Dynamics and Precision Rotational Positioning Control of a Mechanism with a Harmonic Speed Reducer.

Abstract

This paper describes the dynamic characteristics of the mechanism with a harmonic speed reducer and its precision rotational positioning. The harmonic speed reducer is the reduction gear which is often used for precision robots because they can be made very compact and lightweight without backlash. However they have the friction and the low stiffness which make the positioning performance low. The purpose of this research is to clarify the suitable control method for the rotational positioning mechanism with the gearing and to realize high speed and high precision rotational positioning over a wide range. For this purpose, first, the characteristics of the mechanism are examined experimentally. The experimental results show that the mechanism can be represented by two kinds of models, that is macrodynamic and microdynamic models. Then, by using the controller including disturbance observer, the mechanism has the positioning accuracy better than 1" on the working range more than 4.0×105".