Double-Acting Actuator (TL-G)

R2026b

Linear actuator with opposing thermal liquid and gas chambers

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Double-Acting Actuator (TL-G) block

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Libraries:
Simscape / Fluids / Thermal Liquid / Actuators

Description

The Double-Acting Actuator (TL-G) block models a linear actuator with opposing chambers of thermal liquid and gas. The chambers can be individually pressurized to power the actuator in both extension and retraction strokes. A piston between the chambers converts the pressure difference across them into actuation force.

The figure maps the conserving ports of the block to the actuator parts. Ports A and B are the inlets of the thermal liquid and gas chambers. Ports R and C are the translating piston and case. The chambers can exchange heat with the environment and are fitted for this purpose with ports HA and HB. The piston is perfectly insulating. The thermal liquid and gas chambers do not exchange heat with each other.

This diagram shows the block behavior when Mechanical orientation is Pressure at A causes positive displacement of R relative to C.

The sign of the piston displacement relative to the case depends on the mechanical orientation of the actuator. Use the Mechanical orientation parameter to specify this setting. If the mechanical orientation is positive, the piston displacement is positive when the pressure is highest in the thermal liquid chamber (port A). If the mechanical orientation is negative, the piston displacement (under the same pressure conditions) is negative.

Use port P to output the instantaneous piston position. The measurement is absolute (relative to zero). Hard stops limit the motion of the piston to the length of the case. The stops are modeled as spring-dampers, with spring and damping coefficients to capture material compliance. One is located at the bottom of the piston stroke and the other at the top:

• If Mechanical orientation is Pressure at A causes positive displacement of R relative to C, the bottom stop is at zero, and the top stop is at a distance equal to the piston stroke.

• If Mechanical orientation is Pressure at A causes negative displacement of R relative to C, the top stop is at zero, and the bottom stop is at a distance equal to the piston stroke.

The block is a composite component built from Simscape™ Foundation blocks. For more information, see the reference pages of the constituent blocks:

• Translational Mechanical Converter (TL)

• Translational Mechanical Converter (G)

• Translational Hard Stop

• Ideal Translational Motion Sensor

Ports

Output

P — Piston position, m

physical signal

Physical signal output port associated with the piston position. The measurement is absolute. The first reading is the value of the Piston initial displacement parameter.

Programmatic Use

Port: p_out

Conserving

A — Inlet to chamber A

thermal liquid

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

Programmatic Use

Port: A

B — Inlet to chamber B

gas

Gas conserving port representing the inlet to chamber B.

Programmatic Use

Port: B

R — Actuator piston

mechanical translational

Mechanical translational conserving port representing the actuator piston.

Programmatic Use

Port: R

C — Actuator casing

mechanical translational

Mechanical translational conserving port representing the actuator casing.

Programmatic Use

Port: C

HA — Chamber A heat flow

thermal

Thermal conserving port associated with the surface through which heat exchange can occur between the thermal liquid volume and the actuator surroundings. The thermal processes at this port influence the temperature in the thermal liquid chamber and therefore at port A.

Programmatic Use

Port: HA

HB — Chamber B heat flow

thermal

Thermal conserving port associated with the surface through which heat exchange can occur between the gas volume and the actuator surroundings. The thermal processes at this port influence the temperature in the gas chamber and therefore at port A.

Programmatic Use

Port: HB

Parameters

Thermal Liquid Side

Mechanical orientation — Direction of motion of the piston relative to the direction of flow of the fluid

Pressure at A causes positive displacement of R relative to C (default) | Pressure at A causes negative displacement of R relative to C

Orientation of the actuator piston relative to the direction of fluid flow. A positive orientation causes the piston to move in the positive direction relative to the actuator casing in response to a positive flow rate through port A. The mechanical orientation affects the placement of the piston hard stops.

Programmatic Use

Parameter:	mech_orientation
Values:	"foundation.enum.MechOrientationTranslational.Positive" | "foundation.enum.MechOrientationTranslational.Negative"

Piston cross-sectional area in chamber A — Cross-sectional area of the fluid volume in the thermal liquid chamber

0.01 m^2 (default) | scalar in units of area

Area normal to the direction of flow in the body of the thermal liquid chamber. The block uses this area to calculate the hydraulic force due to the fluid pressure in the thermal liquid chamber. This parameter must be greater than zero.

Programmatic Use

Parameter: piston_area_A

Piston stroke — Distance of travel of the piston from hard stop to hard stop

0.2 m (default) | scalar in units of length

Total distance of travel available to the piston, from one hard stop to the other. The hard stops limit the piston motion so that the piston is confined to stroke of the piston. See the block description for more information on the locations of the hard stops.

