Abstract: When the magnitude of a traverse signal exceeds a predetermined level, the value of a microstep drive signal is changed by one microstep angle so that the rotation angle of the stepping motor changes in a rotation direction in which the magnitude of the traverse signal decreases. A determination is made as to whether or not the magnitude of the traverse signal becomes a predetermined level or less. When the magnitude of the traverse signal does not become the predetermined level or less, the magnitude of the microstep drive signal is returned to the pre-change value and the value of the microstep drive signal is incremented by an additional microstep angle so that the rotation angle of the stepping motor changes in a rotation direction in which the magnitude of the traverse signal decreases.

Abstract: A position feedback device for a motor comprises a driven member and a sensing device. The driven member is indirectly connected to the motor and driven by it. The sensing device detects the travel length of the motor by sensing the driven member. With the method of indirectly sensing the motor, the measurement error, production cost can be reduced, and the assembling position is flexible.

Abstract: Feedback potentiometer-type servoactuator uses the ring gear of a planetary gear system to drive the wiper across a resistive arc of less than 360.degree. where the actuator has a travel of multiple turns. The ring gear is supported by spaced struts in the actuator housing.

Abstract: An apparatus (10) for controlling the height of one or more cutting torches (12) above a workpiece (14). The apparatus (10) senses the actual height of the torch (12) above the workpiece (14) and compares the actual height with a desired reference height. The apparatus (10) moves the torch (12) up or down until the actual height and reference height are substantially equal. The apparatus (10) is operable in a manual mode, a semi-automatic mode or a fully automatic mode allowing an operator to select a desired degree of control during a cutting operation.