CAD model based tracking and 3D visual-based control for MEMS microassembly

This paper investigates sequential robotic microassembly for the construction of 3D micro-electro-mechanical systems (MEMS) structures using a 3D visual servoing approach. The previous solutions proposed in the literature for these kinds of problems are based on 2D visual control because of the lack of precise and robust 3D measures from the work scene. In this paper, the relevance of the real-time 3D visual tracking method and the 3D vision-based control law proposed is demonstrated. The 3D poses of the MEMS are supplied in real-time by a computer-aided design (CAD) model-based tracking algorithm. This latter is sufficiently accurate and robust to enable a precise regulation toward zero of the 3D error using the proposed pose-based visual servoing approach. Experiments on a microrobotic setup have been carried out to achieve assemblies of two or more 400 µm × 400 µm × 100 µm silicon micro-objects by their respective 97 µm × 97 µm × 100 µm notches with an assembly clearance from 1 µm to5µm. The different microassembly processes are performed with a mean error of 0.3 µm in position and 0.35×10 −2 rad in orientation