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Chapter 11 — Robots with Flexible Elements

Alessandro De Luca and Wayne J. Book

Design issues, dynamic modeling, trajectory planning, and feedback control problems are presented for robot manipulators having components with mechanical flexibility, either concentrated at the joints or distributed along the links. The chapter is divided accordingly into two main parts. Similarities or differences between the two types of flexibility are pointed out wherever appropriate.

For robots with flexible joints, the dynamic model is derived in detail by following a Lagrangian approach and possible simplified versions are discussed. The problem of computing the nominal torques that produce a desired robot motion is then solved. Regulation and trajectory tracking tasks are addressed by means of linear and nonlinear feedback control designs.

For robots with flexible links, relevant factors that lead to the consideration of distributed flexibility are analyzed. Dynamic models are presented, based on the treatment of flexibility through lumped elements, transfer matrices, or assumed modes. Several specific issues are then highlighted, including the selection of sensors, the model order used for control design, and the generation of effective commands that reduce or eliminate residual vibrations in rest-to-rest maneuvers. Feedback control alternatives are finally discussed.

In each of the two parts of this chapter, a section is devoted to the illustration of the original references and to further readings on the subject.

PID response to impulse in presence of link flexibility

Author  Wayne Book

Video ID : 780

A laboratory gantry robot with a final flexible link is excited by an external impulse disturbance. The video shows the very low damping of the flexible link under PID joint control. This is one of two coordinated videos, the other showing the same experiment under state feedback control. Reference: B. Post: Robust State Estimation for the Control of Flexible Robotic Manipulators, Dissertation, School of Mechanical Engineering, Georgia Institute of Technology, Atlanta (2013)

Chapter 76 — Evolutionary Robotics

Stefano Nolfi, Josh Bongard, Phil Husbands and Dario Floreano

Evolutionary Robotics is a method for automatically generating artificial brains and morphologies of autonomous robots. This approach is useful both for investigating the design space of robotic applications and for testing scientific hypotheses of biological mechanisms and processes. In this chapter we provide an overview of methods and results of Evolutionary Robotics with robots of different shapes, dimensions, and operation features. We consider both simulated and physical robots with special consideration to the transfer between the two worlds.

A swarm-bot of eight robots displaying coordinated motion

Author  Stefano Nolfi, Gianluca Baldassarre, Vito Trianni, Francesco Mondada, Marco Dorigo

Video ID : 115

Each robot is provided with an independent neural controller which determines the desired speed of the two wheels on the basis of the traction force caused by the movements of the other robots. The evolved robots are able to display coordinated-motion capability, independent from the way in which they are assembled, as well as to coordinate in carrying heavy objects.

Chapter 23 — Biomimetic Robots

Kyu-Jin Cho and Robert Wood

Biomimetic robot designs attempt to translate biological principles into engineered systems, replacing more classical engineering solutions in order to achieve a function observed in the natural system. This chapter will focus on mechanism design for bio-inspired robots that replicate key principles from nature with novel engineering solutions. The challenges of biomimetic design include developing a deep understanding of the relevant natural system and translating this understanding into engineering design rules. This often entails the development of novel fabrication and actuation to realize the biomimetic design.

This chapter consists of four sections. In Sect. 23.1, we will define what biomimetic design entails, and contrast biomimetic robots with bio-inspired robots. In Sect. 23.2, we will discuss the fundamental components for developing a biomimetic robot. In Sect. 23.3, we will review detailed biomimetic designs that have been developed for canonical robot locomotion behaviors including flapping-wing flight, jumping, crawling, wall climbing, and swimming. In Sect. 23.4, we will discuss the enabling technologies for these biomimetic designs including material and fabrication.

Omegabot : Inchworm-inspired robot climbing

Author  Je-Sung Koh, Kyu-Jin Cho

Video ID : 290

This robot is an inchworm-inspired robot using a composite structure and a SMA spring actuator. It has gripper and steering joints so that it can climb on rough surfaces and steer as well.

Chapter 18 — Parallel Mechanisms

Jean-Pierre Merlet, Clément Gosselin and Tian Huang

This chapter presents an introduction to the kinematics and dynamics of parallel mechanisms, also referred to as parallel robots. As opposed to classical serial manipulators, the kinematic architecture of parallel robots includes closed-loop kinematic chains. As a consequence, their analysis differs considerably from that of their serial counterparts. This chapter aims at presenting the fundamental formulations and techniques used in their analysis.

