We propose a constructive control design for stabilization of non-periodic trajectories of underactuated mechanical systems. An important example of such a system is an underactuated "dynamic walking" biped ...
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ISBN:
(纸本)9783642194566
We propose a constructive control design for stabilization of non-periodic trajectories of underactuated mechanical systems. An important example of such a system is an underactuated "dynamic walking" biped robot walking over rough terrain. The proposed technique is to compute a transverse linearization about the desired motion: a linear impulsive system which locally represents dynamics about a target trajectory. This system is then exponentially stabilized using a modified receding-horizon control design. The proposed method is experimentally verified using a compass-gait walker: a two-degree-of-freedom biped with hip actuation but pointed stilt-like feet. The technique is, however, very general and can be applied to higher degree-of-freedom robots over arbitrary terrain and other impulsive mechanical systems.
In the research to realize high standard task-oriented assistant robots, a general and strategic way of development is essential. Otherwise high functionality and potential for evolution of those robots cannot be achi...
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ISBN:
(纸本)9783642194566
In the research to realize high standard task-oriented assistant robots, a general and strategic way of development is essential. Otherwise high functionality and potential for evolution of those robots cannot be achieved. Robotic systems are socially expected to assist our daily life in many situations. As a result, projects related to those robots are becoming large, involving many researchers and engineers of universities and companies. This motivated us a new strategy to construct robotic systems based on mother environment and humanoid specialization to keep developing and refining functional elements of robots in an evolutionary way. The mother environment is an entity that creates brains of humanoid robots, where various robotics function elements, libraries, middle-wares and other research tools are integrated. Then the brain of each robot is developed utilizing the functional elements in the mother. We call this process specialization of a humanoid. To enhance this specialization process, we introduce a generator, which realizes conversion of functions in the mother environment for the real-time layer. After the research of these specific robots, enhanced robotics functions are incorporated into the mother again. We call this process feedback. In this chapter, we present these ideas using concrete implementation examples in IRT projects[1], where several robots to assist our daily life are developed.
In this paper we present a method for approximating complete models of objects with 3D shape primitives, by exploiting common symmetries in objects of daily use. Our proposed approach reconstructs boxes and cylindrica...
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ISBN:
(纸本)9783642194566
In this paper we present a method for approximating complete models of objects with 3D shape primitives, by exploiting common symmetries in objects of daily use. Our proposed approach reconstructs boxes and cylindrical parts of objects from sampled point cloud data, and produces CAD-like surface models needed for generating grasping strategies. To verify the results, we present a set of experimental results using real-world data-sets containing a large number of objects from different views.
People detection and tracking are important in many situations where robots and humans work and live together. But unlike targets in traditional tracking problems, people typically move and act under the constraints o...
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ISBN:
(纸本)9783642194566
People detection and tracking are important in many situations where robots and humans work and live together. But unlike targets in traditional tracking problems, people typically move and act under the constraints of their environment. The probabilities and frequencies for when people appear, disappear, walk or stand are not uniform but vary over space making human behavior strongly place-dependent. In this paper we present a model that encodes spatial priors on human behavior and show how the model can be incorporated into a people-tracking system. We learn a non-homogeneous spatial Poisson process that improves data association in a multi-hypothesis target tracker through more informed probability distributions over hypotheses. We further present a place-dependent motion model whose predictions follow the space-usage patterns that people take and which are described by the learned spatial Poisson process. Large-scale experiments in different indoor and outdoor environments using laser range data, demonstrate how both extensions lead to more accurate tracking behavior in terms of data-association errors and number of track losses. The extended tracker is also slightly more efficient than the baseline approach. The system runs in real-time on a typical desktop computer.
This volume is the outcome of the eighth edition of the biennial Workshop Algorithmic Foundations of robotics (WAFR). Edited by G. Chirikjian, H. Choset, M. Morales and T. Murphey, the book offers a collection of a wi...
ISBN:
(数字)9783642003127
ISBN:
(纸本)9783642003110
This volume is the outcome of the eighth edition of the biennial Workshop Algorithmic Foundations of robotics (WAFR). Edited by G. Chirikjian, H. Choset, M. Morales and T. Murphey, the book offers a collection of a wide range of topics in advancedrobotics, including networked robots, distributed systems, manipulation, planning under uncertainty, minimalism, geometric sensing, geometric computation, stochastic planning methods, and medical applications. The contents of the forty-two contributions represent a cross-section of the current state of research from one particular aspect: algorithms, and how they are inspired by classical disciplines, such as discrete and computational geometry, differential geometry, mechanics, optimization, operations research, computer science, probability and statistics, and information theory. Validation of algorithms, design concepts, or techniques is the common thread running through this focused collection. Richin topics and authoritative contributors,WAFR culminates with this unique reference on the current developments and new directions in the field of algorithmic foundations.
