Advanced Grabbing Unit

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Advanced Grabbing Unit
Part image
Docking port by
Kerbal Motion LLC

Radial size Small
Cost (total) 450.00 Funds
Mass (total) 0.08 t
Drag 0.2-0.3
Max. Temp. 2000 K
Impact Tolerance 50 m/s
Research Actuators.png Actuators
Unlock cost 5 200 Funds
Since version 0.23.5
Part configuration part.cfg

The Advanced Grabbing Unit (AGU), or The Klaw, is a medium-sized docking device which can couple to any surface without the requirement of another docking device on the target to mate with. This is a virtual necessity for redirecting asteroids, though the AGU can be used to grab onto much more than just asteroids. In fact, it can grab just about anything, even Kerbals.


Advanced Grabbing Unit opened

The AGU is the primary means of capturing and redirecting asteroids. It's also useful for craft-to-craft docking or for exchanging resources with craft or debris without a docking port. As with docking ports, resources (liquid fuel, electricity, etc.) can be exchanged with the target. And objects connected by claws are controlled together as a single entity. It's like a docking port, but without the complexity of aligning with a receiving port on the target. Kerbals grabbed by the AGU's claw will go limp in a ragdoll state and can be carried with the craft.

Operation is simple. Its state toggles between Armed or Disarmed. While disarmed, it behaves like any other part. Once armed, approach perpendicularly to the target surface at no more than a few m/s and the extended claw will automatically grab anything it collides with (or that collides with it), docking the target to the current vessel.[1] To undocking from the target, right-click the AGU and choose Release.

Once the AGU is attached, its claw's pivot can be toggled. The pivot is locked whenever armed and not attached, but can then be unlocked by right-clicking the AGU and choosing Free Pivot. While freed, reaction wheels or RCS can be used to alter the craft's pitch and yaw (from the AGU's perspective) relative to the target, but not roll; the claw turns, not twists. This is vital when attached to asteroids, as thrust must be aimed directly at the center of mass to keep the asteroid under control while moving it. Note that controls may feel reversed; the opposite end of the craft from the claw will be moving. Note also that the range of motion the pivot provides is bounded by a circle, like the AGU itself, essentially drawing a conical area.

After aligning the craft, the Lock Pivot command can be used to fix the craft's orientation relative to the grabbed target. Note that even when locked, with sufficient lateral force the pivot can be bent, though once the force is removed it will bend back to its locked orientation. It is also possible with pre-assigned Action Groups to “Disarm” the AGU while attached without releasing it − a merely visual effect.

Non-active AGU bug

Shortly after attachment

It is possible to break the game by connecting to a claw, so that it's not the active vessel. Kerbin disappears as soon as the claw connects and the physics is broken as the craft starts to fall even in orbit.[2] It is possible that just the terrain disappears if it's possible to switch to another craft in time. Danny2462 made a video about this bug where he used two claws where one Kerbal is attached to the active claw, but the Kerbal and the claw on the active craft are not necessary.[3]

To avoid this behaviour the player should switch to the craft with the claw before connection.

This error seems related to the existence of script references to no longer existent game objects (i.e. the object that existed prior to docking to it with an AGU). The error can be duplicated with no Advanced Grabbing Unit present in visual range by utilizing the Remote Tech mod. For example if a station with a comm link is connected to a satellite and something is attached to the satellite with an AGU, the target reference of the station's antenna will no longer be valid. This induces the same bug causing the station to plummet to the planet below if time acceleration is attempted.

Grabbing a Kerbal

A Kerbal successfully grabbed with the AGU in orbit

With the Advanced Grabbing Unit it is, although tricky, possible to dock to a Kerbal. The Kerbal must be touched with the exact center of the extended claw in order to capture; touching the Kerbal to the claw arms has no effect. The AGU will not close around the Kerbal; rather, it will simply indicate that it has docked with something, and the Kerbal will be locked in place while still free to ragdoll. The easiest way to grab a Kerbal is to use the Kerbal's own jetpack to steer into the exact center of the claw. When docked successfully, your controls will change to the ship's controls, and the option to EVA with that Kerbal will not be available until the AGU is released. The same Kerbal-AGU system can safely withstand reentry with adequate deceleration to landing velocity.

Product description

Kerbal Motion engineers have long struggled with the problem of how to extract dropped tools from complicated machinery. After observing an intern cleaning out his shoes by turning them upside down and shaking them in the lab, our team was hit with a stroke of inspiration! Why not turn the rocket parts upside-down and shake them? The grabbing arm perfectly filled this niche, and is quite capable of lifting heavy machinery. It has since found other uses, besides delicate tool extraction operations. AKA "The Klaw!"


It is possible the name "Klaw" is a reference to "Toy Story".


  • Initial release


  1. Unofficial fan-made video "How to Capture an Asteroid (Kerbal Space Program)" by YouTuber Harv of HOCgaming
  2. Comment by Aaron K. on Danny2462's video “Kerbal Space Program: The Glitch Device”
  3. Kerbal Space Program: The Glitch Device” by Danny2462 on YouTube