A robot which functions in a variable and dynamic environment must be able to intercept or avoid moving objects whose locations and velocities may not be known. This paper describes a visual guidance technique for such machines which utilizes image sequences from two cameras. Comparing the relative displacements over time of an object on the left and right image planes leads to the recovery of two important quantities: 1) the location where the object will collide with the robot, and 2) the absolute object size. A third quantity, time to collision, can be recovered from the displacement of the object on a single image plane. These three items are sufficient for the robot to approach or avoid the object. Implementation of this technique on an IBM 7565 industrial robot is described. Experimentation indicates that this method is more accurate than traditional stereo analysis.