Main Content

Double-Acting Actuator (TL)

Linear actuator with piston motion controlled by two opposing thermal liquid chambers

  • Library:
  • Simscape / Fluids / Thermal Liquid / Actuators

  • Double-Acting Actuator (TL) block

Description

The Double-Acting Actuator (TL) block represents a linear actuator with piston motion controlled by two opposing thermal liquid chambers. The actuator generates force in the extension and retraction strokes. The force generated depends on the pressure difference between the two chambers.

The figure shows the key components of the actuator model. Ports A and B represent the thermal liquid chamber inlets. Port R represents the translating actuator piston and port C the actuator case. Ports HA and HB represent the thermal interfaces between each chamber and the environment. The moving piston is adiabatic.

Double-Acting Actuator Schematic

Displacement

The piston displacement is measured as the position at port R relative to port C. The Mechanical orientation identifies the direction of piston displacement. The piston displacement is considered neutral, or 0, when the chamber A volume is equal to the chamber dead volume. When displacement is received as an input, ensure that the derivative of the position is equal to the piston velocity. This is automatically the case when the input is received from a Translational Multibody Interface block connection to a Simscape Multibody joint.

The direction of the piston motion depends on the mechanical orientation setting in the block dialog box. If the mechanical orientation is positive, then a higher pressure at port A yields a positive piston translation relative to the actuator case. The direction of motion reverses for a negative mechanical orientation.

Hard Stop

A set of hard stops limit the piston range of motion. The hard stops are treated as spring-damper systems. The spring stiffness coefficient controls the restorative component of the hard-stop contact force and the damping coefficient the dissipative component.

The hard stops are located at the distal ends of the piston stroke. If the mechanical orientation is positive, then the lower hard stop is at x = 0 and the upper hard stop at x = +stroke. If the mechanical orientation is negative, then the lower hard stop is at x = -stroke and the upper hard stop at x = 0.

Block Composite

This block is a composite component based on the Simscape™ Foundation blocks:

Composite Component Diagram

Ports

Input

expand all

Physical signal input port associated with the piston position that you specify using a Simscape Multibody™ block.

Dependencies

To expose this port, set Piston displacement from chamber A cap to Provide input signal from Multibody joint.

Output

expand all

Physical signal port associated with the piston position.

Dependencies

To expose this port, set Piston displacement from chamber A cap to Calculate from velocity of port R relative to port C.

Conserving

expand all

Thermal liquid conserving port associated with the inlet to chamber A.

Thermal liquid conserving port associated with the inlet to chamber B.

Mechanical translational conserving port representing the actuator piston.

Mechanical translational conserving port representing the actuator casing.

Thermal conserving port associated chamber A.

Thermal conserving port associated with chamber B.

Parameters

expand all

Actuator

Sets the piston displacement direction. When you set this parameter to:

  • Pressure at A causes positive displacement of R relative to C the piston displacement is positive when the volume of liquid at port A is expanding. This corresponds to rod extension.

  • Pressure at A causes negative displacement of R relative to C the piston displacement is negative when the volume of liquid at port A is expanding. This corresponds to rod contraction.

Cross-sectional area of the piston rod on the chamber A side.

Cross-sectional area of the piston rod on the chamber B side.

Maximum piston travel distance.

Volume of liquid when the piston displacement is 0 in chamber A. This is the liquid volume when the piston is up against the actuator end cap.

Volume of liquid when the piston displacement is 0 in chamber B. This is the liquid volume when the piston is up against the actuator end cap.

Environment reference pressure. The Atmospheric pressure option sets the environmental pressure to 0.101325 MPa.

User-defined environmental pressure.

Dependencies

To enable this parameter, set Environment pressure specification to Specified pressure.

Hard Stop

Piston stiffness coefficient. This value must be greater than 0.

Piston damping coefficient.

Model choice for the force on the piston at full extension or full retraction. See the Translational Hard Stop block for more information.

Application range of the hard stop force model. Outside of this range of the piston maximum extension and piston maximum retraction, the Hard stop model is not applied and there is no additional force on the piston.

Dependencies

To enable this parameter, set Hard stop model to Stiffness and damping applied smoothly through transition region, damped rebound.

Extended Capabilities

C/C++ Code Generation
Generate C and C++ code using Simulink® Coder™.

Version History

Introduced in R2016a