Programmatic Use

Parameter: stroke

Piston initial displacement — Position of the piston at the start of simulation

0 m (default) | scalar in units of length

Absolute position of the piston at the start of simulation. The zero position coincides with the lower hard stop if the mechanical orientation is positive and with the upper hard stop if the mechanical orientation is negative.

Programmatic Use

Parameter: x0

Dead volume in chamber A — Chamber A minimum volume without hardstop penetration

1e-4 m^3 (default) | positive scalar

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

Programmatic Use

Parameter: dead_volume_A

Enable dynamic compressibility — Choice to model the effects of dynamic compressibility inside the thermal liquid chamber

On (default) | Off

Whether to model the dynamic compressibility of the liquid. Dynamic compressibility affects the transient response of the system at small timescales. If you select this parameter, the pressure responds dynamically based on the accumulation of fluid mass in the volume. If you clear this parameter, the volume does not accumulate mass and the pressure response is instantaneous. Clearing this setting can improve simulation performance, but may have a negative effect on the simulation robustness. Only clear this setting for small fluid volumes or models with long simulation times.

Programmatic Use

Parameter:	compressibility
Values:	"true" | "false"

Initial liquid pressure in chamber A (absolute) — Absolute pressure in the thermal liquid chamber

0.101325 Pa (default) | scalar in units of pressure

Pressure inside the thermal liquid chamber at simulation time zero relative to absolute zero. This parameter helps set the initial states of the thermal liquid volume.

Dependencies

To enable this parameter, select Enable dynamic compressibility.

Programmatic Use

Parameter: p0_A

Initial liquid temperature in chamber A — Temperature in the thermal liquid chamber at the start of simulation

293.15 K (default) | scalar in units of temperature

Average temperature inside the thermal liquid chamber at the start of simulation. This parameter helps set the initial states of the thermal liquid volume.

Programmatic Use

Parameter: T0_A

Nominal liquid pressure in chamber A (absolute) — Pressure at nominal operating conditions in chamber A

0.101325 MPa (default) | scalar

Liquid pressure at nominal operating conditions in chamber A. The block uses this value to calculate the nominal density to use in the mass conservation equation when dynamic compressibility is disabled.

Dependencies

To enable this parameter, clear the Enable dynamic compressibility checkbox.

Programmatic Use

Parameter: p_nominal_A

Nominal liquid temperature in chamber A — Temperature at nominal operating conditions in chamber A

293.15 K (default) | scalar

Liquid temperature at nominal operating conditions in chamber A. The block uses this value to calculate the nominal density to use in the mass conservation equation when dynamic compressibility is disabled.

Dependencies

To enable this parameter, clear the Enable dynamic compressibility checkbox.

Programmatic Use

Parameter: T_nominal_A

Environment pressure specification — Choice of atmospheric or custom environment pressure for the thermal liquid side

Atmospheric pressure (default) | Specified pressure

Option to set the environment pressure of the thermal liquid chamber to the typical value of one earth atmosphere or to a custom value. Selecting Specified pressure exposes an additional parameter, Environment pressure, that you use to specify a custom pressure.

Programmatic Use

Parameter:	environment_spec_A
Values:	"foundation.enum.pressure_spec.specified" | "foundation.enum.pressure_spec.atmospheric"

Environment pressure — Absolute pressure of the environment outside the thermal liquid chamber

0.101325 MPa (default) | scalar in units of pressure

Pressure outside the thermal liquid chamber relative to absolute zero. This pressure acts against the pressure inside the thermal liquid chamber. A pressure of zero corresponds to a perfect vacuum.

Dependencies

This parameter is enabled when the Environment pressure specification is set to Specified pressure.

Programmatic Use

Parameter: environment_p_A

Gas Side

Piston cross-sectional area in chamber B — Cross-sectional area of the fluid volume in the gas chamber

1e-3 m^2 (default) | positive scalar in units of area

Area normal to the direction of flow in the body of the gas chamber. The block uses this area to calculate the pneumatic force due to the fluid pressure in the gas chamber. This parameter must be greater than zero.

Programmatic Use

Parameter: piston_area_B

Cross-sectional area at port B — Cross-sectional area of the inlet of the gas chamber

1e-3 m^2 (default) | positive scalar in units of area

Area normal to the direction of flow at the entrance to the gas chamber. The cross-sectional area at the entrance can differ from that in the body of the chamber. Set the two cross-sectional areas to different values to model the effects of a sudden area change at the inlet. This parameter must be greater than zero.

