Implementation of a 4-DOF parallel mechanism as a needle insertion device

Recently, quite a few practical parallel mechanisms having spatial 3-DOF and 6-DOF have been introduced and implemented. However, not many useful practical applications using low-mobility parallel mechanisms having 4-DOF and 5-DOF have been developed. In this paper, we propose a 4-DOF parallel mechanism for needle insertion application in which proper orientation and needle insertion process are required. The mechanism has four outer chains and one passive middle chain through which a needle insertion motion occurs. The kinematic modeling and kinematic analysis are performed to understand the characteristics of this mechanism. Through the singularity analysis, a singularity-free design for the desired workspace is proposed. Finally, the effectiveness of this device as a needle insertion device is shown through experimental work.