The 'env' file format is used by our group (i.e., it is not any particular standard, just what we use in our planner).

In the workspace, the `robot(s)' (identified by Active tags) and the `obstacle(s)' (identified by Passive tags) are all 'multibodies'. Multibodies are made up of one or more bodies, where each body is described by a ".g" file in BYU format ; all the BYU files are listed in the environment input file. A Body that cannot move is tagged FixedBody and a body that can move is tagged FreeBody.

Multibody descriptions (position and orientation) and connections are given with respect to a global coordinate frame. Each connection description includes the indices of the two bodies it connects, the joint type ( Revolute or Prismatic), DH parameters, and the transformations between the body frames and the DH frames.

The following example `environment' has three multibodies - one robot which moves (Active) and two obstacles which are stationary (Passive). In the example, the left column shows the lines in the `environment' and the right column describes the line to its left; a real .env file would not have these comments. Below the example, we give some more details regarding the connection descriptions.

Angles are usually expressed in degrees (0-360) in the ".env"files. In general, we use degrees when dealing with workspace and normalized values -- [0,n) when describing configurations in C-space.

3	Number of Multibodies
MultiBody Active	Tag(MultiBody) Tag(Active or Passive)
4	Number of Bodies in current MultiBody
FreeBody 0 cube.g 0 0 0 0 0 0	Tag (FreeBody or FixedBody)
	& index
	& geometry description file
	& initial configuration for first freeBody
FreeBody 1 link1.g	Same as above, except no initial configuration
FreeBody 2 link2.g	Same as above
FreeBody 3 link3.g	Same as above
Connection	Tag(Connection)
3	number of connections, details specified below
0 1 Actuated	Connection between Freebodies #i and #j
	& Tag Actuated
0.2 0 0 -90 0 0 90 0.2 0 30 Revolute 0 0 0 0 0 0	Transformation from frame #i
	DH parameters
	Tag joint type(Revolute or Prismatic)
	Transformation from DH frame to frame #j
1 2 Actuated	Same as above
0.2 0 0 -90 0 0 90 0.2 0 30 Revolute 0 0 0 0 0 0
2 3 Actuated	Same as above
0.2 0 0 -90 0 0 90 0.2 0 30 Revolute 0 0 0 0 0 0
MultiBody Passive	Tag (MultiBody) Tag (Active or Passive)
1	number of Bodies in current MultiBody
FixedBody 0 block.g 0 2.0 0 0 0 0	Tag (FreeBody or FixedBody)
	& index
	& geometry description file
	& initial position and orientation
Connection	Tag (Connection)
0	Ie,none
MultiBody Passive	Tag(MultiBody) Tag(Active or Passive)
1	Number of Bodies in current MultiBody
FixedBody 0 block.g 0 2.0 0 0 0 0	Tag(FreeBody or FixBody)
	& index
	& geometry description file
	& initial position and orientation
Connection	Tag (connection)
0	ie, none

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