Building and Controlling Fluidically Actuated Soft Robots

272 Pages·2017·17.67 MB·English

by  Robert Kevin Katzschmann

Building and Controlling Fluidically Actuated Soft
Robots: From Open Loop to Model-based Control
by
Robert Kevin Katzschmann
Dipl.-Ing., Karlsruhe Institute of Technology (2013)
Submitted to the Department of Mechanical Engineering
in partial fulfillment of the requirements for the degree of
Doctor of Philosophy in Mechanical Engineering
at the
MASSACHUSETTS INSTITUTE OF TECHNOLOGY
June 2018
○c Massachusetts Institute of Technology 2018. All rights reserved.
Author ................................................................
Department of Mechanical Engineering
May 4, 2018
Certified by............................................................
Professor Daniela L. Rus
Professor of Electrical Engineering and Computer Science
Thesis Supervisor
Accepted by ...........................................................
Professor Rohan Abeyaratne
Chairman, Department Committee on Graduate Theses
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Building and Controlling Fluidically Actuated Soft Robots:
From Open Loop to Model-based Control
by
Robert Kevin Katzschmann
Submitted to the Department of Mechanical Engineering
on May 4, 2018, in partial fulfillment of the
requirements for the degree of
Doctor of Philosophy in Mechanical Engineering
Abstract
This thesis describes the creation and control of soft robots made of deformable
elastomer materials and powered by fluidics. We embed soft fluidic actuators into
self-contained soft robotic systems, such as fish for underwater exploration or soft arms
for dynamic manipulation. We present models describing the physical characteristics
of these continuously deformable and fully soft robots, and then leverage these models
for motion planning and closed-loop feedback control in order to realize quasi-static
manipulation, dynamic arm motions, and dynamic interactions with an environment.
The design and fabrication techniques for our soft robots include the development
of soft actuator morphologies, soft casting techniques, and closed-circuit pneumatic
and hydraulic powering methods. With a modular design approach, we combine
these soft actuator morphologies into robotic systems. We create a robotic fish for
underwater locomotion, as well as multi-finger hands and multi-segment arms for
use in object manipulation and interaction with an environment. The robotic fish
uses a soft hydraulic actuator as its deformable tail to perform open-loop controlled
swimming motions through cyclic undulation. The swimming movement is achieved
by a custom-made displacement pump and a custom-made buoyancy control unit,
all embedded within the soft robotic fish. The fish robot receives high-level control
commands via acoustic signals to move in marine environments.
Thecontrolofthemulti-segmentarmsisenabledbymodelsdescribingthegeometry,
kinematics, impedance, and dynamics. We use the models for quasi-static closed-
loop control and dynamic closed-loop control. The quasi-static controllers work in
combination with the kinematic models and geometric motion planners to enable the
soft arms to move in confined spaces, and to autonomously perform object grasping.
Leveraging the models for impedance and dynamics, we also demonstrate dynamic arm
motions and end-effector interactions of the arm with an environment. Our dynamic
model allows the application of control techniques developed for rigid robots to the
dynamic control of soft robots. The resulting model-based closed-loop controllers
enable dynamic curvature tracking as well as surface tracing in Cartesian space.
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Thesis Supervisor: Professor Daniela L. Rus
Title: Professor of Electrical Engineering and Computer Science
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Acknowledgments
A great number of people helped me throughout my PhD and made it possible for
me to write this thesis. First of all, I would like to thank my advisor, Prof. Daniela
Rus, for providing me with excellent daily advice, many resources, and an exceptional
environment to work in a field we both share a deep passion for: soft autonomous
robots. Daniela is unique in her ability to motivate and encourage to move our research
forward; she always has good advice when things do not look like they are going
to work out. Looking back at the past five years, we worked on a large variety of
problems, many of which I was not able to capture in this thesis. We went through
many great adventures, went on expeditions to try our robots, both underwater and in
direct contact with humans. I will miss being a PhD student in your lab, and I hope
we will have many mutual fruitful future collaborations. I would also greatly like to
thank my thesis committee consisting of Prof. Russ Tedrake, Prof. John Leonard, and
Prof. Peko Hosoi for all their advice and for their eagerness in supporting me through
the main portion of my PhD. I remember some great conversations and discussions,
and with some of you I actively collaborated during my PhD and hope to continue
doing so in the future. My gratitude also goes to my past supervisors Prof. Torsten
Kröger, Prof. Oussama Khatib, and Prof. Tamim Asfour, who provided me with great
advice during my master thesis (Diplomarbeit) and encouraged me to stay on the
academic track and pursue a PhD.
