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Showing papers on "Robot published in 2001"


Journal ArticleDOI
TL;DR: A more robust algorithm is developed called MixtureMCL, which integrates two complimentary ways of generating samples in the estimation of Monte Carlo Localization algorithms, and is applied to mobile robots equipped with range finders.

1,945 citations


Journal ArticleDOI
01 Dec 2001
TL;DR: This paper addresses the control of a team of nonholonomic mobile robots navigating in a terrain with obstacles while maintaining a desired formation and changing formations when required, using graph theory.
Abstract: This paper addresses the control of a team of nonholonomic mobile robots navigating in a terrain with obstacles while maintaining a desired formation and changing formations when required, using graph theory. We model the team as a triple, (g, r, H), consisting of a group element g that describes the gross position of the lead robot, a set of shape variables r that describe the relative positions of robots, and a control graph H that describes the behaviors of the robots in the formation. Our framework enables the representation and enumeration of possible control graphs and the coordination of transitions between any two formations.

1,175 citations


Journal ArticleDOI
TL;DR: The principal contribution of the present work is to show that the control strategy can be designed in a way that greatly simplifies the application of the method of Poincare to a class of biped models, and to reduce the stability assessment problem to the calculation of a continuous map from a subinterval of R to itself.
Abstract: Biped robots form a subclass of legged or walking robots. The study of mechanical legged motion has been motivated by its potential use as a means of locomotion in rough terrain, as well as its potential benefits to prothesis development and testing. The paper concentrates on issues related to the automatic control of biped robots. More precisely, its primary goal is to contribute a means to prove asymptotically-stable walking in planar, underactuated biped robot models. Since normal walking can be viewed as a periodic solution of the robot model, the method of Poincare sections is the natural means to study asymptotic stability of a walking cycle. However, due to the complexity of the associated dynamic models, this approach has had limited success. The principal contribution of the present work is to show that the control strategy can be designed in a way that greatly simplifies the application of the method of Poincare to a class of biped models, and, in fact, to reduce the stability assessment problem to the calculation of a continuous map from a subinterval of R to itself. The mapping in question is directly computable from a simulation model. The stability analysis is based on a careful formulation of the robot model as a system with impulse effects and the extension of the method of Poincare sections to this class of models.

995 citations


Journal ArticleDOI
TL;DR: This textbook for advanced undergraduates and graduate students emphasizes algorithms for a range of strategies for locomotion, sensing, and reasoning in mobile robots, including significant coverage of SLAM (simultaneous localization and mapping) and multi-robot systems.
Abstract: Mobile robotics is a multidisciplinary field involving both computer science and engineering. Addressing the design of automated systems, it lies at the intersection of artificial intelligence, computational vision, and robotics. This textbook for advanced undergraduates and graduate students emphasizes algorithms for a range of strategies for locomotion, sensing, and reasoning. It concentrates on wheeled and legged mobile robots but discusses a variety of other propulsion systems. The new edition includes advances in robotics and intelligent machines over the last ten years, including significant coverage of SLAM (simultaneous localization and mapping) and multi-robot systems. It includes additional mathematical background and an extensive list of sample problems. Various mathematical techniques that were assumed in the first edition are now briefly introduced in appendices at the end of the text to make the book more self-contained. Researchers as well as students in the field of mobile robotics will appreciate this comprehensive treatment of state-of-the-art methods and key technologies.

676 citations


Proceedings ArticleDOI
21 May 2001
TL;DR: A vision-based mobile robot localization and mapping algorithm is described which uses scale-invariant image features as landmarks in unmodified dynamic environments which are localized and robot ego-motion is estimated by matching them, taking into account the feature viewpoint variation.
Abstract: A key component of a mobile robot system is the ability to localize itself accurately and build a map of the environment simultaneously. In this paper, a vision-based mobile robot localization and mapping algorithm is described which uses scale-invariant image features as landmarks in unmodified dynamic environments. These 3D landmarks are localized and robot ego-motion is estimated by matching them, taking into account the feature viewpoint variation. With our Triclops stereo vision system, experiments show that these features are robustly matched between views, 3D landmarks are tracked, robot pose is estimated and a 3D map is built.

