The capability for a single operator to simultaneously control complex remote multi degree of freedom robotic arms and associated dextrous end effectors is being developed. An optimal solution within the realm of current technology, can be achieved by recognizing that: (1) machines/computer systems are more effective than humans when the task is routine and specified, and (2) humans process complex data sets and deal with the unpredictable better than machines. These observations lead naturally to a philosophy in which the human's role becomes a higher level function associated with planning, teaching, initiating, monitoring, and intervening when the machine gets into trouble, while the machine performs the codifiable tasks with deliberate efficiency. This concept forms the basis for the integration of man and telerobotics, i.e., robotics with the operator in the control loop. The concept of integration of the human in the loop and maximizing the feed-forward and feed-back data flow is referred to as telepresence

Garin, John

Jennings, Von Ayre

Matteo, Joseph

English

NASA Technical Reports Server

TELEPRESENCE AND TELEROBOTICS 
John Garin. 
Joseph Matteo, 
and 
Von Ayre Jennings, Ph.D. 
Martin Marietta Aero & Naval Systems 
103 Chesapeake Park Plaza 
Baltimore, MD 21220 
ABSTRACT 
INTRODUCTION 
Martin Marietta is developing the capability for a 
single operator to simultaneously control complex 
remote multi degree of freedom robotic arms and 
associated dextrous end effectors. An optimal 
solution within the realm of current technology, can 
be achieved by recognizing that (1) maclines/com- 
puter systems are more effective than humans when 
the task is routine and specified, and (2) humans 
process complex data sets and deal with the unpre- 
dictable better than machines. These observations 
lead naturally to a philosophy in which the human’s 
role becomes a higher level function associated with 
planning, teaching, initiating, monitoring, and inter- 
vening when the machine gets into trouble, while 
the machine performs the codifiable tasks with 
deliberate efficiency. 
This concept forms the basis for the integration of 
man and telerobotics. i.e.. robotics with the oper- 
ator in the control loop. The concept of integration 
of the human in the loop and maximizing the feed- 
forward and feed-back data flow is referred to as 
telepresence. 
Telepresence at Martin Marietta consists of an 
exoskeleton master commanding an anthropo- 
morphic slave robot. The slave will serve as a 
human surrogate, replacing man in hostile 
environments. The exoskeleton master controller 
will provide a feeling of transparency (operator 
believes he is in the robot’s surroundings) through 
advanced controls. This approach will address 
integration of the human into the control loop. 
The new, high technology battlefield has become an 
extremely lethal environment where survival will 
depend on human surrogate devices. These 
hazardous environments are such that with the 
human protected by armor and/or environmental 
suits (i.e.. space suit, diving equipment), perform- 
ance is greatly degraded and the human life is 
under unacceptable risk. In some cases human 
access may be impossible. 
Hazardous environments such as Nuclear- 
Biological-Chemical (NBC) environment, subsea 
or outer space, will require robotic systems that can 
perform human-like tasks. The performance of 
these tasks will require robotic arms that have 
redundant kinematics, bandwidth, and weight-to- 
power ratios of the human. 
Modern robotic arms that resemble humans have 
seven or more degrees of freedom (DOF) to allow 
arbitrary positioning and orientation of the end 
effector. Manipulators with more than six DOF can 
have control problems as the manipulator config- 
uration often becomes degenerate (two or more 
DOF produce the same motion of the end effector). 
We are addressing robotic arm requirements of 7 
DOF. This type of kinematic arrangement is 
required to perform human-like tasks and provide 
telepresence functions. 
Redundant kinematics significantly affects tele- 
robotics control, and requires special man-machine 
interfaces. To avoid degeneracies, a special 
controller must be used, one type of which (an 
exoskeleton controller) Martin Marietta is now 
developing. 
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There are basically three (3) types of kinematic 
stances used in telerobotics. The nuclear industry 
typically uses the "elbow up" stance. The upper 
arm extends horizontally outward, lower arm 
dropping vertically downward, and the end effector 
extending horizontally. 
The Japanese have implemented a design that has 
the "elbow sideways" or the actuators causing 
motion in a horizontal plane. This kinematic 
arrangement is referred to as a Selective Compliance 
Articulated Robotic Arm (SCARA). It is very 
useful for industrial applications because motion is 
