grippers_ros2

ROS 2 gripper interface implementations.

This module defines ROS 2-backed gripper wrappers used by RobotBlockSet robot interfaces.

class robotblockset.ros2.grippers_ros2.FrankaGripper(robot: robot | None = None, namespace: str = 'franka_gripper', **kwargs: Any)[source]

Bases: gripper

ROS 2 action-based interface for the Franka gripper (Panda / FR3).

Uses franka_msgs action servers for homing, moving, and grasping, and a std_srvs/Trigger service for stopping.

Can be used standalone (robot=None) or attached to an existing robot instance.

Attributes:

  • Name (str) – Identifier for the gripper instance.

  • GripperTagNames (str) – Tag used for identifying the gripper in logs or systems.

  • Robot (robot or None) – The robot associated with the gripper, or None if standalone.

Initialize the Franka gripper ROS 2 wrapper.

Parameters:

  • robot (robot, optional) – Robot instance to which the gripper is attached. Must be an robot subclass instance. If None, a minimal internal node is created and spun in a background thread so the gripper can be used standalone.

  • namespace (str, optional) – ROS 2 namespace the franka_gripper_node runs in. The node is always named franka_gripper, so topics resolve to /{namespace}/franka_gripper/{action}. Defaults to "franka_gripper" which matches the standard launch setup.

  • **kwargs (Any) – Additional keyword arguments for future extensions or configuration.

__init__(robot: robot | None = None, namespace: str = 'franka_gripper', **kwargs: Any) → None[source]

Initialize the Franka gripper ROS 2 wrapper.

Parameters:

  • robot (robot, optional) – Robot instance to which the gripper is attached. Must be an robot subclass instance. If None, a minimal internal node is created and spun in a background thread so the gripper can be used standalone.

  • namespace (str, optional) – ROS 2 namespace the franka_gripper_node runs in. The node is always named franka_gripper, so topics resolve to /{namespace}/franka_gripper/{action}. Defaults to "franka_gripper" which matches the standard launch setup.

  • **kwargs (Any) – Additional keyword arguments for future extensions or configuration.

property width: float

Get the last known gripper width from joint-state feedback.

Returns:

Current gripper finger width in metres.

Return type:

float

GetState() → str[source]

Return the current state of the gripper as a human-readable string.

Returns:

"Opened", "Closed", or "Undefined".

Return type:

str

Grasp(width: float, speed: float = 0.1, force: float = 5.0, eps: float = 0.005) → bool[source]

Grasp an object with the gripper.

Parameters:

  • width (float) – Target grasp width in metres.

  • speed (float, optional) – Closing speed in m/s (default 0.1).

  • force (float, optional) – Grasp force in N (default 5.0).

  • eps (float, optional) – Inner and outer epsilon tolerance in metres (default 0.005).

Returns:

True if the grasp was reported as successful, False otherwise.

Return type:

bool

Move(width: float, speed: float = 0.1) → bool[source]

Move the gripper to a specified width.

Parameters:

  • width (float) – Target width in metres.

  • speed (float, optional) – Desired speed in m/s (default 0.1).

Returns:

True if the move was reported as successful, False otherwise.

Return type:

bool

Homing() → bool[source]

Home the gripper and open it fully.

Returns:

True if homing was reported as successful, False otherwise.

Return type:

bool

Stop(timeout_sec: float = 1.0) → bool | None[source]

Stop any ongoing gripper action.

Parameters:

timeout_sec (float, optional) – Timeout in seconds for the service call (default 1.0).

Returns:

True if the stop service call succeeded, None if it was unavailable or timed out.

Return type:

bool or None

Classes

FrankaGripper([robot, namespace])

ROS 2 action-based interface for the Franka gripper (Panda / FR3).