Work in progress: this documentation is still being written and reviewed. Check details against the source code.

Gripper motion stages

Build SRDF group-state gripper moves using joint interpolation. An empty gripper group is explicitly a successful no-op.

beambot.stages.end_effector_stages · Source

Tools and end effectors · Guide · Symbol index

How it is used

EndEffectorActionServer calls run() for a standalone gripper request. The orchestrator’s batch path calls add_to_task() to insert the same gripper stage alongside arm moves before planning the combined task.

Targets are configured SRDF group states. An empty gripper group is a successful no-op; it is not evidence that a physical tool actuated.

Start here

Callable

Purpose

EndEffectorStages.run

Return immediately for an empty group; otherwise create, plan and execute an end-effector task.

EndEffectorStages.add_to_task

Append a gripper MoveTo stage, using joint interpolation unless a planner is supplied. An empty group succeeds without requiring an action.

EndEffectorStages

BaseStages subclass for joint-interpolated gripper group-state moves. run() owns a complete task; add_to_task() composes into a caller-owned task.

Inherits from: BaseStages.

EndEffectorStages.run()

Return immediately for an empty group; otherwise create, plan and execute an end-effector task.

Entry point · Source

run(self, goal) -> str | None

Parameter

Meaning

goal

EndEffector action goal.

Returns: None on completion/no-op or error string.

Errors: Unhandled construction errors propagate; planning/execution helpers return error strings.

Side effects: May actuate the gripper through MTC.

EndEffectorStages.add_to_task()

Append a gripper MoveTo stage, using joint interpolation unless a planner is supplied. An empty group succeeds without requiring an action.

Method · Source

add_to_task(self, task: core.Task, goal, planner=None) -> str | None

Parameter

Meaning

task

MTC task receiving a gripper stage.

goal

Goal containing gripper_group and end_effector_action SRDF names.

planner

Optional explicit planner.

Returns: None after append or no-op; error string when a nonempty group has no action.

Errors: MTC construction errors propagate; state/group existence is validated by planning downstream.

Side effects: May append a stage and populate planner cache; logs decisions.

Referenced in source (1)