Androgynous low impact docking mechanism

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Technology abstract

The International Berthing and Docking Mechanism (IBDM), developed by QinetiQ, absorbs relative movement and minimises the impact forces between two vehicles while docking, reduces the solicitation and ensuring that there is an airtight connection between the two vehicles can be benefited from this technology.

The IBDM provides a compelling solution to all kinds of docking where autonomy, flexibility, efficiency (very high capture success rate > 98%) and safety are key. In the light of self-driving vehicles (cars, trains, ships) and aircrafts (planes, drones) this is expected to become increasingly important.

- Sam Waes -

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Technology Description

The International Berthing and Docking Mechanism (IBDM) is the European androgynous low impact docking mechanism that is capable of docking and berthing large and small spacecraft.

The IBDM provides both docking and berthing capability. The docking mechanism comprises a Soft Capture Mechanism (SCS), and a structural mating system called the Hard Capture System (HCS), explained in more detail below. The IBDM avionics runs in hot redundancy.

The SCS utilizes active control using 6 servo-actuated legs from RUAG Space (Switzerland) which are coordinated to control the SCS ring in its 6 degree of freedom. The leg forces are measured to modify the compliance of the SCS ring to facilitate alignment of the active platform during capture. A large range of vehicle mass properties can be handled. Mechanical latches achieve soft capture.

Hard Capture System (HCS) uses structural hook mechanisms to close the sealed mated interface. QinetiQ Space has developed several generations of latches and hooks to come to the final hook design.

Unlike current docking mechanisms, the IBDM absorbs relative movement and minimises the impact forces between two spacecraft while docking. This therefore reduces the solicitation of the spacecraft docking to the space station. This androgynous system will allow two vehicles to berth and dock with each other and ensure that there is an airtight connection between both spacecraft.

Innovations & Advantages

Until now, docking mechanisms requiring a minimum level of energy for their actuation have been used and were designed for large vehicles such as the Space Shuttle. This has meant that the attachment of new generation lighter spacecraft to the ISS has had to take place at a fast speed for a connection to be created, which can lead to potential issues with high forces in play.

The key features:

  • Smooth: it provides a capability for low impact docking in order to reduce or eliminate the need for impact energy to achieve spacecraft interface alignment and capture. 
  • Autonomous: the IBDM comprises autonomous fast switch-over from primary to redundant lane in case of a failure.
  • Flexible: a large range of vehicle mass properties can be handled, as the SCS uses configurable active control, making it possible to be used for a wide variety of applications ranging from explorations to resupply missions.
  • Effective: a very high capture success rate (> 98%), enabled by an agile force-sensing controlled capture mode.
  • SAFE: the IBDM comprises a backup or safe mode in which the Steward platform behaves like an electro-magnetic damper. This mode is used if two failures have occurred in the IBDM avionics - or on command by the hosting vehicle - or in case no electrical power is applied to the IBDM, and hence provides a safe situation for both the vehicle and the ISS, even during the docking phase.

Further Information

The IBDM development has successfully passed the Critical Design Review (December 2015). An engineering model of the mechanism and its hot-redundant avionics has been developed and successfully tested (March 2016). The performance of the system has been verified at the certified SDTS docking test facility at NASA JSC. A proposal for the qualification and flight manufacturing of the complete IBDM system has been submitted to ESA (April 2016).


Dimensions

Outer width: 1.42 m / 4.66 ft

Passageway: 0.8 m  / 2.62 ft


Mass:

< 325 kg / 716.5 lb


Performance

Endurance: At least 210 days

Capture success rate:> 98% using IDSS initial conditions


Avionics

Redundancy: Hot redundant (switch-over in less than 150ms) + passive safe mode

Interfaces: 28 V DC or 120V DC and 28V DC

Current and Potential Domains of Application

Avionics, (military) aircrafts and rockets, space taxi, Maritime ...