Determination Of Angular Position Research Articles

Computer modeling of electrical coil characteristics dedicated for helmet-mounted cueing systems with magnetic method

Paper presents the importance of the helmet-mounted cueing systems in the field of flight safety increasing and mission execution effectiveness. There are presented the selected helmet systems used in the foreign and domestic solutions, utilizing the magnetic method. An original method of pilot’s helmet angular position determination utilizing the magnetic field from single flat coil and quaternion calculus is presented. The valuable elements are given mathematical relationships describing the characteristics of the magnetic field generated by selected types of electric coils as well as the results of simulation tests and the laboratory experimental verification of a flat coil model (designed in the Air Force Institute of Technology - AFIT) with a given number of coils.

Helmet-Mounted Attitude Control Algorithms of the Opto-Electronic Surveillance System for Aircraft Search and Rescue Actions

Abstract This article presents selected results of work concerning the errors modeling of helmet-mounted cueing systems used for guided weapon and opto-electronic surveillance systems target homing (for realizing aircraft search and rescue actions). There were described algorithms of helmet angular position determination on the basis of inertial and magnetic methods, moreover, the possibilities of their modification. On this background there were presented the authorial method of pilot’s helmet angular position determination dedicated for helmet-mounted cueing systems for fighter helicopters. The method is based on the pilot’s helmet and aircraft body linear accelerations measurements, which then are used for the current quaternion evaluation to describe the helmet position relatively to the aircraft. Simulation models were tested in Matlab-Simulink and Borland C++ computational packages for various pilot’s helmet space orientation using specialized rotation test stands.

A Novel Linearization Method of Sin/Cos Sensor Signals Used for Angular Position Determination

In this paper a novel method for angular position determination using sensors with sin / cos output and without an excitation signal, is presented. The linearization of the sensor transfer characteristic and digitalization of the measurement results are performed simultaneously with a goal to increase the measurement resolution. This improvement is particularly important for low angular velocities, and can be used to increase the resolution of incremental Hall, magnetic and optical sensors. This method includes two phases of sin/cos signal linearization. In the first linearization phase the pseudo-linear signal is generated. The second linearization phase, executed by the two-stage piecewise linear ADC, is an additional linearization of the pseudo-linear signal. Based on the LabVIEW software simulations of the proposed method, the contribution of each processing phase to a final measurement error is examined. After the proposed method is applied within 2π [rad] range, the maximal nonlinearity is reduced from 0.3307 [rad] (18.9447°) to 3·10-4 [rad] (0.0172°).

Pulse-vector control with indirect determination of rotor angular position

A system of pulse-vector control with an indirect determination of the angular position of the rotor based on a groundbreaking two-step method for computing the position is considered. The system can be used in electric drives with one-or two-shift work schedules to save energy and resources. A two-phase algorithm for computing the position based on comparison of the voltages at the motor windings is proposed and described. Differential equations and functional dependences of the state variables on the rotational angle of the rotor are presented.

Using 9-Axis Sensor for Precise Cardiosurgical Robot Master Angular Position Determination

The article will focus on the presentation of the possibility of practical application of integrated 9-axis sensor, in which magnetic field, acceleration and angular velocity 3-axis sensors were used. Particular emphasis will be placed to describe the mentioned sensors data fusion algorithm, which is necessary for precise and unequivocal determination of the angular position of the tested device. Another presented issue is a selection of an appropriate data filtering algorithm with selected filtering parameters. Additionally, the possibility of implementing described solutions in the angular positions measurement system of cardiosurgical Robin Heart robot master will be shown. Also, a design concept of mentioned robot master along with its working principle will be mentioned.

Modelling of the cylindrical-rotor synchronous machine for symmetrical and asymmetrical modes of operation

A mathematical model of the three-phase, cylindrical-rotor, synchronous machine for symmetrical and asymmetrical modes of operation has been developed. This model has been represented as system of differential equations for flux linkages, angular velocity and angular position determination. The differential equations for the flux linkages of the armature windings have been expressed in phase coordinates, while the differential equations for the flux linkages of the field winding and the rotor circuits have been expressed in orthogonal coordinates (direct and quadrature axes). The skin effect in the cylindrical-rotor has been considered by representing the rotor as two parallel-connected resistive-inductive circuits. Symmetrical case followed by a steady-state operating conditions (sudden load change) and asymmetrical case in a transient operating conditions (line-to-line short circuit in the electrical power system) have been computed. The waveforms of the machine speed, electromagnetic torque, phase currents and voltages have been illustrated.

Angular Position Determination of Spacecraft by Radio Interferometry

This paper describes a variety of interferometric techniques that may be used for measuring the angular location of a spacecraft with respect to natural celestial radio sources or another spacecraft. The differential propagation time-delay techniques largely cancel the common error sources and normally achieve low angular coordinate errors. Currently, the accuracy of the techniques are in the 1-2 nrad range for observations with a duration of one hour and 3-6deg of mean angular separation between the spacecraft and the reference sources at X-band frequencies. There are various possible ways to implement the differential angular measurements depending upon the determination of the phase cycle ambiguities associated with the differential propagation time delays of remote sources. There are methods that utilize a sufficiently large range of observing frequencies and others that rely upon the spatial arrangement of the receiving system and the rotation of the terrestrial platform. We summarize the methodologies and the advantages and disadvantages of the various techniques.

Four-crystal (+, −, −, +) monochromator for synchrotron radiation

In the conventional design of a (+, −, −, +) monochromator for synchrotron radiation two precise axes of rotation are needed. The precision of the wavelength determination depends on the precision of the angular position determination realized by the rotation around these axes. Here a modification is proposed which needs only one precise axis and thus it may represent a simplification of the monochromator design.

Problems of automated qualitative X‐ray fluorescence analysis. 2–Location of maxima and line identification

AbstractA method is described for the determination of angular positions of maxima in an x‐Ray fluorescence spectrum registered by step scanning. The cases of single and overlapping maxima were investigated. For each maximum the angular interval was determined, containing all lines which may be the cause of its emission.

Maximum Angular Accuracy of a Pulsed Search Radar

An investigation is made of the limits imposed by receiver noise on the accuracy with which the angular position of a target can be determined by a pulsed search radar. Using a result in the theory of statistical estimation, a lower bound is derived for the standard deviation of regular unbiased estimates of target angular position, for a large class of methods of angular position determination; the lower bound depends on scan rate, pulse repetition rate, beamwidth, beam shape, and signal-to-noise ratio. A similar analysis is made of the limits on angular accuracy imposed by a combination of receiver noise and one particular type of target cross section fluctuation. Operations which can be performed on the received signal to form an estimate of target angular position, the standard deviation of which approximately attains the theoretical lower bound, are discussed. The relation between the estimation of angular position and the problem of target detection is discussed. A graphical presentation of the main results is given.