`
`
`
`Z)§
`
`pringer
`
`APPLE 1018
`
`APPLE 1018
`
`1
`
`

`

`Engineering Haptic Devices
`
`2
`
`

`

`“This page left intentionally blank.”
`
`3
`
`

`

`Dr.-Ing. Thorsten A. Kern
`Editor
`
`Engineering Haptic Devices
`
`A Beginner’s Guide for Engineers
`
`123
`
`4
`
`

`

`Editor
`Dr.-Ing. Thorsten A. Kern
`TU Darmstadt
`Inst. Elektromechanische
`Konstruktionen
`Merckstr. 25
`64283 Darmstadt
`Germany
`
`ISBN 978-3-540-88247-3
`DOI 10.1007/978-3-540-88248-0
`Springer Dordrecht Heidelberg London New York
`
`e-ISBN 978-3-540-88248-0
`
`Library of Congress Control Number: 2009930680
`
`c° Springer-Verlag Berlin Heidelberg 2009
`This work is subject to copyright. All rights are reserved, whether the whole or part of the material is
`concerned, specifically the rights of translation, reprinting, reuse of illustrations, recitation, broadcasting,
`reproduction on microfilm or in any other way, and storage in data banks. Duplication of this publication
`or parts thereof is permitted only under the provisions of the German Copyright Law of September 9,
`1965, in its current version, and permission for use must always be obtained from Springer. Violations
`are liable to prosecution under the German Copyright Law.
`The use of general descriptive names, registered names, trademarks, etc. in this publication does not
`imply, even in the absence of a specific statement, that such names are exempt from the relevant protective
`laws and regulations and therefore free for general use.
`
`Cover design: WMXDesign GmbH
`
`Printed on acid-free paper
`
`Springer is part of Springer Science+Business Media (www.springer.com)
`
`5
`
`

`

`The idea for this book was born in 2003. Originally intended as an addition to
`my dissertation, it was thought of filling a gap I had noticed: The regrettably small
`number of comprehensive recapitulating publications on haptics available for, e.g,. a
`technically interested person, confronted with the task of designing a haptic device
`for the first time. In 2004, besides a considerable number of conference proceed-
`ings, journals or PhD-theses, no document was available giving a summary of the
`major findings of this challenging subject. Thanks are due to the support provided
`by colleagues, especially by Prof. Dr.-Ing. Dr.-med Ronald Blechschmidt-Trapp and
`Dr.-Ing. Christoph Doerrer, enabling me to realize my plan in the following years.
`While writing my dissertation, I learnt that the areas to be covered by such a book
`would have to be much more extensive than originally expected. Nevertheless my
`mentor and supervisor Prof. Dr.-Ing. habil. Roland Werthschützky, to whom I have
`a special debt, encouraged me to pursue and finish this project during the time as a
`Post-Doc. It was funded by the DFG (KE1456/1-1) with special regard to the con-
`solidation of our design methodology for haptic devices. Due to this funding the
`financial basis of this task was guaranteed.
`The structuring of the themes made clear that the book would be considerably im-
`proved by contributions made by specialists of several areas. Thus began the multi-
`author project you are holding in your hands. Not only the authors explicitly named
`contributed to the book, but also former and current colleagues could be won over
`to a committed co-operation during the project, like Dr.-Ing. Markus Jungmann or
`Ingmar Stöhr, to name and thank at least two of them.
`The first inquiry at Springer, our preferred publisher, resulted in an impressively
`positive reaction and consequently in a constructive co-operation with Dr. Christoph
`Baumann at any time. We owe to him the project’s final configuration concerning
`language versions and date of publication. Let me add a word of gratitude to the
`many people involved in proofreading the book and removing major errors, all ahead
`of them Anika Kohlstedt, Sebastian Kassner, as well as to the numerous helpers of
`both family and friends.
`For the English version of this book a professional language institute was originally
`hired which, however, was unable to provide the translation in time. Therefore it had
`to be done by the authors themselves. Most of the proofreading was done by Ursula
`and Jürgen Förnges both of whom I want to thank explicitly.
`Without the help of all the people mentioned above and of many other unnamed
`supporters, this book would never have reached its present degree of completeness.
`I owe a great debt to all of them. A very special thanks is due to the Institut für Elek-
`tromechanische Konstruktionen at Technische Universität Darmstadt, Germany, for
`the extraordinary support given to me and many of my co-authors in our research
`and scientific work.
`
`Thorsten A. Kern
`
`6
`
`

