Aspects on design of high precision parallel robots

Abstract

This paper presents a concept for a micro‐assembly station and shows different possibilities for increasing the positioning accuracy. The main part of the station consists of a spatial parallel structure with three translational degrees of freedom. An additional rotational axis is integrated into the working platform. This structure is constructed with low friction joints, which are nearly free of backlash. The construction of these high precision joints is presented and the characteristics of the robot such as workspace and resolution are discussed. After this an approach for increasing the accuracy of parallel robots by integrating flexure hinges into the structure is described.

Size-adapted Parallel and Hybrid Parallel Robots for Sensor Guided Micro Assembly

“…Experimental measurements with the robot structure micabo h with conventional joints lead to a worse repeatability than expected, with insufficient reproducibility. Reasons for the worse results of the repeatability measurements were largely attributed to the ball joints which were poorly adjustable (Hesselbach et al, 2004b). As further development the spatial parallel hybrid robot structure micabo hs (Fig.…”

“…In order to achieve high life cycles of the hinges, the deformation should remain in the elastic part since plastic deformation normally induces defects in the material leading to an earlier crack failure (Hesselbach et al, 2004b).…”

Inverse dynamics and robust sliding mode control of a planar parallel (2-PRP and 1-PPR) robot augmented with a nonlinear disturbance observer

“…Parallel robotic manipulators are often said to be more precise and accurate than serial robotic manipulators because they do not suffer from error accumulation [3]. Though this might be true in theory, the practical reason is that parallel manipulators can be built to be stiffer without being bulkier [1,2]. Compared with serial manipulators, parallel manipulators have the following potential advantages namely higher precision, higher stiffness, higher payload bearing capability and stable structure [1][2][3][4][5].…”

“…Parallel motion platforms, which are developed on the basis of parallel manipulators, can perform with minimal exertion at high speeds due to their closed kinematic chains (loops) [1][2][3]. A high output velocity is vital and crucial for parallel manipulators to be applied to parallel motion platforms [1].…”

Stiffness Analysis of a Fully Compliant Spherical Chain with Two Degrees of Freedom

“…Later on, the ensemble of two universal joints of this kind has been proposed by Machekposhti et al [4] to obtain a compliant constant velocity Double-Hooke's universal joint. Different authors [5,13] employed two in-series connected flexure notch hinges with orthogonal axes to conceive a fully compliant universal joint. Jacobsen et al [7] employed three inseries connected lamina emergent torsional joints with axes intersecting in a single point to make spherical chains with three degrees of freedom (for compliant joints or mechanisms, the number of degrees of freedom is intended as the number of independent prevalent directions of motion).…”