Abstract
This paper is to present the evaluation of a TiNi Shape Memory Alloy (SMA) spring as actuator for the gripping manipulation. The SMA spring employed was a TiNi tensile spring which has a diameter of 50 mm wire and 350 gram hanging mass. The gripper fabricated consists of two fingers and each finger is actuated by the SMA spring. The total angular displacement of the gripper is 300. The power consumptions, the movements and force generations experimentations have been conducted. The DC signal and PWM signal with 12, 12Hz, 25Hz, 125Hz, 250Hz and the 1150Hz have been employed for driving the SMA. The experimental results indicated that the 125Hz of PWM signal was likely to be had a better performance than the other signals. The 125Hz PWM signal generated faster movement, lower power consumption, and constant rate of force. In this study, closed-loop control for gripping manipulation was also conducted. The close loop controller used is PID controller. The Ziegler-Nichols method has been used to predict the optimal gain of the controller, but the best performance was determined by experimentally tuning of the gains. The experimental results indicated that the PID controller is likely to be reliable controller for gripping manipulation of the SMA spring. To obtain the better performance, it is important to consider the SMA cooling responses and the long time of retain in certain position of the gripper.
Highlights
Shape Memory Alloy and Its ApplicationIn recent years, much effort has been devoted to design, construction and control in micro and nano scale
The Power Consumption of Shape memory alloy (SMA) Spring. The aim of this experiment is to obtain the distinguished characteristics of the spring power consumption between PulseWidth Modulation (PWM) and DC signal actuation
The result to be used for diciding the appropriate signal for driving the SMA spring
Summary
Shape Memory Alloy and Its ApplicationIn recent years, much effort has been devoted to design, construction and control in micro and nano scale. The micro and nano technology has been widely developed to produce an integrated circuit (IC) component and micro-processor (chip). The development of circuit technology in micro and nano scale has not been followed in other areas especially in actuator, sensor, material and mechanical technology. Shape memory alloy (SMA) is one of the emerging actuator for MEMS (Micro-electro-mechanical system) and NEMS (Nano-electro-mechanical system) instead of piezoelectric, electrostatic, thermopneumatic, magnetic, electrohydrodynamic, and bimetallic effects [1]. Conventional technologies such as electric, hydraulic, and pneumatic actuators have difficulties generating significant forces when their size and weight are scaled down. SMA actuators has a good high power/ weight ratio, produce a large displacement in a limited space, it has good temperature transformation, low power consumption and an excellent mechanical properties such as ductility and toughness [3,4]
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