Sensor: Proximity

Model ElementThe Sensor_Proximity element defines a sensor that measures the minimum distance between the graphics/mesh of two bodies. The sensor tracks the state of interference of the graphics/mesh, the length of the minimum distance, 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"
   |
     i_flexbody_id     = "integer"
   }
   {   
     num_j_graphics    = "integer"
     j_graphics_id     = "integer_list"
   |
     j_flexbody_id     = "integer"
   }
/>

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. This argument is optional.
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.; Note: Omit this attribute if the body is flexible.
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 Post_Graphic entities must belong to the same body.

Note: Omit this attribute if the body is flexible.
i_flexbody_id: If the first body is flexible, this argument specifies the ID of Body_Flexible for the first body to be considered for contact.; Note: Omit this attribute if the body is rigid.
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.; Note: Omit this attribute if the body is flexible.
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.

Note: Omit this attribute if the body is flexible.
j_flexbody_id: If the second body is flexible, this argument specifies the ID of Body_Flexible for the second body to be considered for contact.; Note: Omit this attribute if the body is rigid.

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.

Figure 1. Minimum Distance Between a Robot End-effector and Workpiece

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

The next image demonstrates how the Sensor_Proximity element is used to track the minimum distance between a rigid sphere and a flexible plate.

Figure 2. Minimum Distance Between a Rigid Sphere and Flexible Plate

<Sensor_Proximity 
     id                  = "70001" 
     num_i_graphics      = "1" 
     i_graphics_id       = "90000" 
     j_flexbody_id       = "30102" 
/>

Comments

Sensor_Proximity does not compute the penetration between two bodies. It only computes the minimum distance between them.

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 CircelFromRadius ArcFromRM ArcFromRadius Point LineMesh SPDP Outline ParamCurve ParamSurface DeformCurve DeformSurface UserGra
Flexible Body	H3D file referenced from Body_Flexible	0D (points) and 1D (lines/beam) elements inside the H3D file.