myoconverter.xml.joints.CustomJoint

Contains the CustomJoint parser.

@author: Aleksi Ikkala

Module Contents

Classes

CustomJoint

This class parses and converts the OpenSim CustomJoint XML element to MuJoCo.
class myoconverter.xml.joints.CustomJoint.CustomJoint[source]

Bases: myoconverter.xml.joints.Joint.Joint

This class parses and converts the OpenSim CustomJoint XML element to MuJoCo.

A CustomJoint in OpenSim can represent any type of a joint through 3 translational and 3 rotational degrees of freedom.

_parse(xml, socket_parent_frame, socket_child_frame, pointer)[source]

This function handles the actual parsing and converting.

The given CustomJoint is parsed into a set of MuJoCo joints (1-6 depending on how many non-zero non-constant joints there are).

Parameters:

  • xml – OpenSim CustomJoint XML element

  • socket_parent_frame – Parent frame socket

  • socket_child_frame – Child frame socket

  • pointer – A pointer to the MuJoCo XML file where this joint will be added

Returns:

A list of MuJoCo XML joints, a list of joint parameters

Raises:

IndexError: If joint components are parsed in incorrect order

Raises:

TypeError: If a joint component type is not recognized

Raises:

RuntimeError: If spline definition cannot be found in the XML element

Raises:

NotImplementedError: If a joint component depends on two or more Coordinates

Raises:

NotImplementedError: If two Coordinates have a non-linear mapping

Raises:

RuntimeError: If a joint component has a non-identity linear mapping to a Coordinate

Raises:

RuntimeError: If a joint transformation type has not been implemented

_designate_dof(t, params, coordinate)[source]

Designate an OpenSim Coordinate as a MuJoCo DoF.

Designate a Coordinate as a MuJoCo DoF (if applicable). This means that one of the MuJoCo joints (DoF) will correspond to an OpenSim Coordinate, although in OpenSim one coordinate can parameterize multiple DoFs. We only allow identity or linear mappings for designated DoFs.

Parameters:

  • t – OpenSim sub-joint XML element

  • params – Joint parameters

  • coordinate – Copy of an OpenSim Coordinate

Returns:

Boolean indicating whether a Coordinate has been designated.

Raises:

NotImplementedError if t is not a SimmSpline or LinearFunction, or if the mapping between Coordinate and designated DoF is not linear.

Raises:

RunTimeWarning if LinearFunction has non-identity coefficients