Research On Drive And Control System For Two-Degrees Of Freedom Robotic Arms Based On Ultrasonic Motors

Ultrasonic motor (abbr. USM) is a relatively new type motor that has been developed step by step since eight decade of last century. Its operating principle is quite different from the one of the traditional electromagnetic motors. USM utilizes the mechanical vibration in the ultrasonic frequency scale that was generated by the converse piezoelectric effect of piezoelectric ceramics. It has the stator in direct contact with the rotor driven by a friction contact. USM has many excellent performances and features such as high torque at a low speed, compactness in size, high holding torque when power is off, insensitive to magnetic fields, fast response, no noise and so on. It has more excellent performance than the electromagnetic motor in the field needing compact, efficient, intermittent motion and fine controls. For a few years now, revolving ultrasonic motors (USMs), in particular those employing rotary traveling-wave-type USM ,have attracted special interest as direct-drive-type actuators for servo-systems in industrial, consumer and automotive processing fields.The paper describes the control system used to operate two USMs that move the joints of a robotic arm.,and offers the embody scheme. The control-board makes use of the chip MSP430F147,making use of MSP430F147 makes for the industrialization of the control-board of USMs.The contents are summarized as follows:The development, characteristic and classify are summarized concretely. Through the compare between the characteristics of USMs and the characteristics of electromagnetism motors, it is testified that USMs will develop rapidly .Present the significance of research on USM. On the basis of this, the theme of the paper is given.The characteristic of structure and the mechanism of movement of Ring-type Travelling-Wave Ultrasonic Motors are summarized. Based on this, the control technique, for example, frequency modulation, phase modulation, amplitude modulation, are summarized and the drive method, for example, push-pull, half-bridge, full-bridge, are also summarized.Drive and control system for two-degree of freedom based on the ring-type travelling-wave ultrasonic motors is designed. Firstly, The plan and purpose of designed are put forward. Secondly, the technique and theory of control-board are described.The software design of the control board and PC interface are described. Present the theory of this speed and position control system. In the end, analysis on the experiment curve is given. To solve the nonlinear problem in the experiment, a simple and effective method is brought forward.Present the summary of the paper and give some advices according to the problems of this positioning and speed control system.