Advanced Space Vision System
Encyclopedia
The Advanced Space Vision System (also known as the Space Vision System or by its acronym SVS) is a computer vision
system designed primarily for International Space Station
(ISS) assembly. The system uses regular 2D cameras in the Space Shuttle
bay, on the Canadarm, or on the ISS along with cooperative targets to calculate the 3D position of an object.
Because of the small number of viewing ports on the station and on the shuttle most of the assembly and maintenance is done using cameras, which do not give stereoscopic vision, and thus do not allow a proper evaluation of depth. In addition the difficult conditions created by the particular conditions of illumination and obscurity in space, make it much more difficult to distinguish objects, even when the assembly work can be viewed directly, without using a camera. For instance, the harsh glare of direct sunlight can blind human vision. Also, the contrasts between objects in black shadows and objects in the solar light are much greater than in Earth's atmosphere, even where no glare is involved.
in the Electromagnetic spectrum
. The result is a black color that appears even blacker than the flattest black paint. In photos the disks look like small black dots, and a minimum of three are needed, so they are quite unobtrusive on most payloads.
in the 1970s, to study car collisions. In 1990, development was transferred to Neptec Design Group
, a small commercial enterprise located in Kanata, a suburb of Ottawa
. The system runs on Neptec's Advanced Vision Unit (AVU) processing platform, which handles video routing, algorithm processing, video overlays, and the system interface. The operating system is the Unix-like
and POSIX
compliant QNX
Real-time operating system
, running the Photon windowing interface. The Photon implementation was optimized to be the most worry free direct manipulation interface
possible for the particular needs and work habits of the astronauts.
The Canadian Space Agency was involved at several stages in the development and deployment of the space vision system. Training for the system takes place in the simulators located at the agency's headquarters at the John H. Chapman Space Centre
near Montreal
.
in October 1992, and used in subsequent missions. The advanced version was first tested on STS-74
in November 1995. The system has been used with success on shuttle flights since then, and with equal success for the assembly and maintenance of the station since 1997.
Computer vision
Computer vision is a field that includes methods for acquiring, processing, analysing, and understanding images and, in general, high-dimensional data from the real world in order to produce numerical or symbolic information, e.g., in the forms of decisions...
system designed primarily for International Space Station
International Space Station
The International Space Station is a habitable, artificial satellite in low Earth orbit. The ISS follows the Salyut, Almaz, Cosmos, Skylab, and Mir space stations, as the 11th space station launched, not including the Genesis I and II prototypes...
(ISS) assembly. The system uses regular 2D cameras in the Space Shuttle
Space Shuttle
The Space Shuttle was a manned orbital rocket and spacecraft system operated by NASA on 135 missions from 1981 to 2011. The system combined rocket launch, orbital spacecraft, and re-entry spaceplane with modular add-ons...
bay, on the Canadarm, or on the ISS along with cooperative targets to calculate the 3D position of an object.
Because of the small number of viewing ports on the station and on the shuttle most of the assembly and maintenance is done using cameras, which do not give stereoscopic vision, and thus do not allow a proper evaluation of depth. In addition the difficult conditions created by the particular conditions of illumination and obscurity in space, make it much more difficult to distinguish objects, even when the assembly work can be viewed directly, without using a camera. For instance, the harsh glare of direct sunlight can blind human vision. Also, the contrasts between objects in black shadows and objects in the solar light are much greater than in Earth's atmosphere, even where no glare is involved.
Background
The Advanced Space Vision System images objects with cooperative targets and uses the known positions of the targets to triangulate their exact relative positions in real time. The targets are composed of thin films of silicon dioxide layered with inconel to form an inconel interference stack. A stack like this has nearly no reflectivityReflectivity
In optics and photometry, reflectivity is the fraction of incident radiation reflected by a surface. In general it must be treated as a directional property that is a function of the reflected direction, the incident direction, and the incident wavelength...
in the Electromagnetic spectrum
Electromagnetic spectrum
The electromagnetic spectrum is the range of all possible frequencies of electromagnetic radiation. The "electromagnetic spectrum" of an object is the characteristic distribution of electromagnetic radiation emitted or absorbed by that particular object....
