**JET PROPULSION LABORATORY**

Submitted to the TeleRobotics Intercenter Working Group (TRIWG)

Meeting to be held at KSC, March 1-3, 1995

**MICRO LANDER DEXTEROUS MANIPULATOR**

C. E. Tucker Dr. Y. Bar-Cohen D. Henderson

Mechanical Systems Space Materials Science & Space Materials Science

Development/352 Engineering/355 & Engineering/355

**ABSTRACT**

This proposal outlines the development of an ultra light microlander
dexterous manipulator arm, and tool set for 1998 and 2001 Mars Surveyor
(MS) science activities. For these missions to conduct surface science,
the ability to collect/analyze samples, move/inspect surface features
and deploy/position instruments has been identified. Unfortunately Mars
Surveyor landers are extremely mass, volume and power constrained and
the desired addition of a manipulator may not be viable due to
downsizing limits inherent with current technology. To meet these
mission constraints, a manipulator must be developed with small volume
stowing capability and low mass. The proposed manipulator develops
advanced materials and actuator concepts and combines them with a unique
mechanical design to achieve these goals. As part of this proposed
activity, advanced high torque micromotors, composite materials and
deployable structures will be developed and combined with an advanced
control system to support the Mars Surveyor Science and other lander
based missions.

**1. [OBJECTIVES]{.underline}**

**1.1** Develop the technology needed to design a light weight and low
power micro lander dexterous

manipulator that can be stowed into a small volume and configured for
multiple scientific applications in a Mars environment.

**1.2** Build a breadboard manipulator using advanced solid state
actuators, composite materials and a unique mechanical configuration.
Build a multiple function end effector for Mars Surveyor (MS) surface

science missions. Use advanced control technologies to conduct a joint
demonstration with the Mars Exploration Technology/Sample
Evaluation/Acquisition Testbed (MET/SEAT) task and perform tests in a
simulated Mars environment.

**1.3** Transfer manipulator, actuator and tool technologies to the Mars
Surveyor

1998 and 2001 Programs.

**2. [JUSTIFICATION]{.underline}**

**2.1 *Mars Surveyor Application Opportunities* *- ***A series of Mars
Lander missions are planned as part of the NASA Mars Exploration
Initiative. Launches start in 1998, 2001, 2003, and continuing through
the next decade. Each of these missions will have a small
mass/power/volume/cost budget for sample acquisition and science
analysis. Because of this mass constraint, innovative compact, light
weight sample acquisition and instrument systems will be required. There
is an expected need for manipulators to deploy instruments for
preliminary in-situ characterization of Martian surface chemistry and to
support sample collection for instruments on-board the Landers.

The emphasis for the \'98 Lander is on detection of water,
characterization of volatiles, active oxygen species, oxidation states
of paramagnetic ions, and detection of possible organics from soil,
minerals and rocks. This information will be important in assessing the
history of formation and evolution of Mars with emphasis on the fate of
the volatiles. Eventually, it is hoped to carry out a Mars Sample Return
mission, which will require innovative sample collection and storage
systems. Based on what is known so far, it appears that:

\(1\) Sampling will be Lander (not Rover) based.

\(2\) Mechanisms deployed by the Lander will take samples, by limited
degree of freedom manipulation of a robot arm in the near field, and/or
coring below the Lander site. Use of a robotic arm will initially
emphasize grasping, scooping and instrument placement (e.g., APX or
camera) and will evolve to probing and actively controlled sample
extraction (e.g., core-drill, chip, scrape).

\(3\) The sampling system for an in situ project will be similar to that
for a sample return project, the difference being that in the former
case, samples are analyzed with instruments on the Lander, while in the
latter case, samples are processed and loaded into cans in a carousel
and transferred to a sample return capsule.

**2.2 *Science Benefits- ***Autonomous manipulators can provide the
means to collect and support the analysis of indigenous Martian
materials. The scientific contribution of such capabilities can be the
determination of the water and rare gases content on Mars leading to the
determination of the conditions prevailing in the nebula 4.5 bya
(billion years ago). The analysis of the volatile and water inventory on
Mars is a major issue and can help the Mars mission unravel many
mysteries associate to its formation and deliver a major triumph for
space science.

