1.
Berbyuk, Viktor, 1953, et al.
(författare)
Speed optimization of transport motion of a portal robot
1992
Ingår i: Soviet journal of computer and systems sciences. - 0882-4002. ; 30:1, s. 94-108
Tidskriftsartikel (refereegranskat) abstract
An algorithm for calculating piecewise-constant control with modulo-limited components is proposed for a nonlinear model of a three-degree portal robot; this control contains two switching points and drives the dynamical system from an arbitrary given initial state to an arbitrary given final phase state in a finite time. Underlying the algorithm is a solution of the speed problem for controlled motion of a mass point in n-dimensional Euclidean space with modulo-limited components of the control vector. It is demonstrated that this solution is nontrivial for non-zero phase velocities at the beginning and end of the control process. The algorithm for solving a nonlinear problem yields a practical speed-optimized control in this simple class of control actions while, in certain cases, where the initial and final conditions are given, it also yields a control in a class of arbitrary piecewise continuous controls. The effectiveness of the algorithm is confirmed by numerical examples.
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4.
Sagatun, Svein I., et al.
(författare)
Optimal and Adaptive Control of Underwater Vehicles
1994
Ingår i: IFAC Proceedings Volumes. ; 27:14, s. 953-958
Tidskriftsartikel (refereegranskat) abstract
This article contains a continuous-time optimal and adaptive control scheme for underwater vehicles moving in six degrees of freedom. The control scheme is an extension of the algorithm in Johansson (1990). The algorithm is optimal in the sense that it minimizes the state errors and the forces which contributes to the vehicle’s kinetic energy that is spend to correct these errors. The performance measure does also contain a term which penalizes the quadratic tracking errors proportional to the rate of energy which dissipates from the system due to damping.
5.
Brunnström, Kjell, et al.
(författare)
Scale and Resolution in Active Analysis of Local Image Structure
1990
Ingår i: Image and Vision Computing. - : Elsevier. ; 8:4, s. 289-296
Tidskriftsartikel (refereegranskat) abstract
Focus-of-attention is extremely important in human visual perception. If computer vision systems are to perform tasks in a complex, dynamic world they will have to be able to control processing in a way that is analogous to visual attention in humans. Problems connected to foveation (examination of selected regions of the world at high resolution) are examined. In particular, the problem of finding and classifying junctions from this aspect is considered. It is shown that foveation as simulated by controlled, active zooming in conjunction with scale-space techniques allows for robust detection and classification of junctions.
6.
Lindeberg, Tony, 1964-
(författare)
Scale-space for discrete signals
1990
Ingår i: IEEE Transactions on Pattern Analysis and Machine Intelligence. - : IEEE Computer Society. - 0162-8828 .- 1939-3539. ; 12:3, s. 234-254
Tidskriftsartikel (refereegranskat) abstract
This article addresses the formulation of a scale-space theory for discrete signals. In one dimension it is possible to characterize the smoothing transformations completely and an exhaustive treatment is given, answering the following two main questions:Which linear transformations remove structure in the sense that the number of local extrema (or zero-crossings) in the output signal does not exceed the number of local extrema (or zero-crossings) in the original signal?How should one create a multi-resolution family of representations with the property that a signal at a coarser level of scale never contains more structure than a signal at a finer level of scale?It is proposed that there is only one reasonable way to define a scale-space for 1D discrete signals comprising a continuous scale parameter, namely by (discrete) convolution with the family of kernels T(n; t) = e^{-t} I_n(t), where I_n are the modified Bessel functions of integer order. Similar arguments applied in the continuous case uniquely lead to the Gaussian kernel.Some obvious discretizations of the continuous scale-space theory are discussed in view of the results presented. It is shown that the kernel T(n; t) arises naturally in the solution of a discretized version of the diffusion equation. The commonly adapted technique with a sampled Gaussian can lead to undesirable effects since scale-space violations might occur in the corresponding representation. The result exemplifies the fact that properties derived in the continuous case might be violated after discretization.A two-dimensional theory, showing how the scale-space should be constructed for images, is given based on the requirement that local extrema must not be enhanced, when the scale parameter is increased continuously. In the separable case the resulting scale-space representation can be calculated by separated convolution with the kernel T(n; t).The presented discrete theory has computational advantages compared to a scale-space implementation based on the sampled Gaussian, for instance concerning the Laplacian of the Gaussian. The main reason is that the discrete nature of the implementation has been taken into account already in the theoretical formulation of the scale-space representation.
7.
Sparr, Gunnar, et al.
(författare)
Discontinuity preserving visual reconstruction by means of potential theory
1990
Ingår i: Pattern Recognition Letters. - 0167-8655. ; 11:2, s. 117-122
Tidskriftsartikel (refereegranskat) abstract
Discontinuity preserving interpolation methods are often desirable in image reconstruction from sparse visual data. Two such schemes are constructed by interpreting the image as the potentialcause by some distribution of charges, and then detecting certain patterns (notably dipole curves) among the charges. Experiments have been performed on an ink-jet plotter, showing good performance.
8.
Bolmsjö, Gunnar, et al.
(författare)
Task planning for welding applications
1993
Ingår i: Systems, Man and Cybernetics : Systems Engineering in the Service of Humans - Systems Engineering in the Service of Humans. - 0780309111 ; , s. 515-519
Konferensbidrag (refereegranskat) abstract
Welding robots that use sensors to compensate for variations in their environment pose new requirements for programming systems and for controller architectures. Tracking sensors must be programmed with the geometry of the welds and the motions of the robot. The process monitoring system must be programmed with the required process tolerances and the type of weld. Finally, the controller must be programmed with the motion parameters, velocity and end-pose. Task planning for welding applications is the specification of the geometrical and the technological parameters that are necessary to the above subsystems. The architecture of the controller also must be process-related to allow the flow of planning information to the different subsystems and the necessary feedback to the planning level. Data from the sensors must be used with path data, process information and the geometry of the welds to adjust the process in real time. This article describes the requirements of process-related programming and real-time control of industrial robots based on sensor data.
9.
Nikoleris, Giorgos, et al.
(författare)
Task oriented robot programming and control
1994
Ingår i: EURISCON 94 : Proceedings of the European Robotics and Intelligent Systems Conference - Proceedings of the European Robotics and Intelligent Systems Conference.
Konferensbidrag (refereegranskat)
10.
