This thesis presents two biomimetic robot eye systems that use an SMA actuator to mimic the focal length tuning mechanism of the human eye. As changing the radius of the lens curvature can be classified into gel-type and liquid-type methods, a biomimetic gel-type and liquid-type lens system are both...
This thesis presents two biomimetic robot eye systems that use an SMA actuator to mimic the focal length tuning mechanism of the human eye. As changing the radius of the lens curvature can be classified into gel-type and liquid-type methods, a biomimetic gel-type and liquid-type lens system are both proposed. In addition, the use of a miniature, lightweight, high-power-density SMA actuator also allows these lens systems to be small and lightweight. First, the gel-type lens system includes a biconvex PDMS lens, synchronised structure to expand the PDMS lens, and winding-type antagonistic SMA actuator. In terms of shock and vibration, this lens system is more stable than a liquid or electrowetting lens. plus It has the unique advantage of expanding the lens diameter. Second, the liquid-type lens system includes a PDMS membrane lens, liquid redistribution mechanism, and SMA actuator. As regards the liquid redistribution mechanism, the focal length displacement of a conventional liquid lens is nonlinear. In this thesis, the linear focal length is designed using a modified piston mechanism based on a cylindrical cam structure. The focus tuning performance of the proposed lens systems is verified in experiments that use an SMA actuator to gain a clean focused image from a defocused image. However, SMA actuators have an inherent nonlinear hysteresis character, which makes precise control difficult. Thus, to overcome this problem, a Duhem modeling and a disturbance observer(DOB) control method are used in this thesis. The Duhem modeling method is useful for avoiding tedious and repetitive tests prior to control test. The DOB controller is designed for cancelling the effect of disturbance by nonlinear hysteresis. The control performance of the DOB controller for SMA actuator is verified by comparing simulation results, where simulations are performed under various control conditions with predetermined parameters.
This thesis presents two biomimetic robot eye systems that use an SMA actuator to mimic the focal length tuning mechanism of the human eye. As changing the radius of the lens curvature can be classified into gel-type and liquid-type methods, a biomimetic gel-type and liquid-type lens system are both proposed. In addition, the use of a miniature, lightweight, high-power-density SMA actuator also allows these lens systems to be small and lightweight. First, the gel-type lens system includes a biconvex PDMS lens, synchronised structure to expand the PDMS lens, and winding-type antagonistic SMA actuator. In terms of shock and vibration, this lens system is more stable than a liquid or electrowetting lens. plus It has the unique advantage of expanding the lens diameter. Second, the liquid-type lens system includes a PDMS membrane lens, liquid redistribution mechanism, and SMA actuator. As regards the liquid redistribution mechanism, the focal length displacement of a conventional liquid lens is nonlinear. In this thesis, the linear focal length is designed using a modified piston mechanism based on a cylindrical cam structure. The focus tuning performance of the proposed lens systems is verified in experiments that use an SMA actuator to gain a clean focused image from a defocused image. However, SMA actuators have an inherent nonlinear hysteresis character, which makes precise control difficult. Thus, to overcome this problem, a Duhem modeling and a disturbance observer(DOB) control method are used in this thesis. The Duhem modeling method is useful for avoiding tedious and repetitive tests prior to control test. The DOB controller is designed for cancelling the effect of disturbance by nonlinear hysteresis. The control performance of the DOB controller for SMA actuator is verified by comparing simulation results, where simulations are performed under various control conditions with predetermined parameters.
주제어
#biomimetic robot eye system shape memory alloy DOB Duhem
학위논문 정보
저자
손형민
학위수여기관
경북대학교 대학원
학위구분
국내박사
학과
전자전기컴퓨터학부 임베디드시스템 및 제어공학
지도교수
이연정
발행연도
2013
총페이지
116 p.
키워드
biomimetic robot eye system shape memory alloy DOB Duhem
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