Strong arguments have been made for believing that there is still a
great deal of water locked up as subsurface ice at high latitudes of
Mars. The upper 2 km of the cratered uplands at high latitudes (\>30o)
may contain ice in amounts that exceed the porosity, estimated to be
10-20%. It would appear desirable to test this conclusion by appropriate
sampling and analysis in a Mars surface mission. Such testing will not
require returning samples to Earth, but will require manipulator sample
collection for in situ water analysis.

**2.3 *Technology Relevance For Future NASA Flight Projects - ***During
the progressive phases of this program, pro-active efforts will be made
to identify launch opportunities for the technologies developed. From a
system standpoint, a light weight science manipulator can applied to
future lunar, comet and asteroid lander missions. Individual
technologies such as chemical joint locks, simplified mechanisms and
solid state actuators can provide significant mission benefits in terms
of mass, power and size Specifically in regards to actuators,
applications include: restowable optical cover mechanisms, deployment
mechanisms for antennas and solar panels, real-time compensation for
thermal expansion in space and articulation of optical devices. Overall
development of micro-mechanical technology is critical to support future
low cost micro-satellites, spacecraft and lander missions.

**3.0 [APPROACH]{.underline}**

**3.1 *Micro Lander Dexterous Manipulator Concept ***- A miniature 5
Degrees of Freedom (DOF) dexterous manipulator will be developed with a
low mass (less than 4 kg), consume low power (less than 10 w during
movements) and with the capability to reach up to 2 m, 360 degrees from
the Lander for sample acquisition and other tasks. An arm-end science
platform will be designed for instrument mounting and support tools as
needed for specific science missions (e.g.; APX, camera, claw scoop, arm
end deployable stabilizer, core drill etc.). The simplest sampling
systems will employ a single degree-of-freedom scoop to pick up surface
soil and weathered pebbles and deposit the sample for lander analysis.
To obtain such a manipulator several technologies will be developed to
support the design and fabrication of prototype and a breadboard. These
technologies include: solid state actuation, compact stowing, and the
use of composite materials to construct the manipulator. While each of
these technologies are in use by various industries, several challenges
will need to be address to adapt them to operate in a Mars environment.
Each of the challenges are manageable and they will be discussed herein.

**3.2 [Technical Challenges]{.underline}**

**3.2.1 *Mechanical Design*** - The constraints of the Mars Lander
mission in terms of volume available during launch restrict the
available space for stowing the manipulator prior to use. Several
possible configuration will be considered with primary emphasis directed
toward a gas deployed carbon-composite telescopic structure which offers
light weight and compact stowage. Efforts will be made to maintain a
simplified design to minimize mass while insuring a high reliability. In
this regards, the challenging development of a multi-staged/soft-stop
gas deployment subsystem to replace conventional spring-damper
deployment subsystem is of great interest. The manipulator arm design,
actuation, construction materials and control specifications will be
analyzed to provide stiffness, stability and controllability of the arm
and its attachments. Joint mounted composite springs will be developed
to counterbalance the arm and minimize actuator loads. Also, a
multifunction attachment set located at the end of the arm will also
require the development of a standard mechanical and electrical
interface to allow flexible selection of scientific instruments.

**3.2.2 *Actuators* -** The use of conventional electric motors to
actuate a robotic arm necessitates gear reduction, provide limited
performance/size characteristics and has low temperature constraints.
Solid state motors were recently introduced in Japanese consumer
products (autofocus lenses), which have significant potential for space
applications. A schematic description of a solid state rotary motor
principle of operation is shown in Figure 1. These motors can be
miniaturized, consume low power and have the following characteristics:
high torque density at low speed; high holding torque; simple
construction; can be made in annular shape (for optical application,
electronic packaging and wiring through the center); quite operation and
quick response.

![](media/image3.emf)

Figure 1

Schematic description of the operation principle of a solid state rotary
motor.

While these motors have been used commercially they were not been used
yet for any application that is related to space technology. Further,
they are designed for intermittent actuation at ambient temperatures.
The challenges to applying these motors to actuate a manipulator arm are
to develop a motor with optimized characteristics that can operate at
Mars environment. Another element that would require attention is the
issue of the motorÕs life time performance as a result of potential wear
of the rotor/stator interface.

