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Chapter 8 — Motion Control

Wan Kyun Chung, Li-Chen Fu and Torsten Kröger

This chapter will focus on the motion control of robotic rigid manipulators. In other words, this chapter does not treat themotion control ofmobile robots, flexible manipulators, and manipulators with elastic joints. The main challenge in the motion control problem of rigid manipulators is the complexity of their dynamics and uncertainties. The former results from nonlinearity and coupling in the robot manipulators. The latter is twofold: structured and unstructured. Structured uncertainty means imprecise knowledge of the dynamic parameters and will be touched upon in this chapter, whereas unstructured uncertainty results from joint and link flexibility, actuator dynamics, friction, sensor noise, and unknown environment dynamics, and will be treated in other chapters. In this chapter, we begin with an introduction to motion control of robot manipulators from a fundamental viewpoint, followed by a survey and brief review of the relevant advanced materials. Specifically, the dynamic model and useful properties of robot manipulators are recalled in Sect. 8.1. The joint and operational space control approaches, two different viewpoints on control of robot manipulators, are compared in Sect. 8.2. Independent joint control and proportional– integral–derivative (PID) control, widely adopted in the field of industrial robots, are presented in Sects. 8.3 and 8.4, respectively. Tracking control, based on feedback linearization, is introduced in Sect. 8.5. The computed-torque control and its variants are described in Sect. 8.6. Adaptive control is introduced in Sect. 8.7 to solve the problem of structural uncertainty, whereas the optimality and robustness issues are covered in Sect. 8.8. To compute suitable set point signals as input values for these motion controllers, Sect. 8.9 introduces reference trajectory planning concepts. Since most controllers of robotmanipulators are implemented by using microprocessors, the issues of digital implementation are discussed in Sect. 8.10. Finally, learning control, one popular approach to intelligent control, is illustrated in Sect. 8.11.

Sensor-based online trajectory generation

Author  Torsten Kröger

Video ID : 761

The video shows the movements of a position-controlled 6-DOF industrial-robot arm equipped with a distance sensor at its end-effector. The task of the robot is to draw a rectangle on the table, while the force on the table is controlled by a force controller which acts only orthogonally to the table surface. The dimensions of the rectangle are determined by the obstacles in the robot's environment. If the obstacles are moved, the distance sensor triggers the execution of a new trajectory segment which is computed within one control cycle (1 ms), so that it can be instantly executed.

Chapter 1 — Robotics and the Handbook

Bruno Siciliano and Oussama Khatib

Robots! Robots on Mars and in oceans, in hospitals and homes, in factories and schools; robots fighting fires, making goods and products, saving time and lives. Robots today are making a considerable impact on many aspects of modern life, from industrial manufacturing to healthcare, transportation, and exploration of the deep space and sea. Tomorrow, robotswill be as pervasive and personal as today’s personal computers. This chapter retraces the evolution of this fascinating field from the ancient to themodern times through a number of milestones: from the first automated mechanical artifact (1400 BC) through the establishment of the robot concept in the 1920s, the realization of the first industrial robots in the 1960s, the definition of robotics science and the birth of an active research community in the 1980s, and the expansion towards the challenges of the human world of the twenty-first century. Robotics in its long journey has inspired this handbook which is organized in three layers: the foundations of robotics science; the consolidated methodologies and technologies of robot design, sensing and perception, manipulation and interfaces, mobile and distributed robotics; the advanced applications of field and service robotics, as well as of human-centered and life-like robotics.

Robots — A 50 year journey

Author  Oussama Khatib

Video ID : 805

In this collection of short segments, this video retraces the history of the most influential modern robots developed in the 20th century (1950-2000). The 50-year journey was first presented at the 2000 IEEE International Conference on Robotics and Automation (ICRA) in San Francisco.

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.

Par2 robot

Author  Sébastien Krut

Video ID : 51

This video demonstrates the Par2 robot, a high-speed planar parallel robot.

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 pole climb

Author  Howie Choset

Video ID : 171

CMU Modsnake climbing and navigating curves on a jagged pole.

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 62 — Intelligent Vehicles

Alberto Broggi, Alex Zelinsky, Ümit Özgüner and Christian Laugier

This chapter describes the emerging robotics application field of intelligent vehicles – motor vehicles that have autonomous functions and capabilities. The chapter is organized as follows. Section 62.1 provides a motivation for why the development of intelligent vehicles is important, a brief history of the field, and the potential benefits of the technology. Section 62.2 describes the technologies that enable intelligent vehicles to sense vehicle, environment, and driver state, work with digital maps and satellite navigation, and communicate with intelligent transportation infrastructure. Section 62.3 describes the challenges and solutions associated with road scene understanding – a key capability for all intelligent vehicles. Section 62.4 describes advanced driver assistance systems, which use the robotics and sensing technologies described earlier to create new safety and convenience systems for motor vehicles, such as collision avoidance, lane keeping, and parking assistance. Section 62.5 describes driver monitoring technologies that are being developed to mitigate driver fatigue, inattention, and impairment. Section 62.6 describes fully autonomous intelligent vehicles systems that have been developed and deployed. The chapter is concluded in Sect. 62.7 with a discussion of future prospects, while Sect. 62.8 provides references to further reading and additional resources.

