Design and analysis of a redundantly actuated parallel mechanism for rapid machining

Abstract

This paper describes the design, construction, and performance analysis of the Eclipse, a redundantly actuated six-degree-of-freedom parallel mechanism intended for rapid machining. The Eclipse is a compact mechanism capable of performing five-face machining in a single setup while retaining the advantages of high stiffness and high accuracy characteristic of parallel mechanisms. We compare numerical and algebraic algorithms for the forward and inverse kinematics of a class of the Eclipse and formalize the notion of machine tool workspace. We also develop a simple method for the first-order elasto-kinematic analysis of parallel mechanisms that is amenable to design iterations. A complete characterization of the singularities of the Eclipse is given, and redundant actuation is proposed as a solution. The Eclipse case study demonstrates how diverse analytical tools originally developed in a robotics context can be synthesized into a practical design methodology for parallel mechanisms.

Trajectory Tracking Control of Parallel Manipulator Based on Udwadia‐Kalaba Approach

“…In comparison with the serial manipulator which has openloop structure, the parallel manipulator has many advantages, such as higher stiffness, higher accuracy, higher payload capacity, lower inertia, and smaller workspace. Therefore, it has attracted a great amount of attention and interest among the researchers and engineers and has been applied to many industrial applications in the past decade, like milling [2], rapid machining [3], medical resuscitation [4], and so on.…”

Redundant Actuation of Parallel Manipulators

“…Redundant actuation can be achieved in different ways, and there are two directions: the actuation of passive joints, and the inclusion of additional kinematic chains without increasing the PKM DOF. Most authors propose using additional chains, such as planar 3RRR (Alba et al, 2007;Buttolo & Hannaford, 2005;Kock & Schumacher, 1998), planar 4RRR , spherical wrists (Kurtz & Hayward, 1992) and shoulder (Yi et al, 1994), Stewart platforms with one (O'Brien & Wen, 1999) or two additional struts, or the Eclipse (Kim et al, 2001). The improvement of kinematic manipulability or dexterity via redundant actuation has been investigated in (O'Brien & Wen, 1999).…”

“…A brief overview of redundancy in PKM can be found in (Merlet, 1996). Redundantly actuated PKM were analyzed with regard to their kinematic and dynamic properties, and in view of singularities in (Alba et al, 2007;Dasgupta & Mruthyunjaya, 1998;Firmani & Podhorodeski, 2004;Gardner et al, 1989;Kim et al, 2001;Kock & Schumacher, 1998;Kurtz & Hayward, 1992;Liao et al, 2004;Mohamed & Gosselin, 1999;Müller, 2005;O'Brien & Wen, 1999;Zhang et al, 2007). It was shown by a number of authors that redundant actuation is a means to eliminate singularities and so enlarges the usable workspace.…”

Kinematic control of constrained robotic systems

“…In this case, implies that there is internal motion of the joints, even when the active joints are locked. This type of singularity is named by unstable singularity or actuator singularity (see (Wen and O'Brien, 2003;Kim et al, 2001) for a detailed discussion).…”