Abstract—In this paper, a 5-DOF serial-parallel manipulator
with RP-(2-RRU/1-RUU) structure is proposed. This
manipulator is used to the automatic production line, to
complete the materials’ loading, delivery and unloading. In
order to ensure the safety and high efficiency production, the
manipulator has good stiffness and high accuracy, and is
suitable for the fast operation. Based on the above requirements,
the manipulator has the big work space characteristic of the
serial mechanism and the high precision and stiffness
characteristic of the parallel mechanism. However, the difficulty
of its dynamics analysis is increasing. In this paper, the modal
analysis and the harmonic response analysis are carried out
using finite element analysis software, and the dynamic
characteristics of the manipulator are derived. The inverse
dynamics modeling has been performed based on the
Newton-Euler method. The dynamics simulation is carried out
to check the correctness of dynamics modeling. This study is
also significant to the trajectory planning and control system.
Keywords: serial-parallel; dynamics; Newton-Euler method
I. INTRODUCTION
HERE are three categories of machine arm: series type,
parallel type, and serial-parallel type[1]. Series type and
parallel type manipulators have their own flaws: the series
manipulator is of small stiffness, low accuracy, and not
suitable for the fast operation; the parallel manipulator is of
little work space, strange position, and easy to interfere. The
serial-parallel manipulator is compatible with their
advantages: good stiffness, high precision, big work space,
easy to fast operation [2]. The research object of this paper is
a five DOF serial-parallel manipulator, as is shown in Fig.1.
The manipulator is constituted by a serial part and a
2-RRU/1–RUU parallel part. The serial part is constituted by
a rotary joint on the base and a mobile joint on the shoulder.
The parallel part has three branch chains: two RRU structure
chains and one RUU structure chain.
This research is supported by Shenzhen/Hongkong Innovation Circle
Project (Project No.ZYB200907070024A), Shenzhen Key Laboratory of
Precision Engineering (No.CXB201005250018A), National Natural Science
Foundation of China (Project No.61210013, 61175124)
Chao Hou is with the Harbin Institute of Technology, Shenzhen Graduate
School(E-mail: chao.hou@siat.ac.cn)
Peng Zhang is with Shenzhen Institutes of Advanced Technology,
Chinese Academy of Sciences. The Chinese University of Hong Kong, Hong
Kong, China and is the co-member of Shenzhen Key Laboratory of Precision
Engineering. (Phone: +86-755-86392180, E-mail: zhangpeng@siat.ac.cn)
Ying Hu is with Shenzhen Institutes of Advanced Technology, Chinese
Academy of Sciences. The Chinese University of Hong Kong (E-mail:
ying.hu@siat.ac.cn)
Jianwei Zhang is with University of Hamburg, Germany (E-mail:
zhang@informatik.uni-hamburg.de).
Now the robot is developing to high precision, high
stiffness and high speed, so in order to ensure the safety and
high precision, the robot must have good dynamic
characteristics and we have to do the dynamics research. In
this paper, we do the dynamic analysis for the serial-parallel
robot by ANSYS, and we get its natural frequency and
vibration model [3,12]. Through this, we can find the weak
link of the structure, in order to ensure its stiffness.
Robot dynamics and the dynamic model is an important
branch of robot research, and the dynamic model is the
foundation of controlling robot [4]. Dynamics is the study of
the relationship between the movement of objects and the
forces. Because of the complexity of the parallel robot, the
dynamic model is usually a complex system of multi-degree
of freedom, multivariable and highly nonlinear parameter.
Therefore, the analysis of dynamic characteristics of the robot
needs some special methods. There are many analysis
methods, such as Lagrange method, Newton-Euler method,
Gauss method, Kane method and so on [5]. The research of
dynamic modeling in the series robot field has made a rapid
progress. However, because of the complexity of the parallel
mechanism, the research content of parallel robot mostly
involves mechanism and the kinematics, and dynamics
research is relatively few. Fichter [6] and Merlet established
Stewart dynamics equations in the event of ignoring the
inertia effect in the legs. Sugimoto took Stewart platform for
example to do the dynamics problems of parallel robot.
However, there are not detailed dynamic derived in his
analysis. Geng made simplifying assumption to the geometric
shape and inertia disturbance of parallel robot, and establish
the parallel robot dynamics equations by using Lagrange
method. ZhenHuang and HongboWang conducted force
analysis by using impact coefficient method and established
the dynamic model of the parallel robot [7].
The Dynamics Analysis for a Five DOF Serial-parallel Manipulator
with RP-(2-RRU/1-RUU) Structure
Chao Hou, Peng Zhang*, Ying Hu, Jianwei Zhang
Fig.1 The 3D model of the manipulator
978-1-4673-2126-6/12/$31.00 © 2012 IEEE
Proceedings of the 2012 IEEE
International Conference on Robotics and Biomimetics
December 11-14, 2012, Guangzhou, China