The authors extend their previous effort in visualizing the spatial aspect of relativistic effects, and treat the phenomenon of time dilation, an inherent temporal effect of special relativity. Here, the authors demon...
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The authors extend their previous effort in visualizing the spatial aspect of relativistic effects, and treat the phenomenon of time dilation, an inherent temporal effect of special relativity. Here, the authors demonstrate through still-frame images and live animations that, in observing the viewing-independent time dilation, the finite light transit time involved in performing the observation makes the observed time dilation also depend on the viewing condition. As the authors introduce the physics of special relativity into ray-tracing and make time to pass as a ray travels through space, they are able to link the spatial and temporal dimensions in a fundamental and consistent way in their simulations, and generate images that reveal the spatial and temporal properties of the 4D geometry of spacetime. The present exploration highlights the interplay of the imaging process and the imaged physical events in producing the final images.< >
In this paper, a dynamic model of a robot manipulator is first derived based on the Euler-Lagrange equation and a state-space representation is derived for it. A number of non-adaptive robot control schemes are then r...
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In this paper, a dynamic model of a robot manipulator is first derived based on the Euler-Lagrange equation and a state-space representation is derived for it. A number of non-adaptive robot control schemes are then reviewed. A robust decentralized control is then proposed for a 5-axis robot manipulator. Numerical simulation results are presented to verify the theory.
The applicability of transputers in controlsystems is investigated. This is done by implementing a controller for a flexible robot arm with one degree of freedom on a system consisting of an IBM-AT and four transpute...
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The applicability of transputers in controlsystems is investigated. This is done by implementing a controller for a flexible robot arm with one degree of freedom on a system consisting of an IBM-AT and four transputers. It is found that a control system with transputers offers a great improvement compared with conventional digital controlsystems. Transputers can solve the common problem in control practice, i.e. having very sophisticted controllers but not being able to implement them because they need too much computing time. However, transputers are not an optimal solution for more sophisticated controlsystems because of shortcomings in the scheduling mechanism.
control of tool-workpiece interaction force is of vital importance in automated assembly. Using a simple linear continuous model of an edge-following system to predict the appropriate accomodation gains in a force con...
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control of tool-workpiece interaction force is of vital importance in automated assembly. Using a simple linear continuous model of an edge-following system to predict the appropriate accomodation gains in a force control loop, previous work has shown that force control by accomodation is feasible. Following up this work, this paper describes the analysis, simulation and implementation of an adaptive force control in a two-dimensional edge-following task with a PUMA 560 robot and wrist force sensor. First, a discrete-time model of an edge-following system is developed and then used as the plant; second, a model reference adaptive control (MRAC) scheme is applied to achieve both tracking and regulation purposes. The reference (tracking) model can be determined by experimental reference input and desired model output information; the reference (regulation) model can be obtained by simulation to smooth out the plant output and improve the augmented filtered plant-model error. Study is done on the values of the adaptation gains in the adaptive mechanism, and hence can be adjusted to insure the best plant output performance.
An intelligent robotic system for multi-sensor based tracking and interception of moving objects which travel at unknown velocities is presented. The capability for multi-sensor assisted object tracking has been achie...
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ISBN:
(纸本)9780819400383
An intelligent robotic system for multi-sensor based tracking and interception of moving objects which travel at unknown velocities is presented. The capability for multi-sensor assisted object tracking has been achieved through the development of techniques to track in multiple dimensions for both the static and dynamic cases. These methods are realized via the fusion of the best attributes of visual and acoustic sensing into an effective configuration that is ideal for real time tracking purposes. The kinematic information for a moving object is extracted via end effector mounted vision and ultrasonic sensors. A hybrid position/force servo-controlled gripper developed at NCSU has been used for the system implementation. One parallel actuation gripper finger houses a fiber optics based Eye-in-Hand vision sensor, while the other accommodates an ultrasonic range sensor. The primary intent of this work is to develop approaches for performing the tasks of: generalized visual/ultrasonic tracking of known rectangular entities;3-D tracking of arbitrary pseudo-planar objects that can change orientation about the optical axis;and a real time paradigm for the tracking of motion in 3-D with variable orientation about the optical axis. This discussion includes both a description of the underlying principles and the initial experimental results.
The problem of automatically generating the possible 3-D sensor locations for observing a scene is defined, and an approach to its solution is presented. The approach taken assumes that the sensor characteristics are ...
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The problem of automatically generating the possible 3-D sensor locations for observing a scene is defined, and an approach to its solution is presented. The approach taken assumes that the sensor characteristics are well understood and that objects expected in the scene are known and modeled. Then, given a set of constraints, a set of actions is specified directing a robot arm to position itself in such a manner that an attached 3-D sensor located in the robot gripper yields the maximum information content with minimum effort with respect to the constraints. Techniques that yield solutions for placement of a triangulation-type 3-D laser range finder are presented.< >
In this paper, the Linear Constrained Regulation Problem for continuous-time systems will be studied and a design algorithm for a linear constrained feedback controller will be developed. Both state and control vector...
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In this paper, the Linear Constrained Regulation Problem for continuous-time systems will be studied and a design algorithm for a linear constrained feedback controller will be developed. Both state and control vectors are assumed to be subjected to linear constraints The approach presented, is based on the notion of positive invariance of polyhedral sets. Existence conditions for a control law that transfers asymptotically to the origin all initial states in a polyhedral subset of the state space is formulated. Then, a solution to the LCRP is derived solving a non-linear optimization problem
In this paper several techniques are given for the identification of stable LSI discrete time systems from input-output data. Explicit H ∞ norm error bounds are given and convergence in the noise free and the unifor...
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In this paper several techniques are given for the identification of stable LSI discrete time systems from input-output data. Explicit H ∞ norm error bounds are given and convergence in the noise free and the uniformly bounded deterministic noise case are established. The assumptions made on the unknown system are minimal and are limited throughout the paper to a lower bound on the decay rate of the unknown system and an upper bound on the gain of the unknown system. Given this information an experiment and a construction are specified: the experiment involves obtaining a specified number of frequency measurements of the unknown systems at a set of specified frequencies; the construction uses this experimental data to generate an identified model with prescribed H ∞ norm error tolerance to the unknown system. The resulting model identification process is highly efficient from a computational point of view.
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