This invention relates to a simulator by which an observer, viewing both a target and an object under his control, can practice mating the object with the target; and such simulator is hereinafter termed a simulator of the type described. 
Space orbital operations currently in preparation for the future involve deployment and retrieval of shuttle orbiter payloads relative to an orbiting space station or space vehicle, as well as refurbishing and repair of orbiting vehicles.  Such operations will often have to be executed using manipulators controlled by an operator aboard one of the spacecrafts viewing the termination of the manipulator and the target through a window in the craft, or by means of a television link which would also enable operations to be carried out by an earth-based operator. 
Maneuvering a manipulator and mating it with the target in a gravity free environment are operations that are different from corresponding operations on earth.  In particular, gravity induced torques, which dominantly influence design and performance on earth are absent in space.  Furthermore, the mating of the termination of the manipulator with the target must take place with essentially zero velocity in order to minimize a target and manipulator reactive impulse.  Such impulse would tend to separate the target from the body carrying the manipulator and therefore must be avoided. 
For personnel destined to carry out missions of the type referred to above, it is essential to practice such missions in ground-based simulators to insure proficiency in space.  One approach to this training is to construct simulators of the type described using actual or replica models with built-in servo operations to simulate the peculiarities of space performance as noted above.  This approach, while having the advantage of visual realism, is very complex and can achieve only limited realism in performance thereby reducing the effectiveness of a training program.  Another approach is to employ computer-generated graphics in which both the target and a manipulator, for example, are created on a surface that is supposed to represent the view from a window of a spacecraft or a television monitor.  This approach more closely simulates the reactions of the components in a weightless environment but at the expense of visual realism.  Complex surfaces familiar to an operator are approximated by polyhedrons in computer-generated graphics and thus appear distorted and hence unrealistic decreasing training effectiveness. 
It is therefore an object of the present invention to provide a new and improved simulator method and apparatus of the type described which is less complex in terms of equipment yet realistic in terms of visual perception and equipment performance, thus overcoming substantially all of the deficiencies of the prior art as noted above.