. The result is a black color that appears even blacker than the flattest black paint. In photos the disks look like small black dots, and a minimum of three are needed, so they are quite unobtrusive on most payloads.
Development
The basic elements of the system were devised at the National Research Council of CanadaNational Research Council of Canada
The National Research Council is an agency of the Government of Canada which conducts scientific research and development.- History :...
in the 1970s, to study car collisions. In 1990, development was transferred to Neptec Design Group
Neptec Design Group
Neptec Design Group is an Ottawa based, Canadian vision systems company, providing machine vision solutions for space, industrial, and military applications. Privately owned and founded in 1990, Neptec is a NASA prime contractor, supplying operational systems to both the Space Shuttle and...
, a small commercial enterprise located in Kanata, a suburb of Ottawa
Ottawa
Ottawa is the capital of Canada, the second largest city in the Province of Ontario, and the fourth largest city in the country. The city is located on the south bank of the Ottawa River in the eastern portion of Southern Ontario...
. The system runs on Neptec's Advanced Vision Unit (AVU) processing platform, which handles video routing, algorithm processing, video overlays, and the system interface. The operating system is the Unix-like
Unix-like
A Unix-like operating system is one that behaves in a manner similar to a Unix system, while not necessarily conforming to or being certified to any version of the Single UNIX Specification....
and POSIX
POSIX
POSIX , an acronym for "Portable Operating System Interface", is a family of standards specified by the IEEE for maintaining compatibility between operating systems...
compliant QNX
QNX
QNX is a commercial Unix-like real-time operating system, aimed primarily at the embedded systems market. The product was originally developed by Canadian company, QNX Software Systems, which was later acquired by Canadian BlackBerry-producer Research In Motion.-Description:As a microkernel-based...
Real-time operating system
Real-time operating system
A real-time operating system is an operating system intended to serve real-time application requests.A key characteristic of a RTOS is the level of its consistency concerning the amount of time it takes to accept and complete an application's task; the variability is jitter...
, running the Photon windowing interface. The Photon implementation was optimized to be the most worry free direct manipulation interface
Direct manipulation interface
In computer science, direct manipulation is a human-computer interaction style which involves continuous representation of objects of interest, and rapid, reversible, incremental actions and feedback. The intention is to allow a user to directly manipulate objects presented to them, using actions...
possible for the particular needs and work habits of the astronauts.
The Canadian Space Agency was involved at several stages in the development and deployment of the space vision system. Training for the system takes place in the simulators located at the agency's headquarters at the John H. Chapman Space Centre
John H. Chapman Space Centre
The John H. Chapman Space Centre is the headquarters of the Canadian Space Agency. It is located in Longueuil, Quebec, Canada, in the borough of Saint-Hubert.-Location:...
near Montreal
Montreal
Montreal is a city in Canada. It is the largest city in the province of Quebec, the second-largest city in Canada and the seventh largest in North America...
.
Implementation
The system was first tested in its early form on STS-52STS-52
-Mission parameters:*Mass:**Orbiter landing with payload: **Payload: *Perigee: *Apogee: *Inclination: 28.5°*Period: 90.6 min-Mission highlights:...
in October 1992, and used in subsequent missions. The advanced version was first tested on STS-74
STS-74
STS-74 was a Space Shuttle Atlantis mission to the Mir space station. It was the fourth mission of the US/Russian Shuttle-Mir Program, and it carried out the second docking of a space shuttle to Mir. Atlantis lifted off for the mission on 12 November 1995 from Kennedy Space Center launch pad 39A,...
in November 1995. The system has been used with success on shuttle flights since then, and with equal success for the assembly and maintenance of the station since 1997.