Study of the effects of link tolerances to estimate mechanical errors in 3-RRS parallel manipulator

Abstract

This paper presents the mechanical error estimation under the effects of link tolerances in a 3-degree-of-freedom (DoF) 3-RRS Spatial Parallel Manipulator (SPM). Position level kinematic analysis and workspace analysis in the form of reachable and orientation workspace are carried out initially. Then, the effect of link tolerances on individual link is studied at the position of mid-point and orientation of the movable platform. The corresponding mechanical errors are estimated. The effect of link tolerance variation is studied to know the pattern of mechanical error. The 3-D CAD model in SolidWorks is used to validate the results. The conclusions are drawn that lead to error minimization at the tolerance design stage.

Comparison of 3-[PP]S-Y Spatial Parallel Manipulators based on link tolerances and parasitic motions

“…The comparison of the 3- R RS PM and the 3-R P S PM based on the link tolerance is carried out by considering the middle working range of the manipulators that is, a range of 675 to 925 mm at a step-size of 5 mm. The previous work presented by Jain and Jawale 31 exhibited a highest possible error due to link tolerance toward the extreme range of operation of the manipulator and minimum toward the mid-position of the moving platform. So, to avoid the in-built higher error zone, restricted motion of the platform is used to have the minimal error possibilities.…”

“…have been carried out in Refs. 31,50–53 Similarly, several works related to the parasitic motions have been found in the literature. 54–62…”

“…12 The many issues related with the 3-RRS PM have already been covered in the literature such as kinematic analysis, [13][14][15][16][17] dynamic analysis, [18][19][20] optimization and performance, [21][22][23] singularities, 24,25 dimensional synthesis, 26 workspace, 27 structure synthesis, 28 static analysis, 29 design modeling, 30 and mechanical error analysis. 31 Similarly, the issues related with the 3-RPS PM have also been explored in the literature such as its introduction, 32 velocity and acceleration analysis, 33,34 architecture and constraint singularities, 35 instantaneous motions, 36 kinematic synthesis, [37][38][39] position and workspace analysis, [40][41][42][43] dynamic parameters, 44 architecture optimization, 45 study kinematic mapping of the Euclidean group SE (3), 46,47 operation modes, 48 and its application in thrust-vectoring propulsion. 49 Since, both these manipulators have a common motion of 1T2R type and their planes are arranged such that they intersect at 120°in a common line that is, a plane arrangement of Y-pattern, they can be compared.…”

“…have been carried out in Refs. 31,[50][51][52][53] Similarly, several works related to the parasitic motions have been found in the literature. [54][55][56][57][58][59][60][61][62] Among the different factors that affect the positional accuracy of a manipulator, the major one is link tolerance that contributes cumulatively in contrast to the other factors that affect randomly.…”

“…The many issues related with the 3- R RS PM have already been covered in the literature such as kinematic analysis, 13–17 dynamic analysis, 18–20 optimization and performance, 21–23 singularities, 24,25 dimensional synthesis, 26 workspace, 27 structure synthesis, 28 static analysis, 29 design modeling, 30 and mechanical error analysis. 31…”