Robust H∞-based control of ARAS-diamond: A vitrectomy eye surgery robot

In this paper, we investigate the challenges of controlling the ARAS-Diamond robot for robotic-assisted eye surgery. To eliminate the system's inherent uncertainty effects on its performance, a cascade architecture control structure is proposed in this paper. For the inner loop of this structure, two different robust controls, namely, H-infinity and mu-synthesis, with stability and performance analysis, are synthesized. The outer loop of the structure, on the other hand, controls the orientation of the surgical instrument using a well-tuned PD controller. The stability of the system as a whole, considering both inner and outer loop controllers, is analyzed in detail. Furthermore, implementation results on the real robot are presented to illustrate the effectiveness of the proposed control structure compared to that of conventional controller designs in the presence of inherent uncertainties of the system and external disturbances, and it is observed that using H-infinity controller in the inner loop has superior robust performance.