An optical image stabilization using novel ultrasonic linear motor and fuzzy sliding-mode controller for portable digital camcorders

A sensor-shift optical image stabilization (OIS) using a novel ultrasonic linear motors (ULMs) and a fuzzy sliding-mode controller (FSMC) is presented in this paper. The proposed sensor-shift OIS compensates the optical path deviation that is caused by user's hand-tremor for avoiding image blurring. An ULM module that is composed of two single-axis ULMs is utilized to carry the image sensor linearly and bi-directionally in two orthogonal axes. The slim ULM is power efficient, and needs no high magnetic fluxes and holding currents. Because of the nonlinearities of the ULM module and gravity, the FSMC is used to stabilize the sensor-shift OIS without an explicit mathematic model. The FSMC with 7 fuzzy rules is implemented in a general purpose microcontroller. A gyroscope and a calibrated Hall sensor are used to sense the hand-tremor and the position of the image sensor, respectively. A digital camcorder that is equipped with the sensor-shift OIS using the novel ULMs and is stabilized by the FSMC is demonstrated by experiments.