Multi-rotor hydraulic drone (1) comprising: —a plurality of hydraulic motors (6) each receiving a pressurised fluid, —propellers (5) driven by the hydraulic motors (6), —at least one hydraulic pump (10) driven by at least one motor (11) for pressurising the fluid, —a system for supplying the hydraulic motors (6) with pressurised fluid, —a flight controller (14) for controlling the supply system according to the desired rotation speed for the hydraulic motors (6), the supply system comprising several channels (35; 36; 37; 38) for adjusting the power of at least one portion of the hydraulic motors (6).

A counter pressure valve arrangement for controlling a pressure level of a hydraulic fluid in a return line from a hydraulic actuator arrangement. The counter pressure valve arrangement comprises a counter pressure valve having: a moveable valve member; a counter pressure regulating port configured for being connected to the hydraulic actuator arrangement via the return line; a tank port configured for being connected to a tank or low pressure reservoir for storing low pressure hydraulic fluid; and a pump port configured for being connected to a source of pressurised hydraulic fluid. A first position of the valve member effects fluid communication between the pump port and the counter pressure regulating port for supplying pressurised hydraulic fluid to the return line, and a second position of the valve member effects fluid communication between the counter pressure regulating port and the tank port for discharging hydraulic fluid from the return line to the tank.

A method for operating a hydraulic valve of a hydraulic device of a motor vehicle transmission device, wherein an actuating current of the hydraulic valve is superposed with a modulation alternating current in order to adjust a shaking vibration of the hydraulic valve by a control device, wherein a deviation between an actual pressure resulting from the actuating current and a setpoint pressure determined as a function of the actuating current is determined for the hydraulic device by means of an electronic computing device, and an amplitude and/or a frequency of the modulation alternating current is increased as compared to a starting value equalizing a hysteresis of the actual pressure relative to the setpoint pressure, as a function of a tolerance range being exceeded by the determined deviation.

A robot device of the present disclosure includes at least one artificial muscle that operates by being supplied with liquid; and a liquid supply device that supplies and discharges the liquid to/from the artificial muscle, and the liquid supply device includes a liquid storage part that stores the liquid; a pump that sucks the liquid from the liquid storage part and discharges the liquid; a pressure regulating device that includes a spool and an electromagnetic part that allows the spool to move, and that generates drive pressure for the artificial muscle by regulating source pressure from the pump side, and regulates the source pressure by balancing at least a force given to the spool from the electromagnetic part and a force given to the spool by action of the drive pressure; and a control device that applies a current to the electromagnetic part of the pressure regulating device so that the drive pressure reaches target pressure.

A controller executes a dither control that cyclically increases and decreases an exciting current in a linear solenoid valve so as to vibrate a spool of the linear solenoid valve. A vibration cycle of the spool obtained through the dither control is referred to a dither cycle. The dither control includes a first dither control that vibrates the spool in a first dither cycle and a second dither control that vibrates the spool in a second dither cycle that is shorter than the first dither cycle. The controller executes the first dither control and the second dither control when an oil temperature of the hydraulic oil is between a first oil temperature and a second oil temperature that is higher than the first oil temperature.

A controller executes a dither control that cyclically increases and decreases an exciting current in a linear solenoid valve so as to vibrate a spool of the linear solenoid valve. A vibration cycle of the spool obtained through the dither control is referred to a dither cycle. The dither control includes a first dither control that vibrates the spool in a first dither cycle and a second dither control that vibrates the spool in a second dither cycle that is shorter than the first dither cycle. The controller executes the first dither control and the second dither control when an oil temperature of the hydraulic oil is between a first oil temperature and a second oil temperature that is higher than the first oil temperature.

A control system includes a variable displacement hydraulic pump, the pump having an inlet for receiving fluid, an outlet for discharging fluid under pressure, and a pump displacement input, a hydraulic motor having an inlet and an outlet, a fluid circuit including a supply conduit for conducting fluid discharged by the pump to the motor and a return conduit for returning fluid discharged by the motor to the pump, a pump displacement control cooperating with the pump displacement input in order to vary a displacement of the pump, a control circuit in communication with the pump displacement control for controlling the pump output such that the motor is driven at a constant rotational speed, and a system controller in communication with the control circuit and a remote location to transmit and receive information to and from the remote location.

Electrically controllable hydraulic system for a vehicle transmission and method for controlling the same An electrically controllable hydraulic system (1) for a vehicle transmission comprises a pressure pump system (4a, 4b) and a subsystem (1A) comprising a transmission element (2) and an electrically controlled hydraulic pressure controlling module (1B) including a hydraulic valve element (15) for controlling a hydraulic pressure for actuating the transmission element (2) and an electromagnetically controllable operating element (21) for operating the hydraulic valve element (15). The subsystem (1A) and the pressure controlling module (1B) have a first and a second cut-off frequency (f1, f2) with f2>f1. The hydraulic system includes a driver circuit (32) for driving the pressure controlling module (1B) that comprises a full bridge circuit and a control circuit (42) for simultaneously controlling both switching elements of the driver circuit with a duty cycle according to an input value of the input signal (lset) dithered with a frequency (f.sub.dith) in the range (f1, f2).

A method for operating a hydraulic valve of a hydraulic device of a motor vehicle transmission device, wherein an actuating current of the hydraulic valve is superposed with a modulation alternating current in order to adjust a shaking vibration of the hydraulic valve by a control device, wherein a deviation between an actual pressure resulting from the actuating current and a setpoint pressure determined as a function of the actuating current is determined for the hydraulic device by means of an electronic computing device, and an amplitude and/or a frequency of the modulation alternating current is increased as compared to a starting value equalizing a hysteresis of the actual pressure relative to the setpoint pressure, as a function of a tolerance range being exceeded by the determined deviation.

The energy recovery system includes an inertial fluid container, a low pressure container, a high pressure container, a low pressure valve, and a high pressure valve, a valve flow conduit, and a valve controller. The valve controller switches, in response to a decrease in volume of the fluid chamber, the inertial fluid container between communicating with the low pressure container and the high pressure container, thereby generating inertial forces of the working fluid flowing toward the low pressure container in the inertial fluid container, and causing the working fluid to flow into the high pressure container by the inertial forces. The valve controller sets a switching frequency for the valves to a frequency close to an Nth-order (where N is a natural number) anti-resonance frequency of a flow conduit for the working fluid.