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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.

3-DOF high-speed 3-RPS parallel robot

Author  Tian Huang

Video ID : 43

This video demonstrates a 3-DOF high-speed 3-RPS parallel robot (with A3 head).

Chapter 69 — Physical Human-Robot Interaction

Sami Haddadin and Elizabeth Croft

Over the last two decades, the foundations for physical human–robot interaction (pHRI) have evolved from successful developments in mechatronics, control, and planning, leading toward safer lightweight robot designs and interaction control schemes that advance beyond the current capacities of existing high-payload and highprecision position-controlled industrial robots. Based on their ability to sense physical interaction, render compliant behavior along the robot structure, plan motions that respect human preferences, and generate interaction plans for collaboration and coaction with humans, these novel robots have opened up novel and unforeseen application domains, and have advanced the field of human safety in robotics.

This chapter gives an overview on the state of the art in pHRI as of the date of publication. First, the advances in human safety are outlined, addressing topics in human injury analysis in robotics and safety standards for pHRI. Then, the foundations of human-friendly robot design, including the development of lightweight and intrinsically flexible force/torque-controlled machines together with the required perception abilities for interaction are introduced. Subsequently, motionplanning techniques for human environments, including the domains of biomechanically safe, risk-metric-based, human-aware planning are covered. Finally, the rather recent problem of interaction planning is summarized, including the issues of collaborative action planning, the definition of the interaction planning problem, and an introduction to robot reflexes and reactive control architecture for pHRI.

Torque control for teaching peg-in-hole via physical human-robot interaction

Author  Alin-Albu Schäffer

Video ID : 627

Teaching by demonstration is a typical application for impedance controllers. A practical demonstration was given with the task of teaching for automatic insertion of a piston into a motor block. Teaching is realized by guiding the robot with the human hand. It was initially known that the axes of the holes in the motor block were vertically oriented. In the teaching phase, high stiffness components for the orientations were commanded (150 Nm/rad), while the translational stiffness was set to zero. This allowed only translational movements to be demonstrated by the human operator. In the second phase, the taught trajectory has been automatically reproduced by the robot. In this phase, high values were assigned for the translational stiffness (3000 N/m), while the stiffness for the rotations was low (60 Nm/rad). This enabled the robot to compensate for the remaining position errors. For two pistons, the total time for the assembly was 6 s. In this experiment, the assembly was executed automatically four-times faster than by the human operator holding the robot as an input device in the teaching phase (24 s), while the free-hand execution of the task by a human requires about 4 s.

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.

AwAS - II: Actuator with adjustable stiffness

Author  Nikolaos Tsagarakis, Darwin Caldwell et al.

Video ID : 699

Actuator with adjustable stiffness(AwAS-II) - variable stiffness and position behavior.

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.

VelociRoACH

Author  Duncan W. Haldane, Kevin C. Peterson, Fernando L. Garcia Bermudez, Ronald S. Fearing

Video ID : 408

UC Berkeley's miniature robot VelociRoACH. It is the latest version of the RoACH series which can run at extremely higher speeds relative to previous versions.

Chapter 51 — Modeling and Control of Underwater Robots

Gianluca Antonelli, Thor I. Fossen and Dana R. Yoerger

This chapter deals with modeling and control of underwater robots. First, a brief introduction showing the constantly expanding role of marine robotics in oceanic engineering is given; this section also contains some historical backgrounds. Most of the following sections strongly overlap with the corresponding chapters presented in this handbook; hence, to avoid useless repetitions, only those aspects peculiar to the underwater environment are discussed, assuming that the reader is already familiar with concepts such as fault detection systems when discussing the corresponding underwater implementation. Themodeling section is presented by focusing on a coefficient-based approach capturing the most relevant underwater dynamic effects. Two sections dealing with the description of the sensor and the actuating systems are then given. Autonomous underwater vehicles require the implementation of mission control system as well as guidance and control algorithms. Underwater localization is also discussed. Underwater manipulation is then briefly approached. Fault detection and fault tolerance, together with the coordination control of multiple underwater vehicles, conclude the theoretical part of the chapter. Two final sections, reporting some successful applications and discussing future perspectives, conclude the chapter. The reader is referred to Chap. 25 for the design issues.

