文档介绍：Available online at hanism
and
Machine Theory
Mechanism and Machine Theory 43 (2008) 491–505
ate/mechmt
Nonlinear dynamic analysis of a parallel mechanism
with consideration of joint effects
Ting-Nung Shiau *, Yi-Jeng Tsai, Meng-Shiun Tsai
Department of Mechanical Engineering, National Chung Cheng University, 168, University Rd., Min-Hsiung, Chia-Yi 621, Taiwan, ROC
Received 4 July 2006; received in revised form 13 February 2007; accepted 21 March 2007
Available online 3 July 2007
Abstract
This paper presents a nonlinear dynamic analysis of a 3-PRS series-parallel mechanism with consideration of joint
effects which includes flexibility, clearance and friction. The Newtonian approach is applied to derive the equations of
motion of the 3-PRS mechanism. The Runge–Kutta method and contact verification criterion bined to solve
the nonlinear piecewise differential equations. The linearization technique is applied to determine the natural frequencies
and their associated mode shapes. The simulation results show that the natural frequencies of the 3-PRS mechanism shift
with the position of prismatic pairs and the physical interpretations are given by using the associate mode shapes. The
effects of joint clearance and friction cause the natural frequencies to decrease and significantly affect the modes of which
rotational motions are dominated. It is also shown that the dynamic response es larger as the joint clearances
increase, and the joint contact forces e larger as joint clearances and friction coefficient increase.
Ó 2007 Elsevier Ltd. All rights reserved.
Keywords: Parallel mechanism; Joint clearance; Natural frequency; Contact dynamics
1. Introduction
Due to their high speed and large load carrying capacity characteristics, parallel mechanisms have e
very popular in the past decade. Parallel mechanisms typically consist of two platforms, which are connected
by several extendable legs and joints. The early design of a parallel manipulator w