`

`“This page left intentionally blank.”
`
`7
`
`

`

`Preface
`
`The term “haptics” unlike the terms “optics” or “acoustics” is not so well-known
`to the majority of people, not even to those who buy and use products related to
`haptics. The words “haptics” and “haptic” refer to everything concerning the sense
`of touch. “Haptics” is everything and everything is “haptic”, because it does not
`only describe pure mechanical interaction, but also includes thermal- and pain- (no-
`ciception) perception. The sense of touch makes it possible for humans and other
`living beings to perceive the “borders of their physical being”, i.e. to identify where
`their own body begins and where it ends. With regard to this aspect, the sense of
`touch is much more efficient than the sense of vision, as well in resolution as in the
`covered dihedral angle, e.g.: In the heat of a basketball match a light touch on our
`back immediately makes us aware of an attacking player we do not see. We notice
`the intensity of contact, the direction of the movement by a shear on our skin or a
`breeze moving our body hairs - all this is perceived without catching a glimpse of
`the opponent.
`“Haptic systems” are divided into two classes1. There are the time-invariant systems
`(the keys of my keyboard), which generate a more or less unchanging haptic effect
`whether being pressed today or in a year’s time. Structures like surfaces, e.g. the
`wooden surface of my table, are also part of this group. These haptically interesting
`surfaces are often named “haptic textures”. Furthermore, there are active, reconfig-
`urable systems, which change their haptic properties partly or totally dependent on
`a preselection - e.g. from a menu. Finally, there are combinations and hybrid forms
`of systems, which are presented and explained in the corresponding chapters. The
`focus of this book is on the technological design criteria for active, reconfigurable
`systems, providing a haptic coupling of user and object in a mainly mechanical un-
`
`1 In engineering there are three terms which are often used but do not have a definite meaning:
`System, Device and Component. Systems are - depending on the task of the designer - either a
`device or a component. A motor is a component of a car, but for the developer of the motor it
`is a device, which is assembled from components (spark-plug, cocks, knocking-sensor). It can be
`helpful when reading a technological text to replace each term with the word “thing”. Although this
`suggestion is not completely serious, it surprisingly increases the comprehensibility of technical
`texts.
`
`vii
`
`8
`
`

`

`viii
`
`Preface
`
`derstanding. Thermal and nociceptive perceptions are mentioned according to their
`significance but are not seriously discussed. This is also the case with regard to pas-
`sive haptic systems.
`The fact that you have bought this book suggests that you are interested in haptics.
`You might have already tried to sketch a technical system meant to fool haptic per-
`ception. And this attempt may have been more or less successful, e.g. concerning
`your choice of the actuators. Maybe, you are just planning a project as part of your
`studies or as a commercial product aimed at improving a certain manual control or
`at introducing a new control concept. Approaches of this kind are quite frequent.
`Many of the first active haptic systems were used in airplanes, to make aware of
`critical situations by a vibrating control handle. Nowadays, the most wide-spread
`active haptic system surely is the vibration of a mobile-phone. It enables its user to
`notice the reception of a message without visual or auditory contact, whereby even
`the type of the message - SMS or phone call - is coded in this buzzing haptic signal.
`More complex haptic systems can be found in automotive technology, as e.g. recon-
`figurable haptic control knobs. They are typically located in the center of the control
`console and are usually part of complex luxury limousines. Today, multidimensional
`haptic interaction is no longer limited to navigation- or modeling purposes of pro-
`fessional users, but has also found its way into interaction during computer gaming.
`Maybe, you are a member of the popular group of doctors and surgeons actively
`using haptics in medical technology. There has been a continuous increase of, the
`complexity of the tools for minimally-invasive surgery - longitudinal instruments
`with a limited degree of freedom to inspect and manipulate human tissue through
`small artificial or natural openings in the human body. This automatically results
`in the loss of the direct contact between surgeon and the manipulated tissue. For
`decades, the wish to improve the haptic feedback during such kinds of applications
`and/or the realization of training methods for minimally-invasive surgery has been
`a high motivation for researchers in haptic device design, however without a satis-
`factory commercial breakthrough, yet significant improvements in telemanipulation
`and simulation have been achieved.
`Despite of or even because of the great variety of projects in industry and research
`working with haptic systems, the common understanding of “haptics” and the terms
`directly referring to it, like “kinaesthetic” and “tactile” are by no means as unam-
`biguous and indisputable as they should be. In this book, we, the authors, intend to
`offer you a help to act more safely in the area of designing haptic devices. This book
`will begin with the presentation of the terminology and its usage according to what
`we regard as appropriate. Then it will provide a deeper understanding of haptics and
`a simplified engineering description, and will finally lead to concrete instructions
`and recommendations for the design of technologically complex haptic systems.
`Besides the intention to generate real hardware design, there is another reason for
`dealing with haptic device design: A continuing ambition to extend one’s knowl-
`edge of haptic perception. This discipline, named “psychophysics” is an “unsharp”,
`non deterministic science formulating hypotheses and systematically checking them
`with the help of experiments and observations. These experiments are paramount to
`any progress. Consequently, special attention has to be paid to their quality and the
`
`9
`
`

