Sub-pixel vision-based inspection and control of a flexure micropositioner

In order to meet the requirement of XYO cooperative precision positioning in the process of wafer-level flip-chip (WLFC) packaging, a novel 3-DOF macro/micro complex motion system with sub-pixel visual detection algorithm is presented in this paper. The key micropositioner is based on a 3-RRR(R is revolute flexure) 3-DOF compliant mechanism. As we know, the employment of interferometers or capacitive sensors is a challenging task in WLFC packaging systems due to their spacial constraints. Meanwhile, according to the coupling characteristics of 3-DOF, a novel heterogeneous regularized extreme learning machine(HRELM)-based intelligent sub-pixel inspection algorithm with high-efficiency and high accuracy is proposed and employed as the position sensing method, which can effectively address the problem that the precision displacement of a flexure micro/nano positioning mechanism is hard to be measured with the traditional capacitive or laser displacement sensors. This novel method can be conducted on the fly in real time making it suitable for time critical vision-guided micro/nano positioning system, while providing comparable inspection accuracy with that of using traditional displacement sensors.