6-DOF cable-suspended robot

Author  Clément Gosselin

Video ID : 44

This video demonstrates a 6-DOF cable-suspended robot acting in a large workspace to scan artefacts. References: 1. C. Gosselin, S. Bouchard: A gravity-powered mechanism for extending the workspace of a cable-driven parallel mechanism: Application to the appearance modeling of objects, Int. J. Autom. Technol. 4(4), 372-379 (2010); 2. J.D. Deschênes, P. Lambert, S. Perreault, N. Martel-Brisson, N. Zoso, A. Zaccarin, P. Hébert, S. Bouchard, C. Gosselin: A cable-driven parallel mechanism for capturing object appearance from multiple viewpoints, Proc. 6th Int. Conf. 3-D Digital Imaging and Modeling, Montréal (2007)

Chapter 21 — Actuators for Soft Robotics

Alin Albu-Schäffer and Antonio Bicchi

Although we do not know as yet how robots of the future will look like exactly, most of us are sure that they will not resemble the heavy, bulky, rigid machines dangerously moving around in old fashioned industrial automation. There is a growing consensus, in the research community as well as in expectations from the public, that robots of the next generation will be physically compliant and adaptable machines, closely interacting with humans and moving safely, smoothly and efficiently - in other terms, robots will be soft.

This chapter discusses the design, modeling and control of actuators for the new generation of soft robots, which can replace conventional actuators in applications where rigidity is not the first and foremost concern in performance. The chapter focuses on the technology, modeling, and control of lumped parameters of soft robotics, that is, systems of discrete, interconnected, and compliant elements. Distributed parameters, snakelike and continuum soft robotics, are presented in Chap. 20, while Chap. 23 discusses in detail the biomimetic motivations that are often behind soft robotics.

CompAct™ robotics technology

Author  Istituto Italiano di Tecnologia (IIT)

Video ID : 471

Brief video showing CompAct™ actuation units and arm, demonstrating the effects of its core variable damping (VPDA) technology. Key features of these units include: 1. intrinsic safety (lightweight and elastic transmission) meant for safe human-robot collaboration; 2. precision, thanks to the variable damping transmission, protected by international patents; 3. ease of use (no need for experts to program it, easy to reprogram, flexible to use).

Variable impedance actuators: Moving the robots of tomorrow

Author  B. Vanderborght, A. Albu-Schäffer, A. Bicchi, E. Burdet, D. Caldwell, R. Carloni, M. Catalano, Ganesh, Garabini, Grebenstein, Grioli, Haddadin, Jafari, Laffranchi, Lefeber, Petit, Stramigioli, Tsagarakis, Van Damme, Van Ham, Visser, Wolf

Video ID : 456

Most of today's robots have rigid structures and actuators requiring complex software control algorithms and sophisticated sensor systems in order to behave in a compliant and safe way adapted to contact with unknown environments and humans. By studying and constructing variable impedance actuators and their control, we contribute to the development of actuation units that can match the intrinsic safety, motion performance and energy efficiency of biological systems and, in particular, of the humans. As such, this may lead to a new generation of robots that can co-exist and co-operate with people and get closer to the human manipulation and locomotion performance than is possible with current robots.

Chapter 64 — Rehabilitation and Health Care Robotics

H.F. Machiel Van der Loos, David J. Reinkensmeyer and Eugenio Guglielmelli

The field of rehabilitation robotics considers robotic systems that 1) provide therapy for persons seeking to recover their physical, social, communication, or cognitive function, and/or that 2) assist persons who have a chronic disability to accomplish activities of daily living. This chapter will discuss these two main domains and provide descriptions of the major achievements of the field over its short history and chart out the challenges to come. Specifically, after providing background information on demographics (Sect. 64.1.2) and history (Sect. 64.1.3) of the field, Sect. 64.2 describes physical therapy and exercise training robots, and Sect. 64.3 describes robotic aids for people with disabilities. Section 64.4 then presents recent advances in smart prostheses and orthoses that are related to rehabilitation robotics. Finally, Sect. 64.5 provides an overview of recent work in diagnosis and monitoring for rehabilitation as well as other health-care issues. The reader is referred to Chap. 73 for cognitive rehabilitation robotics and to Chap. 65 for robotic smart home technologies, which are often considered assistive technologies for persons with disabilities. At the conclusion of the present chapter, the reader will be familiar with the history of rehabilitation robotics and its primary accomplishments, and will understand the challenges the field may face in the future as it seeks to improve health care and the well being of persons with disabilities.

