvous and docking 

• Remaining propellant used to raise orbit from 330 NMi to 

new circular altitude, then deorbit from that altitude 

1200 

1000 

800 

600 

400 

200 

0 

Achievable Boost Altitude 

Delta IV M+ (5,2) Delta IV M+ (5,4) 

Option 1 

Option 2 

Option 3 



test.col.pp4 

Mission Assurance 

• Use existing hardware to initiate comprehensive 

testing program 

– Hubble SM4 EVA neutral buoyancy training hardware 

– Ranger neutral buoyancy robot 

– UMd Neutral Buoyancy Research Facility 

• Three keys to success: 

– Test 

– Test 

– Test 

• Evaluate every SM4 task in first 6-9 months and 

decide on whether or not to perform it on-orbit 

• Aim for 25-30 hours of end-to-end simulation for 

every hour of on-orbit operations 



test.col.pp4 

Why SM4R? 

• No other options come close to matching technology 

readiness: 

– ICM based on “black” spacecraft with flight heritage, currently 

ready to fly 

– Ranger manipulators developed and tested; 70% of dexterous 

manipulator flight components already procured 

• No other options come close to matching the proven 

capabilities 

– Long on-orbit endurance and high maneuvering capacity 

provide assurance of successful deorbit at Hubble end-of-life 

– Ranger manipulators designed for EVA-equivalent servicing, 

building on 20-year heritage of HST robotic servicing operations 

• No other options come close to matching the flexibility 

– Interchangeable end effectors provide unlimited interfaces 

– Ranger arm design parameters (force, speed, clean kinematics) 

unrivaled among flight-qualified manipulators 



test.col.pp4 

Results of a Successful SM4R Mission 

Demonstration of Dexterous 

Robotic Capabilities 

Precursor for Low-Cost 

Free-Flying Servicing Vehicles 

Understanding of Human Factors 

of Complex Telerobot Control 

Lead-in to Cooperative 

EVA/Robotic Work Sites 

Pathfinder for Flight 

Testing of Advanced Robotics 

Dexterous Robotics for 

Advanced Space Science 



test.col.pp4 

Ranger on SMV 



test.col.pp4 

For More Information 

http://www.ssl.umd.edu 

http://robotics.ssl.umd.edu

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