Abstract: In order to estimate a magnetic pole position of a permanent magnet type brushless motor, the following steps are conducted. A given &ggr; axis and a given &dgr; axis in an advanced from the &ggr; axis by an electrical angle of 90° are set. A closed-loop electric current control system in the &ggr; axis direction is formed while forming an open-loop electric current control system in the &dgr; axis direction. It is calculated an interference current generating in the &dgr; axis direction when a current command in the &ggr; axis direction is given as a stepwise alternating current command. The &ggr; axis is finely advanced by an angle of &Dgr;&thgr; when a sign of a product of an integral value of the interference current and a value of the current command in the &ggr; axis direction is positive. Alternatively, the &ggr; axis is finely delayed by an angle of &Dgr;&thgr; when the sign is negative.

Abstract: The invention provides a sensorless control method and apparatus of a permanent magnet synchronous motor where magnetic axis can be assigned in all speed regions and speed can be controlled continuously irrespective of the speed command. In the control method, the d-q axis being the magnetic axis rotating in the real rotation speed .omega..sub.R of the motor is set and also the .gamma.-.delta. axis being the assigned magnetic axis of the motor is set, and when the rotation speed .omega..sub.R.sbsb..gamma. of the .gamma.-.delta. axis is determined, a distribution gain K1 is set so as to be decreased as the absolute value of the rotation speed command .omega..sub.RREF becomes large and a distribution gain K2 is set so as to be increased as the absolute value of the rotation speed command .omega..sub.RREF becomes large, and the rotation speed command .omega..sub.RREF is multiplied by K1 and the speed estimated value .omega..sub.

Abstract: A controller is provided for a multi-axis robot having at least first and second axis assemblies, the first and second axis assemblies each having an arm, a servomotor driven by a control input and a coupling in the form of a decelerator, which includes a spring element, coupling the servomotor and the arm, the second axis assembly being disposed at an end of the arm of the first axis assembly. The controller includes the first and second axis assemblies each including torsional angle detector for detecting a torsional angle of a respective one of the couplings. A dynamic coupling calculator calculates coupling parameters of the couplings. The first and second axis assemblies each include a semi-closed loop.

Abstract: A magnetic levitation and transport system has a plate-like moving element (SFT) which is moved by a linear motor disposed in a stator (STT). The moving element is moved vertically by first through fourth electromagnetic devices (MGV.sub.10 -MGV.sub.41), and fifth and sixth electromagnetic devices (MGH.sub.10 -MGH.sub.21) exert forces on the moving element in a horizontal direction perpendicular to the direction in which the moving element is moved. Gaps between the moving element and the electromagnetic devices are detected by gap sensors which produce gap data. In the vertical direction, for example, attractive force commands (f.sub.V1 -f.sub.V2) are produced from the outputs from a circuit for calculating the amount of feedback (10) which is supplied with the gap data (XV.sub.1 -XV.sub.4) and also with the output from a variable gain g.sub.V (l) generator (60) to which the position (l) of the center of gravity of the moving element is supplied.