关键词： Elastic joint drive   Compliant joint   Elasticity   Elastomer coupling   Compliance identification   System modeling  

摘要： While classical robotics traditionally makes use of stiff constructions in order to achieve a high precision, there is on-going research in development and control of new compliant robotic systems. These systems are suitable for direct human-machine-interaction due to their elastic behavior. The compliance is mostly achieved by control or by the integration of steel springs into the joint drives. This paper proposes a novel approach based on a sensorized elastomer coupling. Due to its damping characteristics, the interaction-safety can be improved in comparison to steel spring or purely control based approaches. The presented coupling is an integral part of a self-contained drive system which is also introduced. Simulation results of the strain/torsion and torque/torsion relationship for different geometrical variations of the elastomer coupling and experimental data of a prototype are presented. Since the sensorized coupling provides torsion measurements of the elastomer inlay, a system identification approach was employed to derive nonlinear and linear models of the coupling which can later be used in model-based joint-control. (C) 2013 Elsevier B.V. All rights reserved.

关键词： 摘钩机器人   运动学   动力学分析   仿真  

摘要： 针对编组站驼峰摘钩问题,设计一种三自由度行走式摘钩机器人。在上关节处建立各连杆的坐标系,用D-H参数法推导出机器人的运动学方程,同时用拉格朗日法建立机器人的动力学方程。在Pro/E软件中建立摘钩机器人的三维模型,并将其导入ADAMS软件进行动力学仿真,得到摘钩机器人各关节的力/力矩-时间曲线。与理论计算结果进行对比,表明所建立的摘钩机器人的动力学方程是正确的,进而说明该摘钩机器人的结构可行。

关键词： Active contours   3D segmentation   3D reconstruction   Robot vision systems   RGB-D sensors  

摘要： In this paper, a simultaneous 3D volumetric segmentation and reconstruction method, based on the so-called Generic Fitted Shapes (GFS) is proposed. The aim of this work is to cope with the lack of volumetric information encountered in visually controlled mobile manipulation systems equipped with stereo or RGB-D cameras. Instead of using primitive volumes, such as cuboids or cylinders, for approximating objects in point clouds, their volumetric structure has been estimated based on fitted generic shapes. The proposed GFSs can capture the shapes of a broad range of object classes without the need of large a-priori shape databases. The fitting algorithm, which aims at determining the particular geometry of each object of interest, is based on a modified version of the active contours approach extended to the 3D Cartesian space. The proposed volumetric segmentation system produces comprehensive closed object surfaces which can be further used in mobile manipulation scenarios. Within the experimental setup, the proposed technique has been evaluated against two state-of-the-art methods, namely superquadrics and 3D Object Retrieval (3DOR) engines. (C) 2013 Elsevier B.V. All rights reserved.

关键词： Reinforcement learning   learning control   robot   survey  

摘要： Reinforcement learning offers to robotics a framework and set of tools for the design of sophisticated and hard-to-engineer behaviors. Conversely, the challenges of robotic problems provide both inspiration, impact, and validation for developments in reinforcement learning. The relationship between disciplines has sufficient promise to be likened to that between physics and mathematics. In this article, we attempt to strengthen the links between the two research communities by providing a survey of work in reinforcement learning for behavior generation in robots. We highlight both key challenges in robot reinforcement learning as well as notable successes. We discuss how contributions tamed the complexity of the domain and study the role of algorithms, representations, and prior knowledge in achieving these successes. As a result, a particular focus of our paper lies on the choice between model-based and model-free as well as between value-function-based and policy-search methods. By analyzing a simple problem in some detail we demonstrate how reinforcement learning approaches may be profitably applied, and we note throughout open questions and the tremendous potential for future research.

