Abstract: To solve the problem of detecting foreign fiber in the textile enterprises, a technical solution was put forward in which a single green modulated light and three silicon photocells regularly arrayed were adopted. It can detect foreign fiber and yarn faults by means of contrasting the reflection and transmission signals received by the silicon photocells and analyzing the color and diameter change of yarn. The mathematical model was established, and the simulation experiment was done based on H∞ filter using software MATLAB. The results proved that the algorithm was more sensitive to signal singularity of the surface brightness signal and the diameter signal of yarn, which can also track the percentage change in color. It is further confirmed that the scheme of detecting foreign fiber and yarn faults is feasible, the H∞ filter algorithm can effectively improve the detection precision to foreign fiber and yarn faults.

Key words: H&infin, filter, foreign fiber, optical signal detection, mathematical model, simulation