Shadow-driven 4D haptic visualization

Just as we can work with two-dimensional floor plans to communicate 3D architectural design, we can exploit reduced-dimension shadows to manipulate the higher-dimensional objects generating the shadows. In particular, by taking advantage of physically reactive 3D shadow-space controllers, we can transform the task of interacting with 4D objects to a new level of physical reality. We begin with a teaching tool that uses 2D knot diagrams to manipulate the geometry of 3D mathematical knots via their projections; our unique 2D haptic interface allows the user to become familiar with sketching, editing, exploration, and manipulation of 3D knots rendered as projected imageson a 2D shadow space. By combining graphics and collision-sensing haptics, we can enhance the 2D shadow-driven editing protocol to successfully leverage 2D pen-and-paper or blackboard skills. Building on the reduced-dimension 2D editing tool for manipulating 3D shapes, we develop the natural analogy to produce a reduced-dimension 3D tool for manipulating 4D shapes. By physically modeling the correct properties of 4D surfaces, their bending forces, and their collisions in the 3D haptic controller interface, we can support full-featured physical exploration of 4D mathematical objects in a manner that is otherwise far beyond the experience accessible to human beings. As far as we are aware, this paper reports the first interactive system with force-feedback that provides "4D haptic visualization" permitting the user to model and interact with 4D cloth-like objects.     

Development of an Intelligent Wheelchair Using Computer Graphics Animation and Simulation

A new robot simulator JC-1 is used as a control software development tool in a project in progress where an intelligent wheelchair for a blind user is being developed. The intelligent wheelchair is planned to be able to fulfill simple symbolic commands like "follow wall" or "follow object" and using the JC-1 simulator an evaluation team which includes e.g. the user, a rehabilitation engineer and a software engineer, can check control algorithms and user interface routines before constructing a real wheelchair prototype. The JC-1 simulator models the environment using simplified boundary- representation where objects, robot sensors and actuators are presented as symbolic objects in the graphics data-base of the simulator. In the JC-1 simulator a robot controller under development controls the motion of the graphical model of the robot while simulator commands or other robot controllers can be used to control the movement of disturbing obstacles. Computer graphics animation and simulation help to find fundamental design errors at an early design stage and as this paper suggests, enable the user of the final product to take part in to the designing process of the robot controller. Benefits and difficulties of using computer graphics simulation in the wheelchair development process are discussed.     

Combining physically-based simulation of colliding objects with trajectory control

This paper describes a method that facilitates the use of physically-based models by animators. The main point is to give the animator a familiar interface, while providing a simulation module which detects collisions, thus enhancing realism. The user gives a set of key-frames to guide motion, but does not have to address problems such as interpenetration avoidance, deformations due to collisions, or realism of motion. The simulator will correct the trajectories and compute deformations according to each object's physical properties (such as mass, inertia, stiffness) as well as the collisions and contacts automatically detected during motion. To achieve this, objects are provided with actuators capable of generating forces and torques computed via generalized proportional-derivative controllers. When deflected by external actions, actuated objects try to return to their initial path. Speed variations over time are computed during the simulation, and depend on the complexity of the paths, on the objects models, and on the events such as collisions occurring during motion. In addition simulations are generated at interactive rates, even in the case of complex articulated objects. This facilitates the fine tuning of an animation sequence.     

Simultaneous remote haptic collaboration for assembling tasks

Stand-alone virtual environments (VEs) using haptic devices have proved useful for assembly/disassembly simulation of mechanical components. Nowadays, collaborative haptic virtual environments (CHVEs) are also emerging. A new peer-to-peer collaborative haptic assembly simulator (CHAS) has been developed whereby two users can simultaneously carry out assembly tasks using haptic devices. Two major challenges have been addressed: virtual scene synchronization (consistency) and the provision of a reliable and effective haptic feedback. A consistency-maintenance scheme has been designed to solve the challenge of achieving consistency. Results show that consistency is guaranteed. Furthermore, a force-smoothing algorithm has been developed which is shown to improve the quality of force feedback under adverse network conditions. A range of laboratory experiments and several real trials between Labein (Spain) and Queen’s University Belfast (Northern Ireland) have verified that CHAS can provide an adequate haptic interaction when both users perform remote assemblies (assembly of one user’s object with an object grasped by the other user). Moreover, when collisions between grasped objects occur (dependent collisions), the haptic feedback usually provides satisfactory haptic perception. Based on a qualitative study, it is shown that the haptic feedback obtained during remote assemblies with dependent collisions can continue to improve the sense of co-presence between users with regard to only visual feedback.     

