Talk:Grapple fixture

Research and info on "SSRMS-compatible Grapple Fixtures"
The FRGF was possibly first flown in 1981 during STS-2 and was possibly first used in 1982 on STS-3. It was developed by SPAR Aerospace. The STS-3 press kit refers to it only as a "grapple fixture". A 1981 NASA doc refers to it as the Flight Standard Grapple Fixture (FSGF).

In 1977 Spar Aerospace filled a patent for a "grappling device", the patent illustrations show that it was intended to be used for the Space Shuttle program. The grapple device shown bears little resemblance to the one that would fly on STS-2. Francis H. A. Mee was listed as the inventor, the patent was issued in 1978.

In 1987 Spar Aerospace filed a patent for a "auxiliary grapple fixture" with Barrie F. Tebb listed as the inventor, the United States Patent Office issued them a patent in 1988. The illustrations bear a strong resemblance to the FRGF with the exception of the target rod being unusually far from the cam arms.

In 1989 NRC filled a patent for an end effector that resembles the one seen on Canadarm2. The Power Data Grapple Fixture is also mentioned but the drawings do not reflect the produced version.

The 1992 book "A Heritage of Excellence: 25 years at Spar Aerospace Limited" mostly clears up the history of the device on pages 41 to 45. It's a rare book that I managed to borrow through the interlibrary loan program, I've scanned and uploaded those pages for other researchers or editors. In the book Francis Mee is credited as the inventor and Barrie F. Tebb (manager of Spar's grapple fixture program) is credited to having refined the design. The book doesn't explicitly state it but I assume the design is the FRGF and not the PDGF. The book includes pictures of the FRGF and there's only a passing reference to the PDGF (it's in a later chapter). I still don't know the first space mission FRGF was launched on. Nor do I know the visual differences between PDGF and the PVGF. I know very little about the development of PDGF.--Craigboy (talk) 08:43, 22 June 2014 (UTC)

http://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/20080008804_2008009021.pdf

Explains how the data connection doors on the PDGF are opened.

http://forum.nasaspaceflight.com/index.php?topic=4392.msg884316#msg884316 (will need better source if ever added to article)

http://forum.nasaspaceflight.com/index.php?topic=4392.1480

http://spaceflight.nasa.gov/gallery/images/station/crew-22/html/iss022e018747.html

http://spacecraft.ssl.umd.edu/design_lib/42004.mss.user.ICD.2.pdf

http://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/20070017847_2007015480.pdf

A "Latching End Effector" on a Canadarm grapples PDGFs. The SRMS or JEM RMS apparently use a different variant of this then Canadarm2. --Craigboy (talk) 23:20, 18 November 2012 (UTC)

New info
"The SSRMS uses more than one type of grapple fixture on the ISS. One type, the Power and Data Grapple Fixture (PDGF) provides power, data, and video connections to the arm. The PDGF, illustrated in Figure 8-5, is the only interface from which the arm can operate. These grapple fixtures are located throughout the ISS (Lab, Mini-Pressurized Logistics Module (MPLM), JEM, Hab, Functional Cargo Block (FGB), MBS, SPDM) and provide interfaces to other elements and payloads.

A second type, the Flight-Releasable Grapple Fixture (FRGF), is primarily used for handling payloads and does not provide any power, data, or video connections. These can be seen along the truss, as well as the elements (Pressurized Mating Adapter 2 (PMA2), Z1, PMA3, P6, Lab, Space Lab Pallet/Lab Cradle Assembly (SLP/LCA), MPLM, Airlock, S0, S1, Node 2, Cupola, P1, and P3/4)"

http://www.spaceref.com/iss/ops/iss.familiarization.pdf

For payloads that require a direct interface with the SSRMS (or POA or SPDM LEE), there are a few different interfaces to be aware of:


 * Flight Releasable Grapple Fixture (FRGF)
 * • Simplest grapple fixture – only allows for grapple


 * Latchable Grapple Fixture (LGF)
 * • Allows for grapple and latching
 * • Intended to be used for longer‐term stowage on the POA (greater than 3 weeks)


 * Power and Video Grapple Fixture (PVGF)
 * • Allows for grapple, latching, and access to data, video, and power
 * • Connectors for data/video/power integrated into the fixture


 * Power and Data Grapple Fixture (PDGF)
 * • Allows for grapple, latching, and access to data, video, and power
 * • Connectors for data/video/power integrated into the fixture
 * • Only fixture that is an On‐orbit Replaceable Unit (ORU)

http://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/20140008717.pdf

http://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/19950020841.pdf

http://robotics.estec.esa.int/i-SAIRAS/isairas2010/PAPERS/079-2759-p.pdf

FSGF ≠ FRGF?
This document says the first FRGF was flown on STS-61 (first Hubble servicing mission), but we know the FSGF was first flown on STS-2.

http://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/19940017339.pdf --Craigboy (talk) 20:17, 26 April 2016 (UTC)

European grapple fixture
"Grapple fixtures (GF) will be mounted to all objects that have to be handled by the EES. Each GF includes the female part of the connector, through which the power, signal and video data is routed to the grappled object. In addition, a GF contains the IST head receptacle, by which the torque will be provided for the grappled object (e.g. to screw/unscrew). The Grapple Mechanism of ERA consist of a three hook/lever systems, which are coupled to the moving platform The grapple mechanisms start pulling at the grapple fixture (GF) or base point (BP) until the gap between the GF/BP and the end effector is closed and the grapple mechanisms are rigidized and pre-tensioned. The hooks of the grapple mechanism are constantly pressed outwards by coil springs. When one hook touches an obstacle during grappling of a grapple fixture (GF) or a base point (BP), the hook induces a force of about 30 N due to the spring deformation to the obstacle. The reaction force will be measured by the TFS, transmitted via the EU to the ERA OBC. The EES will then be re-positioned with respect to the grapple fixture/base point to ease the induced loading."

"The base points are mechanically identical to the grapple fixtures. They do not contain the receptacle for the IST but they provide all system harness connections between ERA and the Russian Segment of ISS. They contain the female parts of the three system harness connectors, through which the power, signal and video data for ERA operation are routed. The base points also provide the mechanical interface between the grapple mechanisms on the end effector side and the Russian Segment of ISS on the other side."

(Pictures in document)

http://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/20140008875.pdf (Page 324/340)

No description or link to what grips them
Nothing in the article ? but comments above mention The Grapple Mechanism of ERA and the Latching End Effectors of Canadarm. Where is description in wp ? - Rod57 (talk) 12:59, 5 May 2017 (UTC)

pages 115, 117, 118 shows good images of the Canadarm2 Latching End Effector including the 3 snare wires that engage on the grapple shaft. - Rod57 (talk) 12:20, 8 May 2017 (UTC)


 * For now added something as subsection of Canadarm2 in MBS - Rod57 (talk) 17:16, 8 May 2017 (UTC)

HST has at least 2 grapple fixtures
Hubble Space Telescope has 2 grapple fixtures (shown on diagrams on aft side  near HGA and bays C-G) - not clear what type they are. - From it looks like an FRGF - but has the rectangle for Shuttle Canadarm. - Rod57 (talk) 20:52, 7 May 2017 (UTC)

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OneWeb grapple fixture DogTags and others
OneWeb satellites appear to be using a third type of grapple fixture; Voyager/Altius appears to make these and market them as DogTags. Official press release here, along with a demo video on Vimeo and Youtube, and I found a writeup here.

Also, the wikipedia page for Webb mentions it having a barebones set of "accessible attachment points" of some kind; would that count as a grapple fixture?