`

`Preface
`
`ix
`
`parameters observed. As a by-product of this important science of haptic research
`a plurality of devices and technical systems have been built. In fact psychophysics
`uses expertise in many different disciplines to solve its problems. As a consequence,
`important and creative engineers and scientists like Prof. HONG TAN and Prof. VIN-
`CENT HAYWARD have not only been designing high fidelity and very efficient haptic
`devices, but are also heavily involved in the research on psychophysical parameters.
`Psychophysics with emphasis on haptic questions is a very dynamic science. Every
`year, an uncounted number of results and experiments are published at congresses
`and in journals. Lately, MARTIN GRUNWALD [79] has published a notable sum-
`mary of the latest state of knowledge. The book you are holding in your hands
`does not claim to keep up with every detail of this psychophysical progress. How-
`ever, it tries to include as many of its findings as possible into the design of haptic
`devices. This book has been written by and is addressed to engineers of all the dis-
`ciplines mentioned before: Design-engineers representing mechanical engineering,
`hardware-near electrical engineering, control-engineering, software-engineering or
`as a synergy of expertise in all disciplines of mechatronics.
`As said before, the haptic sense is doubtlessly gaining in importance. This can be
`concluded from the great number of scientific publications on this subject and from
`the fact that all relevant distal senses like the senses of sight and hearing have already
`been provided with synthetic information in almost perfect quality in every-day life.
`“Perfect quality” may have different meanings depending on the actual context. A
`realistic rendering of a sensual experience can be an important requirement. The
`resolution of a 3D-monitor has to be below the resolution capability of the human
`eye in color dynamics and spatial distances between the picture elements (pixels).
`Sounds have to be traceable in space and must not interfere with artifacts of the
`storage- or transmission medium. In different circumstances attracting attention can
`be another “perfect quality”. Typically, warning signals in the dashboard of a car
`are visual examples, so are acoustic signals in the cockpit of an airplane. Another
`demand on “perfect quality” can be the simultaneous requirement of high discrim-
`inabilty and large range - just think of navigational signals for ships. Both areas -
`optics and acoustics - have been subject to intense research for decades and have
`been provided with numerous intelligent device designs. In many cases the borders
`of the human capability of perception of the information provided have been reached
`or even crossed nowadays. At this point it is obvious to make use of another human
`sense to transmit information. Another motivation is the true-to-life simulation of
`virtual environments. After visual and auditory presentation having reached a high
`quality, the focus is directed to the haptic sense as being the next important one.
`Only this sense enables us to experience our physical borders and the synergy of
`interaction and perception.
`Further areas of haptic research are telepresence and telemanipulation systems. In
`these cases, an intuitive and immediate feedback is a prerequisite for a safe han-
`dling of e.g. dangerous and / or valuable materials. There are reasons enough and
`to spare for dealing with the design of haptic devices which are demanded by the
`market. However, experts are rare and the access to this subject is difficult. The de-
`sign of haptic devices demands interdisciplinary knowledge which should include
`
`10
`
`