**3.2.3 *Materials*** - A major challenge will be to develop an
all-composite manipulator. High modulus composite materials offer
tremendous weight advantages over metals for tubular structures such as
the manipulator arm. However, typical composite tubular designs usually
include bonded metallic fittings which represent a large mass fraction
of the overall structure. Elimination of metallic fittings can lead to a
significant mass reduction. In addition to an all composite design, a
resin/catalyst telescopic locking bond joint will be developed to
further minimize mechanisms and improve manipulator strength and
stiffness.

**3.3 [Technical Approach]{.underline}**

A fully tested and characterized advanced technology manipulator arm
will be developed for deployment from a small planetary Lander. A
detachable science platform and tool set will be developed to utilize
the functionality of the manipulator in support of surface science. The
breadboard manipulator will be tested in a simulated Mars environment to
insure suitability for future mission applications. Advanced actuator
and materials technology will be employed to increase manipulator
dexterity while decreasing power, volume and mass.

This proposed task will be coordinated with the integrate advanced
control technologies developed by the SEAT task. Baselined against
existing flight qualified technologies applied to a Mars Surveyor (MS)
sized manipulator arm, a 30% volume reduction, a 60% mass reduction and
30% power reduction have been established as end goals. Future lander
dexterous manipulator applications include: sample acquisition, core
drilling, science instrument surface placement and recovery. Technology
developed by this task will resolve serious micro-manipulator issues
facing scientists and designers of future micro Lander based missions.
In this regards, we will actively involve potential users in defining
the baseline functional parameters and mission applications.
![](media/image4.emf)

Figure 2

**Manipulator and Science Platform Concept**

**3.3.2 *Mechanical Development:*** Primary activities will center
around the design of a simplified and lightweight manipulator concept
which is optimized and seamlessly integrated with material and actuator
developments. A prototype and breadboard manipulator will be designed
and built to physically verify the overall performance and capabilities.

The baseline manipulator approach is shown in Figure 2 and has the
following design features:

¥ Telescopic composite construction for small stowed volume and low
weight

¥ Gas generator pressure deployment for light weight and reliability.

¥ Locking bond adhesive coated wedge joints for reliability, low weight
and improved stiffness

¥ Standardized articulated science instrument platform for mission
flexibility

¥ Piezo actuators for low power and weight

¥ Optional Kevlar rigging for low weight optimization

¥ Variable height and mounting orientation for maximum mission
flexibility

A standardized rotary science instrument platform with additional
Degrees of Freedom (DoF) will be fabricated from composite materials.
The platform will be outfitted with a science tool set consisting of a
scoop, claw, shallow core drill, rock grinder and stabilizer strut. If
available, test instruments from the science community will also be
integrated. When completed, manipulator and populated science platform
will be characterized through a series of tests. System testing will
include, launch vibration, impact and control system operation in a Mars
environment.

**3.3.3 *Development of Solid State Motors (SSM)* -** JPL jointly with
MIT will develop the required solid state motor technology, prototype
motors for performance evaluation and breadboard motors for the
actuation of the manipulator. A motor optimization analytical model
\[1\] will be developed incorporating space related parameters, such as,
temperature, heat transfer and dissipation, friction and dynamic
analysis of the rotor/stator interaction at the interface and motor
performance. Also, materials issues will be studied including the
coefficient of thermal expansion, material friction/wear as well as the
characteristics of the piezoelectric element that provides the driving
mechanism. JPL\'s Section 355 lab will be used to evaluate the
performance of these motors at a wide range of mechanical loads at
vacuum and cryogenic temperatures. The activation electronics and servo
drive will be examined to ensure low mass and low power drive
electronics. The critical issues related to the design, fabrication and
operation of such motors are identified in FYÕ95. The development of the
motors will be conducted in four subtasks:

*Development of Analytical Model -* An analytical model to *a priori*
predict rotary SSMs steady state and transient performance will be
developed to allow design of space-worthy motors and experiments will be
made to verify the predications. The model will address the major
components that are responsible for the motor operation, i.e. stator,
rotor, interface, and motor performance. Preliminary analysis of this
nonlinear, coupled rotor‑stator dynamic model has demonstrated the
potential to predicting motor steady state and transient performance as
a function of critical design parameters (e.g., interface normal force,
tooth height, and stator radial cross section).

