Actuators

Use the Actuators tool to apply an actuator to features or connected parts.

Actuators drive parts in a translational manner, and can be defined in terms of displacement, velocity, acceleration, or force. Inputs can be based on time or another variable in the model (state dependent variable).

Location: Motion ribbon, Forces group


Click the satellite icon that appears when you hover over the Actuators tool to view a list of all actuators in your model.

Add Actuators to Connected Parts

It's best to connect parts with joints before applying actuators. The connected parts option on the guide bar scans the model for cylindrical or translational joints that are suitable for an actuator.

  1. Select the Actuators tool.
  2. Select Connected Parts on the guide bar. Parts pairs or sliding pin connections that can be actuated are shown in red.
    Note: If nothing appears in red, you either have no joints, or they are locked. Try using the Features option on the guide bar instead.
  3. Click anywhere on a red pair to create the actuator.
  4. In the microdialog, select an input:
    • Time Dependent : Make the actuator dependent on time.
    • State Dependent : Make the actuator dependent on the state of a variable object (joint, motor, actuator, spring-damper, system, or measure). You can then represent input relationships such as Torque vs. Speed, Force vs. Angle, or Force vs. Distance. For details, see State Dependent Inputs.
  5. Use the D, V, A, F drop-down menu to change the type of actuator. Options are displacement, velocity, acceleration, and force.
  6. Use the +/- button to reverse the actuator's direction of translation, as indicated by the arrow.
  7. Enter a magnitude in the text field for the displacement, velocity, acceleration, or force. Click the icon to calculate the default displacement.
  8. Right-click and mouse through the check mark to exit, or double-right-click.

Add Actuators to Features

An actuator is defined by a shaft and a base. The first click positions the shaft, and the second positions the base.

  1. Select the Actuators tool.
  2. Select Features on the guide bar.
  3. Select a hole, surface, or sliding pin.
    • For holes and surfaces, click once to position the shaft, and a second time to position the base.
    • For sliding pins, click once to replace the pin with an actuator.
  4. Use the D, V, A, F drop-down menu on the microdialog to change the type of actuator. Options are displacement, velocity, acceleration, and force.
  5. Use the +/- button to reverse the actuator's direction of translation, as indicated by the arrow.
  6. Enter a magnitude for the displacement, velocity, acceleration, or force. Click the icon to calculate the default displacement.
  7. Right-click and mouse through the check mark to exit, or double-right-click.
Tip:
  • An option to hide all actuators is available in the right-click context menu. In some models hiding all actuators may improve performance of the animation.
  • You can select the same hole or surface twice, in which case the second click is interpreted as reacting against ground. For a sliding pin through a single part, the actuator will be attached between the part and the ground.
  • You can change the appearance of the actuator shaft and base using the Appearance properties in the Property Editor.
  • If you intend to rigidly lock an actuator or motor that is of type=Velocity, you should disable the controller. If you do not do so, then you will need to adjust the PID gains in order to prevent (or at least minimize) movement.
  • Suppress/Unsuppress an actuator to understand its effect on your model. On the actuator, right-click and select Suppress. From the Model Browser or Table, right-click and select Unsuppress.

State Dependent Inputs

You can assign inputs to motors and actuators that are dependent on the state of joints, motors, actuators, systems, spring-dampers, and measures. Example input types include Torque vs. Speed, Force vs. Angle, and Force vs. Distance.

