The subject matter of this specification can be embodied in, among other things, a controller apparatus that includes a digital controller configured to provide a digital position signal based on a setpoint and a differential analog feedback signal, and a converter circuit configured to provide a differential analog electrohydraulic servo valve position control signal based on the digital position signal, and provide the differential analog feedback signal based on the differential analog electrohydraulic servo valve position control signal.

The subject matter of this specification can be embodied in, among other things, a controller apparatus that includes a digital controller configured to provide a digital position signal based on a setpoint and a differential analog feedback signal, and a converter circuit configured to provide a differential analog electrohydraulic servo valve position control signal based on the digital position signal, and provide the differential analog feedback signal based on the differential analog electrohydraulic servo valve position control signal.

This invention regards a hydraulic turbine (1) to operate in pressure circuits, where there is a flow of a fluid, to control the flow and pressure downstream the installation point. Even so, said turbine (1) can generate power for itself based on the difference of pressure and flow, as the remaining power can be used in public power networks or isolated. Its application field comprises sanitation companies, beverage industries, paper and cellulose industries, petrochemical companies or any places, where it is needed to control the flow and pressure in supply networks.

This invention regards a hydraulic turbine (1) to operate in pressure circuits, where there is a flow of a fluid, to control the flow and pressure downstream the installation point. Even so, said turbine (1) can generate power for itself based on the difference of pressure and flow, as the remaining power can be used in public power networks or isolated. Its application field comprises sanitation companies, beverage industries, paper and cellulose industries, petrochemical companies or any places, where it is needed to control the flow and pressure in supply networks.

The subject matter of this specification can be embodied in, among other things, a controller apparatus that includes a digital controller configured to provide a digital position signal based on a setpoint and a differential analog feedback signal, and a converter circuit configured to provide a differential analog electrohydraulic servo valve position control signal based on the digital position signal, and provide the differential analog feedback signal based on the differential analog electrohydraulic servo valve position control signal.

This invention regards a hydraulic turbine (1) to operate in pressure circuits, where there is a flow of a fluid, to control the flow and pressure downstream the installation point. Even so, said turbine (1) can generate power for itself based on the difference of pressure and flow, as the remaining power can be used in public power networks or isolated. Its application field comprises sanitation companies, beverage industries, paper and cellulose industries, petrochemical companies or any places, where it is needed to control the flow and pressure in supply networks.

In a method of controlling a hydraulic actuator of a test station, a differential signal is generated based on a difference between a reference signal and a feedback signal using an actuator controller. A flow rate control circuit is set in one of a first state and a second state based on a flow rate attenuation signal. The differential signal is delivered to the control valve as an actuator command signal when the flow rate control circuit is in the first state. An attenuated differential signal is delivered to the control valve as the actuator command signal when the flow rate control circuit is in the second state. A flow rate and a direction of the hydraulic fluid flow is controlled based on the actuator command signal. The flow rate corresponding to the attenuated differential signal is less than the flow rate corresponding to the differential signal.

A dynamic testing system includes a test station and at least one controller. The test station includes a hydraulic actuator configured to drive an actuation of a test subject using a hydraulic fluid flow, and a control valve that includes a housing, a valve body contained within the housing having a position that controls a flow rate and direction of the hydraulic fluid flow, a valve body driver configured to adjust the position of the valve body based on a reference signal, and a valve position sensor configured to output a position signal that is indicative of the position of the valve body. The at least one controller is configured to obtain a current position of the valve body using the position signal, obtain a diagnostic reference, detect a diagnostic condition based on a difference between the current position and the diagnostic reference, and generate a diagnostic signal.