Control system having variably biased manipulatable unit

A control system comprising a manipulatable control unit displaceable from and toward a null position, input signal generating means connected with said control unit for generating input signals at regular intervals, each having a magnitude that signifies the existing position of displacement of the control unit, actuating means responsive to actuating signals derived from said input signals to actuate a controlled device in substantial correspondence with displacements of the control unit, and biasing means for imposing a force upon the control unit whereby it is yieldingly urged to the control unit null position, said control system being characterized by:

• A. output signal generating means, connected with said input signal generating means and comprising memory means and logic means, for producing for each newly generated input signal an output signal having a magnitude which signifies a magnitude of said force and which depends upon
• (1) information stored in said memory means concerning said magnitudes of the immediately preceding input signal and of the output signal produced for that input signal, and
• (2) a predetermined program whereby said logic means determines said magnitude of the output signal for said newly generated input signal in accordance with a relationship between the magnitude of that input signal and said stored information;
• and
• B. said biasing means comprising variable force generating means responsive to said output signals and connected with the control unit to impose upon the control unit a force which at each instant has the magnitude signified by said magnitude of the output signal for the newly generated input signal.

A method for a control system comprising a manipulatable control unit displaceable from and toward a null position in increase and decrease directions respectively, a controlled device actuated to positions that substantially correspond to the positions of displacement of said control unit, and force generating means for imposing a yielding biasing force upon said control unit that urges the same in said decrease direction, said method providing for control of the force generating means to cause said biasing force to have a higher gradient for trimming displacements of said control unit than for maneuvering displacements thereof, said method being characterized by:

• A. generating an input having a magnitude which at each instant designates the existing position of displacement of said unit from its null position;
• B. producing an output having a variable magnitude which at each instant signifies the magnitude of said biasing force;
• C. varying said magnitude of said output when said unit is displaced in each of said directions while said unit is in a predetermined range of its positions of displacement in which it is spaced in said increase direction from said null position, such variation being dependent as follows upon the direction in which the unit is being displaced and the distance of said unit from a turning point to which it was brought by its last preceding displacement in the opposite direction:
• (1) during every displacement of said unit through no more than predetermined distance from a turning point, varying said magnitude of the output in accordance with a first gain relationship between input and output magnitudes;
• (2) during displacement of said unit in the increase direction when it is beyond said predetermined distance from a turning point, increasing said magnitude of the output in accordance with a second gain relationship between input and output magnitudes having a substantially lower gradient than said first gain relationship;
• (3) during displacement of said unit in the decrease direction when it is beyond said predetermined distance from a turning point, decreasing said magnitude of the output in accordance with a third gain relationship
• (a) which has a gradient on the order of that of said second gain relationship but
• (b) wherein the output magnitude related to each position of displacement of said unit signifies a smaller magnitude of said biasing force than the output magnitude of the second gain relationship that is related to the same position of said unit;
• and
• D. so imposing said output upon said force generating means that said biasing force at each instant has substantially the magnitude signified by the magnitude of the output then produced.