Improvements relating to positional control apparatus

1,112,335. Control of motors. LICENTIA PATENT - VERWALTUNGS - G.m.b.H. 6 Aug., 1965, No. 33710/65. Heading H2J. [Also in Division G3] In a positional control system the speed of a positioning motor is controlled in accordance with a quantity representing the product of the positional error and a multiplication factor which increases during the initial part of a movement and reduces during the latter part of the movement. As shown, a positional error Ra is derived as the difference between a nominal value Ls and an actual position value Li in a comparator S 1 and fed to a multiplying circuit MS, where it is multiplied by a factor Z, and fed as a nominal speed value Ns to a comparator S 2 . The output Nw of the comparator S 2 , which is also responsive to the actual speed value Ni from a tachogenerator DM controls the speed of positioning motor M. The factor Z is derived by feeding pulses from a position transmitter P coupled to the motor M to a main counter Zh and an auxiliary reversible counter Zv. The factor Z from the counter Zh increases up to a value dependent on a count set in the input Z 1 above which it is held constant. The counter Zv counts up to a value Z 4 at which a signal to an input Z 3 of the counter Zh reverses the count. The counter Zh counts down and the factor Z is held constant until the count falls to the count on input Z 1 after which the factor Z reduces to slow down the motor as the position error falls to zero.