Mechatronics design of stiffness enhancement for direct-drive motor system using ER variable damper

摘要

Direct-drive (DD) motors have the characteristics of simple structure and high controllability without reduction gears or ball screws. However, DD motors are more sensitive to the disturbance torque and parameter variation than other motor systems, which have reduction gears. Enhancement of DD motor stiffness by increasing the gain is one of the effective methods to reduce this influence, but large gain will lead to instability and even vibration. Viewed from mechatronics design, an ER variable damper with a damping coefficient that can be changed depending on how the applicable voltage is designed, and directly attached to the shaft of the DD motor to achieve high servo stiffness. The structure and the damping coefficient model of the proposed ER variable damper are developed. The validation of this mechatronics design is demonstrated by a position PD (proportional derivative) control DD motor system with numerical simulations, which achieved both high stiffness and good stability for the controlled DD motor system.