An optical image correlator for robotic applications

The goal of cost effective, high performance optical systems capable of pattern matching tasks has fuelled research for over two decades. It is only recently with the introduction of novel optical/electronic architectures that such systems are becoming viable. Although conceptually elegant, the single output from an optical correlator is of restricted application due to its sensitivity to image distortions. A multichannel hybrid optical/electronic architecture has therefore been devised, exhibiting greatly enhanced flexibility and performance. This hybrid processor is being used in conjunction with a robotic handling system as part of an ESPRIT programme. The video signal from a robot's TV camera is relayed to an electrically addressed spatial light modulator in the processor. This input image is then replicated optically and fed into each of the system's parallel channels where it is cross-correlated with a set of differing reference patterns. The multiple correlation signals are detected and compiled into an electronic descriptor code. A 'Euclidean' search through a look-up table of codes then extracts object identification and rotation. Scale information and out-of-class recognition is also possible since the system can be taught to memorise new codes in real time. © 1989 SPIE.SCOPUS: ar.j