*Materials Analysis and Determination of Baseline* ‑ The materials and
design of the SSM determines the motor efficiency and its ability to
operate effectively in a vacuum over a broad temperature range down to
cryogenic temperatures. Effective interface materials (e.g., diamond
coating) will be selected to assure longer durability and improved
friction capability at broad range of temperatures. The above analytical
model will be modified to incorporate parameters that affect operation
of the motors in space environment. The model will be used to establish
criteria for selection of the critical active and passive materials for
the construction of the motor. Preliminary data have been acquired in a
recent study of linear Inchworm motors for the Pluto-Fast-Flyby project
(conducted jointly by JPL\'s Sections 355 and 382 with UCLA).

*Design, Fabrication and Performance Testing of the Motors -* A series
of prototype solid state motors will be constructed and their
characteristics (e.g., stall torque, power consumption, efficiency,
stability, positioning accuracy, thermal and vacuum effects, effect of
mechanical loads, etc.) will be studied. Test results will be compared
with the analytical model predications to validate its accuracy and
determine the required corrections for fabrication of breadboard motors.

*Evaluation of SSM Control System* - The design of the electronic driver
circuits and motor configurations will be analyzed to determine the
necessary modifications to reduce potential complexity while assuring
compact size and low power consumption of the drive circuit. A
servo-drive analysis will be made to allow feedback control of the SSM
and assuring high precision positioning.

**3.3.4 *Materials Development:*** To create a stiff yet light weight
stowable arm, several areas of material development are needed.
Baselining composite hinges and joints in the manipulator arm design
provides a significant mass reduction over metallic fittings. In
addition, compared to metallics, the low coefficient of thermal
expansion inherent in carbon fiber reinforced composites will reduce the
thermal distortion of the arm. To achieve this, JPL will design and
prototype the arm using high modulus carbon reinforced polycyanate
composites. Currently, to fabricate the thermal enclosure for Mars
Pathfinder, a 78 msi M55J fiber reinforced composite tape is being used.
It is envisioned that this material or another higher modulus fiber will
be used for the arm. The advantage of using the M55J composite is the
large property database and design allowables that already exists.

It is currently envisioned that a locking mechanism will be needed
following the deployment of the arm. For a multifold arm, this locking
mechanism may be a simple flexible composite \"spring\" that will be
compressed during launch and spring back to lock the extended arm.
Another locking alternative for the telescopic arm is a long life resin
system that has a catalyst encapsulated in glass microballoons. As the
tubes complete their deployment, they will drive into a wedge stop. The
surface of the wedge stop will be coated with a resin that has been
combined with catalyst filled microspheres. When released, the adhesive
resin and catalyst system will react and lock-bond the joint for use.

**3.4 [Level 1 Demonstration Milestones/Deliverables]{.underline}**

This RTOP started in January 1995 and is being performed as a four years
program with a level 1 demonstration at the end of each fiscal year. The
following describes the milestones and deliverables for each year of the
program.

**FYÕ95** - Deliverable: A non-stowable MS sized prototype manipulator
with three degree of freedom will be designed, fabricated and tested at
the end of the first year. Current MS performance goals include; Reach:
2.0 m/360 degrees, Mass: less than 5 kg, Operating Power: less than 10
watts, Stowed Volume: 15 cm X 15 cm X 40 cm. The MS manipulator will be
assembled using qualified but unproven Mars Pathfinder MicroRover
actuators and tested to establish a performance benchmark for future
development. Compared to existing flight qualified technologies, a
10-20% reduction in mass and power is anticipated. During FY 95, a
collaborative effort will be established with industry and universities
to develop advanced actuators. In addition, manipulator requirements
will be established to provide flexible yet positive performance
parameters to obtain program objectives.

