Joint¶

class urdfpy.Joint(name, joint_type, parent, child, axis=None, origin=None, limit=None, dynamics=None, safety_controller=None, calibration=None, mimic=None)[source]¶

Bases: urdfpy.URDFType

A connection between two links.

There are several types of joints, including:

fixed - a joint that cannot move.
prismatic - a joint that slides along the joint axis.
revolute - a hinge joint that rotates about the axis with a limited range of motion.
continuous - a hinge joint that rotates about the axis with an unlimited range of motion.
planar - a joint that moves in the plane orthogonal to the axis.
floating - a joint that can move in 6DoF.

Parameters:

name (str) – The name of this joint.
parent (str) – The name of the parent link of this joint.
child (str) – The name of the child link of this joint.
joint_type (str) – The type of the joint. Must be one of Joint.TYPES.
axis ((3,) float, optional) – The axis of the joint specified in joint frame. Defaults to [1,0,0].
origin ((4,4) float, optional) – The pose of the child link with respect to the parent link’s frame. The joint frame is defined to be coincident with the child link’s frame, so this is also the pose of the joint frame with respect to the parent link’s frame.
limit (JointLimit, optional) – Limit for the joint. Only required for revolute and prismatic joints.
dynamics (JointDynamics, optional) – Dynamics for the joint.
safety_controller (:class`.SafetyController`, optional) – The safety controller for this joint.
calibration (JointCalibration, optional) – Calibration information for the joint.
mimic (JointMimic, optional) – Joint mimicry information.

Attributes Summary

`TYPES`
`axis`	The joint axis in the joint frame.
`calibration`	The calibration for this joint.
`child`	The name of the child link.
`dynamics`	The dynamics for this joint.
`joint_type`	The type of this joint.
`limit`	The limits for this joint.
`mimic`	The mimic for this joint.
`name`	Name for this joint.
`origin`	The pose of child and joint frames relative to the parent link’s frame.
`parent`	The name of the parent link.
`safety_controller`	The safety controller for this joint.

Methods Summary

`get_child_pose`([cfg])	Computes the child pose relative to a parent pose for a given configuration value.
`is_valid`(cfg)	Check if the provided configuration value is valid for this joint.

Attributes Documentation

TYPES = ['fixed', 'prismatic', 'revolute', 'continuous', 'floating', 'planar']¶

axis¶

The joint axis in the joint frame.

Type:	(3,) float

calibration¶

The calibration for this joint.

Type:	`JointCalibration`

child¶

The name of the child link.

Type:	str

dynamics¶

The dynamics for this joint.

Type:	`JointDynamics`

joint_type¶

The type of this joint.

Type:	str

limit¶

The limits for this joint.

Type:	`JointLimit`

mimic¶

The mimic for this joint.

Type:	`JointMimic`

name¶

Name for this joint.

Type:	str

origin¶

The pose of child and joint frames relative to the parent link’s frame.

Type:	(4,4) float

parent¶

The name of the parent link.

Type:	str

safety_controller¶

The safety controller for this joint.

Type:	`SafetyController`

Methods Documentation

get_child_pose(cfg=None)[source]¶

Computes the child pose relative to a parent pose for a given configuration value.

Parameters:

cfg (float, (2,) float, (6,) float, or (4,4) float) –

The configuration values for this joint. They are interpreted based on the joint type as follows:

fixed - not used.
prismatic - a translation along the axis in meters.
revolute - a rotation about the axis in radians.
continuous - a rotation about the axis in radians.
planar - the x and y translation values in the plane.
floating - the xyz values followed by the rpy values, or a (4,4) matrix.

If cfg is None, then this just returns the joint pose.

Returns: pose – The pose of the child relative to the parent.

Return type: (4,4) float

is_valid(cfg)[source]¶

Check if the provided configuration value is valid for this joint.

Parameters:	cfg (float, (2,) float, (6,) float, or (4,4) float) – The configuration of the joint.
Returns:	is_valid – True if the configuration is valid, and False otherwise.
Return type:	bool