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Small and precise actuators for multi-degrees of freedom (DOF) motion is needed to construct a dexterous robot arms and manipulators. Ultrasonic motors are suitable for the multi-DOF actuation of the robot arms and manipulators because of its characteristics such as its output power per unit volume, high stationary limiting torque, high maximum operating torque, simple design, silence, and high controllability. In this study we develop a three-DOF ultrasonic motor. It is found that the three-DOF ultrasonic motor can be constructed when natural frequencies of two second bending modes and a first longitudinal mode of a bar-shaped stator correspond. A spherical rotor in contact with the stator head rotates around three perpendicular axes. Geometry and structure of the ultrasonic motor in detail is determined using finite element analysis. Measured natural frequencies and natural modes of bending and longitudinal vibrations of the stator agree well with calculated ones. The rotational speed of the spherical rotor around three perpendicular axes are measured.

The invention is to provide a vibration wave driving apparatus for obtaining driving force in 3D direction. For achieving such purpose, a vibration wave driving apparatus comprises a vibration member having a shape line symmetrical with respect to two orthogonal axes, electromechanical energy conversion elements which can excite three different types of bending vibrations, in the vibration member, which displace in a direction perpendicular to the two axes, and a driven member which is brought into contact with driving portions of the vibration member and driven by vibrations excited in the vibration member.

The present invention relates to a vibration type actuator or a vibration type driving apparatus that includes a vibration member that generates therein respective vibration displacements in at least three different directions, and a plurality of contact members contacting the vibration member, wherein the respective vibration displacements in the three different directions generate a composite vibration that simultaneously moves selected contact members of the plurality of contact members relative to the vibration member.