**FYÕ96** - Deliverable: By the end of the second year, the prototype
manipulator will be upgraded with prototypeadvanced actuators and
demonstrated using an advanced SEAT control system and prototyped tool
set. Actuator technology developed during this period is expected to
provide an additional mass and power reduction of 10-15% over the
previous baseline. Actuator testbed components will be designed and
tested under Mars operating conditions (-100 C, 10 torr, dust). Also
during this period, a new optimized structure, science platform and
preliminary tool set will be designed to allow fabrication, integration
and test of a 5 DOF breadboard arm to occur the following year. In
addition to lightweight actuators, advanced composites, bearings and
lubrication will be evaluated.

**FYÕ97** - Deliverable: At the close of this year, a newly designed
breadboard manipulator will be fabricated and demonstrated with advanced
actuators, materials, science platform and tool set. During this period,
improved force and feedback technologies developed by the SEAT task will
be integrated with the manipulator and tested. Low temperature operation
and feedback loops will be verified. In addition, a small core drill be
fabricated and separately characterized prior to manipulator
integration.

**FYÕ98** - Deliverable: As the fourth year ends, themanipulator system
will be optimized and demonstrated in a Mars simulated environment. A
final report will be published. Compared to the three degrees of freedom
baseline, a 50 % volume reduction, a 50% mass reduction and a 30% power
reduction is anticipated. Primary activities of this period will center
around systems optimization, characterization and environmental testing.
Initial vibration characterization of a coredrill and feedback to the
control system are expected be of significant interest. The manipulator
will be tested with tools and instrument simulators to determine the
system\'s performance envelope. At the end of this period, a summary
report will be completed to insure that the developed technology is
accessible to support multi-task operations for future mission use.

**4.0 [FUNDING/SCHEDULE OVERVIEW]{.underline}**

![](media/image5.wmf){width="6.895833333333333in"
height="3.4868055555555557in"}

**5.0 [PARTICIPANTS]{.underline}**

The proposed dexterous manipulator will be developed by JPL with support
from composite manufactures. The solid state actuator will be developed
jointly with MIT. Efforts will be made to involve an industry partner in
a cooperative agreement in order to establish a solid state motor
manufacturing capability in the USA. Burleigh Instruments, THK and
Allied Signal are currently being considered. Prior cooperation with
Burleigh Instruments in the development of a piezoelectric Inchworm
linear motor that operates at cryogenic temperatures for the
Pluto-Fast-Flyby Preproject will serve as a model for this partnership.

**6.0 [COMMERCIALIZATION POTENTIAL ]{.underline}**

Environmentally qualified solid state motors and lock-bond coatings have
been identified as potential technical spin-offs from this program.
Motor applications include; actuators for commercial aircraft,
spacecraft, automotive and consumer products. Lock-bond joint technology
can be applied to a variety of consumer assembled products and space
structures.

**7.0 [FACILITIES]{.underline}**

**JPL**

¥ *ROBOTICS TEST LABORATORY*: This RTOP will co-locate its test
activities within the MET/Sample Evaluation/Acquisition Testbed (SEAT)
Test Facility. Co-location within this existing laboratory will decrease
costs and improve coordination between the mechanical and control
activities.

¥ *ACTUATOR TEST LABORATORY*: Actuators Characterization laboratory is
available to measure the electrical, mechanical (displacement) and
thermal performance of actuation materials and devices under controlled
conditions. A large number of electrical parameters can be analyzed in
the 10 Hz to 32 MHz frequency range using a Schlumbeger Impedance
Analyzer Model 1260. For temperature control at vacuum conditions a
custom modified Janis ST-400 system is used to perform tests at high
vacuum up to 10-8 torr at a temperature range from 77K to 450K. To
activate actuators, a series of function generators and amplifiers are
available. To determine the static and dynamic performance of the solid
state motors under vacuum and cryogenic temperatures a mechanical
testing machine was procured from SATEC (expected delivery in March 95).
This lab was established adjacent to the Nondestructive Evaluation Lab
which has extensive state-of-the-art capabilities for the determination
of the integrity of actuators.

¥ *MECHANICAL TEST LABORATORIES:* A materials laboratory and
environmental test facilities are available to support development of
composite structures. All mechanical tests will be performed at JPL.

