Design And Experimental Study Of A New SMA Rotary Actuator Based On Compliant Mechanisms

Positioning manipulators are found in optical engineering, precision machining, medical operations, and micromanipulation. Traditional positioning manipulators use motorized ball-bearing screws with feedback from encoders to achieve linear and/or rotary motion. Although their technologies are well-developed, they consist of many moving parts and are subject to wear and backlash. To increase accuracy and compactness of positioning manipulators, Various actuating techniques have been proposed as alternatives for manipulators, especially at the micro scale. Among them, magnetic ,electrostatic, and thermal actuators have been applied. An alternative is shape memory alloy (SMA), which exhibits large stroke, large energy density, and low driving voltage. SMA is categorized by the two types of shape memory effects it exhibits. Although SMA of two-way effect provides contractive and tensile forces, its tensile force is much smaller than contraction force and recoverable strain normally less than half that of one-way type. Thus SMA actuators of one-way effect, especially wire and strip type alloy, are more attractive in aerospace and robotic applications.This paper describes the shape memory alloy materials, mechanical properties and the advantages and disadvantages of compliant mechanisms based on the design, select a one-way shape memory effect of NiTi memory alloy material as the driving component, select the drive compliant mechanisms as the driving mechanism, design SMA-based compliant mechanisms to reverse the drive, and drive the modeling, simulation and analysis, and finally through the experiment to test the drive with a lightweight, two-way drive, the larger the output torque and large output angle drive performance. Drive has been designed to drive performance data.Finally, the paper gives the main conclusions of this research and innovation, and made follow-up research work, mainly to improve structural design, further reducing the quality and volume of the drive to achieve compact and lightweight, large torque and large output angle, high-precision SMA torsional actuator.