Manipulation Planning for Deformable Linear Objects

Research on robotic manipulation has mainly focused on manipulating rigid objects so far. However, many important application domains require manipulating deformable objects, especially deformable linear objects (DLOs), such as ropes, cables, and sutures. Such objects are far more challenging to handle, as they can exhibit a much greater diversity of behaviors, and their manipulation almost inevitably requires two robotic arms, or more, performing well-coordinated motions. This paper describes a new motion planner for manipulating DLOs and tying knots (both self-knots and knots around simple static objects) using two cooperating robotic arms. This planner blends new ideas with preexisting concepts and techniques from knot theory, robot motion planning, and computational modeling. Unlike in traditional motion planning problems, the goal to be achieved by the planner is a topological state of the world, rather than a geometric one. To search for a manipulation path, the planner constructs a topologically biased probabilistic roadmap in the configuration space of the DLO. During roadmap construction, it uses inverse kinematics to determine the successive robot configurations implied by the DLO configurations and tests their feasibility. Also, inspired by the real life, the planner uses static ldquoneedlesrdquo (by analogy to the needles used in knitting) for maintaining the stability of the DLO during manipulation and to make the resulting manipulation plan robust to imperfections in the physical model of the DLO. The implemented planner has been tested both in graphic simulation and on a dual-PUMA-560 hardware platform to achieve various knots, like bowline, neck-tie, bow (shoe-lace), and stun-sail.     

Near-future perception system: Previewed Reality

ABSTRACT

The present paper introduces a near-future perception system called Previewed Reality. In a co-existence environment of a human and a robot, unexpected collisions between the human and the robot must be avoided to the extent possible. In many cases, the robot is controlled carefully so as not to collide with a human. However, it is almost impossible to perfectly predict human behavior in advance. On the other hand, if a user can determine the motion of a robot in advance, he/she can avoid a hazardous situation and exist safely with the robot. In order to ensure that a user perceives future events naturally, we developed a near-future perception system named Previewed Reality. Previewed Reality consists of an informationally structured environment, a VR display or an AR display, and a dynamics simulator. A number of sensors are embedded in an informationally structured environment, and information such as the position of furniture, objects, humans, and robots, is sensed and stored structurally in a database. Therefore, we can forecast possible subsequent events using a robot motion planner and a dynamics simulator and can synthesize virtual images from the viewpoint of the user, which will actually occur in the near future. The viewpoint of the user, which is the position and orientation of a VR display or an AR display, is also tracked by an optical tracking system in the informationally structured environment, or the SLAM technique on an AR display. The synthesized images are presented to the user by overlaying these images on a real scene using the VR display or the AR display. This system provides human-friendly communication between a human and a robotic system, and a human and a robot can coexist safely by intuitively showing the human possible hazardous situations in advance.     

Experiences with component‐oriented technologies in nuclear power plant simulators

This paper proposes the application of modern component‐oriented technologies to the development of nuclear power plant simulators. On the one hand, as a significant improvement on previous simulators, the new kernel is based on the Common Component Architecture (CCA). The use of such a high‐performance computing oriented component technology, together with a novel algorithm to automatically resolve simulation data dependencies, allows the efficient execution of both parallel and sequential simulation models. On the other hand, RT‐CORBA is employed in the development of the rest of the applications that comprise the simulator. This real‐time communication middleware not only makes the management of communications easier, but also provides the applications with real‐time capabilities. Software components used in these two ways, simulation models integrating the kernel and distributed applications from which the simulator is comprised, improve the evolution and maintenance of the entire system, as well as promoting code reusability in other projects. Copyright © 2006 John Wiley & Sons, Ltd.     

一种卫星半实物模拟训练等效器的设计与实现

由于在实装上进行卫星地面测试的日常训练可能会造成设备的严重损耗,不能用真实卫星作为日常训练对象。通过分析大量卫星的供配电特性,设计半实物供配电设备模拟器,用其代替真实部件引入闭环回路,实现卫星内部供配电分系统的实物等效。以计算机为核心实现数据采集及数据处理系统,并可实时接收遥控指令、模拟生成遥测数据,配合地面测试系统响应测试流程。硬件实物仿真设计了数据采集、信号产生等硬件板卡,实现配电等效、指令等效、测量等效的功能。模拟器整体设计以PXI总线为接口,满足了系统的模块化及通用化设计,可方便实现其他模拟器的组合及扩展。经过现场运行表明及用户实际测试表明,该设备可完全替代卫星供配电分系统实现卫星电气性能模拟,有效配合地面测试人员的日常训练。     

