The invention relates to a fluid-driven drive having a movable working surface and a volume-variable cavity, further having an unstable element, wherein given a movement of the working surface in a first movement direction, the unstable element can initially be moved at least in a section with an increased expenditure of force out to an unstable point, wherein when going past the unstable point in the first movement direction, in addition to the force that is provided by fluid pressure, a force exerted by the unstable element is also available in the direction of the first movement direction, wherein given a subsequent movement of the working surface in a second movement direction opposite to the first movement direction, the unstable element can be initially moved with an increased expenditure of force out to an unstable point, wherein when passing the unstable point in the second movement direction, a lower expenditure of force is required for movement at least sectionally.

A mechanical transmission system that transmits motions and forces from one location to another while allowing the relative position/orientation of the two locations to change continuously is disclosed. The system can be used to actuate the joints and tooling of a robotic arm using stationary motors in the robot's base. Since the motors do not contribute any weight or inertia to the arm, this yields a lightweight and agile arm that is more human safe. The transmission includes a controller hydraulic cylinder connected to a remote cylinder by a tubing assembly, which contains hydraulic fluid, and a wire cable. The fluid transmits pushing forces between pistons of the cylinders, while the cable transmits pulling forces. The tubing assembly allows the cylinders to move in space relative to one another.

A control system (50) for an electro-hydraulic servo-actuator (26) envisages: a controller (55), to generate a control current (I.sub.c), designed to control actuation of the electro-hydraulic servo-actuator (26), implementing a position control loop based on a position error (e.sub.p), the position error (e.sub.p) being a difference between a reference position (Pos.sub.ref) and a measured position (Pos.sub.meas) of the electro-hydraulic servo-actuator (26); and a limitation stage (58), coupled to the controller (55) to provide a limitation of the actuator speed of the electro-hydraulic servo-actuator (26); the limitation stage (58) limits a rate of change of a driving current (I.sub.d) to be supplied to the electro-hydraulic servo-actuator (26), in order to limit the actuator speed.

An aircraft landing gear actuation system which uses two separate actuation forces to retract aircraft landing gear is disclosed. One of the actuation forces may be provided by an actuator, such as a hydraulic actuator. Another of these actuation forces may be provided by a pressurized fluid that is directed into the actuator through a conduit that extends into a hollow interior of an actuator rod of the actuator. The pressurized fluid may be provided from a pressurized fluid source that contains a fixed volume of pressurized fluid. This pressurized fluid may exert a force on an actuator piston of the actuator or the actuator rod. The pressurized fluid may also be used to dampen the deployment of the landing gear.

An electromechanical brake pressure generator including a spindle drive unit for converting a rotational motion of an electric motor-driven drive shaft into a translatory motion of a piston that is coupled to the spindle drive unit, the spindle drive unit being operatively connected to the drive shaft via a multi-stage transmission. The multi-stage transmission is a planetary gear set having a first and a second stage. With the aid of the transmission, a spindle or a spindle nut of the spindle drive unit is drivable, which is rotatably mounted in a housing of the brake pressure generator via a bearing assembly receiving axial and radial forces. A braking system for a vehicle including an electromechanical brake pressure generator is also described.

A control system (50) for an electro-hydraulic servo-actuator (26) envisages: a controller (55), to generate a control current (I.sub.c), designed to control actuation of the electro-hydraulic servo-actuator (26), implementing a position control loop based on a position error (e.sub.p), the position error (e.sub.p) being a difference between a reference position (Pos.sub.ref) and a measured position (Pos.sub.meas) of the electro-hydraulic servo-actuator (26); and a limitation stage (58), coupled to the controller (55) to provide a limitation of the actuator speed of the electro-hydraulic servo-actuator (26); the limitation stage (58) limits a rate of change of a driving current (I.sub.d) to be supplied to the electro-hydraulic servo-actuator (26), in order to limit the actuator speed.

[Object] To provide a compact, high-output actuator device allowing force control. [Solution] An actuator device 1000 includes an electromagnetic coil member 110 provided over a prescribed width on an outer circumference of a cylinder 100, and a movable element 200 slidable as a piston in the cylinder 100. The movable element 200 has a magnetic member 202, and is moved relatively by excitation of the electromagnetic coil member 110. Fluid is supplied to first and second chambers 106a and 106b such that when the movable element 200 is to be moved relatively, the movable element 200 is driven in the same direction.

A device for amplifying a force includes a prime mover configured to receive a first force, and a secondary mover configured to generate a second force that is greater than the first force in response to the prime mover receiving the first force. The prime mover includes an output that, in response to the first force, rotates about a first axis through a power stroke defined by an angular displacement that is less than ninety degrees. The prime mover's output includes a first end that revolves about the first axis during the power stroke. The secondary mover includes an input, an output, and a body. The input includes a second end that is coupled with the first end of the prime mover's output, and that, as the first end of the prime mover's output revolves about the first axis through the power stroke, the second end of the secondary mover's input also revolves about the first axis and moves relative to the secondary mover's body. The secondary's mover's output is configured to apply the second force to an object. The secondary mover's body is pivotally anchored at a location such that as the first end of the prime mover's output revolves about the first axis through the power stroke, the body of the secondary mover pivots about a second axis that passes through the location. The position of the device's secondary mover relative to the first end of the prime mover's output is such that, as the first end approaches the end of the power stroke, the first end of the prime mover's output accelerates, without an additional force applied to the prime mover's output.

An asymmetric linear actuator is provided which integrates a hydraulic dissipater and an electric motor and power screw which generates small forces. The actuator is configured so that an electric motor drives a power screw which drives a rod through a cylinder to provide linear actuation. The cylinder is fluid-filled and incorporates a piston that separates the cylinder into a first and second fluid chamber which are filled with a first and second volume of working fluid. Movement of the piston and rod assembly results in fluid movement between the first and second volumes of working fluid and through the fluidic restriction. The fluidic restriction can be proportionally controllable via an electric motor which enables controllable power dissipation via control of the fluidic restriction motor and controllable power generation via control of the power screw motor.

Disclosed herein are hydraulic actuators and methods for the operation of actuators having variable relative pressure ratios. Further disclosed are methods for designing and/or operating a hydraulic actuator such that the actuator exhibits a variable relative pressure ratio. In certain embodiments, the relative pressure ratio of the hydraulic actuator may be dependent on one or more characteristics (such as, for example, frequency or rate of change) of an oscillating input to the hydraulic actuator.