SimMechanics

Driver Actuator

Apply relative motion between a pair of constrained bodies through a driver

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 degree 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 output of the Driver Actuator is this time-dependent function f(t) and its first two derivatives.

You specify these three functions as a bundled Simulink input signal. This signal can be any Simulink signal, including 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 specific meaning of f(t) depends on the connected Driver block being actuated. Select the specific Driver block for details.
  
  

  Linear Motions	Angular Motions
  Distance Driver	Angle Driver
  Linear Driver
  Velocity Driver

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 Connector Port you connect to the Driver block you want to actuate.

Note    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.

Dialog Box and Parameters

The dialog box has one active area, Actuation.

Actuation

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.

Position

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

If the Driver Actuator is connected to a Velocity Driver, this field does not appear.

Velocity

In the pull-down menu, choose the units of the actuating df(t)/dt you apply to the relative motion of the bodies.

If the Driver Actuator is connected to a Velocity Driver, this field refers to f(t).

Acceleration

In the pull-down menu, choose the units of the actuating d²f(t)/dt² you apply to the relative motion of the bodies.

If the Driver Actuator is connected to a Velocity Driver, this field refers to df(t)/dt.

See Also

Body Actuator, Constraint & Driver Sensor, Joint Actuator

See Creating Constraints and Drivers.

In Simulink, see the Signal Routing Library and the Sources Library.

Distance Driver

Gear Constraint