`

`x
`
`Preface
`
`the basics of the properties of haptic perception and its dynamic-dependence on am-
`plitude and frequency. Furthermore an overview of technological solutions, like the
`designs of actuators, kinematics or complete systems including software-solutions
`and the interfaces to simulations and virtual reality systems may be extremely help-
`ful. For designing virtual reality systems it is also necessary to know the concepts of
`haptic renderings to enhance communication between soft- and hardware engineers.
`
`The authors of this book regard their task as being fulfilled as soon as this book
`helps to fascinate more design-engineers by the development of haptic devices, thus
`speeding up the creation of more and better haptic systems available on the market.
`
`Darmstadt, February 2009
`
`Thorsten A. Kern
`
`11
`
`

`

`Preface
`
`xi
`
`Thorsten A. Kern received his Doctor in electrical en-
`gineering in 2006 at the Technische Universität Darm-
`stadt for the design of a haptic assistive system for
`cardio-catheterizations. He is working as a group leader
`at Continental Corporation, and is responsible for the
`development and production of actuators for visual
`and haptic applications. Before he was working in
`the area of medical simulation technology and VR-
`applications using haptics at PolyDimensions GmbH.
`His research focused on engineering methods to quan-
`tify the haptic impression of actuators and devices.
`He is associated lecturer for biomedical engineering
`(t.kern@hapticdevices.eu).
`
`Marc Matysek graduated in electrical engineering at
`the Technische Universität Darmstadt in 2003. There,
`he is working as a PhD student at the Institut für
`Elektromechanische Konstruktionen since 2003. His re-
`search focuses on the technology of dielectric elastomer
`actuators and their use in applications as tactile displays
`(m.matysek@hapticdevices.eu).
`
`Oliver Meckel received his degree for mechanical en-
`gineering in 2002 at Technische Universität Darmstadt.
`He is working as group leader of the technical depart-
`ment at the Wittenstein motion control GmbH. He is re-
`sponsible for the development, simulation, testing, and
`technical product support of electrical gear motors and
`actuator systems. Before he was working at the Institute
`for Flight Systems and Control at Technische Univer-
`sität Darmstadt. His research was focused on adaptive
`control systems and the development of Unmanned Au-
`tonomous Vehicles (o.meckel@hapticdevices.eu).
`
`X?Y
`
`X?Y
`
`12
`
`

`

`xii
`
`Preface
`
`X?Y
`
`Photo: Lichtbildatelier Darmstadt
`
`Jacqueline Rausch received her diploma in electri-
`cal engineering and information technology in 2005
`at the Technische Universität Darmstadt. There, she
`is currently working as a research associate at the
`Institute for Electromechanical Design. Her main
`topic is the development of miniaturized piezoresis-
`tive multi-axis force/torque sensors to be integrated
`at the tip of minimally invasive surgical manipulators
`(j.rausch@hapticdevices.eu).
`
`Alexander Rettig received his diploma in mathematics
`at the Technical Universität Darmstadt in 1998. He is
`working as team leader software development for Poly-
`Dimensons GmbH in the area of medical graphics and
`simulation applications. Before he was research asso-
`ciate at the Fraunhofer Institute for Graphics Darmstadt,
`where he focused on the integration of haptics into vir-
`tual reality systems and development of virtual reality
`applications (a.rettig@hapticdevices.eu).
`
`Andreas Röse received his engineering degree in 2002
`in electromechanical engineering. He is working as a
`research associate at the Institute of Electromechan-
`ical Design at the Technische Universität Darmstadt.
`His research work is focussed on parallel-kinematic
`mechanisms for minimally invasive surgical telema-
`nipulators including numerical calculation techniques,
`mechanical design and performance evaluation meth-
`ods. From 2002 to 2005 he was with Fresenis Med-
`ical Care and developed hemodialysis machines with
`emphasis on safety systems and control architecture
`(a.roese@hapticdevices.eu).
`
`13
`
`

