Modelling And Experimental Vibration Control Of A Two-link Three-dimensional Manipulator With Flexible Links

Current industrial and space manipulators are required to achieve higher speeds in a lighter structure without sacrificing payload capabilities. Consequently, undesirable vibration occurs during the motion. By suitable modelling of the manipulator flexibility, advanced control strategies can be formulated to improve the joint tracking performance and reduce the residual vibration of the end-point in the presence of payload uncertainties.;Toward this goal, an experimental two-link, 3D, anthropomorphic manipulator with flexible links was designed and built to be used as a test bed for the verification and refinement of the proposed modelling and control strategies.;The nonlinear equations of motion for the robot were derived using Lagrangian dynamics. The model was verified using experimental modal analysis techniques. Based on experimental results, a simplified nonlinear model, that contains the relevant modes of the system, was derived and subsequently used in controller designs and state estimation.;A conventional Proportional-plus-Derivative (PD) controller that implements joint angles feedback was designed to be used as a baseline controller due to its wide applicability on industrial manipulators.;By measuring the links tip vibration using accelerometers, several adaptive controllers and state observers were designed and implemented successfully on the manipulator, namely, a gain-scheduling linear quadratic regulator, a model reference adaptive controller, an adaptive inverse dynamics controller, a least-squares nonlinear state estimator and a robust sliding observer. The controllers performance and robustness were tested and experimentally verified against the change of the payload.;The control strategies and identification techniques, developed in this thesis, are applicable to a wide range of robot manipulators including industrial manipulators

Digital all-computer simulation in managerial problems

Management problems are becoming more and more complex. True scientific management demands the exact consideration of all the factors that are significant to the problem under study. In dealing with practical problems, one cannot tease out separate psychological, economic, or technological aspects as the problem mostly always involves working with a total integrated organizational unit. Due to the abundancy and interrelation of these factors, it made it more difficult if not impossible in many cases to reach a solution by the analytical methods. Thus, many managerial problems if they are to be accurately identified and quantifiably solved, should be simulated. Simulation has become a very important process or tool available to modern managers. But, to be a useful tool, it should be used effectively. Realizing: 1. The usefulness of the simulation process to managers to the point that in many cases it becomes imperative to simulate if a system is to be precisely understood or a problem is to be correctly solved. 2. The degree of controversy that has flared-up about the exact definition of simulation to the point that it has become difficult to state what is simulation and what is not. The researcher has chosen to direct this research towards discovering a practical and systematic approach to simulating managerial problems. There are different types of simulations that are used for different purposes. All types are to be mentioned and defined in this research. But, due to the fact that Digital all-computer simulation is the type mostly used in solving managerial problems, it is to be the purpose of this research. This research has been organized in the following manner: 1. Chapters 1, 2, and 3 explain in detail the concept, definition, and the different phases of the simulation process in order to set the stage for a detailed and practical discussion of a simulation application. 2. Chapter 4 presents an inventory control problem together with its solution via a digital all-computer simulation. The reason behind choosing such a problem is that inventory problems are the most common problems that managers encounter especially in the U.A.R. where inventory control has not received enough attention and where it is the problem to most if not all sectors (Government, public, and private). 3. Appendix I has been added to the research in order to provide the reader with the exact definitions of the terms that are mostly used in such operations. As uncertainty in business is more the rule than the exception, most of its models are proba­bilistic in nature. Appendix II has been added to introduce the elements of the probability theory and the most commonly used and encountered probability distributions to help the simulator in designing, manipulating, and reaching conclusions in such a context

Indoor/Outdoor Air Quality and Children Health Risk Assessment for PM10 and PM2.5 on Urban Areas at Al- Mukalla City, Yemen

Particulate matter was measured inside and outside eight homes within urban areas of Al- Mukalla city, Yemen by Gravimetric analysis using Tuff-Plus 3 Air Sampler. Sources observation and health risk assessment were done using survey. Meteorological parameters and outdoor sources as well as indoor sources of particulate matter were the main producer of indoor particulate matter air pollution, where wind speed and direction showed significant effect on PM10 I/O ratio and positive effect of relative humidity, while negative effect was from temperature. On the other hand, PM2.5 was positively affected by temperature, wind speed and relative humidity and negatively affected by wind direction. Air Quality was classified using health questionnaire air quality index and was confidential as hazardous air over the urban areas of the Al- Mukalla city with extremely high level of PM2.5&PM10 causing respiratory disease and symptoms of wheezing, itchy rash and asthma from the exposure of PM10 rather than the exposure of PM2.5. This is because the PM10I/O ratio was 0.63 higher than PM2.5 ratio of 0.52.In addition to that, PM2.5 andPM10 outdoor concentration were above the WHO and EPA standards, although the outdoor concentration of PM2.5 was higher than that of PM10. Finally, PM2.5& PM10 were derived through migration of outdoor particles since I/OPM10 and PM2.5 were