590 citations


Journal ArticleDOI
TL;DR: An efficient probabilistic algorithm for the concurrent mapping and localization problem that arises in mobile robotics is presented, which addresses the problem in which a team of robots builds a map on-line while simultaneously accommodating errors in the robots’ odometry.
Abstract: An efficient probabilistic algorithm for the concurrent mapping and localization problem that arises in mobile robotics is presented. The algorithm addresses the problem in which a team of robots builds a map on-line while simultaneously accommodating errors in the robots’ odometry. At the core of the algorithm is a technique that combines fast maximum likelihood map growing with a Monte Carlo localizer that uses particle representations. The combination of both yields an on-line algorithm that can cope with large odometric errors typically found when mapping environments with cycles. The algorithm can be implemented in a distributed manner on multiple robot platforms, enabling a team of robots to cooperatively generate a single map of their environment. Finally, an extension is described for acquiring three-dimensional maps, which capture the structure and visual appearance of indoor environments in three dimensions.

566 citations


Journal ArticleDOI
TL;DR: This paper has successfully compelled a simulated seven-link planar biped to walk blindly up and down slopes and over rolling terrain and described how the algorithm can be augmented for rough terrain walking based on geometric consideration.
Abstract: Virtual model control is a motion control framework that uses virtual components to create virtual forces generated when the virtual components interact with a robot system. An algorithm derived based on the virtual model control framework is applied to a physical planar bipedal robot. It uses a simple set of virtual components that allows the robot to walk successfully over level terrain. This paper also describes how the algorithm can be augmented for rough terrain walking based on geometric consideration. The resulting algorithm is very simple and does not require the biped to have an extensive sensory system. The robot does not know the slope gradients and transition locations in advance. The ground is detected using foot contact switches. Using the algorithm, we have successfully compelled a simulated seven-link planar biped to walk blindly up and down slopes and over rolling terrain.

553 citations


Proceedings ArticleDOI
29 Oct 2001
TL;DR: Player combines an efficient message protocol with a simple device model that provides transparent network access to a collection of sensors and actuators, often comprising a robot, and is implemented as a multithreaded TCP socket server.
Abstract: Successful distributed sensing and control require data to flow effectively between sensors, processors and actuators on single robots, in groups and across the Internet. We propose a mechanism for achieving this flow that we have found to be powerful and easy to use; we call it Player. Player combines an efficient message protocol with a simple device model. It is implemented as a multithreaded TCP socket server that provides transparent network access to a collection of sensors and actuators, often comprising a robot. The socket abstraction enables platform- and language-independent control of these devices, allowing the system designer to use the best tool for the task at hand Player is freely available from http://robotics.usc.edu/player.

445 citations


Proceedings ArticleDOI
21 May 2001
TL;DR: A sample-based variant of joint probabilistic data association filters is introduced to track features originating from individual objects and to solve the correspondence problem between the detected features and the filters.
Abstract: One of the goals in the field of mobile robotics is the development of mobile platforms which operate in populated environments and offer various services to humans. For many tasks it is highly desirable that a robot can determine the positions of the humans in its surrounding. In this paper we present a method for tracking multiple moving objects with a mobile robot. We introduce a sample-based variant of joint probabilistic data association filters to track features originating from individual objects and to solve the correspondence problem between the detected features and the filters. In contrast to standard methods, occlusions are handled explicitly during data association. The technique has been implemented and tested on a real robot. Experiments carried out in a typical office environment show that the method is able to track multiple persons even when the trajectories of two people are crossing each other.

432 citations


Journal ArticleDOI
TL;DR: The tracking control problem with saturation constraint for a class of unicycle-modeled mobile robots is formulated and solved using the backstepping technique and the idea from the LaSalle's invariance principle, and computer simulations confirm the effectiveness of the proposed tracking control law.
Abstract: The tracking control problem with saturation constraint for a class of unicycle-modeled mobile robots is formulated and solved using the backstepping technique and the idea from the LaSalle's invariance principle. A global result is presented in which several constraints on the linear and the angular velocities of the mobile robot from recent literature are dropped. The proposed controller can simultaneously solve both the tracking and regulation problems of a unicycle-modeled mobile robot. With the proposed control laws, the robot can globally follow any path specified by a straight line, a circle or a path approaching the origin using a single controller. As demonstrated, the circular and parallel parking control problem are solved using the proposed controller. Computer simulations are presented which confirm the effectiveness of the proposed tracking control law. Practical experimental results validate the simulations.

