GB1273632A - Speed control of line followers - Google Patents

Abstract

1,273,632. Programmed electric control. G. J. TRAPP. July 16, 1969, No.35784/69. Heading G3N. A number of outlines 136, 137 are followed by separate (photo-electric) line followers 130, 132 to guide separate tools, e.g. flame cutters 131, 133, the drive in one direction being at a common speed which is determined by comparing "desired speed" signals from each of the followers and selecting that which represents the slowest in the said direction. Each follower has a magslip or potentiometric resolver whose X and Y outputs depend upon the direction of the line immediately beneath it and attempt to control speed of movement in these directions so as to keep cutting speed (i.e. the resolute) constant. However, the followers and cutters are mounted on a common main carriage for longitudinal (Y, or downwards as shown) movement, driven by a motor whose speed is controlled by a magnetic amplifier having a control winding energized by a transistor circuit. In Fig. 3 (not shown) this circuit applies the Y output of each resolver, via transistors, to a network of diodes, all of which are reverse biased except that associated with the lowest input, which is thus effective to control the common Y motor. An alternative circuit Fig. 4 (not shown) is similar, except that X input signals are used and the circuit responds to the highest (which corresponds to lowest Y). The arrangement shown includes a modification which provides brief reverse travel in the Y direction, to follow reentrant portions 142, 145. For this, one or more of the followers and cutters are mounted on sub carriages 128, 129; the control circuit Fig. 7 (not shown) has a phase sensitive network which detects a requirement for back travel and this stops, or preferably decreases to a minimum, the travel of the main carriage while controlling a separate motor which produces the required back travel. This circuit also has a diode network similar to that of Fig. 3