independent of gravity, but has limited use in 
telerobotics. 
The third configuration is the anthropomorphic 
stance which resembles that of the human arm. 
The upper arm drops vertically, and the lower arm 
and end effector axes are aligned, extending 
forward horizontally. Martin Marietta will be 
concentrating on the anthropomorphic stance of the 
human as their model. The choice affects control 
issues greatly and is based on the rationale in the 
following paragraph (Figure 1). 
ANTHROPOMORPHIC RATIONALE 
I I I I 
ANTHROPOMORPHIC-SLAVE 
EXOSKELETON-MASTER I-F?SYSTEM TASK 
UNSTRUCTURED 
UNCERTAINTY 
H U M A N  
BIOLOGICAL MODEL 
I I I I 
Figure 1. Teleoperator System Modelled After Human 
Operators will be More Intuitive, Easier to Use, 
Reliably Controlled 
A telerobotic system that is modelleci after the 
human operator will be more intuitive, and thus 
easier to use (less cognitive input) and more reliably 
controlled (less fatigue to the operator). This 
reduces learning time, and creates a more natural 
control environment. 
TELEPRESENCE AND TELEROBOTICS 
I Martin Marietta Aero and Naval Systems started the development of telepresence systems in 1986. 
The objective of the Aero & Naval Systems Exo- 
skeleton Master and Anthropomorphic Slave 
(EMAS) arms system is to provide dextrous 
manipulation. This system will utilize and develop 
the man-machine interface and be used in a tele- 
operational control mode to provide maximum 
telepresence effect: sensory information back to 
the operator. 
The term telepresence refers to the information 
required by the operator to "feel" a sense of 
"presence" in the working environment. The issues 
dealing with telepresence relate to three major 
human factor issues: 
Perception 
Cognition 
0 Psychomotor Control 
To complete any task, whether teleoperated or not, 
the task must first be understood (perception), a 
decision must be made about what action to take 
(cognition). and then that action must be carried 
out (psychomotor control). This same thought 
process is paralleled in the robot controller. 
The ultimate goal of this system is to provide 
human-like manipulation capabilities. In some 
cases. physical capabilities will exceed those of 
humans. 
The measure of these capabilities can be summed 
into dexterity which refers to the ability of the 
manipulator to perform tasks that require human- 
like manipulative capabilities. The robotic arms will 
provide that type of manipulation. The degree of 
dexterity will be characterized by comparing the 
time to perform this task b y  a human with hidher 
bare hands to that of the robotic arms. The 
measured parameters will be: 
0 rate of task completion 
accuracy/quality of task performance 
impact of system on remote environment 
0 impact on operator, Le. workload/fatigue 
The overall relationship between the major com- 
ponents of the exoskeleton master and anthropo- 
morphic slave are shown in Figure 2. 
ANTHROPOMORPHIC SLAVE 
Thc snthropomorphic slave arm will approximate 
human performance dnd be scaled in both size and 
strength. Specifically, a single manipulator can 
handle an object up to 50 pounds in weight and 
412 
v v 
EXOSKELETON TRUNKnORSO 
MASTER CONTROLS GLOVE 
NECK-3DOF- 
CAMER4MIKES.LlES 
WAIST-3DOF 
ANTHROPOMORPHIC 
-l 
Figure 2 Telepresence System Exoskeleton Master and Anthropomorphic Slaw 
move it throughout most of a hemisphere with a 
radius of approximately 4 feet. The total weight of 
1.Sx scaled up slave arm should be no more than 
approximately 160 pounds. For portability, it can 
be quickly disassembled into modules weighing no 
more than 40 pounds each. The most demanding 
sequence of operations involving motion of a heavy 
(approaching capacity) object, grasping the object, 
and reorienting and moving the object across the 
manipulator range of motion to a new location can 
be accomplished in less than S seconds with great 
accuracy. At lesser load. the arm can reach speeds 
of 160 ft/sec2 and 360 ft/sec2 tip speed carrying 
25 lb. and 0 Ib. payloads, respectively. The single 
arm manipulator system is able to meet the 
performance specifications while mounted on a 
platform, a ROV submersible, or on the back of a 
light truck and while subjected to an adverse field 
environment. 
Hand Controller (Master) 
1. Force Reflection 
2. Somesthetic Feedback 
- Tactile 
- Pressure (below skin surface, deep 
- Temperature 
3. Joint Angle Sensing 
4. Haptic Display 
muscular pressure) 
Arm Controller (Exoskeleton Master) 
1. Force Reflection 
2. Joint Angle Sensing 
3. Stiffness Sensing (Kinesthesia) 
- EMG 
- Muscle Sorno 
- Co-Contraction 
EXOSKELETON MASTER 
SERVO CONTROL REQUIREMENTS 
The exoskeleton master goals include being used by 
5-95th percentile operators. This is achieved by 
providing adjustments in the major anthropometric 
ranges. These ranges of adjustments are still being 
determined. 
The following information and sensory feedback 