Neptus command and control infrastructure

Author  Laboratario de Sistemas e Tecnologias Subaquaticas - Porto University

Video ID : 324

See how Neptus is used to plan, simulate, monitor and review missions performed by autonomous vehicles. Neptus, originally developed at the Underwater Systems and Technology Laboratory, is open source software available from http://github.com/LSTS/neptus / NOPTILUS project [NOPTILUS is funded by European Community's Seventh Framework Programme ICT-FP]

Chapter 20 — Snake-Like and Continuum Robots

Ian D. Walker, Howie Choset and Gregory S. Chirikjian

This chapter provides an overview of the state of the art of snake-like (backbones comprised of many small links) and continuum (continuous backbone) robots. The history of each of these classes of robot is reviewed, focusing on key hardware developments. A review of the existing theory and algorithms for kinematics for both types of robot is presented, followed by a summary ofmodeling of locomotion for snake-like and continuum mechanisms.

Binary-manipulator object recovery

Author  Greg Chirikjian

Video ID : 164

Video of Greg Chirikjian's binary manipulator performing an object retrieval task for satellite-recovery applications.

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.

Underactuated adaptive gripper using flexural buckling

Author  Gwang-Pil Jung, Je-Sung Koh, Kyu-Jin Cho

Video ID : 409

Biologically-inspired gripper. The scalable design enables the manufacture of various sizes of the gripper. Flexure buckling provides the adaptability to grip objects of various shapes. Its differential mechanism has no wires and linkages.

Chapter 20 — Snake-Like and Continuum Robots

Ian D. Walker, Howie Choset and Gregory S. Chirikjian

This chapter provides an overview of the state of the art of snake-like (backbones comprised of many small links) and continuum (continuous backbone) robots. The history of each of these classes of robot is reviewed, focusing on key hardware developments. A review of the existing theory and algorithms for kinematics for both types of robot is presented, followed by a summary ofmodeling of locomotion for snake-like and continuum mechanisms.

Modsnake climbing a tree

Author  Howie Choset

Video ID : 168

The CMU Modsnake climbing a tree and surveying an area from this high vantage point.

Chapter 52 — Modeling and Control of Aerial Robots

Robert Mahony, Randal W. Beard and Vijay Kumar

Aerial robotic vehicles are becoming a core field in mobile robotics. This chapter considers some of the fundamental modelling and control architectures in the most common aerial robotic platforms; small-scale rotor vehicles such as the quadrotor, hexacopter, or helicopter, and fixed wing vehicles. In order to control such vehicles one must begin with a good but sufficiently simple dynamic model. Based on such models, physically motivated control architectures can be developed. Such algorithms require realisable target trajectories along with real-time estimates of the system state obtained from on-board sensor suite. This chapter provides a first introduction across all these subjects for the quadrotor and fixed wing aerial robotic vehicles.

Autopilot using total-energy control

Author  Randy Beard

Video ID : 436

This video shows simulation results of an autopilot wich controls the lateral modes using a standard nested loop structure; the longitudinal autopilot is designed using the total-energy control structure. The commands to the autopilot are for airspeed, course angle, and altitude. The video shows a number of different step commands in these variables and the performance of a six-DOF aerodynamic model of a Zagi-style fixed-wing aircraft.

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.

Feedforward/feedback law for path tracking with a KUKA KR15/2 robot

Author  Michael Thümmel

Video ID : 136

This 2006 video shows the performance of a type of model-based feedforward (using the elastic joint model) plus state-feedback stabilization for trajectory tracking. Designed for an industrial KUKA KR15/2 manipulator having cycloidal gearboxes, which are known for their visco-elasticity, this controller is compared to a standard one for the robot task of moving in a rest-to-rest mode along three (orthogonal) square paths in Cartesian space. References: 1. M. Thümmel: Modellbasierte Regelung mit nichtlinearen inversen Systemen und Beobachtern von Robotern mit elastischen Gelenken, Dissertation, Technische Universität München, Munich, (2006) (in German); 2. A. De Luca, D. Schröder, M. Thümmel: An acceleration-based state observer for robot manipulators with elastic joints, IEEE Int. Conf. Robot. Autom. (ICRA), Rome (2007), pp. 3817-3823, 2007. doi: 10.1109/ROBOT.2007.364064