Method for controlling the position of an actuator in a manner whereby the adjustment is adaptive

An arrangement for self-adjusting the position of an actuator with the following features:

• an actuator including an electrohydrolic servo valve which drives a working cylinder connected thereto;
• a measured value transmitter connected to an adjustable piston of the working cylinder, said transmitter generating an actual value determined as a function of the movement of said adjustable piston;
• means for determining controlled deviation from a required value and said actual value as directed to a control loop;
• the control loop consisting of a controller means and an adaptation means, said controller means generating a correcting value at its output and said adaptation means generating an auxiliary correcting value at its output,
• the control loop is arranged in such a manner that the controller means and adaptation means' outputs are combined to produce a correcting value which controls the servo valve, wherein the arrangement for self-adjusting the position of an actuator is characterized by the following features:
• a means for supplying said controlled deviation to the inputs of both said controller means and said adaptation means,
• said adaptation means including a non-linear element in series with first integrator means and hysteresis means, the output of said hysteresis means providing the input to a second integrator means in addition to providing a negative feedback signal from its output to the input of the first integrator means, said second integrator means thereby providing the output of said adaptation system, said adaptation means thereby transforming said controlled deviation into said auxiliary correcting value;
• output means connected to said controller means and said adaptation means for combining their outputs to form said single correcting value.