Example: Force Applied to Blade as a Function of Blade Angle Rotation

  1. Select a motor or actuator.
  2. Make the motor or actuator dependent on a variable object:
    1. In the microdialog, click , and then select the option.
    2. Click .
    3. In the modeling window, select a measure, system, actuator, motor, joint, or spring-damper to make it the independent variable.
      Note: To plot results such as displacement, velocity, and rotation, select a system. By selecting a system, you can plot for example:
      • Displacement vs. Rotation
      • Force vs. Angular Speed
      • Displacement vs. Rotation
      The independent variable is displayed in red.
  3. In the Profile Editor, specify the variable range or cycle over which the input function will be applied.
    1. In the microdialog click Profile Editor.
    2. Specify the variable range or cycle over which the input function will be applied:
    Option Description
    Function Select a profile function. Supported functions include:
    • Step
    • Step Dwell Step
    • Single Wave
    • Impulse
    • Table
    Variable The independent variable object (system, measure, motor, actuator, joint, or spring-damper).
    Reference Frame The reference frame used by the variable component.
    Variable Component The independent variable component output that the state dependent object will monitor. Use the dropdown menu to access to the library of functions.
    One Cycle (for cyclic rotations) Specify the cycle range within which the V(i) and V(f) values fall. For example, a 4-stroke piston engine will experience combustion force every 2 revolutions (or 720 degrees) of the crankshaft.
    Variable (i) Enter the initial value of the independent variable object (system, measure, motor, actuator, joint, or spring-damper).
    Variable (f) Enter the final value of the independent variable object (system, measure, motor, actuator, joint, or spring-damper).
    [Variable Object] Force (i) Enter the initial value of the state dependent object.
    [Variable Object] Force (f) Enter the final value of the state dependent object.

Microdialog Options

Use the options in the microdialog to edit the behavior and appearance of an actuator. Click the to view advanced options.



Figure 1. Actuators Microdialog
Type
Use the D, V, A, F drop-down menu on the microdialog to change the type of actuator. Options are displacement, velocity, acceleration, and force.
Reverse Direction
Use the +/- button to reverse the actuator's direction of translation, as indicated by the arrow.
Set Displacement/Velocity/Acceleration
Enter a magnitude for the displacement, velocity, acceleration, or force. Click the icon to calculate the default displacement.
Note: If you enter zero for the magnitude, the actuator will be locked and most of the options in the microdialog and Profile Editor will become uneditable.
Lock the Actuator
Lock the actuator to stop it from translating. This is useful for debugging.
Time
Make the actuator profile dependent on time.
Independent Variable
Make the actuator profile dependent on a selected variable.
Select Independent Variable
In the modeling window, select a measure, system, actuator, motor, joint, or spring-damper to make it the independent variable.
Profile Function
Use the profile function to change how the shaft translates as time elapses. Examples include step, single wave, or oscillating.
Edit the Profile Function
Open the Profile Editor, which allows you to edit profile data and view it in an interactive chart.
Use Controller
A controller is used to achieve the target displacement or velocity. If you disable the controller it will use the target profile directly, which could result in excessive deformations or other warnings.
Move Actuator
Click to open the Move tool, allowing you to reposition the actuator.
Align shaft with connection
Click to align the actuator so it is perpendicular to the connection to which it was applied.

Actuator Properties

Refine the behavior and appearance of actuators using the properties available in the Property Editor (F3).

Rotate with Part
Enables an actuator to either rotate (or not rotate) with the shaft part.
Maintain Coaxiality
Enable this property to create an implicit joint. There are two joint options for the coaxial joint type: cylindrical and translational.
Base Scale
Use to change the appearance of the motor shaft and base by changing the size of the motor.
For... Do this
Hole-based motors
  1. Click the gray circle patch overlaying the motor.
  2. In the microdialog, change the Base Scale by doing one of the following:
    • Drag the slider.
    • Enter a value between 0.5 and 2.0.
Shaft Radius
Use to adjust the overall size of the shaft. This property is not available for motors applied to holes.
For... Do this
Non-hole-based motors
  1. Click the white arrow overlaying the actuator.
  2. In the microdialog, change the Shaft Radius by doing one of the following:
    • Drag the slider.
    • Enter a value in the microdialog.
Shaft Radius
Use to adjust the overall size of the shaft. This property is not available for motors applied to holes.

Actuators Table

The Actuators table lists all of the actuators in your model and allows you to edit various attributes.

Location: Actuators tool, satellite icon



Figure 2. Actuators Table
To Do this
Rename a actuator Select the cell in the table and then click again to make the field editable.
Change the type Select the cell in the table and then select a different option from the list.
Sort a column Click the column header. Click repeatedly to toggle between ascending and descending order.
Add or remove columns Right-click on a column header.

Shortcuts

To Do this
Deselect a feature Hold down the Ctrl key and left-click a selected (red) hole or surface.
Exit the tool Right-click and mouse through the check mark to exit, or double-right-click.