Rendezvous and Proximity Operations (RPO) Research

The SERC is working on several different modalities, techniques and areas that focus on the general area of rendezvous and proximity operations or RPO.  RPO is typically associated with the ability or operation of two (or more) independent space objects that purposefully manuever to within close "proximity" of each other, via various rendezvous techniques.  RPO is critical for any "servicing" missions that are coming on line this year, which may include inspection, repair, refuel, upgrade or assembly activities.  RPO is a wide and robust area of research, which includes sensors, orbital dynamics techniques, processing and data fusion, and hardware for contact and dock.  SERC is exploring multiple arenas within this robust field.  Each are listed below.

 

RPO:  Test Facility and Platforms

Over the years SERC has created and operated several unique frictionless facilities to support simulated Zero-G operations in support of RPO.

Microsatellite Dynamic Test Facility (MDTF -No longer operating).  SERC Engineers created the 2nd largest surface platen for air bearing frictionless operations in the US.  The facility was located at Northrop Grumman through a unique partnership at the time.

RPO:  Standards and Guidelines

The SERC is a co-founding member of the Consortium for Execution of Rendezvous and Servicing Operations (CONFERS) which is an industry led initiative to leverage best practices from government and industry to research, develop and publish non-binding, consensus driven technical and operations standards for on-orbit servicing (OOS) and RPO.  The SERC provided input to the technical evaluation and survey of past and present RPO related missions for consideration of past and current practices.  Multiple papers were created that explored the past practices of RPO, postulated metrics for safety for design and operations, and offered a taxonomy of how to develop safety standards based on functions and attributes.  (Publications located here.)

For more information on CONFERS or to join please visit the CONFERS web site, www.satelliteconfers.org 

RPO:  Docking/Capture Mechanisms

The Lab has been working on two different types of "contact" or capture mechanisms:

CLING and CLING-ERS.

Created/patented by Dr Berok Khoshnevis from USC, CLING is a genderless traditional mechanical coupling system that can be put on any type of vehicle or platform to make an automatic joint connection. The first picture depicts the working mechanism, the second picture shows two undergraduate students testing an initial prototype on the SERC airbearing testbed.

  

 

REACCH (Reactive Electro-Adhesion Capture ClotH)

The SERC and the Jet Propulsion Laboratory (JPL) created a unique “octopus” tentacle end effector for robotic systems that uses formable electro-adhesion (EA) and Gecko adhesion capture cloth material. REACCH, or Reactive Electro-Adhesive Capture ClotH, supports soft capture of objects of any size, shape, surface finish or material on-orbit. To-date the SERC/JPL team developed initial tentacles and backing spines that proved control of the EA/G material. Prototypes with two tentacles were built and demonstrated and tested on the SERC 3-DOF air bearing device in 1g in one plane of grip. The results showed promise to further develop this new type of grappling mechanism able to make first soft contact with an object, with a technology that merges compliance and control elements for future on-orbit servicing and assembly missions.

   
 

STARFISH (Soft Translatable Advanced Robot For In Space Handling)

A new concept is being explored with The Aerospace Corporation on creation of a soft robotic crawling inspection robot for satellites and space platform applications.  STARFISH is mergingin electro-gecko adhesive technology with soft robotic locomotion and onboard sensors to provide a unique self powered crawling device that can provide independent visual or sensor validation of joints on large structures or other sensing modalities.

  

 

RPO:  Sensors and Data Fusion

Fusion of LIDAR and Optical and Radar

Varying modalities of sensor information at different points in the orbit that account for both light, darkness, glint and even temperature can be fused in realtime into point clouds for on orbit characterization.  This is a challenging and processor intensive activity but could provide unique safety and situational awarness information for future rendezvous vehicles.  A student team explored LIDAR, optical and mini-radar/range information and the challenge of fusing disparate data sets to create 3-dimensional point clouds that represented a prototype satellite.  Picture 1 is the model and picture 2 is the optical point cloud generated.

  

4pi steredian situational contact sensor system

One attribute useful in an RPO execution is the ability to have constant situational awareness of where the object to rendezvous with is.  Thus a student project at SERC looked at creating a 2pi steredian range based sensor system that could be tested on the SERC airbearing testbed (shown in picture).

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