396 citations


Book
01 Jan 2001
TL;DR: From the Publisher: A complete overview of the fundamentals of robotics is presented, including case study examples of educational, industrial and generic robots discussed.
Abstract: From the Publisher: A complete overview of the fundamentals of robotics. Case study examples of educational, industrial and generic robots are discussed. Class demonstration software is provided with the laboratory manual. (vs. Craig, Fu, and Asada).

Book ChapterDOI
01 Jan 2001
TL;DR: This chapter investigates the utility of particle filters in the context of mobile robotics, and reports results of applying particle filters to the problem of mobile robot localization, which is theproblem of estimating a robot’s pose relative to a map of its environment.
Abstract: This chapter investigates the utility of particle filters in the context of mobile robotics. In particular, we report results of applying particle filters to the problem of mobile robot localization, which is the problem of estimating a robot’s pose relative to a map of its environment. The localization problem is a key one in mobile robotics, because it plays a fundamental role in various successful mobile robot systems; see e.g., (Cox and Wilfong 1990, Fukuda, Ito, Oota, Arai, Abe, Tanake and Tanaka 1993, Hinkel and Knieriemen 1988, Leonard, Durrant-Whyte and Cox 1992, Rencken 1993, Simmons, Goodwin, Haigh, Koenig and O’Sullivan 1997, Weis, Wetzler and von Puttkamer 1994) and various chapters in (Borenstein, Everett and Feng 1996) and (Kortenkamp, Bonasso and Murphy 1998). Occasionally, it has been referred to as “the most fundamental problem to providing a mobile robot with autonomous capabilities” (Cox 1991).

Journal ArticleDOI
TL;DR: This work exploits the biologically inspired notion of a “virtual pheromone,” implemented using simple transceivers mounted atop each robot, that enables the robot collective to become a distributed computing mesh embedded within the environment, while simultaneously acting as a physical embodiment of the user interface.
Abstract: We describe techniques for coordinating the actions of large numbers of small-scale robots to achieve useful large-scale results in surveillance, reconnaissance, hazard detection, and path finding. We exploit the biologically inspired notion of a “virtual pheromone,” implemented using simple transceivers mounted atop each robot. Unlike the chemical markers used by insect colonies for communication and coordination, our virtual pheromones are symbolic messages tied to the robots themselves rather than to fixed locations in the environment. This enables our robot collective to become a distributed computing mesh embedded within the environment, while simultaneously acting as a physical embodiment of the user interface. This leads to notions of world-embedded computation and world-embedded displays that provide different ways to think about robot colonies and the types of distributed computations that such colonies might perform.

Proceedings ArticleDOI
21 May 2001
TL;DR: The paper describes the recent design and development efforts in DLR Robotics Lab towards the second generation of light-weight robots, and the mechatronic approach incorporates a tight collaboration between mechanics, electronics and controller design.
Abstract: The paper describes the recent design and development efforts in DLR Robotics Lab towards the second generation of light-weight robots The design of the light weight mechanics, integrated sensors and electronics is outlined The fully sensory joint, with motor and link position sensors as well as joint torque sensors enables the implementation of effective vibration damping and advanced control strategies for compliant manipulation The mechatronic approach incorporates a tight collaboration between mechanics, electronics and controller design The authors hope that important steps towards a new generation of service and personal robots have been achieved

Journal ArticleDOI
TL;DR: The clinical applications include neurosurgery, orthopedics, urology, maxillofacial surgery, radiosurgery, ophthalmology, and cardiac surgery, and a listing of technology challenges and research areas are discussed.
Abstract: Although it has been over 15 years since the first recorded use of a robot for a surgical procedure, the field of medical robotics is still an emerging one that has not yet reached a critical mass. Although robots have the potential to improve the precision and capabilities of physicians, the number of robots in clinical use is still very small. In this review article, we begin with a short historical review of medical robotics, followed by an overview of clinical applications where robots have been applied. The clinical applications are then discussed; they include neurosurgery, orthopedics, urology, maxillofacial surgery, radiosurgery, ophthalmology, and cardiac surgery. We conclude with a listing of technology challenges and research areas, including system architecture, software design, mechanical design, imaging compatible systems, user interface, and safety issues.

