Virtual Fixtures from Rosenberg

Question

this is not a technical question, but I've read multiple times now, that Virtual Fixtures, developed from L.B. Rosenberg in 1992, is one of the first augmented reality applications. I would like to know a little bit more about this Virtual Fixtures, but I cannot see any informative website about this "application". Can someone explain to me, what Vitural Fixtures is about? Are there any good literature sources available? The only thing i found with google are summaries of the history from ar - Nobody explains Virtual Fixtures.

Thanks a lot

Edit: Also a picture about the system would also be useful :)

Answer 1

The 1993 paper of Rosenberg Virtual fixtures: Perceptual tools for telerobotic manipulation explains what they are, and the protocol he used as an application.

If you can't access the article, I'll summarize briefly the idea, and I guess there is no harm to show the pictures here, from Rosenberg.

The idea is that the user wears an exoskeleton to perform a task from the operator space to the remote environment. In addition, either the exoskeleton or physical objects (in the fixture board) will constrain the possible movements of the arm of the operator, like a physical ruler constrains the movement of your pencil (so that you are able to draw a straight line much faster and with more accuracy). The difference between the virtual fixture and the ruler is that the virtual fixture does not physically exist in the remote environment, i.e. where the task is actually performed (it can exist in the operator space), but you still obtain its haptic (sensory) feedback. For instance, it's like if a surgeon was able to have a ruler during an operation, but for obvious reason you can't physically put this ruler through the patient's body.

In addition (this is the innovative augmented-reality part), the virtual fixtures can be displayed on top of the real world using a composition of the real image and the rendered virtual fixtures. Hence, not only you feel them through the exoskeleton or actual ruler, but you also see them through the vision system, so it increases your feeling that the fixture is actually present in the remote environment, even though they do not exist physically there. Example of fixtures used (planes) are given here:

All in all, these fixtures help the user to perform various task, giving him more accuracy, in the case when physical ruler cannot physically share the space where the task actually occurs.

The conclusion of the article is:

The results confirm that overlaying abstract sensory information in the form of virtual fixtures on top of sensory feedback from a remote environment can greatly enhance teleoperator performance. Virtual fixtures composed of simple combinations of impedance surfaces and abstract auditory information increased operator performance by up to 70%. Analysis of some basic perceptual elements suggests that virtual fixtures enhance perfcrmance by simplifying the perception of the workspace, altering the conceptualization of the task, by providing localizing references to the remote worksite, and by reducing the demands on taxed sensory modalities by providing information through alternative sensory pathways. Post testing interviews revealed that the use of virtual fixtures caused subjects altered their conceptualization of the task such that a successful trial no longer just looked a certain way but also felt a certain way and sounded a certain way.