`

`Preface
`
`xiii
`
`Stephanie Sindlinger b. Klages received her diploma
`in electrical engineering and information technology
`at the Technische Universität Darmstadt in 2004. She
`is working as a research associate at the Institut für
`Elektromechanische Konstruktionen. There she devel-
`ops a haptic device for cardiologic catheterisations. Her
`expertises are the development of piezoelectric ultra-
`sonic actuators and the design of the user-interface for
`integrating the system in the operational environment
`(s.sindlinger@hapticdevices.eu).
`
`14
`
`

`

`“This page left intentionally blank.”
`
`15
`
`

`

`Contents
`
`Symbols . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . xxi
`
`Part I Some Basics of Haptics
`
`5
`1 Motivation and Application of Haptic Systems . . . . . . . . . . . . . . . . . . . . .
`5
`1.1 The Meaning of Haptics from a Philosophical and Social Viewpoint
`5
`1.1.1 Haptics as a Physical Being’s Boundary . . . . . . . . . . . . . . . . .
`8
`1.1.2 Formation of the Sense of Touch . . . . . . . . . . . . . . . . . . . . . . .
`1.1.3 Special Aspects of the Design Process . . . . . . . . . . . . . . . . . . . 11
`1.2 The Significance of Haptics in Everyday Professional Life . . . . . . . . 13
`1.2.1 The Sense of Touch in Everyday Medical Life . . . . . . . . . . . . 13
`1.2.2 The Sense of Touch in the Cockpit . . . . . . . . . . . . . . . . . . . . . . 14
`1.2.3 The Sense of Touch at the Desk . . . . . . . . . . . . . . . . . . . . . . . . 16
`1.2.4 The Sense of Touch in Music . . . . . . . . . . . . . . . . . . . . . . . . . . 17
`
`2
`
`3
`
`Terminology . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
`2.1 Scientific Disciplines as Part of Haptic Research . . . . . . . . . . . . . . . . 19
`2.2 Terms and Terminology Used for the Description of Haptic Systems 21
`2.2.1 Basic Concepts of Haptics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21
`2.2.2 Definition of Haptic Systems . . . . . . . . . . . . . . . . . . . . . . . . . . 22
`2.2.3 Parameters of Haptic Systems . . . . . . . . . . . . . . . . . . . . . . . . . . 26
`2.2.4 Characterization of Haptic Object Properties . . . . . . . . . . . . . 28
`2.2.5 Technical examples . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29
`
`Biological Basics of Haptic Perception . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35
`3.1 The Sense of Touch and its Biology . . . . . . . . . . . . . . . . . . . . . . . . . . . 35
`3.2 Haptic Perception . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39
`3.2.1 Psychophysical Concepts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40
`3.2.2 Frequency Dependency . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 46
`3.2.3 Characteristics of Haptic Interaction . . . . . . . . . . . . . . . . . . . . 50
`3.3 Conclusions from the Biology of Haptics . . . . . . . . . . . . . . . . . . . . . . . 54
`
`xv
`
`16
`
`

