# Sensor: Proximity

Model ElementThe Sensor_Proximity element defines a sensor between two bodies which monitors their minimum separation. The sensor tracks the state of interference of the two bodies, the minimum distance between them, and the coordinates of a pair of closest points. These quantities can be accessed using the PROXIMITY function for use in defining expressions or for plotting.

## Format

<Sensor_Proximity
id                = "integer"
[ label             = "string"  ]
num_i_graphics    = "integer"
i_graphics_id     = "integer_list"
num_j_graphics    = "integer"
j_graphics_id     = "integer_list"
/ >

## Attributes

id
Element identification number (integer>0). This number is unique among all Sensor_Proximity elements and uniquely identifies the element.
label
The name of the Sensor_Proximity element.
num_i_graphics
Specifies the number of Post_Graphic elements on the first body that are to be considered in evaluating the proximity. num_i_graphics > 0.
i_graphics_id

This is the list of the Post_Graphic element IDs on the first body to be considered for proximity. The number of IDs in this list is specified by num_i_graphics.

Note: All the Post_Graphic entities must belong to the same body. For a list of supported graphic types, please see comment 2.
num_j_graphics

Specifies the number of Post_Graphic elements on the second body that are to be considered in evaluating the proximity.

num_j_graphics > 0.

j_graphics_id

This is the list of the Post_Graphic element ids on the second body to be considered for proximity. The number of IDs in this list is specified by num_j_graphics.

Note: All the Post_Graphic entities must belong to the same body. For a list of supported graphic types, please see comment 2.

## Example

The image below demonstrates how the Sensor_Proximity element is used to track the minimum distance between a robot end-effector and a work piece.

<Sensor_Proximity
id                  = "70002"
num_i_graphics      = "1"
i_graphics_id       = "90013"
num_j_graphics      = "1"
j_graphics_id       = "90011"
/>

1. Sensor_Proximity does not compute the penetration between two bodies. It only computes the minimum distance between them.
2. The table below lists the graphic types that are supported by the Sensor_Proximity element for minimum distance calculations.
Type of Body Supported Graphics Unsupported Graphics
Rigid Body BoxDefinedFromCorner

BoxDefinedFromCenter

Cylinder

Frustum

Ellipsoid

Sphere

Plane

Triamesh

CircleFromRM

ArcFromRM

Point

LineMesh

SPDP

Outline

ParamCurve

ParamSurface

DeformCurve

DeformSurface

UserGra

Flexible Body Flexible bodies are not supported for proximity calculations.