Abstract: Methods of operating, and apparatus including, a rotary electric motor to translate rotation of the motor into linear travel with the aid of a linearly traveling device. This linearly traveling device is restrained against rotation at points peripherally distributed relative to the device. In particular, there is a pair of interfitting parts including a linear keyplate and keyway at each of the peripherally distributed points. One of these interfitting parts is connected to the linearly traveling device and the other of these parts is maintained stationary relative to that one interfitting part. One of the linear keyplates may be provided with a first scale indicating the linear travel in a first system of measurement, such as the metric system, and another linear keyplate may be provided with a second scale indicating the linear travel in a second system of measurement, different from the first or metric system.

Abstract: Methods and apparatus for controlling an electric motor effect operation of such motor by electric energization thereof, and derive from a motor winding or from the back electromotive force of the motor an electric signal indicative of motor speed. The motor is thereupon mechanically stalled, and such stalling is detected from a comparison of the derived speed signal and the electric energization. Deenergization of the motor is effected in response to the stalling detected from the latter comparison. Limit switching of electric motors and actuators without limit switches may be provided in this manner.

Abstract: A reference diffraction pattern is generated by radiating an invariant physical characteristic such as a fingerprint with coherent light, this reference diffraction pattern being converted by a detector into a reference electrical function which is stored. A person to be identified then has a corresponding invariant physical characteristic such as his fingerprint radiated by coherent light to cause generation of a sample diffraction pattern. The frequency domain of the entire sample diffraction pattern is detected simultaneously to provide a sample electrical function. The reference electrical function in storage is then compared with the sample electrical function and if a correlation exists within a given tolerance, it is known that the person from which the sample electrical function is derived corresponds to the person from which the reference electrical function was derived. The invariant physical characteristics may be fingerprints as mentioned, or signatures, or combinations of both.