Targeted reinnervation and the DEKA Arm

Author  Rehabilitation Institute of Chicago

Video ID : 513

Claudia Mitchell, 28, of Arkansas, demonstrates advanced, multidegree control of the DEKA Research arm at The Rehabilitation Institute of Chicago. Mitchell, who lost her arm in a motorcycle accident in 2004, underwent targeted muscle reinnervation in 2005. Video courtesy of the Rehabilitation Institute of Chicago and DEKA Research. Learn more at www.ric.org/bionic.

Chapter 7 — Motion Planning

Lydia E. Kavraki and Steven M. LaValle

This chapter first provides a formulation of the geometric path planning problem in Sect. 7.2 and then introduces sampling-based planning in Sect. 7.3. Sampling-based planners are general techniques applicable to a wide set of problems and have been successful in dealing with hard planning instances. For specific, often simpler, planning instances, alternative approaches exist and are presented in Sect. 7.4. These approaches provide theoretical guarantees and for simple planning instances they outperform samplingbased planners. Section 7.5 considers problems that involve differential constraints, while Sect. 7.6 overviews several other extensions of the basic problem formulation and proposed solutions. Finally, Sect. 7.8 addresses some important andmore advanced topics related to motion planning.

Kinodynamic motion planning for a car-like robot

Author  Caleb Voss

Video ID : 24

In this video, the objective of the car is to reach a goal location by jumping over a ramp and pushing a block out of the way. This problem requires kinodynamic motion planning for a car-like robot using a physics simulator. This video was generated using the software tools OMPL, Blender, and MORSE.

Chapter 39 — Cooperative Manipulation

Fabrizio Caccavale and Masaru Uchiyama

This chapter is devoted to cooperative manipulation of a common object by means of two or more robotic arms. The chapter opens with a historical overview of the research on cooperativemanipulation, ranging from early 1970s to very recent years. Kinematics and dynamics of robotic arms cooperatively manipulating a tightly grasped rigid object are presented in depth. As for the kinematics and statics, the chosen approach is based on the socalled symmetric formulation; fundamentals of dynamics and reduced-order models for closed kinematic chains are discussed as well. A few special topics, such as the definition of geometrically meaningful cooperative task space variables, the problem of load distribution, and the definition of manipulability ellipsoids, are included to give the reader a complete picture ofmodeling and evaluation methodologies for cooperative manipulators. Then, the chapter presents the main strategies for controlling both the motion of the cooperative system and the interaction forces between the manipulators and the grasped object; in detail, fundamentals of hybrid force/position control, proportional–derivative (PD)-type force/position control schemes, feedback linearization techniques, and impedance control approaches are given. In the last section further reading on advanced topics related to control of cooperative robots is suggested; in detail, advanced nonlinear control strategies are briefly discussed (i. e., intelligent control approaches, synchronization control, decentralized control); also, fundamental results on modeling and control of cooperative systems possessing some degree of flexibility are briefly outlined.

Cooperative grasping and transportation of an object using two industrial manipulators

Author  Francesco Basile, Fabrizio Caccavale, Pasquale Chiacchio, Jolanda Coppola, Alessandro Marino

Video ID : 69

This video shows an example of cooperative grasping and transportation of an object using two industrial manipulators. A two-layer hierarchical, kinematic control is adopted, based on a suitable task formulation for general multi-arm systems. Reference: F. Basile, F. Caccavale, P. Chiacchio, J. Coppola, A. Marino: A decentralized kinematic control architecture for collaborative and cooperative multi-arm systems, Mechatronics, 23, 1100-1112 (2013).

Chapter 24 — Wheeled Robots

Woojin Chung and Karl Iagnemma

The purpose of this chapter is to introduce, analyze, and compare various wheeled mobile robots (WMRs) and to present several realizations and commonly encountered designs. The mobility of WMR is discussed on the basis of the kinematic constraints resulting from the pure rolling conditions at the contact points between the wheels and the ground. Practical robot structures are classified according to the number of wheels, and features are introduced focusing on commonly adopted designs. Omnimobile robot and articulated robots realizations are described. Wheel–terrain interaction models are presented in order to compute forces at the contact interface. Four possible wheel-terrain interaction cases are shown on the basis of relative stiffness of the wheel and terrain. A suspension system is required to move on uneven surfaces. Structures, dynamics, and important features of commonly used suspensions are explained.

An omnidirectional robot with four Swedish wheels

Author  Nexus Automation Limited

Video ID : 328

This video shows a holonomic omnidirectional mobile robot with four Swedish wheels. The wheel enables lateral motion by the use of rotating rollers. Although the structure of each wheel becomes complicated, the driving mechanisms of the wheels become simpler. Another advantage is that the footprint locations remain unchanged during omnidirectional movements.