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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.

Learning from failure I

Author  Aude Billard

Video ID : 476

This video illustrates how learning from demonstration can be bootstrapped using failed demonstrations only (in place of traditional approaches that use successful demonstrations). The algorithm is described in detail in two publications: 1)D.-H. Grollman, A. Billard: Donut as I do: Learning from failed demonstrations, Proc. IEEE Int. Conf. Robot. Autom. (ICRA), Shanghai (2011) Best Paper Award (Cognitive Robotics); 2) D.-H. Grollman, A. Billard: Robot learning from failed demonstrations, Int. J. Social Robot. 4(4), 331-342 (2012).

Chapter 40 — Mobility and Manipulation

Oliver Brock, Jaeheung Park and Marc Toussaint

Mobile manipulation requires the integration of methodologies from all aspects of robotics. Instead of tackling each aspect in isolation,mobilemanipulation research exploits their interdependence to solve challenging problems. As a result, novel views of long-standing problems emerge. In this chapter, we present these emerging views in the areas of grasping, control, motion generation, learning, and perception. All of these areas must address the shared challenges of high-dimensionality, uncertainty, and task variability. The section on grasping and manipulation describes a trend towards actively leveraging contact and physical and dynamic interactions between hand, object, and environment. Research in control addresses the challenges of appropriately coupling mobility and manipulation. The field of motion generation increasingly blurs the boundaries between control and planning, leading to task-consistent motion in high-dimensional configuration spaces, even in dynamic and partially unknown environments. A key challenge of learning formobilemanipulation consists of identifying the appropriate priors, and we survey recent learning approaches to perception, grasping, motion, and manipulation. Finally, a discussion of promising methods in perception shows how concepts and methods from navigation and active perception are applied.

Catching objects in flight

Author  Seungsu Kim, Ashwini Shukla, Aude Billard

Video ID : 653

We target the difficult problem of catching in-flight objects with uneven shapes. This requires the solution of three complex problems: predicting accurately the trajectory of fast-moving objects, predicting the feasible catching configuration, and planning the arm motion, all within milliseconds. We follow a programming-by-demonstration approach in order to learn models of the object and the arm dynamics from throwing examples. We propose a new methodology for finding a feasible catching configuration in a probabilistic manner. We leverage the strength of dynamical systems for encoding motion from several demonstrations. This enables fast and online adaptation of the arm motion in the presence of sensor uncertainty. We validate the approach in simulation with the iCub humanoid robot and in real-world experiment with the KUKA LWR 4+ (7-DOF arm robot) for catching a hammer, a tennis racket, an empty bottle, a partially filled bottle and a cardboard box.

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.

Physical human-robot interaction in imitation learning

Author  Dongheui Lee, Christian Ott, Yoshihiko Nakamura, Gerd Hirzinger

Video ID : 625

This video presents our recent research on the integration of physical human-robot interaction (pHRI) with imitation learning. First, a marker control approach for real-time human-motion imitation is shown. Second, physical coaching in addition to observational learning is applied for the incremental learning of motion primitives. Last, we extend imitation learning to learning pHRI which includes the establishment of intended physical contacts. The proposed methods were implemented and tested using the IRT humanoid robot and DLR’s humanoid upper-body robot Justin.

Chapter 40 — Mobility and Manipulation

Oliver Brock, Jaeheung Park and Marc Toussaint

Mobile manipulation requires the integration of methodologies from all aspects of robotics. Instead of tackling each aspect in isolation,mobilemanipulation research exploits their interdependence to solve challenging problems. As a result, novel views of long-standing problems emerge. In this chapter, we present these emerging views in the areas of grasping, control, motion generation, learning, and perception. All of these areas must address the shared challenges of high-dimensionality, uncertainty, and task variability. The section on grasping and manipulation describes a trend towards actively leveraging contact and physical and dynamic interactions between hand, object, and environment. Research in control addresses the challenges of appropriately coupling mobility and manipulation. The field of motion generation increasingly blurs the boundaries between control and planning, leading to task-consistent motion in high-dimensional configuration spaces, even in dynamic and partially unknown environments. A key challenge of learning formobilemanipulation consists of identifying the appropriate priors, and we survey recent learning approaches to perception, grasping, motion, and manipulation. Finally, a discussion of promising methods in perception shows how concepts and methods from navigation and active perception are applied.

Task-consistent, obstacle avoidance for mobile manipulation

Author  Oliver Brock, Oussama Khatib, Sriram Viji

Video ID : 784

This robot can avoid moving obstacles with real-time path modification by using an elastic-strip framework. However, the real-time path modification can interfere with task execution. The proposed task-consistent, elastic planning method can ensure the task execution while achieving obstacle avoidance.

Chapter 78 — Perceptual Robotics

Heinrich Bülthoff, Christian Wallraven and Martin A. Giese

Robots that share their environment with humans need to be able to recognize and manipulate objects and users, perform complex navigation tasks, and interpret and react to human emotional and communicative gestures. In all of these perceptual capabilities, the human brain, however, is still far ahead of robotic systems. Hence, taking clues from the way the human brain solves such complex perceptual tasks will help to design better robots. Similarly, once a robot interacts with humans, its behaviors and reactions will be judged by humans – movements of the robot, for example, should be fluid and graceful, and it should not evoke an eerie feeling when interacting with a user. In this chapter, we present Perceptual Robotics as the field of robotics that takes inspiration from perception research and neuroscience to, first, build better perceptual capabilities into robotic systems and, second, to validate the perceptual impact of robotic systems on the user.

