The Interface Circuitry Design Of High Speed 1394 Bus For Multi-Sensor Vision Systems

For measuring a small part using a machine vision technique in industry, a system containing one vision sensor may be employed. However, for measureing a large object, such as a car body, a large scale measuring system consisting of several dozens of vision sensors may be adopted. In such a large scale multi-sensor vision system, it is apparently time-consuming to transmit the images from the vision sensors into the master computer and then process the image data. Therefore, to reduce the measurement time of a multi-sensor vision system for 100% on-line measurement of a large scale object in a production line, the issues involved in using a high speed bus to control the sensors working effectively and increase the speed of image signal transmission, and develping a parallel image processing technique to process the iamge data are crucial.Considering 1394 bus has the excellent abilities of very credible asynchronous transmission for control command and data, high speed synchronous transmission for image signal, easy network configuration and point-to-point communication, etc., the architecture of a multi-sensor vision system based on high speed 1394 bus and the technique of DSP parallel image grabbing and processing in the system are investigate in the paper. Thanks to the 1394 bus which has high speed data transmission and can carry out synchronous and asynchronous transmission at the same time, the control signal and image signal of the system can share the same 1394 bus. This facilitates the configuration of a large scale multi-sensor vison sytem. In the paper, the research wrok is concentrated in designing the 1394 bus interface circuitry for a multi-sensor vision system. The interface circuitry designed can connect 2 to 4 1394 cameras. In the paper, the schematic and PCB diagrams of the circuitry are illustrated. The communication procedure of control command and image data in the circuitry is depicted. The degugging program of the circuitry also listed. In order to facilitate debugging the interface circuitry as well as the corresponding multi-sensor vision systems, a LED unit showing the 1394 bus node number in a multi-sensor vison system and a video signal transformation unit are designed. To further develop a DSP parallel image processing unit on the basis of the 1394 interface circutry, the extension ability of the circuitry is fully optimized. A 16-bits parallel read /write port, which can seamlessly connect the 1394 bus to the future DSP unit, is designed on the circuitry. The debugging experimental results show that the design of the 1394 interface circuitry is successeful.