| Scientists have been pursuing the dream that equipping bionic eyes to robot, vision equipment and even visually impaired human. This technology can not only enhance visual ability of machinery or equipment but also can help people with eyes disabilities to regain the light. Research on bionic eye is a comprehensive and challenging issue. So, the study and design of hybrid stepper motor driving system used in bionic eye has important theory significance and practical value. Detailed studies are described as follows.Part I reviews the development of bionic eyes all over the world, including the structure of bionic eye, platform and driving components, and control algorithms, etc.. Firstly, by analyzing the current developments, the paper found that the more feasible bionic eye movement platform solution is a platform which combines camera, mechanical structure and motor drive as a whole. Secondly, through the comparing of a number of driving components, hybrid stepper motor with outstanding performance and practical feasibility is proved to be a optimal choice as a driving component. At last, development of stepper motor driving technology is summarized, which helps to clear the practical significance of stepping motor to be the bionic eye movement platform’s driving component.Part II describes the basic structure of hybrid stepping motor as well as analyses the linear models at first of all, which helps to view operation rules of the motor. And then, the paper introduces the simulation analysis by Ansoft about the positive effectiveness on stator current harmonics elimination when hybrid stepper motor’ rotor and stator applies unequal blade spacing design, which lays foundation that subdivided driving method uses sine wave as stator current reference.Part III has compared various stepper motor drive technology, and the subdivided driving is confirmed as a best solution for bionic eye application. The study of subdivided driving indicates that motor has good pullout characteristic and the vibration, noise, heat can be restrained for the using of subdivided driving. Then, this paper studies the subdivided driving in detail and proposes a improved fixed-frequency PWM driving which can realize the subdivided driving in a simple way.In Part IV, circuit simulation under Simulink is carried out to analyze the work state of the circuit as well as the impact of different current reflowing mode on wingding current. Simulation results prove that mix-current reflowing mode which can reduce current fluctuating in ascend period and reduce the current distortion in descend period has better performance compared to quick-current reflowing and slow-current reflowing mode.Part V has designed the hardware and software components of driving and controlling system of hybrid stepper motors used in bionic eye based on requirements for bionic eye applications. In which, Atmegal6 microcontroller and Drv8834 driver are adopted to realize subdivided driving with the aim of small size and compact structure. Besides, external control unit is designed to control the driving and controlling system of hybrid stepper motors in command mode, in this way, the performance of driving and controlling system can be test under the control of external control unit; Software part includes several functional modules, such as: motor driving, communication procedures, peripheral drivers, etc., each module establishs the function independently, this approach has better scalability and portability.Part VI tests the overall performance of the prototype. In the first stage, the basic function of hardware or software modules including communication, power source and motor driver are tested, and results achieved the expected conditions; In the second stage, the experiment of the whole system is implemented, results indicate that the system has the characteristics of easy to use feature and can meet the movement function requirements of the bionic eye. |
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