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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.

Control experiments for a flexible-joint robot arm

Author  Mark Spong

Video ID : 135

This 1989 video is about an experimental single-link arm with an elastic joint moving under gravity, which was developed at the Coordinated Science Lab of the University of Illinois at Urbana. The video illustrates some of the control techniques that are mentioned in the first part of Chap. 11: e.g., computed torque using the rigid model (unstable), feedback linearizing control including elasticity (perfect design), and corrective control based on singular perturbation analysis (and its adaptive version). Reference: F. Ghorbel, J.Y. Hung, M.W. Spong: Adaptive control of flexible joint robots, IEEE Control Syst. Mag. 9(7), 9-13 (1989) doi: 10.1109/37.41450

Chapter 67 — Humanoids

Paul Fitzpatrick, Kensuke Harada, Charles C. Kemp, Yoshio Matsumoto, Kazuhito Yokoi and Eiichi Yoshida

Humanoid robots selectively immitate aspects of human form and behavior. Humanoids come in a variety of shapes and sizes, from complete human-size legged robots to isolated robotic heads with human-like sensing and expression. This chapter highlights significant humanoid platforms and achievements, and discusses some of the underlying goals behind this area of robotics. Humanoids tend to require the integration ofmany of the methods covered in detail within other chapters of this handbook, so this chapter focuses on distinctive aspects of humanoid robotics with liberal cross-referencing.

This chapter examines what motivates researchers to pursue humanoid robotics, and provides a taste of the evolution of this field over time. It summarizes work on legged humanoid locomotion, whole-body activities, and approaches to human–robot communication. It concludes with a brief discussion of factors that may influence the future of humanoid robots.

Footstep planning modeled as a whole-body, inverse-kinematic problem (experiment)

Author  Eiichi Yoshida

Video ID : 600

The whole-body, inverse-kinematic motion including locomotion in video 596 has been experimentally validated by using HPR-2 humanoid robot. The challenging motion-planning problem of picking up an object almost between its feet has been successfully solved with the proposed framework.

Chapter 56 — Robotics in Agriculture and Forestry

Marcel Bergerman, John Billingsley, John Reid and Eldert van Henten

Robotics for agriculture and forestry (A&F) represents the ultimate application of one of our society’s latest and most advanced innovations to its most ancient and important industries. Over the course of history, mechanization and automation increased crop output several orders of magnitude, enabling a geometric growth in population and an increase in quality of life across the globe. Rapid population growth and rising incomes in developing countries, however, require ever larger amounts of A&F output. This chapter addresses robotics for A&F in the form of case studies where robotics is being successfully applied to solve well-identified problems. With respect to plant crops, the focus is on the in-field or in-farm tasks necessary to guarantee a quality crop and, generally speaking, end at harvest time. In the livestock domain, the focus is on breeding and nurturing, exploiting, harvesting, and slaughtering and processing. The chapter is organized in four main sections. The first one explains the scope, in particular, what aspects of robotics for A&F are dealt with in the chapter. The second one discusses the challenges and opportunities associated with the application of robotics to A&F. The third section is the core of the chapter, presenting twenty case studies that showcase (mostly) mature applications of robotics in various agricultural and forestry domains. The case studies are not meant to be comprehensive but instead to give the reader a general overview of how robotics has been applied to A&F in the last 10 years. The fourth section concludes the chapter with a discussion on specific improvements to current technology and paths to commercialization.

An autonomous cucumber harvester

Author  Elder J. van Henten, Jochen Hemming, Bart A.J. van Tuijl, J.G. Kornet, Jan Meuleman, Jan Bontsema, Erik A. van Os

Video ID : 308

The video demonstrates an autonomous cucumber harvester developed at Wageningen University and Research Centre, Wageningen, The Netherlands. The machine consists of a mobile platform which runs on rails, which are commonly used in greenhouses in The Netherlands for the purpose of internal transport, but they are also used as a hot- water heating system for the greenhouse. Harvesting requires functional steps such as the detection and localization of the fruit and assessment of its ripeness. In the case of the cucumber harvester, the different reflection properties in the near infrared spectrum are exploited to detect green cucumbers in the green environment. Whether the cucumber was ready for harvest was identified based on an estimation of its weight. Since cucumbers consist 95% of water, the weight estimation was achieved by estimating the volume of each fruit. Stereo-vision principles were then used to locate the fruits to be harvested in the 3-D environment. For that purpose, the camera was shifted 50 mm on a linear slide and two images of the same scene were taken and processed. A Mitsubishi RV-E2 manipulator was used to steer the gripper-cutter mechanism to the fruit and transport the harvested fruit back to a storage crate. Collision-free motion planning based on the A* algorithm was used to steer the manipulator during the harvesting operation. The cutter consisted of a parallel gripper that grabbed the peduncle of the fruit, i.e., the stem segment that connects the fruit to the main stem of the plant. Then the action of a suction cup immobilized the fruit in the gripper. A special thermal cutting device was used to separate the fruit from the plant. The high temperature of the cutting device also prevented the potential transport of viruses from one plant to the other during the harvesting process. For each successful cucumber harvested, this machine needed 65.2 s on average. The average success rate was 74.4%. It was found to be a great advantage that the system was able to perform several harvest attempts on a single cucumber from different harvest positions of the robot. This improved the success rate considerably. Since not all attempts were successful, a cycle time of 124 s per harvested cucumber was measured under practical circumstances.

