The kinematic path planning problem of a nonholonomic system can be posed as a point-to-point control problem of a nonlinear system. This system has the property that it is not locally stabilizable but is globally con...
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The kinematic path planning problem of a nonholonomic system can be posed as a point-to-point control problem of a nonlinear system. This system has the property that it is not locally stabilizable but is globally controllable. In this paper, we present a new algorithm for constructing a feasible path between specified initial and final configurations. Polyhedral constraints in both configuration and non-configuration spaces (possibly non-convex) can also be incorporated in this framework. The algorithm is based on the assumption that the system is usually controllable about a non-trivial trajectory, which is true for many cases. An initial trajectory is iteratively warped until the desired final configuration is reached. Examples of a front-wheel driven car, and tractors with one, two, and three trailers are included to illustrate the efficacy of the proposed algorithm.
A hierarchical stereo system is described that uses structural descriptions up to the surface level. Surface descriptions are computed from monocular images, by using a perceptual grouping technique. Occlusion can be ...
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A hierarchical stereo system is described that uses structural descriptions up to the surface level. Surface descriptions are computed from monocular images, by using a perceptual grouping technique. Occlusion can be a major problem in stereo analysis and is often not treated explicitly. An analysis is presented of occlusion effects in stereo, and it is shown how structural descriptions can be used to deal with them. Experimental results are given for scenes with curved objects and significant occlusions.< >
The reduction of the state space of generalized stochastic Petri net (GSPN) models is discussed. For a certain class of GSPNs it is possible to analyze subnets in isolation by keeping the number of tokens in the net c...
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The reduction of the state space of generalized stochastic Petri net (GSPN) models is discussed. For a certain class of GSPNs it is possible to analyze subnets in isolation by keeping the number of tokens in the net constant. The authors construct a flow equivalent net (FEN), which has the same temporal and input/output properties of the original net, but with a strongly reduced state space. The FEN is substituted back into the complement of the original net.< >
A new approach to solving the collision detection problem for mobile robots in the presence of moving obstacles is proposed. Both the robot and obstacles in the two-dimensional space are assumed to be polygonal and ar...
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A new approach to solving the collision detection problem for mobile robots in the presence of moving obstacles is proposed. Both the robot and obstacles in the two-dimensional space are assumed to be polygonal and are composed of a set of convex polygons. The half-plane representation uses an algebraic method to describe the object motion including translation and rotation through time. Compared with previous methods, the proposed representation is more general in that obstacles are now allowed to move at nonconstant velocities. To detect collision between polygonal objects, a traversability vector method was developed. Traversability vectors are a simple mechanism used to analyze geometric constraints imposed by polygons. Using these vectors, a simple algorithm for predicting collision is derived. computer simulations were conducted to show the feasibility of the proposed method.< >
In this paper, a multi-objective approach to controller tuning is described. An algorithm for implementation of this tuning is given. This approach has the following merits: there is no restriction on the type or numb...
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In this paper, a multi-objective approach to controller tuning is described. An algorithm for implementation of this tuning is given. This approach has the following merits: there is no restriction on the type or number of performance criteria; no a 'priori weights need be chosen since performance criteria are not combined into a single objective function. The intention is that the algorithm is implemented to run in real-time so as to provide immediate feedback to a process operator about the current operating point. If the current operating point is not Pareto optimal, the algorithm can automatically adjust the parameters to achieve this. If it is Pareto optimal but not desirable, the algorithm can provide information on how trade-offs can be made so that the desired operating point is achieved. The algorithm is applied to the tuning of a PID controller for the plastication phase of an injection molding process. An analytic model for this process is presented. Experiments are described in which data was collected from this process, and an empirical discrete-time transfer function was identified. This transfer function was then used, within a simulation, to allow the algorithm to tune the controller, with respect to two objective functions. The tradeoff curve for these objectives, and corresponding controller gains is presented.
The design and implementation of flexible manufacturing systems require the planning of task requirements to meet standards of reliability, cost, and throughput over a family of products. Tools for computer-aided engi...
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Wc have developed an innovative ray-tracing simulation algorithm to describe Welativistic Effects in SpaceTime ("REST"). Our algorithm, called REST-frame, models light rays that have assumed infinite speed i...
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An intelligent externally powered orthotic system (exoskeleton) for the treatment of motor dysfunctions of the upper extremities of stroke patients is described. IROS is an interactive and cooperative human-machine sy...
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An intelligent externally powered orthotic system (exoskeleton) for the treatment of motor dysfunctions of the upper extremities of stroke patients is described. IROS is an interactive and cooperative human-machine system, with both controlling the human arm. Initially, the machine is the main controller of the arm. As the patient improves, the human control of the arm increases, and the machine control of the arm decreases. The system combines the skills of professional therapists with a sensor-integrated orthosis and a real-time graphics system to ensure proper interaction and cooperation with the patient in order to achieve the goals of therapy. It uses the expertise of the therapists, which is incorporated into its knowledge system, while monitoring the sensory information from the patient, including the force, motion, and electromyogram (EMG) signals. The treatment-related tasks are displayed on the real-time graphic system to increase the interest and enhance the motivation of the patient. Such a system can be used to improve the rehabilitation process for stroke patients.< >
This work extends our previous effort in visualizing the spatial aspect of relativistic effects, and treats the phenomenon of time dilation; an inherent temporal effect of special ***, we demonstrate through still-fra...
ISBN:
(纸本)9780897914123
This work extends our previous effort in visualizing the spatial aspect of relativistic effects, and treats the phenomenon of time dilation; an inherent temporal effect of special ***, we 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 *** we introduce the physics of special relativity into ray-tracing and make time to pass as a ray travels through space, we are able to link the spatial and temporal dimensions in a fundamental and consistent way in our simulations, and generate images that reveal the spatial and temporal properties of the 4D geometry of *** exploration highlights the interplay of the imaging process and the imaged physical events in producing the final images. It reveals a richly detailed physical reality which the mathematical language of thought experiment in relatively does not directly provide.
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