Joints task#
A JointsTask is a task that can be used to define a target value for some joints.
Warning
While it is possible to explicitely set a joint value by using set_joint()
on the robot wrapper (see joints configurations),
it is not equivalent to using a joint task.
Using the joints task will allow to account for everything
that the solver is enforcing (joint limits, joint velocity limits, other tasks such as loops closing constraints
etc…), while set_joint() will immediately update the joint value
in the robot state regardless of the solver.
Task initialization#
You can use the following code to initialize the joint task:
# Initializing a joints task as a soft task with weight 1.0
joints_task = solver.add_joints_task()
joints_task.configure("joints", "soft", 1.0)
Task update#
You can configure the task by passing a dict to set_joints():
# Setting the target for the joints task
joints_task.set_joints({
"joint1": 0.5,
"joint2": -0.2,
})
Note
Unit values will depend on the joint types, it will be radians for revolute joints and meters for prismatic
Used as regularization#
As explained in the concepts, it is possible to use a task with a low weight for regularization. A joint task can be adapted for that purpose, by using a robot posture as “fallback” target when the problem is underconstrained.
Example#
Here is an example of a 6-axis arm, where it’s base joint (r1) is controlled by a joint task:
6-axis joint