关键词： Swarm robotics   Modelling   Bio-PEPA   Fluid flow analysis   Statistical model checking  

摘要： In this paper we analyse a swarm robotics system using Bio-PEPA. Bio-PEPA is a process algebra language originally developed to analyse biochemical systems. A swarm robotics system can be analysed at two levels: the macroscopic level, to study the collective behaviour of the system, and the microscopic level, to study the robot-to-robot and robot-to-environment interactions. In general, multiple models are necessary to analyse a system at different levels. However, developing multiple models increases the effort needed to analyse a system and raises issues about the consistency of the results. Bio-PEPA, instead, allows the researcher to perform stochastic simulation, fluid flow (ODE) analysis and statistical model checking using a single description, reducing the effort necessary to perform the analysis and ensuring consistency between the results. Bio-PEPA is well suited for swarm robotics systems: by using Bio-PEPA it is possible to model distributed systems and their space-time characteristics in a natural way. We validate our approach by modelling a collective decision-making behaviour.

关键词： Dataset   autonomous driving   mobile robotics   field robotics   computer vision   cameras   laser   GPS   benchmarks   stereo   optical flow   SLAM   object detection   tracking   KITTI  

摘要： We present a novel dataset captured from a VW station wagon for use in mobile robotics and autonomous driving research. In total, we recorded 6 hours of traffic scenarios at 10-100 Hz using a variety of sensor modalities such as high-resolution color and grayscale stereo cameras, a Velodyne 3D laser scanner and a high-precision GPS/IMU inertial navigation system. The scenarios are diverse, capturing real-world traffic situations, and range from freeways over rural areas to inner-city scenes with many static and dynamic objects. Our data is calibrated, synchronized and timestamped, and we provide the rectified and raw image sequences. Our dataset also contains object labels in the form of 3D tracklets, and we provide online benchmarks for stereo, optical flow, object detection and other tasks. This paper describes our recording platform, the data format and the utilities that we provide.

摘要： Improvements in efficiency and usability of robotic systems are increasingly being explored. In the paper by Simaan et al., a robotic system for single port access undergoes preliminary evaluation, demonstrating its design and functionality for basic tasks in minimally invasive surgery, manipulation, knot tying and visualisation/tracking. Given the increased use of robotic systems, it is important to monitor and assess the surgeon’s skills as well as the technical developments.

关键词： Wireless Networked Robotics System   Search and rescue   Complex environments   Mobile ad hoc networks   Experimental and prototype results   Wireless Backbone Deployment  

摘要： A Wireless Networked Robotics System can assist in settings that lack infrastructure e.g., urban search and rescue. A team of networked mobile robots can provide a communication substrate in those settings by acting as routers in a wireless mesh network. We study the problem of deploying a few mobile robots, and how to position them, so that all clients using the resulting robotic network are connected and all network links satisfy minimum rate requirements. The key challenge we address is that in an environment with obstacles the strength of a wireless link is a non-monotonic function of the distance between the link end-points. The problem is thus fundamentally one of making router placement decisions in a non-metric space. Our approach to the problem is based on virtual potential fields. Clients and environmental obstacles are modeled as virtual charged particles exerting virtual forces on the robots. We validate our algorithm with physical robots in an indoor environment and demonstrate that we are able to get feasible solutions. (C) 2012 Elsevier B.V. All rights reserved.

关键词： Contact modeling   Mobility   Surgery   Biomechanics   Tissue engineering  

摘要： Wheel-driven mobile in vivo robotic devices can provide an unconstrained platform for visualization and task performance. Careful understanding of the wheel-tissue interaction is necessary to predict in vivo performance of medical mobility systems. Here, an analytical study of the friction involving rolling contact of a surgical wheel, moving at constant velocities over soft tissue, is presented and verified. A quasi-static frictionless solution is first derived from existing theory, and newly developed theory considering frictional effects is later introduced. In this analysis, the effect of friction on wheel mobility over a viscoelastic substrate is analyzed with wheel velocity as the only changing variable. The analytical model is later verified by experiments and Finite Element Method (FEM) simulations. A simple application of this model to help design a surgical robot is also presented. Additional results indicate that the resistance force, which arises from the tissue viscosity, approaches zero for small and very large wheel velocities. (C) 2013 IPEM. Published by Elsevier Ltd. All rights reserved.