OPTICAL SYSTEMS FOR THE REMOTE TRACKING OF THE POSITION AND/OR ORIENTATION OF AN OBJECT

摘要

In an optical system for the remote tracking of the position and/or orientation of an object such as a pilot's helmet (6), a light source such as the LED groups (4, 5) on the object are imaged onto photosensitive layers of position-sensitive detectors (10) of sensors (2, 3), the output from the layers depending upon the position of light spots imaged on those layers, the output then being used to track movement of the object. Instead of illuminating the LEDs sequentially as hitherto and then subtracting a reference value corresponding to all LEDs being off i.e. just to background radiation, the LEDs are driven by a periodic waveform, and filter means in digital signal processor (15) detects that varying waveform to distinguish the contribution to the output of the position-sensitive detector from the LEDs and from background radiation. The LEDs can now be illuminated simultaneously at different frequencies to provide more accurate location of the object.