GB828191A - Improvements in and relating to control systems - Google Patents

Abstract

828,191. Electric control systems. NATIONAL RESEARCH DEVELOPMENT CORPORATION. Jan. 30, 1956 [Nov. 29, 1954], No. 34564/54. Class 40 (1). In a control system for effecting movement in a non-linear relation with a voltage applied to a servo system, the voltage is compared with part of a non-linear voltage gradient established along a potentiometer, the non-linear gradient being produced by tappings on the potentiometer to which are connected shunting resistors or auxiliary voltages. An arrangement is described for converting an output voltage into the movement of a carriage across a plotting table. Along one edge of the table is arranged a non- linear potentiometer. The carriage carries a stylus or permanently inked pen over the table and a sensing contact over a non-linear potentiometer. The voltage developed at the sensing contact is applied to a circuit in which it is compared with the applied voltage and the difference used to drive a servomotor which positions the carriage. The potentiometer is a linear wire-wound potentiometer having taps at various points along it at which are connected resistors shunting various sections. If the voltage gradient over part of the potentiometer is steep, the spacing of the tapping contacts should be reduced. The tapping contacts may be carried in a frame adjustable relatively to the potentiometer. The non-linear voltage gradient along the potentiometer may be derived by using independently adjustable tapping contacts between which are connected tapping resistors. A combination of these methods may be used. Two control systems of the type described may be arranged along perpendicular sides of a plotting table to act on a common pointer or a single control system may move a pointer across a sheet advancing steadily or in correspondence with a second variable, the co-ordinate of which is to be plotted parallel to the sheet movement.