Proceedings ArticleDOI
07 Oct 2001
TL;DR: This work designs a human-robot system with adjustable autonomy that grants the human meta-level control over the level of robot autonomy, but allows the robot a varying amount of self-direction with each level.
Abstract: Human-robot interaction is becoming an increasingly important research area. In this paper, we present our work on designing a human-robot system with adjustable autonomy and describe not only the prototype interface but also the corresponding, robot behaviors. In our approach, we grant the human meta-level control over the level of robot autonomy, but we allow the robot a varying amount of self-direction with each level. Within this framework of adjustable autonomy, we explore how existing, robot control approaches can be adapted and extended to be compatible with adjustable autonomy.

Journal ArticleDOI
20 Oct 2001-BMJ
TL;DR: This review describes the application of virtual reality and robotics to surgical training and planning and the execution of procedures in theatre and discusses the near term future of this new technology.
Abstract: New technologies, in particular virtual reality and robotics, will have a major impact on health care in the next decade. Clinically validated, powerful medical simulators are now available and in use across the world. General surgery leads in the use of simulators, and neurosurgery leads with augmented reality and image guided surgery. Robotics are used in orthopaedics and cardiology. Other virtual reality applications are being used in mental health, anaesthetics, and emergency medicine. Rapid developments in the internet and “e-learning” domains have accelerated the dissemination of simulation techniques, interactive 3D images, and structured courseware. This review describes the application of virtual reality and robotics to surgical training and planning and the execution of procedures in theatre and discusses the near term future of this new technology. A successful medical simulator or surgical system based on virtual reality requires the participation of a team of specialists including experts in ergonomics and applied psychology, software engineering and digital 3D design, electromechanical engineering, robotics, and microtechnology. Consequently, no single database adequately covers all the issues involved. This review is based on our experience supplemented with data from searches of Medline and the Ergonomics Information Analysis Centre (University of Birmingham) and of the internet with various web search engines. Current virtual reality surgical systems owe their existence to pioneering developments in the early and middle 1980s. Organisations developing robots to replace humans from hostile and hazardous environments—undersea, in nuclear installations, in space, and on the battlefield—turned to an emerging technology that seemed to offer the ideal solution. The developers claimed that, with a special helmet equipped with head tracking devices and 3D displays, it was possible to create an illusion for the wearer that he or she was present in such an environment (“telepresence”) and, with a fibre optic glove, possible for them to …

Journal ArticleDOI
TL;DR: This paper proposes a hierarchical reinforcement learning architecture that realizes practical learning speed in real hardware control tasks and applies it to a three-link, two-joint robot for the task of learning to stand up by trial and error.

