Control device for the position control of a hydraulic cylinder unit comprising a linearization unit

A control device for the position control of a hydraulic cylinder unit, comprising

• a controller which is embodied as a P controller and receives, on the input side, a control variable, determines a manipulated variable for a valve control unit of the hydraulic cylinder unit on the basis of the control variable, and outputs the manipulated variable to the valve control unit, so that the piston is adjusted at an adjustment speed,
• wherein a linearization unit is arranged upstream of the controller and receives a setpoint position of a piston of the hydraulic cylinder unit and an actual position of the piston, multiplies the difference between said positions by a linearization factor, and outputs the difference, multiplied by the linearization factor, as a control variable to the controller,
• wherein the linearization unit determines the linearization factor dynamically as a function of the actual position of the piston, and of working pressures prevailing on both sides of the piston and on the inflow side and outflow side of the valve control unit, and
• wherein the linearization unit determines the linearization factor in such a way that a ratio of the adjustment speed with respect to the difference between the setpoint position and actual position of the piston is independent of the actual position of the piston and of the working pressures.

A method comprising the step of using a hydraulic cylinder unit and controlling the hydraulic cylinder unit by means of a control device for controlling the positioning of a rolling stand, wherein the control device comprises:

• a controller which receives, on the input side, a setpoint position of a piston of the hydraulic cylinder unit and an actual position of the piston and determines a preliminary manipulated variable for a valve control unit of the hydraulic cylinder unit on the basis of the difference between the setpoint position and the actual position,
• wherein a linearization unit is arranged downstream of the controller and multiplies the preliminary manipulated variable by a linearization factor and outputs the preliminary manipulated variable multiplied by the linearization factor, as the final manipulated variable to the valve control unit, so that the piston is adjusted at an adjustment speed,
• wherein the linearization unit determines the linearization factor dynamically as a function of the actual position of the piston, and of working pressures which prevail on both sides of the piston and on the inflow side and outflow side of the valve control unit, and
• wherein the linearization unit determines the linearization factor in such a way that a ratio between the adjustment speed and the difference between the setpoint position and actual position is independent of the actual position of the piston and of the working pressures.

A method comprising the step of using a hydraulic cylinder unit and controlling the hydraulic cylinder unit by means of a control device for controlling the positioning of a rolling stand, wherein the control device comprises:

• a controller which is embodied as a P controller and receives, on the input side, a control variable, determines a manipulated variable for a valve control unit of the hydraulic cylinder unit on the basis of the control variable, and outputs the manipulated variable to the valve control unit, so that the piston is adjusted at an adjustment speed,
• wherein a linearization unit is arranged upstream of the controller and receives a setpoint position of a piston of the hydraulic cylinder unit and an actual position of the piston, multiplies the difference between said positions by a linearization factor, and outputs the difference, multiplied by the linearization factor, as a control variable to the controller,
• wherein the linearization unit determines the linearization factor dynamically as a function of the actual position of the piston, and of working pressures prevailing on both sides of the piston and on the inflow side and outflow side of the valve control unit, and
• wherein the linearization unit determines the linearization factor in such a way that a ratio of the adjustment speed with respect to the difference between the setpoint position and actual position of the piston is independent of the actual position of the piston and of the working pressures.