Close Gripper

SUMMARY

Close Gripper commands a parallel gripper to close its fingers to 0 mm and grasp an object.

This skill is used to pick an object after the robot has positioned the gripper around it.

SUPPORTED GRIPPERS

Available on Robotiq and OnRobot grippers.

UNITS

speed / force in the configured speed and force units (default percent for Robotiq; OnRobot ignores speed and uses N for force).

The Skill

status = gripper.close(speed=100.0, force=100.0, asynchronous=False)

The Code

Example: Close to Grasp an Object

from telekinesis.synapse.tools.parallel_grippers import robotiq

gripper = robotiq.Robotiq2F85()
# Connect
gripper.connect(ip="192.168.1.1", protocol="RTDE")
# Close to grasp
status = gripper.close(speed=100.0, force=100.0, asynchronous=False)
print(status)
# Disconnect
gripper.disconnect()

The Explanation of the Code

close commands the gripper to move its fingers toward each other until they contact an object or reach the fully closed position (0 mm). The call blocks until the gripper stops when asynchronous=False.

Speed. Expressed in the configured speed unit (default: percent, 0-100). Pass -1.0 to use the session default set by set_speed.

Force. Expressed in the configured force unit (default: percent, 0-100). Pass -1.0 to use the session default set by set_force.

Grasp detection. "STOPPED_OUTER_OBJECT" or "STOPPED_INNER_OBJECT" means the fingers stopped against an object - a grasp was detected. "AT_DEST" means the fingers closed fully without contact. OnRobot hardware cannot distinguish inner from outer grip - every detected grasp returns "STOPPED_INNER_OBJECT".

Return Values

Status	Description
"MOVING"	Returned when asynchronous=True
"AT_DEST"	Fingers reached fully closed - no object detected
"STOPPED_OUTER_OBJECT"	Robotiq only - stopped against an external object (grasp detected). OnRobot hardware cannot distinguish inner from outer grip, so this value is never returned by OnRobot.
"STOPPED_INNER_OBJECT"	Robotiq: stopped by internal contact (grasp detected). OnRobot: any detected grasp (the hardware does not distinguish inner from outer).
"UNKNOWN_STATUS_<code>"	Unexpected hardware status

How to Tune the Parameters

Robotiq 2F-85

Parameter	Type	Default	Description
speed	float	100.0	Motion speed in percent (0-100). Pass -1.0 to use the session default.
force	float	100.0	Gripping force in percent (0-100). Pass -1.0 to use the session default.
asynchronous	bool	False	If True, returns "MOVING" immediately without waiting.

OnRobot RG2 / RG6

Parameter	Type	Default	Description
force	float	-	Gripping force in Newtons, clamped to the model's max force.
asynchronous	bool	False	If True, returns "MOVING" immediately without waiting.

TIP

Check the return value after closing. "STOPPED_OUTER_OBJECT" or "STOPPED_INNER_OBJECT" confirms a successful grasp before transporting the object.

Where to Use the Skill

• Pick operations - Close after the robot is positioned at the pick target
• Grasp verification - Check the return status to confirm a successful grasp before transporting
• Re-grasp - Open and close again if the initial grasp is unsuccessful

When Not to Use the Skill

Do not use Close Gripper when:

• A specific intermediate position is required - use Tool Move to close to a defined width
• The gripper is not connected - always call connect before issuing motion commands