**MIT**

¥ Design of the motor and room temperature performance characterization
will be performed in the MIT Space Engineering Research Center (SERC).
SERC was established by NASA as the university center for the
development of controlled structures technology for space. SERC has
extensive project experience in active device development including 2
flight experiments and several terrestrial testbeds in controlled
structures and precision optical systems. The Center has available
state‑of‑the‑art dynamic and static structural analysis equipment and
extensive capability for data acquisition and device instrumentation
using strain gages, accelerometers, force transducers, and laser shape
determination equipment ranging to nanometer level resolution. In
addition, SERC has facilities for material characterization under load
conditions including transduction, stiffness, and dielectric testing of
active materials at temperatures from 200 to 670K and voltage levels of
+10KV.

**8.0 [PRINCIPAL INVESTIGATORS]{.underline}**

**Curtis E. Tucker** is the task lead and chief mechanical engineer for
this task.

He is a technical group supervisor in the Mechanical Systems Development
Group/Section 352 and has 17 years of JPL experience in mechanical
development and management of hardware tasks. His most current project
assignments include lead mechanical engineer for the Mars Oxidents
Experiment (MOx), mechanical task manager for the NASA Scatterometer
(NSCAT) instrument and the lead engineer for preliminary development of
astronaut equipment for the Wide Field Planetary Camera/Hubble Telescope
service mission.

**Dr. Yoseph Bar-Cohen** is the Advanced Actuation Principal
Investigator for this Task. He is a member of the Technical Staff and is
responsible for the Advanced Actuation Technologies at the Materials
Science and Engineering Section of JPL. Since joining JPL in 1991, he
has established state-of-the-art Active Materials Characterization and
NDE Labs. He received his Ph. D. in Physics from the Hebrew University
at Jerusalem, Israel, in 1979. He has more than 23 years experience in
areas of sensors, active materials and NDE, including his positions at
the Israel Aircraft Industry, SRL at the Air Force Materials Laboratory
and McDonnell Douglas Corporation. He originated the use of linear solid
state motors for the articulation of the scanning mirror of the PFF
pre-project phase. He is currently developing solid state rotary motors
for the Micro Lander Dexterous Manipulator. He is the author of more
than 100 publications and holds many patents. He is also an Adjunct
Professor at the University of California, Los Angeles (UCLA).

**Douglas Henderson** is responsible for the development of composite
structures at the Materials Science and Engineering Section. He has more
that 16 years experience in defining and developing novel tooling
concepts and manufacturing processes. He has been involved in producing
cocured and secondary bonded complex geometry composites. He has
extensive background in design and development of both metallic and
composite inserts and their incorporation into structural composite
applications, e.g. , joints and hinges. He published several technical
papers on composite manufacturing concepts and processes and he taught
classes on this subject at California State University, Northridge. He
received B. S. degree in Chemistry from California State Polytechnic
University,Pomona.

**Dr. Nesbitt W. Hagood IV** is the Charles Stark Draper Assistant
Professor of Aeronautics and Astronautics at MIT where he previously
earned his B.S. (1985), M.S. (1988), and Ph.D. (1991) degrees. Professor
Hagood is a member of AIAA, ASME, and the SPIE. He is currently a
technical chairman in the SPIE 1994 Smart Structures and Materials
Conference and member of the editorial board on the IOP Journal of Smart
Materials and Structures. He has published material on piezoelectric
actuation in several technical journals and is currently writing a book
entitled, Piezoelectric Active Structures, to be published by Technomics
Publishing Co. in the Fall of 1995. His primary research interest is in
development of active material systems and devices. He currently holds
two patents in the area of solid state actuation and is co founder of a
startup company for the commercialization of active device technology.

**9.0 [REFERENCES]{.underline}**

1\. N. W. Hagood and A. McFarland, \"Modeling of a Piezoelectric Rotary
Ultrasonic Motor,\" SPIE Paper no. 2190‑52, Smart Structures and
Materials 1994: Smart Structures and Integrated Systems, Nesbitt Hagood,
Editor, SPIE Proc. Vol. 2190, 1994, pp. 814‑828.