Gold wire bonding is used in the packing process for semiconductor chip assembly. The diameter of the gold wire used in the process becomes smaller from 25pm to 18pm or less as the size of the semiconductor chip become very
smaller. The tension of the fine gold wire during the process of drawing, winding, or unwinding should be kept constant
to avoid or reduce the wire disconnection. If the wire is cut during the process, the spool of the wire cannot be used, thus
the productivity and yield rate become worse. Therefore, it is important to develop a system that can minimize instantaneous tension variation caused by the wire speed change.This problem can be categorized as relative motion control between two systems as shown in Fig. 1, where object A moves independently and object B follows object A keeping desired property d constant such as position, velocity, tension etc. In general the desired property d is the function of the object A and object B.