Abstract: An electromagnetic actuator for a valve stem comprising a stator core having concentratedly wound coils around salient poles and the stator is positioned outside of a tubular member made of a nonmagnetic material. The electromagnetic actuator for a valve stem also has a rotor provided inside the tubular member for driving a threaded operating shaft such that it operats an objective member reciprocally an electromagnetic actuator for a valve stem is further constructed such that permanent magnets, alternately magnetized into a number of pole-pairs, are arranged along the surface of each salient pole of the stator core at a constant pitch, while a number of induction teeth are formed along the circumference of the rotor at a pitch equal to the pitch of the pole-pairs of the permanent magnets. The difference between the total number of the induction teeth and the total number of the polepairs of the permanent magnets is made equal to an even number.

Abstract: There is disclosed a method of controlling a voltage-to-frequency inverter which controls an induction motor by the use of an open-loop system. The motor drives a machine such as a crane, and is braked by a mechanical brake. When the machine is started or stopped, a low-frequency voltage is supplied to the motor so that the motor may produce a torque necessary to hold the load, until the actuation of the mechanical brake ends completely.

Abstract: A method of detecting information on an arc welding position by monitoring the shape and/or position of an welding arc. When in the arc welding along a welding groove position while locating the same, the shape of the arc is picked up from above the joint portion of a member to be welded by means of an image pickup device, and the arc shape picked up is binary-coded. This binary arc shape and/or position are monitored to detect the welding groove position, the height of the welding torch, the welding start point, the welding end point, the external corner point, the internal corner point, the contact point of the welding wire with the work, and the welding groove gap.

Abstract: The present invention relates to an improvement in a method and an apparatus for magnetic levitation of a linear slider through a PI control action. When the slider is horizontally moved while levitated vertically by two fixed magnetic forces, the angle of inclination of the slider cannot be settled in a preset position because of a control delay caused by integral action, which results in an angle offset. In order to eliminate the offset, a signal which is the sum of an angle deviation and a delay compensation signal that is proportional to the product of the velocity of the slider and an integral time is used as an error signal to settle the angle of inclination. The vertical position of the slider is controlled so that the sum of the magnetic forces applied to the slider balances the weight of the slider.

Abstract: The present invention provides a wrist mechanism with three degrees of freedom for an industrial robot, which is compactly formed and to which a tool is mounted. The first degree of freedom is associated with a first input shaft for rotating a wrist portion at a low speed. The second and third degrees of freedom are associated with rotating the tool or tilting the wrist. In order to attain these motions, second and third input shafts concentrically arranged relative to the first input shaft are used for transmitting motion to, through bevel gears, speed reduction mechanisms each symmetrically disposed at right and left sides, and the outputs therefrom are used to drive the tool and wrist.