shall be provided back to the operator (Figure 3). 
Innovation in servo-control system design has been 
under development. This architecture is as shown 
in Figure 4. Control of both force and position are 
required. The system must adapt to payload, be 
achievable on a flexible or moving platform, and 
driven by sensors of position and force. Control 
algorithms are arranged for rapid computation on 
distributed processing computers. The following 
(4) control modes are provided. 
41 3 
-----_ 
VlSUAL AUDIO KINESTHESIA TACTILE 
WORLD WORLD WORLD WORLD 
I I 
------- 
2/SD AUDIO EXOSKELETON MASTrR 
HELMET/CRT/PROJECTION DISPLAYS 
Figure 3. Telepreseno Control Station Feed Back 
-----. 
WSUAL AUDIO K l N E N E S l A  TACTILE 
WORLD WORLD WORLD WORLD 
t t t t 
RCS 
EXOSKELETON 2/3D AUDIO MASTER HELMET/CRT/PROJECTION DISPLAYS 
GRAPHIC H w n c  HAPTIC 
COGNITIVE 
SENSORS 
SYSTEMS 
’ REMOTE 
INFORMATION 
PROCESSING 
INTERFACE 
HUMAN 
SENSORS 
SYSTEMS 
. REMOTE 
. INFORMATION 
PROCESSING 
INTERFACE 
HUMAN 
Figure 4. Telepfesence Control Station Feed Forward 
414 
Computer Supervisory Control - The slave 
arms shall be able to perform prepro- 
grammed functions such as: 
- manipulator arm storage 
- tool extraction and storage 
- repetitive tasks that have been previously 
- collision avoidance (arm to arm) 
- end of arm camera tracking 
Control Adaptive to Accuracy - Speed of 
motion is faster when less accuracy of posi- 
tion or force control is required. 
Cooperation Control - Two arms are able 
to cooperate on the handling of a long and 
heavy object and on the application of op- 
posing forces to one or two objects. 
Collision Survival - The arm will stop mo- 
tion without damage to itself upon contact- 
ing an obstruction to the motion of any link 
of the arm, when the speed of motion is 
one quarter of the highest speed. 
taught 
INTEGRATED WORK STATION 
For telerobotics to be a cohesive system or provide 
telepresence, four key perceptual functions, visual, 
audio, kinesthesia and tactile world (Figures 3 and 
4), must be integrated. 
The visual feedback will be achieved through a 
video system with enough resolution to match 
operator acuity. The audio system will provide 
real-time auditory information with 3D cues. The 
kinesthesia information is provided through the 
exoskeletal controller in the form of forces and 
torques. The tactile world is addressed through 
touch sensors on the surfaces of the arms and 
fingers. 
a) Development of a corm rehensive conceDt for an 
anthroDomomhic manimlator svstem (Fieure 5 ) .  
The overall concept for this system consists of 
the slave manipulator, an exoskeleton master 
controller, telepresence sensory displays and a 
computer control system. The underlying 
approach to the concept is to integrate the 
human operator into the system in a way that 
takes advantage of the human’s tremendous 
perceptual, cognitive and psychomotor capa- 
bilities. For example, the manipulator arni has 
7 degrees of freedom that are identical to the 
arrangement of joints on the human arm. 
Similarly, forces and torques acting on the 
manipulator will be fed back to the human’s 
arm in a way that will cause operators to feel as 
if they were doing the manipulator task 
themselves. In this way, the anthropomorphic 
approach will allow the operator to concentrate 
on the task to be done instead of what motors 
to turn on or off. 
Figure 5. Telepresence Control Concept 
41 5 
b) Definition of Functional Reauirements for 
AnthroDomorphic Performance. Several psych- 
omotor and perceptual characteristics of the 
human operator were considered in defining the 
system functional requirements. For example, 
the movement characteristics of single joints in 
limiting conditions for the corresponding 
manipulator joint (Figure 6).  Other parameters 
examined included range of motion, accuracy, 
repeatability, static and dynamic torque for joint 
movements and a variety of psychophysical 
characteristics such as position and force 
sensitivity. 
humans were evaluated to help define the d) 
noloev assess ment and trade-off sq&s for . .  c) Tech actuators. sensors and Dowe r transmiss Ion. 
Using the functional requirements derived from 
anthropomorphic considerations, various 
manipulator parameters were defined and 
analyzed. These include the joint ranges of 
motion, static and dynamic torques (Figure 7), 
and actuator optimization (Figure 8). 
Comp letion of Final Mec hanical De b. The 
final design of the anthropomorphic manipu- 
lator, based on the design requirements 
described above, consists of a series of inter- 
changeable modules that can be configured not 
only as an anthropomorphic design but in a 
variety of other configurations (Figure 9). This 
manipulator will serve as a unique test bed that 
represents a critical first step towards teleoper- 
ated control of highly maneuverable robot 
systems. 
... -. -.. 
c of Motion 
YIII1UCO"dl -Yammum Force 