Book
01 Jun 2001
TL;DR: This chapter begins with an Introduction and concludes with a Summary, References and Problems, focusing on the Denavit-Hartenberg Representation of Forward Kinematic Equations of Robots.
Abstract: Most chapter begins with an Introduction and conclude with a Summary, References and Problems. 1. Fundamentals. What is a Robot? Classification of Robots. What is Robotics? History of Robotics. Advantages and Disadvantages of Robots. Robot Components. Robot Degrees of Freedom. Robot Joints. Robot Coordinates. Robot Reference Frames. Programming Modes. Robot Characteristics. Robot Workspace. Robot Languages. Robot Applications. Other Robots and Applications. Social Issues. 2. Robot Kinematics: Position Analysis. Robots as Mechanisms. Matrix Representation. Homogeneous Transformation Matrices. Representation of Transformations. Inverse of Transformation Matrices. Forward and Inverse Kinematics of Robots. Denavit-Hartenberg Representation of Forward Kinematic Equations of Robots. The Inverse Kinematic Solution of Robots. Inverse Kinematic Programming of Robots. Degeneracy and Dexterity. The Fundamental Problem with the Denavit-Hartenberg Representation. Design Project 1: A Three-Degree-of-Freedom Robot. 3. Differential Motions and Velocities. Differential Relationships. Jacobian. Differential Motions of a Frame. Interpretation of the Differential Change. Differential Changes Between Frames. Differential Motions of a Robot and Its Hand Frame. Calculation of the Jacobian. How to Relate the Jacobian and the Differential Operator. Inverse Jacobian. Design Project. 4. Dynamic Analysis and Forces. Lagrangian Mechanics: A Short Overview. Effective Moments of Inertia. Dynamic Equations for Multiple-Degree-of-Freedom Robots. Static Force Analysis of Robots. Transformation of Forces and Moments Between Coordinate Frames. Design Project. 5. Trajectory Planning. Path vs. Trajectory. Joint-Space vs. Cartesian-Space Descriptions. Basics of Trajectory Planning. Joint-Space Trajectory Planning. Cartesian-Space Trajectories. Continuous Trajectory Recording. Design Project. 6. Actuators. Characteristics of Actuating Systems. Comparison of Actuating Systems. Hydraulic Devices. Pneumatic Devices. Electric Motors. Microprocessor Control of Electric Motors. Magnetostrictive Actuators. Shape-Memory Type Metals. Speed Reduction. Design Project 1. Design Project 2. 7. Sensors. Sensor Characteristics. Position Sensors. Velocity Sensors. Acceleration Sensors. Force and Pressure Sensors. Torque Sensors. Microswitches. Light and Infrared Sensors. Touch and Tactile Sensors. Proximity Sensors. Range-finders. Sniff Sensors. Vision Systems. Voice Recognition Devices. Voice Synthesizers. Remote Center Compliance (RCC) Device. Design Project. 8. Image Processing and Analysis with Vision Systems. Image Processing versus Image Analysis. Two- and Three-Dimensional Image Types. What is an Image. Acquisition of Images. Digital Images. Frequency Domain vs. Spatial Domain. Fourier Transform of a Signal and its Frequency Content. Frequency Content of an Image Noise, Edges. Spatial Domain Operations: Convolution Mask. Sampling and Quantization. Sampling Theorem. Image-Processing Techniques. Histogram of Images. Thresholding. Connectivity. Noise Reduction. Edge Detection. Hough Transform. Segmentation. Segmentation by Region Growing and Region Splitting. Binary Morphology Operations. Gray Morphology Operations. Image Analysis. Object Recognition by Features. Depth Measurement with Vision Systems. Specialized Lighting. Image Data Compression. Real-Time Image Processing. Heuristics. Applications of Vision Systems. Design project. 9. Fuzzy Logic Control. Fuzzy Control: What is Needed. Crisp Values vs. Fuzzy Values. Fuzzy Sets: Degrees of Membership and Truth. Fuzzification. Fuzzy Inference Rule Base. Defuzzification. Simulation of Fuzzy Logic Controller. Applications of Fuzzy Logic in Robotics. Design Project. Appendix. Matrix Algebra and Notation: A Review. Calculation of an Angle From its Sine, Cosine, or Tangent. Problems. Index.

Proceedings ArticleDOI
21 May 2001
TL;DR: A framework for controlling a group of nonholonomic mobile robots equipped with range sensors is described, using the leader-following approach, that allows the robots to automatically switch between continuous-state control laws to achieve a desired formation shape.
Abstract: We describe a framework for controlling a group of nonholonomic mobile robots equipped with range sensors. The vehicles are required to follow a prescribed trajectory while maintaining a desired formation. By using the leader-following approach, we formulate the formation control problem as a hybrid (mode switching) control system. We then develop a decision module that allows the robots to automatically switch between continuous-state control laws to achieve a desired formation shape. The stability properties of the closed-loop hybrid system are studied using the Lyapunov theory. We do not use explicit communication between robots; instead we integrate optimal estimation techniques with nonlinear controllers. Simulation and experimental results verify the validity of our approach.

Proceedings ArticleDOI
01 Oct 2001
TL;DR: A physically inspired 'mesh-based' formalism for solving the concrete tasks of multirobot mapping and calibration of a distributed sensor network is outlined and described.
Abstract: This paper considers two problems which at first sight appear to be quite distinct: localizing a robot in an unknown environment and calibrating an embedded sensor network. We show that both of these can be formulated as special cases of a generalized localization problem. In the standard localization problem, the aim is to determine the pose of some object (usually a mobile robot) relative to a global coordinate system. In our generalized version, the aim is to determine the pose of all elements in a network (both fixed and mobile) relative to an arbitrary global coordinate system. We have developed a physically inspired 'mesh-based' formalism for solving such problems. This paper outlines the formalism, and describes its application to the concrete tasks of multirobot mapping and calibration of a distributed sensor network. The paper presents experimental results for both tasks obtained using a set of Pioneer mobile robots equipped with scanning laser range-finders.

