Driver Actuator

Time-dependent motion input for driver blocks

Library

Sensors & Actuators

Description

The Driver Actuator block actuates a Driver block connected between a pair of bodies. You connect the block to the Driver block connected between the Bodies. The Driver block represents a time-dependent (rheonomic) constraint on a relative degrees of freedom (DoF) between the two bodies. A Driver requires a time-dependent function to specify the relative position, velocity, and acceleration of the connected Bodies. The input of the Driver Actuator is this time-dependent function f(t) and its first two derivatives.

The Driver connects a base (B) and a follower (F) Body. The base-follower sequence determines the sense of the actuation signal. The inport is the Simulink® input signal. The output is the follower you connect to the Driver block you want to actuate.

    Tip   You do not have to connect a Driver block to a Driver Actuator. If you do not actuate a Driver, the Driver block acts as a time-independent constraint that freezes the driven relative DoF between the Bodies at its initial value during the simulation.

Driver Actuation Requires Two or Three Input Signals

You specify the three actuation functions as a bundled Simulink input signal (which can include a signal feedback from a Sensor block) satisfying these conditions:

  • The signal must consist of three bundled components.

    • Exception: The Velocity Driver requires two bundled components.

  • The three components must be ordered [f(t), df(t)/dt, d2f(t)/dt2].

    • Exception: The Velocity Driver requires a function and its derivative [f(t), df(t)/dt].

  • Each successive signal component must be the time derivative of the previous component.

  • The meaning of f(t) depends on the connected Driver block being actuated. Select the specific Driver block for details.

    Linear MotionsAngular Motions
    Distance Driver
    Linear Driver
    Velocity Driver
    Angle Driver

Dialog Box and Parameters

The dialog has one active area, Actuation. The block parameters are not displayed unless you connect it to a specific Driver block.

Actuation

The block dialog parameters depend on the specific Driver block to which you have connected it.

Driving Linear Motion

Position units

In the pull-down menu, choose the units of the actuating f(t) you apply to the relative motion of the bodies. The default is m (meters).

Velocity units

In the pull-down menu, choose the units of the actuating df(t)/dt you apply to the relative motion of the bodies. The default is m/s (meters/second).

Acceleration units

In the pull-down menu, choose the units of the actuating d2f(t)/dt2 you apply to the relative motion of the bodies. The default is m/s2 (meters/second2).

Driving Angular Motion

Angular units

In the pull-down menu, choose the units of the actuating f(t) you apply to the relative motion of the bodies. The default is deg (degrees).

Angular velocity units

In the pull-down menu, choose the units of the actuating df(t)/dt you apply to the relative motion of the bodies. The default is deg/s (degrees/second).

Angular acceleration units

In the pull-down menu, choose the units of the actuating d2f(t)/dt2 you apply to the relative motion of the bodies. The default is deg/s2 (degrees/second2).

Example

Here is a Driver Actuator connected to a Distance Driver, which connects two Bodies:

You must add an Actuator port (connector port) to the Driver block to connect the Driver Actuator to it. The base (B)-follower (F) Body sequence on the two sides of the Driver determines the sense of the Driver Actuator data.

The Driver Actuator drives the relative motion between the two Bodies connected to the Driver. The nature of the connected Driver block determines the exact meaning of the actuation data, including the choice of units.

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