Experimental investigations and error analysis on 3-PRS parallel kinematic machine

Abstract

Industrial robots play a predominant role in factory automation particularly in the area of machining like grinding, cutting, milling, drilling, polishing etc. In these applications serial manipulators could not provide rigidity and accuracy. This research focuses on the need for precise angular drilling applications. Generally, special fixtures are used to make angular hole in drilling machines. In this research, the 3-PRS (Prismatic – Revolute – Spherical) parallel mechanism is redesigned to execute angular drilling operations. The moving/mobile platform (MP) of the proposed manipulator is utilized as worktable. The experimental model is fabricated with lead screw and nut pair to obtain precise position of drill tool and to maintain high stiffness. By varying the geometric parameters, the positions of parallel kinematic machine (PKM) are analysed. Moreover, the orientation error and parallelism of the developed PKM are studied in detail using laser torch and height gauge. Further, the PKM positions are simulated through ADAMS software package and the same is compared with the real-time accelerometer values. From the experimental study, the deviations in orientation, parallelism and position of the PKM are found to be minimal and satisfactory.