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 robust controller has very simple structures and can be divided into two separate parts: a servo controller and an auxiliary controller. The two controllers are designed independently. The function of the auxiliar...
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The robust controller has very simple structures and can be divided into two separate parts: a servo controller and an auxiliary controller. The two controllers are designed independently. The function of the auxiliary controller is to cancel out the plant uncertainties directly without the use of the high loop gain principle. Interpretation of robot controller as a signal-synthesis adaptive controller is given. Practical implementation issues of the auxiliary controller are discussed. Simulations of a design example with large parameter uncertainty, nonlinearity, and external disturbance are presented to demonstrate the effectiveness of the design technique. This technique is further tested with success in an experimental study of joint position control of a PUMA 560 robot arm.< >
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.
A hardware and software methodology for the design of the three interactive levels of intelligent robotic systems is proposed. The organization level is modeled as an expert system, the coordination level as a loosely...
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The paper considers the problem of using reduced-order models for robot control. A feedback linearizing and decoupling transformation (FLDT) is first developed and applied to the full-order robot model. Then it is sho...
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This paper presents a new algorithm for determining the position and orientation of objects. The problem is formulated as an optimization problem using dual number quaternions. It is shown that this reduces to an eige...
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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.
This paper describes the realization of an expert system prototype of a robot task planning system used for automatic assembly of simple structures. The system involves a module which learns and identifies physical de...
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This paper describes the realization of an expert system prototype of a robot task planning system used for automatic assembly of simple structures. The system involves a module which learns and identifies physical descriptions from functional definitions in order to help the user to specify the tasks s(he) wants to achieve. The output of the system is a sequence of main goals which are decomposed in a set of elementary manipulation actions, and ensure the satisfaction of the assembly task specifications. Two other supplementary modules are also included; the first for describing the items to be assembled only by their functional characteristics, and the second for dealing with space problems, such as the problem of finding free place for putting an item out of the way. The system is written in C-Prolog of a VAX 11/750, and has been tested in several cases
An adaptive controller is presented for the coordinated motion control of two manipulators handling an object of unknown mass. Global convergence in tracking of both position and internal force trajectories of the obj...
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An adaptive controller is presented for the coordinated motion control of two manipulators handling an object of unknown mass. Global convergence in tracking of both position and internal force trajectories of the object is proved, assuming perfect models for both manipulators. The computational algorithm is similar to the Newton-Euler inverse dynamics algorithm with complexity linear in the number of links in the manipulators. A significant feature of the control method is that both manipulators use the identical computational algorithm. Thus, the concept of master/slave relationship between the two manipulators is avoided. Two simulations are presented. The first assumes an ideal model for each manipulator. As expected, the controller is stable and provides excellent tracking ability of the manipulator. The second simulation investigates the effects of modeling errors in the mass properties of each arm. The position trajectories track very close to their desired values; however, they never completely converge.< >
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