Double-acting hydraulic rotary actuator
The Double-Acting Rotary Actuator block models a double-acting hydraulic rotary actuator, which directly converts hydraulic energy into mechanical rotational energy without employing intermediary transmissions such as rack-and-pinion, sliding spline, chain, and so on. Hydraulic fluid pumped under pressure into one of the two actuator chambers forces the shaft to rotate and generate torque. Double-acting actuators generate torque and motion in both directions.
The model of the actuator is built of Simscape™ Foundation library blocks. The schematic diagram of the model is shown below.
The blocks in the diagram perform the following functions:
|Rotational Hydro-Mechanical Converter A||Converts hydraulics energy into mechanical rotational energy when fluid is pumped into actuator chamber A, while accounting for fluid compressibility.|
|Rotational Hydro-Mechanical Converter B||Converts hydraulics energy into mechanical rotational energy when fluid is pumped into actuator chamber B, while accounting for fluid compressibility.|
|Rotational Hard Stop||Imposes limits on shaft rotation.|
|Linear Hydraulic Resistance||Accounts for leakages.|
Connections A and B are hydraulic conserving ports. Port A is connected to chamber A and port B is connected to chamber B. Connection S is a mechanical rotational conserving port associated with the actuator shaft.
The block directionality is adjustable and can be controlled with the Actuator orientation parameter.
No loading, such as inertia, friction, spring, and so on, is taken into account. If necessary, you can easily add them by connecting an appropriate building block to port S.
Effective displacement of the actuator. The default value is
Shaft maximum travel between stops. The default value is
The position of the shaft at the beginning of simulation. You
can set the shaft position to any angle within its stroke. The default
0, which corresponds to the shaft position
at the very beginning of the stroke.
Fluid volume in chamber A that remains in the chamber when the
shaft is positioned at the very beginning of the stroke. The default
Fluid volume in chamber B that remains in the chamber when the
shaft is positioned at the end of the stroke. The default value is
Leak coefficient for the Linear Hydraulic Resistance block.
The default value is
Gas-specific heat ratio for the Hydraulic Piston Chamber block.
The default value is
Specifies the elastic property of colliding bodies for the Rotational
Hard Stop block. The greater the value of the parameter, the less
the bodies penetrate into each other, the more rigid the impact becomes.
Lesser value of the parameter makes contact softer, but generally
improves convergence and computational efficiency. The default value
Specifies dissipating property of colliding bodies for the Rotational Hard Stop block. At zero damping, the impact is close to an absolutely elastic one. The greater the value of the parameter, the more energy dissipates during an interaction. Keep in mind that damping affects slider motion as long as the slider is in contact with the stop, including the period when slider is pulled back from the contact. For computational efficiency and convergence reasons, MathWorks recommends that you assign a nonzero value to this parameter. The default value is 150 N*m/(rad/s).
Specifies actuator orientation with respect to the globally
assigned positive direction. The actuator can be installed in two
different ways, depending upon whether it generates torque in the
positive or in the negative direction when pressure is applied at
its inlet. If pressure applied at port A generates torque in the negative
direction, set the parameter to
Acts in negative direction.
The default value is
Acts in positive direction.
Parameter determined by the type of working fluid:
Fluid bulk modulus
The block has the following ports:
Hydraulic conserving port associated with the actuator chamber A.
Hydraulic conserving port associated with the actuator chamber B.
Mechanical rotational conserving port associated with the actuator shaft.