Development of a Δ-Type Mobile Robot Driven by Three Standing-Wave-Type Piezoelectric Ultrasonic Motors

We propose a new mobile robot that uses three standing-wave-type ultrasonic motors (USMs). The USMs are composed of two stacked-type piezoelectric actuators. Recently, with the miniaturization of electronic and microelectromechanical system devices and progress in the biomedical sciences, the demand for multifunctional manipulation of chip parts and biomedical cells has increased. Conventional multiaxial stages are too bulky for multifunctional manipulation in which multiple manipulators are required. Using conventional precise mobile robots is feasible for miniaturization of multifunctional manipulation, although their cables influence positioning repeatability. USMs are feasible actuators for realizing cableless robots because their energy efficiency is relatively higher than that of other motors of millimeter scale. The aim of this study is to develop a new type of omnidirectional mobile robot driven by USMs. In experiments, we evaluated the feasibility by investigating velocity, positioning deviation, and achieving repeatability of translational movements under open-loop control. We determine the repeatability as a ratio of the standard deviation of the final points to the average path length. The proposed mobile robot achieves velocities of 18.6-31.4 mm/s and repeatability of 4.1%-9.1% with a 200-g weight.