`

`xvi
`
`Contents
`
`3.3.1 Stiffnesses . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 54
`3.3.2 One Kilohertz - Significance for the Mechanical Design? . . . 56
`
`4 Modeling the User . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 59
`4.1 Mapping of Frequency Ranges onto the User’s Mechanical Model . . 59
`4.2 A Model of the User as a Mechanical Load . . . . . . . . . . . . . . . . . . . . . 63
`4.2.1 Types of Grasps . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 64
`4.2.2 Measurement Setup and Equipment . . . . . . . . . . . . . . . . . . . . . 66
`4.2.3 Models . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 68
`4.2.4 Modeling Parameters . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 69
`4.3 Modelling Haptic Perception . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 80
`4.4 Application Remarks . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 84
`4.4.1 Kinaesthetic System . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 84
`4.4.2 Tactile System . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 85
`4.4.3 Examples in Time and Frequency Domain . . . . . . . . . . . . . . . 87
`4.5 Summarizing Remarks on the Application of the Method . . . . . . . . . 93
`
`5
`
`Internal Structure of Haptic Systems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 95
`5.1 System Engineering . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 95
`5.1.1 Open-Loop Impedance Controlled . . . . . . . . . . . . . . . . . . . . . . 96
`5.1.2 Closed-Loop Impedance Controlled . . . . . . . . . . . . . . . . . . . . . 97
`5.1.3 Open-Loop Admittance Controlled . . . . . . . . . . . . . . . . . . . . . 98
`5.1.4 Closed-Loop Admittance Controlled Devices . . . . . . . . . . . . . 100
`5.1.5 Qualitative Comparison of the Internal Structures of
`Haptic Systems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 102
`5.2 Abstraction of the System Components . . . . . . . . . . . . . . . . . . . . . . . . 104
`5.2.1 Basic System Analysis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 104
`5.2.2 Analysis of System Components . . . . . . . . . . . . . . . . . . . . . . . 105
`
`Part II Designing Haptic Systems
`
`6
`
`Identification of Requirements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 115
`6.1 The Right Questions to Ask . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 115
`6.1.1
`Interaction as a Classification Criterion . . . . . . . . . . . . . . . . . . 117
`6.1.2 Cluster “Kinaesthetic” . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 118
`6.1.3 Cluster “Surface-Tactile” . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 119
`6.1.4 Cluster “Vibro-Tactile” . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 120
`6.1.5 Cluster “Vibro-Directional” . . . . . . . . . . . . . . . . . . . . . . . . . . . 121
`6.1.6 Cluster “Omni-Dimensional” . . . . . . . . . . . . . . . . . . . . . . . . . . 121
`6.1.7 Cluster “always” . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 122
`6.2 Experiments Together With the Customer . . . . . . . . . . . . . . . . . . . . . . 122
`6.3 Requirement Specifications of a Haptic System . . . . . . . . . . . . . . . . . 124
`6.4 Order of Technical Decisions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 128
`
`17
`
`

`

`Contents
`
`xvii
`
`7
`
`Control of Haptic Systems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 131
`7.1
`Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 131
`7.2 System Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 132
`7.2.1 Linear SISO-System Description . . . . . . . . . . . . . . . . . . . . . . . 132
`7.2.2 Linear State Space Description . . . . . . . . . . . . . . . . . . . . . . . . . 136
`7.2.3 Nonlinear System Description . . . . . . . . . . . . . . . . . . . . . . . . . 139
`7.3 System Stability . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 141
`7.3.1 Analysis of Linear System Stability . . . . . . . . . . . . . . . . . . . . . 141
`7.3.2 Analysis of Nonlinear System Stability . . . . . . . . . . . . . . . . . . 145
`7.3.3 Passivity in Dynamic Systems . . . . . . . . . . . . . . . . . . . . . . . . . 150
`7.4 Control Design for Haptic Systems . . . . . . . . . . . . . . . . . . . . . . . . . . . . 152
`7.4.1 Structuring of the Control Design . . . . . . . . . . . . . . . . . . . . . . . 152
`7.4.2 Requirement Definition . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 154
`7.4.3 Control Law Design . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 156
`7.5 Conclusion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 163
`
`8 Kinematic Design . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 165
`8.1 Basics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 165
`8.1.1 Mechanisms and their Classification . . . . . . . . . . . . . . . . . . . . 166
`8.1.2 Calculating Kinematics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 168
`8.1.3 Transfer Characteristics and Jacobian Matrix . . . . . . . . . . . . . 170
`8.1.4 Optimizing the Transfer Characteristics . . . . . . . . . . . . . . . . . . 174
`8.2 Serial Mechanisms . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 175
`8.2.1 Topological Synthesis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 175
`8.2.2 Calculation of the Kinematic Problems . . . . . . . . . . . . . . . . . . 177
`8.2.3 Example of a Serial Mechanism . . . . . . . . . . . . . . . . . . . . . . . . 179
`8.3 Parallel Mechanisms . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 182
`8.3.1 Topological Synthesis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 182
`8.3.2 Calculation of the Kinematic Transfer Functions . . . . . . . . . . 185
`8.3.3 Examples of a Parallel Mechanism . . . . . . . . . . . . . . . . . . . . . . 186
`8.4 The Complete Process of Kinematic Design . . . . . . . . . . . . . . . . . . . . 188
`
`9
`
`Actuator Design . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 191
`9.1 General Facts about Actuator Design . . . . . . . . . . . . . . . . . . . . . . . . . . 192
`9.1.1 Overview of Actuator Principles . . . . . . . . . . . . . . . . . . . . . . . . 192
`9.1.2 Actuator Selection Aid Based on its Dynamics . . . . . . . . . . . . 196
`9.1.3 Gears . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 197
`9.2 Electrodynamic Actuators . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 199
`9.2.1 The Electrodynamic Effect and its Influencing Variables . . . 199
`9.2.2 Actual Actuator Design . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 213
`9.2.3 Actuator Electronics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 218
`9.2.4 Examples for Electrodynamic Actuators in Haptic Devices . 224
`9.2.5 Conclusion about the Design of Electrodynamic Actuators . . 227
`9.3 Electromagnetic Actuators . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 229
`9.3.1 Magnetic Energy . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 229
`
`18
`
`