Figure 6. Human Performance Characteristics 
Manipulator Model 
XI6 
1.C 
1 
s.c-1 
a 
-C . f - l  
I 
m -8 cv ilp. n-31 c q  T l p .  hn I l l .  
11K 21 WIG3 FDsC I II 
Plot of Actuator Torque Versus Time 
Figure 7. Analysis of Manipulator Dynamics 
416 
<Y' r-----o*~ Numerical Characterizallon 
Fixed Paramelor Technlques 
Component Selactlon L- 
Figure 8. Actuator Optimization 
Figure 9. Anthropomoqhic Manipulator 
to be directly applied to the operator's arm, 
resulting in an intuitive and easy to understand 
presentation of complex sensory data. 
1) Conceptual design of the exoskeleton master 
controller is shown in Figure 5 .  The exoskel- 
eton controller will be a unique method for 
controlling the anthropomorphic manipulator by 
using movements of a human operator's arm. 
This form of teleoperator control will also allow 
the forces and torques acting on the manipulator 
2) A test bed for teleoperator control of the 
anthropomorphic manipulator is being developed 
initially using a single degree of freedom 
417 
master-slave arrangement (Figure 10). This will 
consist of the elbow joint from the manipulator 
with its associated sensors and servo control and 
the elbow joint of the exoskeleton master device 
(described in the previous section). This test 
bed will be used to develop force reflection 
algorithms and algorithms for position or force 
control of the manipulator. These algorithms 
will allow a unique and powerful form of robot 
control to be tested, where human operators 
command robot movements by performing the 
movement themselves. This will provide initia! 
information of kinesthesia. 
, I  I 
I I  I 
Figure 10. Telepsence Anthropomorphic MasterlSlave 
Test Bed 
i 
The tactile information will be provided through a 
glove like device to feed information back to the 
operator's hands (see Figure 5). 
We have proceeded to develop the manipulator 
system and the control station as described below. 
Sienificant DrQeress was made in two a r :  eas 
1) Design of anthropomorphic manipulator system: 
The design of a unique 7 degree-of-freedom 
manipulator was completed. This manipulator, 
when constructed this year, will be one of the 
most advanced robot arms available in terms of 
speed, dexterity, accuracy and load-to-weight 
ratio. Progress was made in several key areas 
that contributed to the overall design. 
2) Control approach 
The control development has also progressed. 
The Advanced Servo Computer (ASC). 
Figure 11, developed in 1986 was enhanced to 
address the needs of teleoperation. 
The ASC board is an extremely powerful data 
acquisition and processing system that will allow a 
variety of high-speed and sophisticated low-level 
servo control algorithms to be implemented. 
The ASC board will be used as shown in Figure 11 
as part of the low level control for the masterklave 
system. The RCS (Real-time Control) approach is 
being implemented as shown in Figure 12. The 
functionality is also shown in Figures 13 and 14. 
The basic concept is to utilize a powerful servo 
board which can handle sensory inputs and 
communications. As the cycle time to complete 
these tasks increases, the system stability increases 
and allows the use of more simple models. 
I 
- ,  
I 
p$rot 
Figure 11. Dual Axis Senro Control Card 
418 
HOST 
- START-UP 
-HIGH LEVEL CONTROL 
-AXIS COORDINATION 
-MONITOR 
[O) 
J 
MASTER SLAVE 
Figure 12 DOF Control Architecture 
OPERATOR 
I 
MASTEWSLAVE 
COORDINATOR 
MASTER 
CONTROLLER 
MOTOR BRAKE 1 ( SENSOR ) (-Ed [COMMANDER COMMANDER 
SLAVE 
CONTROLLER 
Figure 13. RCS Task Decomposition - MasterlSlave 
419 
OPERATOR (a 
Figure 14. Data flow 
CONCLUSION . 
In conclusion, Martin Marietta is developing a 
significant capability to develop and test new 
concepts for man-machine interface and telerobotic 
systems. Through these test beds. the 1 DOF and 7 
DOF systems, we will be developing the solutions for 
telepresence and optimizing methods of control and 
performance of teleoperations. The intention is to 
provide systems that will truly be functional human 
surrogates in hazardous environments. 
The mechanical design uses state-of-the-art 
actuation components in an extremely compact 
design (patent pending). Special techniques were 
developed to optimize system components, and 
often custom-made parts are used. 
The control system is designed to allow investigation 
into many types of tele-operation control. The 
system is based around a powerful and flexible servo 
controller uniquely designed for teleoperation. The 
online system’s approach addresses the basic pre- 
mise of teleoperation (man is best for the unstruc- 
tured thinking, the robot is best for repetition) by 
keeping the algorithms simple, improving the sensory 
feed back to the human, and allowing him to make 
natural high level and high speed inputs to the 
controller. 
420 


Telepresence and telerobotics

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