Active in-hand object recognition

Author  Christian Wallraven

Video ID : 569

This video showcases the implementation of active object learning and recognition using the framework proposed in Browatzki et al. [1, 2]. The first phase shows the robot trying to learn the visual representation of several paper cups differing by a few key features. The robot executes a pre-programmed exploration program to look at the cup from all sides. The (very low-resolution) visual input is tracked and so-called key-frames are extracted which represent the (visual) exploration. After learning, the robot tries to recognize cups that have been placed into its hands using a similar exploration program based on visual information - due to the low-resolution input and the highly similar objects, the robot, however, fails to make the correct decision. The video then shows the second, advanced, exploration, which is based on actively seeking the view that is expected to provide maximum information about the object. For this, the robot embeds the learned visual information into a proprioceptive map indexed by the two joint angles of the hand. In this map, the robot now tries to predict the joint-angle combination that provides the most information about the object, given the current state of exploration. The implementation uses particle filtering to track a large number of object (view) hypotheses at the same time. Since the robot now uses a multisensory representation, the subsequent object-recognition trials are all correct, despite poor visual input and highly similar objects. References: [1] B Browatzki, V. Tikhanoff, G. Metta, H.H. Bülthoff, C. Wallraven: Active in-hand object recognition on a humanoid robot, IEEE Trans. Robot. 30(5), 1260-1269 (2014); [2] B. Browatzki, V. Tikhanoff, G. Metta, H.H. Bülthoff, C. Wallraven: Active object recognition on a humanoid robot, Proc. IEEE Int. Conf. Robot. Autom. (ICRA), St. Paul (2012), pp. 2021-2028.

Chapter 17 — Limbed Systems

Shuuji Kajita and Christian Ott

A limbed system is a mobile robot with a body, legs and arms. First, its general design process is discussed in Sect. 17.1. Then we consider issues of conceptual design and observe designs of various existing robots in Sect. 17.2. As an example in detail, the design of a humanoid robot HRP-4C is shown in Sect. 17.3. To design a limbed system of good performance, it is important to take into account of actuation and control, like gravity compensation, limit cycle dynamics, template models, and backdrivable actuation. These are discussed in Sect. 17.4.

In Sect. 17.5, we overview divergence of limbed systems. We see odd legged walkers, leg–wheel hybrid robots, leg–arm hybrid robots, tethered walking robots, and wall-climbing robots. To compare limbed systems of different configurations,we can use performance indices such as the gait sensitivity norm, the Froude number, and the specific resistance, etc., which are introduced in Sect. 17.6.

Torque-controlled humanoid robot TORO

Author  Christian Ott

Video ID : 531

A torque-controlled humanoid robot TORO developed by the German Aerospace Center (DLR).

Chapter 26 — Flying Robots

Stefan Leutenegger, Christoph Hürzeler, Amanda K. Stowers, Kostas Alexis, Markus W. Achtelik, David Lentink, Paul Y. Oh and Roland Siegwart

Unmanned aircraft systems (UASs) have drawn increasing attention recently, owing to advancements in related research, technology, and applications. While having been deployed successfully in military scenarios for decades, civil use cases have lately been tackled by the robotics research community.

This chapter overviews the core elements of this highly interdisciplinary field; the reader is guided through the design process of aerial robots for various applications starting with a qualitative characterization of different types of UAS. Design and modeling are closely related, forming a typically iterative process of drafting and analyzing the related properties. Therefore, we overview aerodynamics and dynamics, as well as their application to fixed-wing, rotary-wing, and flapping-wing UAS, including related analytical tools and practical guidelines. Respecting use-case-specific requirements and core autonomous robot demands, we finally provide guidelines to related system integration challenges.

Project Skye - Autonomous blimp

Author  Project Skye

Video ID : 690

Project Skye presents a novel concept combining the elegant and energy efficient flight of a blimp with the precise handling characteristics of a quadrocopter. Thanks to its symmetrical mechanical design, Skye can orient itself in any direction. With its integrated camera system, Skye resembles a hovering eye in the sky which enables applications in countless situations thanks to its long flight duration and high safety standards.

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.

Resilent machines through continuous self-modeling

Author  Josh Bongard, Victor Zykov, Hod Lipson

Video ID : 114

This video demonstrates a typical experiment with a resilent machine.

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.

Cartesian impedance control with damping off

Author  Alin Albu-Schaeffer

Video ID : 133

This 2010 video shows the performance of a Cartesian impedance controller for the torque-controlled KUKA-LWR robot holding an extra payload, when the damping term in the controller has been turned off. The response to a contact force (a human pushing on the end-effector) is oscillatory due to the joint elasticity. This is one of two coordinated videos, the other for the case with controller damping turned on. Reference: A. Albu-Schaeffer, C. Ott, G. Hirzinger: A unified passivity-based control framework for position, torque and impedance control of flexible joint robots, Int. J. Robot. Res. 26(1), 23-39 (2007) doi: 10.1177/0278364907073776

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.

Discrimination of objects through sensory-motor coordination

Author  Stefano Nolfi

Video ID : 116

A Khepera robot provided with infrared sensors is evolved for the ability to find and remain close to a cylindrical object randomly located in the environment. The discrimination of the two types of objects (walls and cylinders) is realized by exploiting the limit-cycle oscillatory behavio,r which is produced by the robot near the cylinder and which emerges from the robot/environmental interactions (i.e., by the interplay between the way in which the robot react to sensory stimuli and the perceptual consequences of the robot actions).