Quantum knots and mosaics

In this paper, we give a precise and workable definition of a quantum knot system, the states of which are called quantum knots. This definition can be viewed as a blueprint for the construction of an actual physical quantum system. Moreover, this definition of a quantum knot system is intended to represent the “quantum embodiment” of a closed knotted physical piece of rope. A quantum knot, as a state of this system, represents the state of such a knotted closed piece of rope, i.e., the particular spatial configuration of the knot tied in the rope. Associated with a quantum knot system is a group of unitary transformations, called the ambient group, which represents all possible ways of moving the rope around (without cutting the rope, and without letting the rope pass through itself.) Of course, unlike a classical closed piece of rope, a quantum knot can exhibit non-classical behavior, such as quantum superposition and quantum entanglement. This raises some interesting and puzzling questions about the relation between topological and quantum entanglement. The knot type of a quantum knot is simply the orbit of the quantum knot under the action of the ambient group. We investigate quantum observables which are invariants of quantum knot type. We also study the Hamiltonians associated with the generators of the ambient group, and briefly look at the quantum tunneling of overcrossings into undercrossings. A basic building block in this paper is a mosaic system which is a formal (rewriting) system of symbol strings. We conjecture that this formal system fully captures in an axiomatic way all of the properties of tame knot theory.     

A virtual environment simulator for mechanical system dynamics with online interactive control

Virtual prototyping is an effective tool in the development of mechanical product. Physically accurate simulation of multi-body mechanical system enables designers to investigate, explore, and experience the performance and behavior of an evolving product and thus reduce the number of physical prototypes needed. For the sake of better support for designers to manipulate the simulation, we have developed a dynamic simulation package of mechanical system, which provides an interactive control during the simulation process. The package incorporates physical behaviors and dynamic interactions by dynamics based modeling approach in multi-body mechanical system. In the package, user’s actions (e.g., loading a model, picking and dragging objects, steering objects during simulation process, etc.) are based on an ATN task management, and a multi-modal interface is provided which supports 2D desktop devices and 3D VR devices. The main contribution of the simulator is providing supports that allow users’ interactive manipulation in the simulation loop. During the simulation process, users can modify the constraints between components, apply force/torque to interested components and change the parameters of forces/torques. The simulator automatically updates the dynamic model of the mechanical system in real time, and then continuously simulates the behavior of the model under the current condition in the loop. An example of dynamic simulation of a vehicle is implemented and the simulation result is compared to that of ADAMS to verify the correctness and accuracy of the simulator. With the real-time interaction, solution and visualization of simulation model, the package affords better support for designers to participate in the simulation interactively and effectively.     

Collision detection in motion simulation

This paper describes a method of detecting collisions in motion simulation. In motion simulation, objects occasionally share a sphere in the simulated world. This would not occur in the real world, since objects would have collided before they shared a common sphere. In order to avoid such sharing and to accurately simulate collisions, a collision detection method called the Space Occupancy Method is proposed here, in which the detection of collisions between free form objects in 3-D space can be made quickly and precisely. An implementation design of the collision detection method and some results of simulations are shown.     

An interactive data-driven driving simulator using motion blending

Compared to the motion equations the data-driven method can simulate reality from sampling of real motions but real-time interaction between a user and the simulator is problematic. Existing data-driven motion generation methods simply record and replay the motion of the vehicle. Character animation technology enables a user to control motions that are generated by a motion capture database and an appropriate motion control algorithm. We propose a data-driven motion generation method and implement a driving simulator by adapting the method of motion capture. The motion data sampled from a real vehicle are transformed into appropriate data structures called motion blocks, and then a series of motion blocks are saved into the motion database. During simulation, the driving simulator searches for and synthesizes optimal motion blocks from the motion database and generates motion streams that reflect the current simulation conditions and parameterized user demands. We demonstrate the proposed method through experiments with the driving simulator.     