I would like to thank all my direct collaborators during the PhD, including Brandon
Araki, Prof. Antonio Bicchi, Cosimo Della Santina, Youbin Kim, Dr. Shuguang Li,
Austin de Maille, Joseph DelPreto, Prof. Mehmet Dogar, David Dorhout, Bianca
Homberg, Prof. Robert MacCurdy, Dr. Andrew Marchese, Dr. Santani Teng, and
Prof. Hsueh-Cheng Wang. I learned many things from each of you while we were
making and controlling new robots together.
Without all the members of our lab, the Distributed Robotics Laboratory, this
journey would have been much harder and more difficult. I would also like to thank all
of my current lab members: Alexander Amini, Brandon Araki, Thomas Balch, Cenk
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Baykal, Lillian Chin, Cosimo Della Santina, Joseph DelPreto, Dr. Igor Gilitschenski,
Dr. Shuguang Li, Dr. Jeffrey Lipton, Lucas Liebenwein, Mieke Moran, Felix Naser,
Teddy Ort, Dr. Alyssa Pierson, John Romanishin, Wilko Schwarting, Dr. Hayim Shaul,
Andrew Spielberg, Dr. Cristian Vasile, and Alexander Wallar. I am lucky to be in
a lab environment that is very supportive and collaborative. The atmosphere of the
lab is always warm and welcoming, it provides for great discussions, both in terms
of science and just about anything else. I will always remember our daily lunches
altogether, our yearly lab outings to the mountains for hiking or rafting, and our
regular celebrations with lots of coffee and cake. I would like to thank our lab admin
Mieke Moran, who ensures on a daily basis that everyone in the lab has everything
needed and that we always stay well-fed.
I also want to mention all my previous lab members that have already graduated or
finished their assignments, all of you also helped to create a great PhD journey for me,
andIenjoyeditverymuchworkingwithallofyou: Prof.JavierAlonso-Mora, Byoungk-
won An, Stuart Baker, Thomas Bertossi, Dr. Stephane Bonardi, Prof. Changhyun Choi,
Sebastian Claici, Prof. Mehmet Dogar, Dr. Marek Doniec, David Dorhout, Prof. Daniel
Feldman, Prof. Stephanie Gil, Dr. Kyle Gilpin, Bianca Homberg, Prof. Ross Knepper,
Prof. Robert MacCurdy, Dr. Andrew Marchese, Prof. Ankur Mehta, Prof. Shuhei
Miyashita, Tobias Nägli, Dr. Sedat Ozer, Prof. Liam Paull, Dr. Guy Rosman, Dr. An-
drés Salazar-Gómez, Jenny Shen, Daniel Soltero, Prof. Cynthia Sung, Prof. Michael
Tolley, Dr. Mikhail Volkov, and Prof. Jingjin Yu.
Many thanks also go to all the other CSAIL staff, including Ron Wiken, Adam
Conner-Simons, Rachel Gordon, and Lauralyn Smith. I want to acknowledge all the
help I received from everyone in The-Infrastructure-Group, Human Resources and
Headquarters.
A big thank you goes out to all my friends for always standing by my side and
supporting me for all those years. I especially would like to express gratitude to my
friends Alex, Mikhail, Joao, Affi, Sara, Uyanga, Felix, Joseph, Philipp, Christian,
Gregor and everyone else I forgot to mention. You all were amazing, you were there
for me during different phases of my life, thank you for all the fun times, great
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conversations, and special adventures we had together.
I would like to thank all my family members back in Germany. I miss our regular
family gatherings with lots of cakes, fun conversations, and just hanging out together
on the weekends. I am very proud of my family for holding together so strongly and
being there for each other. I always received so much support and encouragement
from everyone.
To my love Grace, thank you so much for your support, advice, and encouragement.
You stood by me during success and failure, tirelessly encouraging and supporting me
every day. Thank you for all the inspiring discussions and all the loving words. I am
looking forward to many more fun times of creating things together and going on new
adventures with you.