Inria/Ligier automated parallel-parking demo in an open parking area

Author  Christian Laugier, Igor Paromtchik

Video ID : 567

This video shows a pioneer demonstration of the concept of "autonomous parallel parking" on the early Inria/Ligier autonomous vehicle (1996). The approach does not require any prior model of the parking area. The car is controlled using information coming from inexpensive, on-board sensors, and motion control decisions (including parking maneuvers) are taken online according to the state of the sensed environment. Public demonstrations of the systems have been performed during several publicized and scientific events (including during three days at the IEEE/RSJ IROS 1997 Conference). More technical details can be found in [62.89].

Chapter 58 — Robotics in Hazardous Applications

James Trevelyan, William R. Hamel and Sung-Chul Kang

Robotics researchers have worked hard to realize a long-awaited vision: machines that can eliminate the need for people to work in hazardous environments. Chapter 60 is framed by the vision of disaster response: search and rescue robots carrying people from burning buildings or tunneling through collapsed rock falls to reach trapped miners. In this chapter we review tangible progress towards robots that perform routine work in places too dangerous for humans. Researchers still have many challenges ahead of them but there has been remarkable progress in some areas. Hazardous environments present special challenges for the accomplishment of desired tasks depending on the nature and magnitude of the hazards. Hazards may be present in the form of radiation, toxic contamination, falling objects or potential explosions. Technology that specialized engineering companies can develop and sell without active help from researchers marks the frontier of commercial feasibility. Just inside this border lie teleoperated robots for explosive ordnance disposal (EOD) and for underwater engineering work. Even with the typical tenfold disadvantage in manipulation performance imposed by the limits of today’s telepresence and teleoperation technology, in terms of human dexterity and speed, robots often can offer a more cost-effective solution. However, most routine applications in hazardous environments still lie far beyond the feasibility frontier. Fire fighting, remediating nuclear contamination, reactor decommissioning, tunneling, underwater engineering, underground mining and clearance of landmines and unexploded ordnance still present many unsolved problems.

Bozena 5 remotely-operated robot vehicle

Author  James P. Trevelyan

Video ID : 574

This is an example of several videos available on YouTube showing this Slovak-designed and -constructed machine. It shows the vehicle being used in different test areas with brief glimpses of other mine-resistant vehicles. BOZENA 5 was designed to support mine-clearance teams operating in Croatia, Serbia and Bosnia Herzegovina, removing mines left over from the civil war in the 1990s. In the areas affected by mines, one of the biggest challenges is the rapid growth of vegetation during the summer months. Bare ground can be submerged in vegetation over 1 m high after just two or three weeks. Military defensive positions were often set up on uneven ground with steep slopes which were then mined to deter attacks from other parties in the conflict. Mines were also removed from these defensive minefields and re-laid along routes used for smuggling goods and people. The smugglers would be able to charge higher prices because only they knew how to safely move along the routes. The smuggling routes (and their parent organizations) persisted long after the end of the formal conflict, complicating mine-clearance operations. That is why small, remote control vehicles like this proved to be so effective. They were highly manoeuvrable, easily transported, adaptable with different tools and equipment, and could be safely operated. The machine comes with an armored operator cabin and the whole system can be packed and deployed from a 40-foot shipping container weighing 16 tons. The greatest threat to the de-miners was from bounding fragmentation mines which typically had a lethal radius of several hundred meters. These vehicles provided a means to operate safely in areas affected by these mines. One of the major disadvantages of these machines is the destruction of surface vegetation that can lead to rapid erosion, if there is heavy rain in the weeks following mine clearance operations. Sudden heavy downpours are common in summer months. Therefore, they had to be used with considerable discretion and local knowledge.

Chapter 74 — Learning from Humans

Aude G. Billard, Sylvain Calinon and Rüdiger Dillmann

This chapter surveys the main approaches developed to date to endow robots with the ability to learn from human guidance. The field is best known as robot programming by demonstration, robot learning from/by demonstration, apprenticeship learning and imitation learning. We start with a brief historical overview of the field. We then summarize the various approaches taken to solve four main questions: when, what, who and when to imitate. We emphasize the importance of choosing well the interface and the channels used to convey the demonstrations, with an eye on interfaces providing force control and force feedback. We then review algorithmic approaches to model skills individually and as a compound and algorithms that combine learning from human guidance with reinforcement learning. We close with a look on the use of language to guide teaching and a list of open issues.

Demonstration by visual tracking of gestures

Author  Ales Ude

Video ID : 99

Demonstration by visual tracking of gestures. Reference: A. Ude: Trajectory generation from noisy positions of object features for teaching robot paths, Robot. Auton. Syst. 11(2), 113–127 (1993); URL: http://www.cns.atr.jp/~aude/movies/ .

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.

A day in the life of a Kiva robot

Author  Mick Mountz

Video ID : 210

Kiva Systems founder and CEO Mick Mountz narrates a play-by-play video of how Kiva robots automate a warehouse environment. http://www.kivasystems.com/

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 autonomous pole-climbing

Author  Howie Choset

Video ID : 166

Video of the CMU Modsnake autonomously climbing a pole using LIDAR.