Skip to content

action_interface.md

Latest commit

 

History

History
90 lines (57 loc) · 2.27 KB

action_interface.md

File metadata and controls

90 lines (57 loc) · 2.27 KB

Gripper action interface

This workspace standardizes gripper control around two ROS 2 actions (from the gripper_msgs package):

  • /open_gripper (gripper_msgs/action/OpenGripper)
  • /close_gripper (gripper_msgs/action/CloseGripper)

Multiple implementations (e.g. Dynamixel, Feetech) expose these same action names so higher-level software can stay gripper-agnostic.

Action types

gripper_msgs/action/OpenGripper

Goal:

  • torque (float): implementation-defined “effort” value
  • use_torque_mode (bool): if true, the driver may apply torque/current limiting

Result:

  • success (bool)
  • message (string)

Feedback:

  • progress (float32): $0.0 \rightarrow 1.0$ best-effort progress estimate

gripper_msgs/action/CloseGripper

Goal:

  • close (bool): whether to close (some nodes also support close_default as a parameter so {} still closes)
  • torque (float): implementation-defined “effort” value
  • use_torque_mode (bool)

Result:

  • success (bool)
  • message (string)

Feedback:

  • progress (float32)

CLI usage

Discover actions:

source install/setup.bash
ros2 action list

Inspect the interface:

source install/setup.bash
ros2 interface show gripper_msgs/action/OpenGripper
ros2 interface show gripper_msgs/action/CloseGripper

Send an open goal:

source install/setup.bash
ros2 action send_goal /open_gripper gripper_msgs/action/OpenGripper "{torque: 0.0, use_torque_mode: false}"

Send a close goal:

source install/setup.bash
ros2 action send_goal /close_gripper gripper_msgs/action/CloseGripper "{close: true, torque: 0.0, use_torque_mode: false}"

Close with torque/current limiting (if supported by the active driver):

source install/setup.bash
ros2 action send_goal /close_gripper gripper_msgs/action/CloseGripper "{close: true, torque: 80.0, use_torque_mode: true}"

Notes on torque

The action goal field is named torque, but its meaning is intentionally driver-specific:

  • A Dynamixel-based driver will typically treat it like Goal Current (raw value; model-specific units).
  • A Feetech STS/SCS-based driver will typically treat it like a torque limit register value (raw value; model-specific units).

See the driver-specific docs for how that value is used.