Chapter 55 — Space Robotics

Kazuya Yoshida, Brian Wilcox, Gerd Hirzinger and Roberto Lampariello

In the space community, any unmanned spacecraft can be called a robotic spacecraft. However, Space Robots are considered to be more capable devices that can facilitate manipulation, assembling, or servicing functions in orbit as assistants to astronauts, or to extend the areas and abilities of exploration on remote planets as surrogates for human explorers.

In this chapter, a concise digest of the historical overview and technical advances of two distinct types of space robotic systems, orbital robots and surface robots, is provided. In particular, Sect. 55.1 describes orbital robots, and Sect. 55.2 describes surface robots. In Sect. 55.3, the mathematical modeling of the dynamics and control using reference equations are discussed. Finally, advanced topics for future space exploration missions are addressed in Sect. 55.4.

DLR ROTEX: The first remotely-controlled space robot

Author  Gerd Hirzinger, Klaus Landzettel

Video ID : 330

Remotely-controlled space robot ROTEX in the Spacelab D2 mission flown with Shuttle Columbia in April 1993. Among the highlights of the experiment were the verification of shared autonomy when opening a bayonet closure and the fully autonomous grasping of a free-flying object with 6 s round-trip delay.

Chapter 56 — Robotics in Agriculture and Forestry

Marcel Bergerman, John Billingsley, John Reid and Eldert van Henten

Robotics for agriculture and forestry (A&F) represents the ultimate application of one of our society’s latest and most advanced innovations to its most ancient and important industries. Over the course of history, mechanization and automation increased crop output several orders of magnitude, enabling a geometric growth in population and an increase in quality of life across the globe. Rapid population growth and rising incomes in developing countries, however, require ever larger amounts of A&F output. This chapter addresses robotics for A&F in the form of case studies where robotics is being successfully applied to solve well-identified problems. With respect to plant crops, the focus is on the in-field or in-farm tasks necessary to guarantee a quality crop and, generally speaking, end at harvest time. In the livestock domain, the focus is on breeding and nurturing, exploiting, harvesting, and slaughtering and processing. The chapter is organized in four main sections. The first one explains the scope, in particular, what aspects of robotics for A&F are dealt with in the chapter. The second one discusses the challenges and opportunities associated with the application of robotics to A&F. The third section is the core of the chapter, presenting twenty case studies that showcase (mostly) mature applications of robotics in various agricultural and forestry domains. The case studies are not meant to be comprehensive but instead to give the reader a general overview of how robotics has been applied to A&F in the last 10 years. The fourth section concludes the chapter with a discussion on specific improvements to current technology and paths to commercialization.

The Intelligent Autonomous Weeder

Author  Tijmen Bakker, Kees Van Asselt, Jan Bontsema, Joachim Müller, Gerrit van Straten

Video ID : 310

The Intelligent Autonomous Weeder is a four-wheel, steered, four-wheel-drive, autonomous platform which can be used for autonomous weeding operations in arable farming. An RTK DGPS system is used for navigation. The control architecture is based on a hybrid deliberative and behavior-based reactive approach.

Chapter 41 — Active Manipulation for Perception

Anna Petrovskaya and Kaijen Hsiao

This chapter covers perceptual methods in which manipulation is an integral part of perception. These methods face special challenges due to data sparsity and high costs of sensing actions. However, they can also succeed where other perceptual methods fail, for example, in poor-visibility conditions or for learning the physical properties of a scene.

The chapter focuses on specialized methods that have been developed for object localization, inference, planning, recognition, and modeling in activemanipulation approaches.We concludewith a discussion of real-life applications and directions for future research.

