University of Genoa
PMAR Robotics

Eighth International Summer School on

Screw-Theory Based Methods in Robotics

02 - 10 December, 2017
Monash University, Melbourne, Australia

univ Monash University
LMGA Lab

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Objective

Applications of the theory of screws are based on a combined representation of angular and linear velocity, or similarly force and moment, as a single element of a six-dimensional vector space.

The importance of screw theory in robotics is widely recognised, in principle. In practice, almost nowhere is it taught to engineering students and few know how to use it. Yet, in a variety of areas of robotics, methods and formalisms based on the geometry and algebra of screws have been shown to be superior to other techniques and have led to significant advances. These include the development of fast and efficient dynamics algorithms, discoveries in the nature of robot compliance and mechanism singularity, and the invention of numerous parallel mechanisms.

The Summer Screws instructors are the authors of many of these results. They will teach the participants to apply existing techniques and to develop new ones for their own research. The basic theoretical concepts will be introduced in a rigorous manner, but the emphasis will be on applications, with numerous examples and exercises.

 

Background

The school is intended for graduate students and young researchers in robotics. Participants are expected from both academia and industry.

The course delivers a comprehensive overview of the basic concepts and some of the main applications of screw-theory, and hence will be particularly attractive to doctoral students and young researchers in robotics and related fields, mechanical engineering, or applied mathematics.

As has been the case in all previous editions of Summer Screws, the advanced topics and the presentation of current progress in this very active field will also be of considerable interest to many senior researchers. The key role of the presented methods in robot design and control underpins the value of the course material to robotics experts from industry.

It is recommended that attendees have their own portable computers, preferably with Matlab and Maple. Alternative equivalent software can also be used. Some experience with (and availability of) 3D CAD software would be helpful but not required.

 

Topics

The lectures address subjects sufficiently fundamental to be within the desirable competence of any roboticist. In each of these area advanced screw-theory based methods have been used to great advantage. The material is based in part on the lecturers’ research and teaching and is being constantly tested, updated, and developed.

Basic vector-space properties of twists and wrenches: physical interpretation of the linear operations; linear dependence and independence, subspaces; bases and coordinates. Screw systems: geometry and classification, invariance and persistance. (Lecturers: Dimiter Zlatanov and Marco Carricato)

Scalar products, dual spaces, reciprocity. Constraint and freedom in mechanisms. Constraint analysis. Type synthesis of single-loop mechanisms and parallel manipulators. (Lecturers: Xianwen Kong and Dimiter Zlatanov)

Velocity and singularity analysis of parallel and interconnected-chain mechanisms. Derivation of input-output velocity equations and singularity conditions. (Lecturers: Matteo Zoppi and Dimiter Zlatanov)
Mappings between screw spaces, stiffness and inertia. Structure of robot compliance. Eigenvalue problems and eigenscrews. Synthesis with springs. (Lecturers: Harvey Lipkin and Dimiter Zlatanov)
6D formulation of the dynamics of individual rigid bodies and rigid-body systems. Equations of motion. Dynamics algorithms. (Lecturers: Roy Featherstone and Harvey Lipkin)
Basic Lie group theory, matrix representations of the group of rigid-body displacements. Lie algebras as related to screw theory. The exponential map and its applications in modern robotics (Lecturers: Jon Selig and Peter Donelan).

 

Invited Lectures

In this special edition, Summer Screws will have several invited talks. A number of speakers, including Professor Kenneth Waldron (Stanford and University of Technology Sydney) and Marcus Pansy (Monash), have agreed to talk about Kenneth Hunt’s life and work and the role played by him and his collaborators in Australia in the recent history of screw theory. Professor Chao Chen from Monash will present recent research results at the Laboratory of Motion Generation and Analysis.

 

Lecturers

Dimiter Zlatanov has used screw theory in the singularity and mobility analysis of mechanisms. He is the inventor of one of the first-known 4-dof parallel mechanisms and has presented courses and talks on screw-based methods in various universities.

Xianwen Kong is the inventor of numerous parallel mechanisms and the co-author of the book Type synthesis of parallel mechanisms. His results have been based on methods from screw-system theory.

Marco Carricato has research interests in the theory of mechanisms and robotic systems, with focus on parallel robots, cable-driven manipulators and screw theory. In this summer school, he will contribute lectures on the geometry and classification of screw systems, with applications to homokinetic couplings and examples from the theory of chains with persistent screw systems, which he originated.

Matteo Zoppi has developed screw-theoretical techniques for the derivation and application of velocity equations for complex-chain manipulators. He is also the inventor of a number of mechanisms.

Harvey Lipkin has worked more than any one on applying screw-theoretical methods in different areas of robotics and mechanisms, such as hybrid control, compliance, vibrations, and dynamics. He has taught various aspects of screw theory and supervised graduate students in the use of such methods.

Roy Featherstone is the inventor of the Articulated-Body Dynamics Algorithm, and the author of the books Robot Dynamics Algorithms and Rigid Body Dynamics Algorithms. His ground-breaking work in dynamics has relied on a screw-theoretical formalism for the formulation of the equations of motion.

Jon Selig is the foremost specialist on advanced geometrical and group-theoretical methods in robotics. He is the author of the book Geometric Fundamentals of Robotics, and several book chapters on the application of Clifford algebras and Lie group theory. He edited and co-authored the collection Geometrical Foundations of Robotics.

Peter Donelan has undertaken research on a range of applications of mathematical theories in robotics including singularity theory, Lie groups and Lie algebras, differential geometry and algebraic invariant theory. His paper On the Hierarchy of Screw Systems, with Christopher Gibson, sets out the mathematical foundations for the classification of screw systems.

The lecturers are listed in the order in which they usually teach at Summer Screws. In cooperation with local hosts around the world, all have worked hard to support our school and to ensure its success for so many years. The content of the lectures is based to a large degree on the past and current research and teaching work of all.

Every member of this team shares a conviction that screw-theoretical methods play an increasingly central and crucial role in modern robotics. All know each other’s work well, and agree on the main principles and ideas which animate Summer Screws’ mission. Thus, each of the topics can be presented by a choice of several experts in that area, while all lecturers actively participate and assist attendees during the lectures, discussions, and tutorials throughout the full duration of the workshop. A selection of five to seven teachers are present in each edition. In 2017, Dimiter Zlatanov, Marco Carricato, Matteo Zoppi, Harvey Lipkin, and Peter Donelan have already confirmed their participation.



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