Steerable needles can be used in medical applications to reach targets behind sensitive or impenetrable areas. The kinematics of a steerable needle are nonholonomic and, in 2D, equivalent to a Dubins car with constant...
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ISBN:
(纸本)9783642003110
Steerable needles can be used in medical applications to reach targets behind sensitive or impenetrable areas. The kinematics of a steerable needle are nonholonomic and, in 2D, equivalent to a Dubins car with constant radius of curvature. In 3D, the needle can be interpreted as an airplane with constant speed and pitch rate, zero yaw, and controllable roll angle. We present a constant-time motion planning algorithm for steerable needles based on explicit geometric inverse kinematics similar to the classic Paden-Kahan subproblems. Reachability and path competitivity are analyzed using analytic comparisons with shortest path solutions for the Dubins car (for 2D) and numerical simulations (for 3D). We also present an algorithm for local path adaptation using null-space results from redundant manipulator theory. The inverse kinematics algorithm can be used as a fast local planner for global motion planning in environments with obstacles, either fully autonomously or in a computer-assisted setting.
Physical human-robot interaction and cooperation has become a topic of increasing importance and of major focus in robotics research. Industrial and domestic applications unifying the workspace of humans and robots ar...
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ISBN:
(纸本)9783642147432
Physical human-robot interaction and cooperation has become a topic of increasing importance and of major focus in robotics research. Industrial and domestic applications unifying the workspace of humans and robots are foreseeable in the close future and will require safe and dependable robot design and control. In this paper we will give an overview of our systematic evaluation of safety in human-robot interaction, covering various aspects of major significance. Based on initial impact tests we carried out with the DLR-LWRIII, several industrial robots of increasing weight were evaluated and the influence of robot mass and velocity was investigated. Such non-constrained impacts are only partially capturing the nature of human-robot safety. A possibly constrained environment and its effect on resulting injuries have to be discussed and evaluated. Apart from these impact tests and simulations we will analyze the major problem of quasi-static clamping, which poses under certain circumstances a serious threat to the human even for low-inertia robots. After treating blunt, impacts and contacts with and without the human being clamped, various soft-tissue injuries likely to occur in robotics and related physical injury tolerances are introduced. Finally, possible injuries relevant in robotics are summarized and systematically classified.
This paper presents a motion planner that enables a humanoid robot to push an object on a flat surface. The robot's motion is divided into distinct walking, reaching, and pushing modes. A discrete change of mode c...
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ISBN:
(纸本)9783642147432
This paper presents a motion planner that enables a humanoid robot to push an object on a flat surface. The robot's motion is divided into distinct walking, reaching, and pushing modes. A discrete change of mode can he achieved with a continuous single-mode motion that satisfies mode-specific constraints (e.g. dynamics, kinematic limits, avoid obstacles). Existing techniques can plan well in single modes, but choosing the right mode transitions is difficult. Search-based methods are vastly inefficient due to over-exploration of similar modes. Our new method, Random-MMP, randomly samples mode transitions to distribute a sparse number of modes across configuration space. Results are presented in simulation and on the Honda ASIMO robot.
In this paper, we address the cooperative towing of payloads by multiple mobile robots that move in the plane. Robots pull via cables attached to an object or a pallet carrying a payload and they coordinate their moti...
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ISBN:
(纸本)9783642003110
In this paper, we address the cooperative towing of payloads by multiple mobile robots that move in the plane. Robots pull via cables attached to an object or a pallet carrying a payload and they coordinate their motion to manipulate the payload through a planar, warehouse-like environment. We formulate a quasi-static model for manipulation and derive equations of motion that yield the motion of the payload for a prescribed motion of the robots in the presence of dry friction and tension constraints. We derive conditions of stable equilibrium for one, two, and three or more robots towing the payload and propose abstractions for the task that lend themselves to simple algorithms for motion planning. We present simulation and experimental results that demonstrate the basic concepts.
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