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RISS 인기검색어
- 검색키워드
- 저자 : D. Ezhilarasi (검색결과 5 건)
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D. Ezhilarasi,Anjali S. Nair 한국정밀공학회 2021 International Journal of Precision Engineering and Vol.8 No.3
In this paper, an integrated human-in-the-loop simulation paradigm for the design and performance analysis of a 6 DOF lower extremity exoskeleton is presented. An adaptive Super Twisting Sliding Mode Controller (ASTSMC) is designed for the trajectory tracking control of the exoskeleton by considering the human motion as reference trajectory. The dynamic model, that include linear and rotational displacement of hip, knee and ankle joints of both the legs is developed using Lagrange energy formulation. The position and angular velocity error of the wearer and the exoskeleton are being considered to establish the control law. Super twisting SMC is a robust control scheme that works effectively in the presence of external disturbances and parameter variations. However, the STSMC introduces chattering in the closed loop because of its high gain, to overcome this drawback, an adaptive STSMC is proposed for the control of exoskeleton against unknown disturbances without chattering. An adaptation scheme using Lyapunov criterion is derived that ensures the stability of the system in closed loop. The performance of the proposed control strategy is verified by implementing on the integrated CAD model of the exoskeleton along with the wearer. The effectiveness of the controller is tested under wind disturbance of varying velocity and direction. The results demonstrate improved tracking performance of the proposed control scheme with least error and less control effort compared to constant gain STSMC in normal and uneven terrain.
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Anjali S. Nair,D. Ezhilarasi 한국정밀공학회 2020 International Journal of Precision Engineering and Vol.7 No.3
Lower extremity exoskeleton is a kind of wearable robot and is used both in medical and industrial applications for diff erent purposes. In the medical fi eld it is used as a piece of therapeutic equipment and in the industry especially in defense, to carry heavy loads. This paper deals with the analysis of the performance of super twisting sliding mode controller (STSMC) on tracking the motion of the wearer by the lower extremity exoskeleton using automatic dynamic analysis of mechanical systems (ADAMS)–MATLAB co-simulation during walking and step climbing and the results are compared with a conventional PID controller. The model of the lower extremity exoskeleton is developed by solid-works software and the model of the human body is done with ADAMS software. Super twisting sliding mode controller (STSMC) is designed and simulated with Simulink. This paper also aims to develop a mathematical model of the system and analyze the performance of STSMC to control hip, knee, and ankle movements and also to point out the advantages of the ADAMS–MATLAB co-simulation over the conventional methods of modeling and simulation analysis of the controller to control the exoskeleton. Stability analysis of the controller is also done.
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Dhanalakshmi, K.,Umapathy, M.,Ezhilarasi, D.,Bandyopadhyay, B. Techno-Press 2011 Smart Structures and Systems, An International Jou Vol.8 No.4
This paper presents the design and experimental evaluation of fast output sampling feedback controller to minimize structural vibration of a cantilever beam using Shape Memory Alloy (SMA) wires as control actuators and piezoceramics as sensor and disturbance actuator. Linear dynamic models of the smart cantilever beam are obtained using online recursive least square parameter estimation. A digital control system that consists of $Simulink^{TM}$ modeling software and dSPACE DS1104 controller board is used for identification and control. The effectiveness of the controller is shown through simulation and experimentation by exciting the structure at resonance.
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K. Dhanalakshmi,M. Umapathy,D. Ezhilarasi,B. Bandyopadhyay 국제구조공학회 2011 Smart Structures and Systems, An International Jou Vol.8 No.4
This paper presents the design and experimental evaluation of fast output sampling feedback controller to minimize structural vibration of a cantilever beam using Shape Memory Alloy (SMA) wires as control actuators and piezoceramics as sensor and disturbance actuator. Linear dynamic models of the smart cantilever beam are obtained using online recursive least square parameter estimation. A digital control system that consists of Simulink modeling software and dSPACE DS1104 controller board is used for identification and control. The effectiveness of the controller is shown through simulation and experimentation by exciting the structure at resonance.
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Modelling and experimental investigations on stepped beam with cavity for energy harvesting
A. Rami Reddy,M. Umapathy,D. Ezhilarasi,G. Uma 국제구조공학회 2015 Smart Structures and Systems, An International Jou Vol.16 No.4
This paper presents techniques to harvest higher voltage from piezoelectric cantilever energy harvester by structural alteration. Three different energy harvesting structures are considered namely, stepped cantilever beam, stepped cantilever beam with rectangular and trapezoidal cavity. The analytical model of three energy harvesting structures are developed using Euler-Bernoulli beam theory. The thickness, position of the rectangular cavity and the taper angle of the trapezoidal cavity is found to shift the neutral axis away from the surface of the piezoelectric element which in turn increases the generated voltage. The performance of the energy harvesters is evaluated experimentally and is compared with regular piezoelectric cantilever energy harvester. The analytical and experimental investigations reveal that, the proposed energy harvesting structures generate higher output voltage as compared to the regular piezoelectric cantilever energy harvesting structure. This work suggests that through simple structural modifications higher energy can be harvested from the widely reported piezoelectric cantilever energy harvester.
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