`

`xviii
`
`Contents
`
`9.3.2 Design of Magnetic Circuits . . . . . . . . . . . . . . . . . . . . . . . . . . . 232
`9.3.3 Examples for Electromagnetic Actuators . . . . . . . . . . . . . . . . . 236
`9.3.4 Magnetic Actuators in Haptic Devices . . . . . . . . . . . . . . . . . . . 239
`9.3.5 Conclusion about the Design of Magnetic Actuators . . . . . . . 241
`9.4 Piezoelectric Actuators . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 243
`9.4.1 The Piezoelectric Effect . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 243
`9.4.2 Designs and Properties of Piezoelectric Actuators . . . . . . . . . 247
`9.4.3 Design of Piezoelectric Actuators for Haptic Systems . . . . . . 258
`9.4.4 Procedure for the Design of Piezoelectric Actuators . . . . . . . 258
`9.4.5 Piezoelectric Actuators in Haptic Systems . . . . . . . . . . . . . . . 266
`9.5 Electrostatic Actuators . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 277
`9.5.1 Definition of the Electric Field . . . . . . . . . . . . . . . . . . . . . . . . . 277
`9.5.2 Designs of Capacitive Actuators with Air-Gap . . . . . . . . . . . . 279
`9.5.3 Dielectric Elastomer Actuators . . . . . . . . . . . . . . . . . . . . . . . . . 285
`9.5.4 Designs of Dielectric Elastomer Actuators . . . . . . . . . . . . . . . 289
`9.5.5 Electro-Rheological Fluids . . . . . . . . . . . . . . . . . . . . . . . . . . . . 292
`9.6 Special Designs of Haptic Actuators . . . . . . . . . . . . . . . . . . . . . . . . . . . 301
`9.6.1 Haptic-Kinaesthetic Devices . . . . . . . . . . . . . . . . . . . . . . . . . . . 301
`9.6.2 Haptic-Tactile Devices . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 305
`
`10 Force Sensor Design . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 313
`10.1 Constraints . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 313
`10.1.1 Topology of the Device . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 313
`10.1.2 Contact Situation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 314
`10.1.3 Mechanical Properties of Measuring Objects . . . . . . . . . . . . . 315
`10.1.4 Texture of Measuring Objects . . . . . . . . . . . . . . . . . . . . . . . . . . 317
`10.1.5 Selection of Design Criteria . . . . . . . . . . . . . . . . . . . . . . . . . . . 319
`10.2 Sensing Principles . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 321
`10.2.1 Basics of Elasto-mechanics . . . . . . . . . . . . . . . . . . . . . . . . . . . . 322
`10.2.2 Resistive Strain Measurement . . . . . . . . . . . . . . . . . . . . . . . . . . 325
`10.2.3 Piezoresistive Silicon Sensoren . . . . . . . . . . . . . . . . . . . . . . . . . 329
`10.2.4 Further Resistive Sensors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 334
`10.2.5 Capacitive Sensors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 335
`10.2.6 Optic Sensors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 340
`10.2.7 Piezoelectric Sensors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 347
`10.2.8 Exotic Ones . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 350
`10.3 Selection of a Suitable Sensor . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 352
`
`11 Application of Positioning Sensors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 357
`11.1 Basi