Copyright © IFAC Intelligent Assembly and Disassembly, Bucharest, Romania, 2003 ELSEVIER IFAC PUBLICATIONS www.elsevier.comllocatelifac ROBOTIC ARM WITH 9 DOF DRIVEN BY SPHERICAL ULTRASONIC MOTORS Liviu CIUPITU I) , Shigeki TOY AMA 1) , Eko PURW ANTO 2) /) POLlTEHNICA University of Bucharest, Machines and Manufacturing Systems Dept., Splaiullndependentei 313, RO-772061, Bucharest-6, Romania, E-mail: Iiviuc@japan.com, phone: +402 I 4029838, fax: +40244251017. 1) Tokyo University of Agriculture and Technology, Mechanical Systems Engineering Dept., 2-24-16, Naka-cho, Koganei-shi, 184-8588, Japan, E-mail: toyama@cc.tuat.ac.jp, phone: +810423887097,fax: +810423887207. Abstract: Research team of Prof. Shigeki TOY AMA is developing at Tokyo University of Agriculture and Technology a new type of ultrasonic motor. It's spherical shape confers 2 or 3 DOF in a single joint which makes it suitable for mechatronics field and especially for industrial robots of articulated kind. In that paper is presented a robotic arm with 9 DOF driven by 3 Spherical Ultrasonic Motors (SUM) which can by used in assembly and manipulating operations. Copyright © 20031FAC Keywords: Robotic manipulators, Static models, Arm, Equilibrium, Motor, Ultrasonic Transducers. I. INTRODUCTION Spherical Ultrasonic Motor (SUM) is a new type of ultrasonic motor developed at Tokyo University of Agriculture and Technology in Toyama Lab. It's spherical shape confers 2 or 3 DOF in a single joint which makes it suitable for mechatronics field and especially for industrial robots of articulated kind. There is also a necessity to use SUM for acting a robotic arm like human arm. Purpose of present paper is to presents a robotic arm with 9 DOF driven by 3 SUMs that can by used in assembly and manipulating operations in hostile environments. I. I. Functioning Principle and Structure of SUM The SUM is (Toyama and Fukaya, 1996) an unconventional motor with 2 or 3 DOF that is using the acting principle of ultrasonic motors (Fig. I). It consists in principal of (Fig. 2): a) a spherical rotor and an output shaft; b) 3 or 4 stators kept together and pushed onto rotor by a holder system (not represented). 85 The rotor is processed in order to obtain a highly accurate sphere and the material of it should have good frictional characteristics and superior wave performance. The stator consists of an elastic body (metallic) of ring shape and two semicircular pieces of piezoelectric ceramics (PZT) glued onto the back of elastic body (Fig. 3). ROTOR Piezoelectric Ceramics Fig. I Acting principle of ultrasonic motors