Analysis Modeling > Moves > Types of Moves

The Gravity Move is used to move an object part to a target part while simulating the effects of gravity. This move involves floating holes and pins along a vector direction (the gravity direction). Please note use of this move can impact the Contributor Analysis and GeoFactor Equation-Based results, see the Analysis Comparison & Assumptions and Linearity sections for more information.

The Gravity Move assumes the axis of the holes and pins are perpendicular to the Gravity Vector. It translates the object part in the direction of the gravity vector until one hole/pin pair makes contact. Then it rotates around that hole/pin pair until another hole/pin pair makes contact. When it is complete only two of the multiple hole/pin pairs will make or have contact. This can be checked if you measured each pair with the circular interference measure.

Also See:

Applying Moves

Common Parameters

Inputs:

Object Points: The holes or pins on the part to be moved.

O1: The first hole/pin on the part to be moved.

O2: The second hole/pin on the part to be moved.

On: The nth hole/pin on the part to be moved.

Target Points: The part or parts locating the object.

T1:	The first hole/pin on the line.

T2:	The second hole/pin on the line.

Tn:	The nth hole/pin on the plane.

Direction: A vector indicating the direction of the gravity move.

Procedure:

First, the object (hole/pin) has to be moved to the target (pin/hole) by means of a regular move. This establishes the nominal relationship between the holes and pins between the object and the target. Once the object has been moved to the target, the float between the object holes/pins and the target pins/holes is calculated. The object (hole/pin) is then dropped on the target (pin/hole) by the float amount available for each hole/pin match in the direction specified by the vector.

Note: The default settings are:

Constant Magnitude and Constant Angle for hole/pin assembly.

Constant Magnitude and +/-1 for Scale.

STEP 1

The object holes O1 and O2 are moved to the target pins T1 and T2. The object holes and the target pins have a nominal float between them.

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STEP 2:

The float between the object holes and target pins is calculated and the object holes are dropped down by the lesser amount of float between the object holes and the target pins in the specified reference direction. One hole is on the resting on the pin and the other still has clearance to the pin.

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STEP 3

The object holes are then rotated about the center of the hole resting on the pin until the other hole is resting on it's mating pin. This drop is to simulate the effect of gravity on the object.

Notes:

•If AssocDir is selected, the direction will be the Associated Vector of first Target Point. All associated vectors default to (0, 0, 1) if corresponding point is not selected.

•Care must be taken when moving the holes to the pins prior to the gravity move. If a hole interferes with a pin, the gravity move will not work properly.

•The Gravity Move doesn't consider weight or size of the object being moved. Depending on the weight and size, the object may actually rotate (STEP3) in the opposite direction.

•Because the Gravity Move generally causes a mean shift rather than a change in variation, its effects are not considered in the HLM.