A Novel Five-Degree-of-Freedom Parallel Manipulator and Its Kinematic Optimization

Abstract

Driven by requirements of five-axis numerical control (NC) machine for its executive mechanism, this paper creatively proposes a flow path to synthesize a novel class of n-degree-of-freedom (n-DoF, 4 ≤ n ≤ 6) parallel manipulators (PMs) resorting to four steps, and takes a patented 5-DoF PM, named T5, for example to demonstrate the flow path in depth. Comparing with existing five-axis executive mechanisms, this novel class of the PMs has some advantages of light end-effector, good static, dynamic performance, and so on. Upon the underlying architecture of T5, the kinematic analysis and optimal design are carried out for the first time, in which two essential procedures are involved, one is the kinematic performance index by means of the reciprocal product associated with the wrench screw and twist screw with specific physical meaning, the other is the design method adopted to perform the multi-objective dimensional synthesis using an artificial intelligence approach, that is nondominated sorting genetic algorithm II (NSGA-II). This paper is aimed at laying a solid theoretical and technical foundation for the prototype design and manufacture of T5 PM.

Stiffness analysis and experiment of a novel 5-DoF parallel kinematic machine considering gravitational effects

“…Similarly, points A 12 , A 34 are the midpoints of line A 1 A 2 and A 3 A 4 which are also mutually perpendicular, and the distance between A 12 (or A 34 ) to A j ( j 1 4 = -) is denoted by h 0 . In order to describe the motion in a distinct way, T5 PKM can be divided into two parallel mechanims in terms of a 3-DoF redundant parallel mechanisms and a 2-DoF overconstrained parallel mechanism [19]. Topology strucutre of the 3-DoF redundant parallel mechanisms is described by the fixed base, platform I, five UPS limbs, IR 1 , IR 2 and UP limb, which is named as substructure I in this paper.…”

“…As shown in [19], the twist $ t of T5 PKM with respect to reference point D is the liner superposition of twists $ t 1 and $ t 2 produced by substructures I and II respectively, which is…”

“…It is concluded from aforementioned compliance/stiffness modeling of T5 PKM that: (1) the gravities of two substructures are equivalent to external payloads exerting on point A 6 and point D by means of static equilibrium, respectively; (2) the wrench and twist models of two substructures are the same as those presented in [19] since the gravities are regarded as the external payloads;…”

“…Moreover, the parasitic motion in the 3-DoF pose parallel mechanism [18] may lead to the increment of the control cost. Driven by these problems, the authors of this paper proposed a novel 5-DoF PKM (hereafter referred to as 'T5 PKM') [19], whose servomotors are all arranged adjacent to the fixed base to reduce the weight of the 2-DoF rotating head and avoid integration with two long guideways.…”

Optimum design of a novel redundantly actuated parallel manipulator with multiple actuation modes for high kinematic and dynamic performance

“…The global kinematic performance indices (GKPIs) can be presented by the mean value [29] and standard deviation [30] of algebraic characteristics of the Jacobian matrix throughout the entire workspace, for instance, the condition number, determinant and minimum singular value, etc. Some of these have been widely accepted and extended into various modified versions to deal with the kinematic dimensional synthesis problem of some PMs [31][32][33][34][35][36][37]. However, merely optimizing the KPIs is not sufficient because the inertia and centrifugal/Coriolis effects must be taken into consideration when such a PM runs at high speed and high acceleration.…”