Programmatic Use

Parameter: area_B

Dead volume in chamber B — Chamber B minimum volume without hardstop penetration

1e-4 m^3 (default) | positive scalar

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

Programmatic Use

Parameter: dead_volume_B

Initial gas pressure in chamber B (absolute) — Absolute pressure inside the gas chamber at the start of simulation

0.101325 MPa (default) | scalar in units of pressure

Pressure inside the gas chamber at simulation time zero relative to absolute zero. This pressure helps set the initial state of the gas volume.

Programmatic Use

Parameter: p0_B

Initial gas temperature in chamber B — Temperature in the gas chamber at the start of simulation

293.15 K (default) | scalar in units of temperature

Average temperature inside the gas chamber at the start of simulation. This parameter helps set the initial states of the gas volume.

Programmatic Use

Parameter: T0_B

Environment pressure specification — Choice of atmospheric or custom environment pressure for the gas side

Atmospheric pressure (default) | Specified pressure

Option to set the environment pressure of the gas chamber to the typical value of one earth atmosphere or to a custom value. Selecting Specified pressure exposes an additional parameter, Environment pressure, that you use to specify a custom pressure.

Programmatic Use

Parameter:	environment_spec_B
Values:	"foundation.enum.pressure_spec.specified" | "foundation.enum.pressure_spec.atmospheric"

Environment pressure — Absolute pressure of the environment outside the gas chamber

0.101325 MPa (default) | scalar in units of pressure

Pressure outside the gas chamber relative to absolute zero. This pressure acts against the pressure inside the gas chamber. A pressure of zero corresponds to a perfect vacuum.

Dependencies

This parameter is enabled when the Environment pressure specification is set to Specified pressure.

Programmatic Use

Parameter: environment_p_B

Hard Stop

Hard stop model — Select the hard stop model

Stiffness and damping applied smoothly through transition region, damped rebound (default) | Full stiffness and damping applied at bounds, undamped rebound | Full stiffness and damping applied at bounds, damped rebound | Based on coefficient of restitution

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

Programmatic Use

Parameter:	hardstop_model
Values:	"simscape.enum.hardstop.smooth" | "simscape.enum.hardstop.fullundamped" | "simscape.enum.hardstop.fulldamped" | "simscape.enum.hardstop.modechart"

Hard-stop stiffness coefficient — Stiffness coefficient

1e6 N/m (default) | positive scalar

Piston stiffness coefficient.

Dependencies

To enable this parameter, set Hard stop model to

• Stiffness and damping applied smoothly through transition region, damped rebound

• Full stiffness and damping applied at bounds, undamped rebound

• Full stiffness and damping applied at bounds, damped rebound

Programmatic Use

Parameter: stiff_coeff

Hard-stop damping coefficient — Damping coefficient

150 N*s/m (default) | positive scalar

Piston damping coefficient.

Dependencies

To enable this parameter, set Hard stop model to

• Stiffness and damping applied smoothly through transition region, damped rebound

• Full stiffness and damping applied at bounds, undamped rebound

• Full stiffness and damping applied at bounds, damped rebound

Programmatic Use

Parameter: damping_coeff

Transition region — Application range of hard stop force model

0.1 mm (default) | positive scalar

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.

Programmatic Use

Parameter: transition

Coefficient of restitution — Ratio of final-to-initial relative speed between slider and stop after collision

0.7 (default) | unitless value between 0 and 1

Ratio of the final to the initial relative speed between the slider and the stop after the slider bounces.

Dependencies

To enable this parameter, set Hard stop model to Based on coefficient of restitution.

Programmatic Use

Parameter: coeff_rest

Static contact speed threshold — Threshold relative speed between slider and stop before collision

0.001 m/s (default) | nonnegative scalar

Threshold relative speed between slider and stop before collision. When the slider hits the case with speed less than the value of the Static contact speed threshold parameter, they stay in contact. Otherwise, the slider bounces. To avoid modeling static contact between the slider and the case, set this parameter to 0.

Dependencies

To enable this parameter, set Hard stop model to Based on coefficient of restitution.

Programmatic Use

Parameter: v_tol

Static contact release force threshold — Threshold force needed to transition from contact mode to free mode

0.001 N (default) | positive scalar

Minimum force needed to release the slider from a static contact mode.

Dependencies

To enable this parameter, set Hard stop model to Based on coefficient of restitution.

Programmatic Use

Parameter: f_tol

Extended Capabilities

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

Version History

Introduced in R2016b

R2023a: New hard stop parameterization option

The block has a new option for the Hard stop model parameter. This option, called Based on coefficient of restitution, models the hard stop by using a mode chart.