System of stabilization for a sampledata servo using a variable gain sampled-data loop and a proportional loop

Claim 1

IN A SAMPLED-DATA SERVO SYSTEM INCLUDING A SOURCE OF INPUT VARIABLE SIGNALS, A SUMMER HAVING FIRST AND SECOND INPUTS AND AN OUTPUT, SAID FIRST INPUT BEING SUPPLIED WITH SAID INPUT VARIABLE SIGNALS FROM SAID SOURCE, SAMPLING MEANS FOR SAMPLING THE OUTPUT OF SAID SUMMER, A SAMPLEHOLD CIRCUIT FOR HOLDING SAID SAMPLED SIGNAL IN THE INTERVAL BETWEEN SAMPLINGS TO PRODUCE A SAMPLE-HOLD OUTPUT SIGNAL, A CONTROLLER FOR PRODUCING AN OUTPUT SIGNAL, SAID CONTROLLER HAVING AN INPUT AND AN OUTPUT, SAID INPUT BEING SUPPLIED WITH SAID SAMPLE-HOLD OUTPUT SIGNAL, AND A PRIMARY NEGATIVE FEEDBACK PATH FROM THE OUTPUT OF SAID CONTROLLER TO SAID SECOND INPUT OF SAID SUMMER TO ESTABLISH A CLOSED PRIMARY SERVO LOOP, THE IMPROVEMENT COMPRISING: A SECOND SUMMER INTERPOSED BETWEEN SAID SAMPLE-HOLD CIRCUIT AND SAID CONTROLLER, SAID SUMMER HAVING ONE INPUT SUPPLIED FROM THE OUTPUT OF SAID SAMPLE-HOLD CIRCUIT AND HAVING A SECOND INPUT SUPPLIED FROM A SECONDARY NEGATIVE FEEDBACK PATH CONNECTED FROM THE OUTPUT OF SAID CONTROLLER, SAID SECONDARY FEEDBACK ESTABLISHING A SECONDARY LOOP, SAID SECONDARY NEGATIVE FEEDBACK VARIABLE PROPORTIONAL TO THE CHANGE IN A FEEDBACK VARIABLE PROPORTIONAL TO THE CHANGE IN SAID OUTPUT VARIABLE SIGNALS DURING INTERVALS BETWEEN INPUT SAMPLES, WHEREBY SAID SECONDARY FEEDBACK LOOP EFFECTIVELY MAINTAINS A CLOSED LOOP SERVO IN THE INTERVALS BETWEEN SAMPLES; AND FIRST ADJUSTABLE GAIN CONTROL MEANS IN SAID PRIMARY LOOP, AND SECOND ADJUSTABLE GAIN CONTROL MEANS IN SAID SECONDARY LOOP, SAID MEANS BEING ADJUSTABLE TO PROVIDE EQUAL GAINS IN SAID LOOPS.