Humanitarian International Law in Islam: A General Outlook

This article covers the following topics: humanitarian law and humanistic law, general concepts of humanitarian international law in Islam: armed conflict of a non-international nature and armed conflict of an international nature, and wars against polytheists and apostates

Good Codes From Generalised Algebraic Geometry Codes

Algebraic geometry codes or Goppa codes are defined with places of degree one. In constructing generalised algebraic geometry codes places of higher degree are used. In this paper we present 41 new codes over GF(16) which improve on the best known codes of the same length and rate. The construction method uses places of small degree with a technique originally published over 10 years ago for the construction of generalised algebraic geometry codes.Comment: 3 pages, to be presented at the IEEE Symposium on Information Theory (ISIT 2010) in Austin, Texas, June 201

CROSSTALK-RESILIANT CODING FOR HIGH DENSITY DIGITAL RECORDING

Increasing the track density in magnetic systems is very difficult due to inter-track interference (ITI) caused by the magnetic field of adjacent tracks. This work presents a two-track partial response class 4 magnetic channel with linear and symmetrical ITI; and explores modulation codes, signal processing methods and error correction codes in order to mitigate the effects of ITI. Recording codes were investigated, and a new class of two-dimensional run-length limited recording codes is described. The new class of codes controls the type of ITI and has been found to be about 10% more resilient to ITI compared to conventional run-length limited codes. A new adaptive trellis has also been described that adaptively solves for the effect of ITI. This has been found to give gains up to 5dB in signal to noise ratio (SNR) at 40% ITI. It was also found that the new class of codes were about 10% more resilient to ITI compared to conventional recording codes when decoded with the new trellis. Error correction coding methods were applied, and the use of Low Density Parity Check (LDPC) codes was investigated. It was found that at high SNR, conventional codes could perform as well as the new modulation codes in a combined modulation and error correction coding scheme. Results suggest that high rate LDPC codes can mitigate the effect of ITI, however the decoders have convergence problems beyond 30% ITI

OPEP: presente, pasado y futuro

Traducción de la conferencia sobre la "OPEP: pasado, presente y futuro" que pronunció Su Excelencia el Jeque Yamani en Madrid el 21 de noviembre de 2007, como parte del ciclo de conferencias del Programa de Energía del Real Instituto Elcano

High-Rate Space-Time Coded Large MIMO Systems: Low-Complexity Detection and Channel Estimation

In this paper, we present a low-complexity algorithm for detection in high-rate, non-orthogonal space-time block coded (STBC) large-MIMO systems that achieve high spectral efficiencies of the order of tens of bps/Hz. We also present a training-based iterative detection/channel estimation scheme for such large STBC MIMO systems. Our simulation results show that excellent bit error rate and nearness-to-capacity performance are achieved by the proposed multistage likelihood ascent search (M-LAS) detector in conjunction with the proposed iterative detection/channel estimation scheme at low complexities. The fact that we could show such good results for large STBCs like 16x16 and 32x32 STBCs from Cyclic Division Algebras (CDA) operating at spectral efficiencies in excess of 20 bps/Hz (even after accounting for the overheads meant for pilot based training for channel estimation and turbo coding) establishes the effectiveness of the proposed detector and channel estimator. We decode perfect codes of large dimensions using the proposed detector. With the feasibility of such a low-complexity detection/channel estimation scheme, large-MIMO systems with tens of antennas operating at several tens of bps/Hz spectral efficiencies can become practical, enabling interesting high data rate wireless applications.Comment: v3: Performance/complexity comparison of the proposed scheme with other large-MIMO architectures/detectors has been added (Sec. IV-D). The paper has been accepted for publication in IEEE Journal of Selected Topics in Signal Processing (JSTSP): Spl. Iss. on Managing Complexity in Multiuser MIMO Systems. v2: Section V on Channel Estimation is update