01 Jan 2001
TL;DR: This research presents a probabilistic procedure for simulating human-robot interaction in the context of mobile robots and its applications in the field of teleoperation and robotics.
Abstract: Keywords: mobile robots ; teleoperation ; human-robot interaction ; [VRAI] Note: Carnegie Mellon University Reference LSRO2-REPORT-2001-002 Record created on 2005-02-04, modified on 2017-05-10

Journal ArticleDOI
01 Sep 2001
TL;DR: This work presents an approach that allows a robot to learn task representations from its own experiences of interacting with a human, and describes a generalization of the framework to allow a robots to interact with humans in order to handle unexpected situations that can occur in its task execution.
Abstract: We focus on a robotic domain in which a human acts both as a teacher and a collaborator to a mobile robot. First, we present an approach that allows a robot to learn task representations from its own experiences of interacting with a human. While most approaches to learning from demonstration have focused on acquiring policies (i.e., collections of reactive rules), we demonstrate a mechanism that constructs high-level task representations based on the robot's underlying capabilities. Next, we describe a generalization of the framework to allow a robot to interact with humans in order to handle unexpected situations that can occur in its task execution. Without using explicit communication, the robot is able to engage a human to aid it during certain parts of task execution. We demonstrate our concepts with a mobile robot learning various tasks from a human and, when needed, interacting with a human to get help performing them.

Proceedings ArticleDOI
29 Oct 2001
TL;DR: The design and implementation of a vision-based system for cooperative manipulation at millimeter to micrometer scales based on an admittance control algorithm that implements a broad class of guidance modes called virtual fixtures is presented.
Abstract: The "steady hand" concept is a way of providing assistance for direct manipulation by applying constraints on the motion of a tool shared by a user and a robot. We explore in detail one family of constraints: virtual fixtures for use in path following tasks. Vision is used to sense the desired path, and then the robot encourages motion toward and along the path through a direction-based control law. This "soft" virtual fixture allows the user to move in other, non-preferred directions, maintaining the user's sense of autonomy and control. Experimental results show that user performance in assisted path following improves with virtual fixture augmentation, and differs with varying fixture compliance.

Book
15 Dec 2001
TL;DR: The inverse geometric model is used for dynamic modeling of serial robots and the dynamic control law in the task space is compared to the Lyapunov theory for dynamic control of passive systems.
Abstract: Terminology and general definitions. Transformation matrix between vectors, frames and screws. Direct geometric model of serial robots. Inverse geometric model of serial robots. Direct kinematic model of serial robots. Inverse kinematic model of serial robots. Geometric and kinematic models of complex chain robots. Introduction to geometric and kinematic modelling of parallel robots. Dynamic modelling of serial robots. Dynamics of robots with complex structure. Geometric calibration of robots. Identification of the dynamic parameters. Trajectory control. Motion control. Compliant motion control. Appendices.

Proceedings ArticleDOI
29 Oct 2001
TL;DR: A cooperative scheme for localizing the robots based on visual imagery that is more robust than decentralized localization and a set of control algorithms that allow the robots to maintain a prescribed formation are described.
Abstract: We describe a framework for coordinating multiple robots in cooperative manipulation tasks in which vision is used for establishing relative position and orientation and maintaining formation. The two key contributions are a cooperative scheme for localizing the robots based on visual imagery that is more robust than decentralized localization, and a set of control algorithms that allow the robots to maintain a prescribed formation (shape and size). The ability to maintain a prescribed formation allows the robots to "trap" objects in their midst, and to "flow" the formation to a desired position. We derive the cooperative localization and control algorithms and present experimental results that illustrate the implementation and the performance of these algorithms.

