Coupled and Rotational Coordinates

[Nicholas Sotirelis]

I apologize if this has been asked and answered before, but if it has I could not find it.

Unlike rotational coordinates, *.mot files give coupled coordinates in radians. inDegrees is set to yes, I checked just to make sure. The coordinates panel is the exact same way, rotational coordinates in degrees, and coupled coordinates in radians. Is there a way of making both coupled and rotational coordinates use one or the other?

[jimmy d]

The MotionType of a Coordinate is now fully determined by the Joint. The user cannot set the MotionType for a Coordinate. There are instances such as in the leg6dof9musc and Rajagopal2015 models, where a Coordinate was assigned an incorrect type (e.g. when a coordinate of a CustomJoint is not a measure of a Cartesian angle). In 4.0, the coordinate is correctly marked as Coupled since a function couples the coordinate value to the angular displacement of the patella in Cartesian space. NOTE, this causes issues (e.g. opensim-org/opensim-gui#617, #2088) when using kinematics files generated in 3.3 (or earlier) where Rotational coordinates have been converted to degrees. Because OpenSim 4.0 does not recognize the coordinate's MotionType to be Rotational it will not convert it back to radians internally. For motion files generated prior to 4.0 where the file has inDegrees=yes, please use the following conversion utility: updatePre40KinematicsFilesFor40MotionType(). When loading a pre-4.0 model, OpenSim will warn users of any changes in MotionType when updating an existing model to OpenSim 4.0.