Require Complex Calculations Research Articles

Creation of an Index Phase on a Magnetic Rotary Encoder by Using a Superposed Magnetizing Method

In recent years, sensors have come to require high resolution and accuracy because of the progress of control technology. Magnetic encoders are widely used in servo motors in factory automation, because of their suitability for use in difficult environments. Research on efficiency tends to favor the use of a magnetic simulation method. However, this requires complex calculations and much time. Therefore, a simplified simulation method has been developed and used. In this paper, to obtain an ideal index phase signal, a new magnetization pattern is proposed and calculated by using the developed simulation method, named the superposed magnetizing method. The experimental results showed that by expanding the detection gap it is possible to obtain a highly accurate index phase signal.

Neural Networks and the Applications for Robot Control

It is well known that robots are being skillfully applied and with favorable performance in a variety of fields, for use in the Japanese manufacturing industry in particular, thanks to progress in robot technology. Today, robots are expected to accommodate men and in the near future be utilized in the field of home life in compliance with human beings. Pessimistically speaking, however, it is impossible to deny that conventional robots, such as teaching playback robots (which men must operate directly), are not able to play roles in the future as expected, so that the development of a new control system which is able to overcome conventional systems in performance ability is indispensable. In other words, flexible control systems by which robots are able to behave autonomously, with minimum human interference is urgently required. We believe that the following three concepts are indispensable for a robot to be equipped with flexibility. a) Manipulators/hands and lggs / wheek with human flexibility. b) Control of flexible and intelligent motions for control in manipulation/handling and locomotion; c) Flexible intelligence and a sense of judgement which permits the robot to execute motions autonomously, adapting itself to the requirements of the human environment. Solving these problems will require investigation into information processing, a study into the function of the brain and central nervous system of human and other living bodies. Thus the information processing theory about neural networks which simulate the functions of the brain has progressed rapidly to activate R & D on the application of motion control and speech processing which have made use of the conventional Neumann computer difficult to handle. Neural networks have the capacity of parallel distributed processing and self-organization as well as learning capacity. Its theory has provided an effective basis for materialization of flexible robots. In the field of level b. and c. mentioned earlier, the neural network theory comprises a large potential to be applied to robots, so that attention is being focused on it. Nevertheless, information processing by neural network is not omnipotent for solving such problems. Presently, it is difficult for a neural network to solve problems which require complex calculations in robot control; for instance, such controls that take force and acceleration into account. Control of flexible robots which mobilize whole arms will require parallel processing of data obtained from many sensors and to control numerous degrees of motion. Therefore, it has become increasingly important for problem solving to combine such problems inherent to robots with parallel processing, self-organization and learning ability of neural networks. From this point of view, therefore, further promotion of R & D on the application technology of neural network for robots is important. These efforts will produce a new neural network-theory for robots and eventually permit autonomous motion. This special issue compilied articles related to applications of neural network to robots, which were produced in the above mentioned environment, from a review on neuromorfhic control, through dynamic system control, optimal trajectory, planning of motion for handling, manipulator locomotion and travelling, to problems in application systems. We hope these articles help our readers understand the present state of Japanese R & D and the application of neural network for robots, as well as new subjects possible for progress in the future. Finally, we gratefully acknowledge Prof. Toshio Fukuda (who contributed a review) and other contributors on their latest achievements.

Compressive Ultimate Strength of Rectangular Plate with Initial Imperfections due to Welding (4th Report)

In general, a deck plate of a ship hull is subjected to inplane tensile and/or compressive load due to longitudinal bending. When the strength of a deck plate is considered, the contribution of the plate elements subdivided by stiffeners and girders are very important, and the accurate evaluation of their compressive strength is essential. In this report, based on the results obtained in this series of research, the authors have developed a simple estimation method of the ultimate strength with a limited amount of information on the kind of steel, sizes of deck plate, welding condition, etc., which does not require complex calculation such as FEM.The main results obtained in this study are as follows.(1) A simple estimating method of welding deformation and residual stresses produced in a deck plate is proposed. The calculation can be performed by using the yield stress of material, welding condition, etc.. The estimation is very accurate compared with the actual measurement.(2) In order to describe the influence of actual complex initial deflection, the effective coefficient of initial deflection is theoretically determined for the standard initial deflection which was idealized from the actually measured initial deflection. The maximum initial deflection influences the ultimate strength fully for thick plates and less than a half for thin plates.(3) The ultimate strength is evaluated from the ultimate strength formulae proposed in the previous report, taking into account of the effective coefficient of initial deflection. The estimated ones are very accurate in the comparison with those obtained by direct FEM calculation to the actual panel.

Pitch damping of helicopter rotor with nonuniform inflow

Pitch or roll damping of helicopter rotor has been experimentally studied by using model rotors in rocking motion. The rotors have articulated blades with spring constrained hinges and different combinations of Lock number, flapping hinge offset, and hinge constrained stiffness. By considering nonuniform induced velocity distribution a theoretical estimation based on the momentum and blade element theory has shown good coincidence with the experimental results. In contrast with analyses based on the vortex theory the present theory is very simple and does not require complex calculations so that the analytic evaluation and the quick estimation of the dynamic stability derivatives of rotor will be possible. The blade flapping behavior during sinusoidal rocking motion has also been analytically and experimentally analyzed and the mechanism of generation of direct damping and cross coupling moments have been clearly explained.

Sediment Sorting Related to Basin Mobility and Environment

Environment analysis and paleogeographic reconstruction are used increasingly in petroleum exploration to evaluate distribution of source and reservoir rocks in a basin and to delimit areas that may include stratigraphic traps. This paper introduces an aid to environment and paleogeographic investigations which may bring significant progress to petroleum exploration. Sorting of clastic sediments is related to basin mobility and environment, but traditional sorting parameters are a function of so many independent variables that the relations are not clear. Two new sorting parameters are introduced. They define the sorting of a clastic deposit as a whole by the sorting of selected sediments deposited under known hydrodynamic conditions. These new parameters, clearly related to basin mobility and environment, show how sediments are distributed in a basin and indicate significant texture changes corresponding to changes in the environment. The proposed parameters also contribute to the analysis of transport and deposition of sediments. Particularly, these sorting parameters show and explain differences between fluviatile and shallow-marine sands, and between turbidites and the shallow sands that form the turbidity currents. Measurements of the sorting parameters require only a limited number of samples. Measurement techniques are simple and do not require complex calculations. Maps, easily constructed, show clearly the significant texture changes.