A control device controls a hydraulic cylinder unit having a piston. The device receives a setpoint variable and an actual variable and determines, based on a difference between the setpoint variable and the actual variable, a preliminary manipulated variable for valves of the hydraulic cylinder unit. The setpoint variable and the actual variable relate to a position of the piston or a force applied by the piston. Linearization factors are determined dynamically as a function of the actual position of the piston and working pressures on both sides of the piston and a hydraulic fluid tank/pump. Definitive manipulated variables to control the valves are determined from the preliminary manipulated variable and the linearization factors. With the linearization factors, a ratio of the piston adjustment speed to the difference between the setpoint variable and the actual variable is independent of the actual position of the piston and the working pressures.

A controller (15) which receives a target value (g*) related to a piston (3) of the hydraulic cylinder unit (1) and an actual value (g) related to the piston (3) of the hydraulic cylinder unit (1). On the basis of the difference (g) of the values, the controller determines a provisional manipulated variable (u). A linearization unit (17) downstream of the controller (15) multiplies the provisional manipulated variable (u) by a linearization factor (F) and outputs the product to a valve control unit (7) as a final manipulated variable (u) such that the actual value (g) is brought toward the target (g*) at an adjustment speed. On the basis of working pressures (pA, pB) on both sides of the piston (3) and/or working pressures (pP, pT) on the feed side and on the outflow side of the valve control unit (7) and a target piston force (FKL) to be applied by the piston (3), the linearization unit (17) determines target values (pA*, pB*) for the working pressures (pA, pB). The linearization unit determines the linearization factor (F) dynamically as a function of an actual position(s) of the piston (3), the target values (pA*, pB*), and the working pressures (pP, pT) on the feed side and on the outflow side of the valve control unit (7).

A controller (15) which receives a target value (g*) related to a piston (3) of the hydraulic cylinder unit (1) and an actual value (g) related to the piston (3) of the hydraulic cylinder unit (1). On the basis of the difference (g) of the values, the controller determines a provisional manipulated variable (u). A linearization unit (17) downstream of the controller (15) multiplies the provisional manipulated variable (u) by a linearization factor (F) and outputs the product to a valve control unit (7) as a final manipulated variable (u) such that the actual value (g) is brought toward the target (g*) at an adjustment speed. On the basis of working pressures (pA, pB) on both sides of the piston (3) and/or working pressures (pP, pT) on the feed side and on the outflow side of the valve control unit (7) and a target piston force (FKL) to be applied by the piston (3), the linearization unit (17) determines target values (pA*, pB*) for the working pressures (pA, pB). The linearization unit determines the linearization factor (F) dynamically as a function of an actual position(s) of the piston (3), the target values (pA*, pB*), and the working pressures (pP, pT) on the feed side and on the outflow side of the valve control unit (7).

In automatic process-control systems, the integral action term in Proportional plus Integral action (P+I) control is used primarily to prevent any continued deviations from a set-point, and concomitantly to secure a bump-less transfer from manual control to automatic control. However, there are serious set-backs when using the integral action term for level controls, due to the liability of the integral action term to cause overflows from vessels, which can result in disastrous oil-spills, when a process is on automatic control. Hence, to secure a bump-less transfer without the integral action term, an alternate method is necessary. The method advocated calls for an additional term, which has been termed as a Bump-less Transfer BT(t) term, to be included into the control algorithm. This term accepts deviations from the set-point, and even brings about sufficient deviation from the set-point to secure a bump-less transfer, since deviations within the proportional band are normally acceptable for level controls.

In automatic process-control systems, the integral action term in Proportional plus Integral action (P+I) control is used primarily to prevent any continued deviations from a set-point, and concomitantly to secure a bump-less transfer from manual control to automatic control. However, there are serious set-backs when using the integral action term for level controls, due to the liability of the integral action term to cause overflows from vessels, which can result in disastrous oil-spills, when a process is on automatic control. Hence, to secure a bump-less transfer without the integral action term, an alternate method is necessary. The method advocated calls for an additional term, which has been termed as a Bump-less Transfer BT(t) term, to be included into the control algorithm. This term accepts deviations from the set-point, and even brings about sufficient deviation from the set-point to secure a bump-less transfer, since deviations within the proportional band are normally acceptable for level controls.

A parameter tuning method of an unknown proportional-integral-derivative (PID) controller is provided. The unknown PID controller is replaced with the control algorithm of the generic controller to perform the optimal parameter tuning to obtain the target parameter of the generic controller. The unknown PID controller is set with a first parameter group so that the corresponding input signal, the control signal and the output signal are measured for performing the parameter identification procedure of the generic controller to obtain a second parameter group of the generic controller. When the second parameter group is not within a specification range of the target parameter, the first parameter is re-calculated and modified by a direct search method in accordance with the difference between the second parameter group and the target parameter for setting the unknown PID controller again, and then the input signal, the control signal and the output signal are measured again.

A system and method for controlling a speed of a pumping system includes a controller, a variable frequency drive connected to the controller, a motor connected to the variable frequency drive, a pump connected to the motor, a set of sensors connected to the motor, the pump, and the controller, and an interface connected to the controller. The controller includes a processor and a memory connected to the processor. A motor control process is saved in the memory and executed by the processor that generates a motor control signal to control the speed of the motor and the pump.

A method is provided for controlling a technical system by means of a Two Degree of Freedom controller, which allows for increased accuracy, higher robustness and better safety even in cases of changes of the technical system. The method comprises deriving an anomaly detection signal at an anomaly detection time point during control of the technical system. At least one control parameter parametrizing the Two Degree of Freedom controller is adapted depending on the anomaly detection signal and, from the anomaly detection time point onwards, the technical system is controlled by means of the Two Degree of Freedom controller parameterized by said at least one adapted control parameter.

A method is provided for controlling a technical system by means of a Two Degree of Freedom controller, which allows for increased accuracy, higher robustness and better safety even in cases of changes of the technical system. The method comprises deriving an anomaly detection signal at an anomaly detection time point during control of the technical system. At least one control parameter parametrizing the Two Degree of Freedom controller is adapted depending on the anomaly detection signal and, from the anomaly detection time point onwards, the technical system is controlled by means of the Two Degree of Freedom controller parameterized by said at least one adapted control parameter.