Tactile exploration and modeling using shape primitives

Author  Francesco Mazzini

Video ID : 76

This video shows a robot performing tactile exploration and modeling of a lab-constructed scene that was designed to be similar to those found in interventions for underwater oil spills (leaking pipe). Representing the scene with geometric primitives enables the surface to be described using only sparse tactile data from joint encoders. The robot's movements are chosen to maximize the expected increase in knowledge about the scene.

Chapter 30 — Sonar Sensing

Lindsay Kleeman and Roman Kuc

Sonar or ultrasonic sensing uses the propagation of acoustic energy at higher frequencies than normal hearing to extract information from the environment. This chapter presents the fundamentals and physics of sonar sensing for object localization, landmark measurement and classification in robotics applications. The source of sonar artifacts is explained and how they can be dealt with. Different ultrasonic transducer technologies are outlined with their main characteristics highlighted.

Sonar systems are described that range in sophistication from low-cost threshold-based ranging modules to multitransducer multipulse configurations with associated signal processing requirements capable of accurate range and bearing measurement, interference rejection, motion compensation, and target classification. Continuous-transmission frequency-modulated (CTFM) systems are introduced and their ability to improve target sensitivity in the presence of noise is discussed. Various sonar ring designs that provide rapid surrounding environmental coverage are described in conjunction with mapping results. Finally the chapter ends with a discussion of biomimetic sonar, which draws inspiration from animals such as bats and dolphins.

Side-looking multipulse sonar moving down cinder-block hallway

Author  Roman Kuc

Video ID : 303

Rather than producing a single TOF reading per emission, the multipulse sonar produces multiple spikes by quickly resetting the sonar-detector integrator, thereby producing a spike density related to the echo amplitude. A side-looking sonar scans a cinder-block wall containing a door and window jambs. The resulting spikes have been processed to differentiate the first cinder-block wall, the cider-block surface and localize the window and door jambs. The red circles indicate the initial TOF values and illustrate the additional echo waveform data produced by the multipulse sonar. Reference: R. Kuc: Recognizing retro-reflectors with an obliquely-oriented multi-point sonar and acoustic flow, Int. J. Robot. Res. 22(2), 129-145, (2003); doi:10.1177/0278364903022002004.

Chapter 70 — Human-Robot Augmentation

Massimo Bergamasco and Hugh Herr

The development of robotic systems capable of sharing with humans the load of heavy tasks has been one of the primary objectives in robotics research. At present, in order to fulfil such an objective, a strong interest in the robotics community is collected by the so-called wearable robots, a class of robotics systems that are worn and directly controlled by the human operator. Wearable robots, together with powered orthoses that exploit robotic components and control strategies, can represent an immediate resource also for allowing humans to restore manipulation and/or walking functionalities.

The present chapter deals with wearable robotics systems capable of providing different levels of functional and/or operational augmentation to the human beings for specific functions or tasks. Prostheses, powered orthoses, and exoskeletons are described for upper limb, lower limb, and whole body structures. State-of-theart devices together with their functionalities and main components are presented for each class of wearable system. Critical design issues and open research aspects are reported.

L-Exos for upper-limb motor rehabilitation

Author  Massimo Bergamasco

Video ID : 180

The video shows the L-Exos integrated into a virtual environment, which has been specifically developed for the motor rehabilitation of the upper limb.

Chapter 53 — Multiple Mobile Robot Systems

Lynne E. Parker, Daniela Rus and Gaurav S. Sukhatme

Within the context of multiple mobile, and networked robot systems, this chapter explores the current state of the art. After a brief introduction, we first examine architectures for multirobot cooperation, exploring the alternative approaches that have been developed. Next, we explore communications issues and their impact on multirobot teams in Sect. 53.3, followed by a discussion of networked mobile robots in Sect. 53.4. Following this we discuss swarm robot systems in Sect. 53.5 and modular robot systems in Sect. 53.6. While swarm and modular systems typically assume large numbers of homogeneous robots, other types of multirobot systems include heterogeneous robots. We therefore next discuss heterogeneity in cooperative robot teams in Sect. 53.7. Once robot teams allow for individual heterogeneity, issues of task allocation become important; Sect. 53.8 therefore discusses common approaches to task allocation. Section 53.9 discusses the challenges of multirobot learning, and some representative approaches. We outline some of the typical application domains which serve as test beds for multirobot systems research in Sect. 53.10. Finally, we conclude in Sect. 53.11 with some summary remarks and suggestions for further reading.

Transport of a child by swarm-bots

Author  Ivan Aloisio, Michael Bonani, Francesco Mondada, Andre Guignard, Roderich Gross, Dario Floreano

Video ID : 212

This video shows a swarm of s-bot, miniature, mobile robots in swarm-bot formation pulling a child across the floor.

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.