SimMechanics

Ground

Represent an immobile point at rest in World

Library

Bodies

Description

A Ground block represents an immobile ground point at rest in the absolute inertial World reference frame (RF). Connecting it to a Joint prevents one side of that Joint from moving.

Ground is a type of Body, but you can connect only one side of a Ground to a Joint block. A Ground block automatically carries a Grounded coordinate system (CS). This Grounded CS is inertial, at rest in the World reference frame, with coordinate axes parallel to the World axes:

• +x points right

  +y points up (gravity in -y direction)

  +z points out of the screen, in three dimensions

But a Ground's origin is the ground point, which in general is shifted with respect to the World origin.

Every valid SimMechanics model must have at least one Ground block. Multiple Ground blocks represent different fixed points in the global inertial World. In the topology of a machine model, multiple Ground blocks function as a single body.

You cannot connect a Sensor or Actuator to a Ground block, because the ground point cannot be moved.

Dialog Box and Parameters

Grounded point

Enter in this field the position of the ground point translated from the origin of the World CS. The position is specified as a translation vector (x,y,z), with components projected on to the fixed World CS axes. Set the Ground position units using the pull-down menu to the right. The defaults are [0 0 0] and m (meters).

See Also

Body

See Creating Body CS Ports and Modeling Joints for more on setting up Grounds.

Gimbal

In-Plane