Journal ArticleDOI
TL;DR: This article presents an experiment which investigates how collaboration in a group of simple reactive robots can be obtained through the exploitation of local interactions, and shows that, compared to homogeneous groups of robots without communication, heterogeneity and signalling can significantly increase the collaboration rate when there are fewer robots than sticks.
Abstract: This article presents an experiment which investigates how collaboration in a group of simple reactive robots can be obtained through the exploitation of local interactions. A test-bed experiment is proposed in which the task of the robots is to pull sticks out of the ground—an action which requires the collaboration of two robots to be successful. The experiment is implemented in a physical setup composed of groups of 2 to 6 Khepera robots, and in Webots, a 3D simulator of Khepera robots. The results using these two implementations are compared with the predictions of a probabilistic modeling methodology (A. Martinoli, A. Ijspeert, and F. Mondada, 1999, i>Robotics and Autonomous Systems, 29:51–63, 1999s A. Martinoli, A. Ijspeert, and L. Gambardella, 1999, in i>Proceedings of Fifth European Conference on Artificial Life, ECAL99, Lecture Notes in Computer Science, Springer Verlag: Berlin, pp. 575–584) which is here extended for the characterization and the prediction of a collaborative manipulation experiment. Instead of computing trajectories and sensory information, the probabilistic model represents the collaboration dynamics as a set of stochastic events based on simple geometrical considerations. It is shown that the probabilistic model qualitatively and quantitatively predicts the collaboration dynamics. It is significantly faster than a traditional sensor-based simulator such as Webots, and its minimal set of parameters allows the experimenter to better identify the effect of characteristics of individual robots on the team performance. Using these three implementations (the real robots, Webots and the probabilistic model), we make a quantitative investigation of the influence of the number of workers (i.e., robots) and of the primary parameter of the robots' controller—the gripping time parameter—on the collaboration rate, i.e., the number of sticks successfully taken out of the ground over time. It is found that the experiment presents two significantly different dynamics depending on the ratio between the amount of work (the number of sticks) and the number of robots, and that there is a super-linear increase of the collaboration rate with the number of robots. Furthermore, we investigate the usefulness of heterogeneity in the controllers' parameters and of a simple signalling scheme among the robots. Results show that, compared to homogeneous groups of robots without communication, heterogeneity and signalling can significantly increase the collaboration rate when there are fewer robots than sticks, while presenting a less noticeable or even negative effect otherwise.

Proceedings ArticleDOI
29 Oct 2001
TL;DR: This work presents an algorithm for planning safe navigation strategies for biped robots moving in obstacle-cluttered environments that takes into account the unique ability of legged robots such as bipedal humanoids to traverse obstacles by stepping over them.
Abstract: We present an algorithm for planning safe navigation strategies for biped robots moving in obstacle-cluttered environments. From a discrete set of plausible statically-stable, single-step motions, a forward dynamic programming approach is used to compute a sequence of feasible footstep locations. In contrast to existing navigation strategies for mobile robots, our method is a global method that takes into account the unique ability of legged robots such as bipedal humanoids to traverse obstacles by stepping over them. Heuristics designed to minimize the number and complexity of the step motions are used to encode cost functions used for searching a footstep transition graph. We show preliminary results of an experimental implementation of the algorithm using a model of the H6 humanoid navigating on an office floor littered with obstacles.

Proceedings ArticleDOI
08 Jul 2001
TL;DR: In this paper, the authors described the research on mental commit robot that seeks a different direction that is not so rigidly dependent on such objective measures as accuracy, speed, and cost.
Abstract: This paper describes the research on mental commit robot that seeks a different direction that is not so rigidly dependent on such objective measures as accuracy, speed, and cost. The main goal of this research is to explore a new area in robotics, with an emphasis on human-robot interaction. In the previous research, we categorized robots into four categories in terms of appearance. Then, we introduced a cat robot and a seal robot, and evaluated them by interviewing many people. The results showed that physical interaction improved subjective evaluation. Moreover, a priori knowledge of a subject has much influence into subjective interpretation and evaluation of the robot. In this paper, 785 subjects were asked to evaluate the seal robot and the results were analyzed by multivariate analysis. In addition, we applied the mental commit robot to therapy of children similar to the animal assisted therapy. This paper describes some of the results of the "robot assisted therapy".

Proceedings ArticleDOI
21 May 2001
TL;DR: The experimental results demonstrate that the method is able to greatly reduce the number of failures and to significantly reduce the overall path length for different prioritized and decoupled path planning techniques and even for large teams of robots.
Abstract: The coordination of robot motions is one of the fundamental problems for multi-robot systems. A popular approach to avoid planning in the high-dimensional composite configuration space is the prioritized and decoupled technique. In this paper we present a method for optimizing priority schemes for such prioritized and decoupled planning technique. Our approach performs a randomized search with hill-climbing to find solutions and to minimize the overall path lengths. The technique has been implemented and tested on real robots and in extensive simulation runs. The experimental results demonstrate that our method is able to greatly reduce the number of failures and to significantly reduce the overall path length for different prioritized and decoupled path planning techniques and even for large teams of robots.