To my son Colin, you have always borne with a father still in graduate school,
happily accompanying me to work when a deadline was close or just because I really
wanted to finish building something. Thank you for always cheering me up with your
deep curiosity and strong interest in learning new things. I am looking forward to
continue instilling your desire to make things. Together we will create many more
robots in the future!
To my brother Philip, thank you for all the advice and support you have given
me since I was born. I could not have wished for a more supportive and encouraging
brother than what I found in you. You are my rock in the ocean, whenever I call you
up, you have time and patience for me, thank you so much!
To Tanti and Onkel Heinz, I miss both of you very much and would wish to be
closer to home so we could spend more time together. I learned many things from
you, especially a great outlook on life. I admire the cordiality and sincerity that you
both live and taught me. I happily remember all the care and love I received from
both of you.
Finally, my deepest gratitude goes to my mother Wilhelmina and my father Ulrich,
who have always encouraged me to follow my dreams. I could not have wished for
more loving and caring parents than what I found in both of you. I admire you greatly
for all you have shown and taught me in my life so far, and I am looking forward to
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many more years of joyful adventures together.
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Contents
List of Figures 18
List of Tables 19
List of Algorithms 21
List of Processes 23
List of Notations 25
1 Introduction 31
1.1 Vision . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31
1.2 New Capabilities . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34
1.2.1 Safe Interactions . . . . . . . . . . . . . . . . . . . . . . . . . 35
1.2.2 Controlled Continuous Deformation . . . . . . . . . . . . . . . 36
1.2.3 Dexterity Through Compliance . . . . . . . . . . . . . . . . . 36
1.2.4 Simplification of Mechanisms . . . . . . . . . . . . . . . . . . 37
1.2.5 Biomimicry . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38
1.3 Applications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38
1.3.1 Manipulation . . . . . . . . . . . . . . . . . . . . . . . . . . . 38
1.3.2 Observation of Marine Life . . . . . . . . . . . . . . . . . . . . 39
1.4 Challenges . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40
1.4.1 Why are Soft Robots Hard to Model and Control? . . . . . . . 40
1.4.2 Why are Current Solutions Inadequate? . . . . . . . . . . . . 42
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1.5 Our Approach . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45
1.5.1 Overview of Our Approach . . . . . . . . . . . . . . . . . . . . 45
1.5.2 Design and Fabrication . . . . . . . . . . . . . . . . . . . . . . 46
1.5.3 Modeling and Control . . . . . . . . . . . . . . . . . . . . . . 47
1.5.4 Control Demonstrated in Applications . . . . . . . . . . . . . 48
1.6 Thesis Contributions . . . . . . . . . . . . . . . . . . . . . . . . . . . 49
1.6.1 Overview of Contributions . . . . . . . . . . . . . . . . . . . . 49
1.6.2 Contributions in Detail . . . . . . . . . . . . . . . . . . . . . . 49
1.7 Thesis Outline . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 52
2 Related Work 55
2.1 Design . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 56
2.1.1 Actuation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 56
2.1.2 Sensing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 59
2.1.3 Design Tools . . . . . . . . . . . . . . . . . . . . . . . . . . . . 60
2.2 Fabrication . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 61
2.3 Control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 62
2.3.1 Kinematics . . . . . . . . . . . . . . . . . . . . . . . . . . . . 63
2.3.2 Planning . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 64
2.3.3 Closed-Loop Grasping Control . . . . . . . . . . . . . . . . . . 65
2.3.4 Dynamic Model-Based Feedback Control . . . . . . . . . . . . 65
2.4 Devices and Applications . . . . . . . . . . . . . . . . . . . . . . . . . 67
2.4.1 Soft Locomotory Robots on Land . . . . . . . . . . . . . . . . 67
2.4.2 Soft Locomotory Robots Underwater . . . . . . . . . . . . . . 68
2.4.3 Soft Grippers . . . . . . . . . . . . . . . . . . . . . . . . . . . 69
2.4.4 Soft Manipulator Arms . . . . . . . . . . . . . . . . . . . . . . 70
3 Design and Fabrication of Fluidic Elastomer Robots 73
3.1 Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 73
3.1.1 Outline of this Chapter . . . . . . . . . . . . . . . . . . . . . . 74
3.2 Actuators . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 75
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