平面三次NURBS曲线的自动光顺算法

针对平面三次NURBS曲线的光顺问题，基于节点插入，节点消法和重新确定权因子等技术，给出了平面三次NURBS曲线的一种同算法，算法根据给定的光顺准则，自动选择需要光顺的节点，局部修改控制顶点和权因子。     

Interaction model between elastic objects for haptic feedback considering collisions of soft tissue

The simulation of organ–organ interaction is indispensable for practical and advanced medical VR simulator such as open surgery and indirect palpation. This paper describes a method to represent real-time interaction between elastic objects for accurate force feedback in medical VR simulation. The proposed model defines boundary deformation of colliding elements based on temporary surface forces calculated by temporary deformation. The model produces accurate deformation and force feedback considering collisions of objects as well as prevents unrealistic overlap of objects. A prototype simulator of rectal palpation is constructed on general desktop PC with a haptic device, PHANToM. The system allows users to feel different stiffness of a rear elastic object located behind another elastic object. The results of experiments confirmed the method expresses organ–organ interaction in real-time and produces realistic and perceivable force feedback.     

MulTiSIM: An object-based distributed framework for mission simulation

The MulTiSIM object-based framework for implementing real time simulations is described. This can be used to create a world of interacting objects, distributed over a heterogeneous processing network. Communication between objects is handled by the framework in such a way that the operation of the objects is unaffected by changes to their distribution. A prototype of this framework has been implemented in Ada, augmented by support for object-oriented constructs. This has been used as the foundation for a helicopter mission simulator, operating in real time, some of whose features are also described.     

B样条曲线节点插入和升阶的统一方法

利用 B样条基转换矩阵的有关结果 ,本文给出了 B样条曲线插入节点和升阶的统一方法及算法 .本文方法建立在严密的数学背景上 ,以简洁严谨的递推公式给出其算法的数学模型 ,相应的算法效率高且易实现 ,算法的时间复杂性为 O((k- k 1) kn) ,其中 k,k分别为升阶前后曲线的阶 ,n k 1为插入节点和升阶后的节点数 .而且 ,本文方法及算法使用灵活 ,适用范围广 ,可用于同时插入任意个相同的或不同的节点并升任意阶 ,也可用于只插入节点或只升阶 .Cohen等的 Oslo算法、升阶方法都是本文方法的特例 ,而且本文方法效率更高     

Knotting task execution based a hand-rope relation

In this paper, we focus on relationship between the rope and fingers to implement a knot and estimate error occurred during execution of knotting task. In the previous work, the authors have proposed a method for making various knots from synthesis of basic operations called skills that are derived from analyzing the knotting processes. Each individual skill has an operation to handle the rope and conditions for executing and completing the task skill. By combining these skills, we can make the whole knotting process robust. In this paper, the ‘relations’, which describe the positions of the rope relative to the fingers, found from the successful cases, using the teaching data, were defined as the conditions of the task skills. Relation of rope and fingers at a specific state is presented by using propositional variables and logical connectives. Knotting skills were constructed to be executed robustly using the detected conditions. Occurrence of an error is estimated by finding out an abnormal relation. In this case, a corrective action can be inserted to modify the position of contact points, which are relative to the unsatisfied conditions to satisfy the detected conditions; therefore, skill execution is more reliable. We confirm the effectiveness of the methods through experiments.     

浅谈中国结元素在现代产品设计中的应用

中国结站在一个文化传承的起点上,体现了美与真、善的和谐统一,是内容与形式美的一种结合体。本文回顾了中国结文化的产生与发展,探讨了中国结作为独立符号系统的特性,以及中国结在现实生活中的象征意义,通过本文的研究,总结出中国结元素应用于设计的可行性设计规律,设计出中国结应用于在新的现代产品,从而保护弘扬民族物质文化遗产。     

Physically-based stochastic simplification of mathematical knots

The article describes a tool for simplification and analysis of tangled configurations of mathematical knots. The proposed method addresses optimization issues common in energy based approaches to knot classification. In this class of methods, an initially tangled elastic rope is “charged” with an electrostatic like field which causes it to self repel, prompting it to evolve into a mechanically stable configuration. This configuration is believed to be characteristic for its knot type. We propose a physically based model to implicitly guard against isotopy violation during such evolution and suggest that a robust stochastic optimization procedure, simulated annealing, be used for the purpose of identifying the globally optimal solution. Because neither of these techniques depends on the properties of the energy function being optimized, our method is of general applicability, even though we applied it to a specific potential here. The method has successfully analyzed several complex tangles and is applicable to simplifying a large class of knots and links. Our work also shows that energy based techniques will not necessarily terminate in a unique configuration, thus we empirically refute a prior conjecture that one of the commonly used energy functions (J. Simon, 1994) is unimodal. Based on these results we also compare techniques that rely on geometric energy optimization to conventional algebraic methods with regards to their classification power