Abstract
This paper proposes a new shape memory alloy (SMA)-driven compliant rotary actuator that can perform both passive and self-actuated motions. This SMA actuator is suitable as a redundant actuation part in a parallel robot joint to assist with singularity postures where the robot might lose the ability to maintain the position and orientation of the end effector. The double helical compliant joint (DHCJ) was chosen as a candidate mechanism; it can act in soft compliance with linear characteristics and a wide range of motion. The experimental results validated that the proposed model can be used to simulate the DHCJ behavior. The use of this mechanism exhibits advantages such as one-axis rotational motion, linear behavior even for a compliant mechanism, stiffness in the other axes of motion, and compact size. SMA leaves (strips) were used as actuation parts, and a single SMA leaf was tested before combining with the double helical frame as an SMA actuator. The prototype was fabricated, and necessary parameters such as deflection angle, temperature, torque, and stress–strain were collected to define the model for a controller. This actuator is controlled by a feedforward controller and provides rotational motion for both forward and reverse sides with a maximal range of 40 degrees.
Highlights
Shape Memory Alloy (SMA) is a special material that can recover itself to its original shape when the proper heat is applied
The purpose of this paper is to propose a new shape memory alloy (SMA) compliant actuator based on the double helical structure
This paper proposes the design of a new SMA-driven compliant actuator based on a double helical structure
Summary
Shape Memory Alloy (SMA) is a special material that can recover itself to its original shape when the proper heat is applied. SMA has been used as a smart actuator by providing electrical current directly to its part. Using SMA material as a smart actuator, it shows advantages such as high force per weight ratio, simple electrical current drive, and operation in silence [2]. The common shapes of SMA, which are produced are wire-shaped, spring-shaped and strip-shaped. Farias [3] proposed a four-fingered robot hand by using SMA wire as an actuation part. Hamid [4] designed the morphing wing mechanism by using an SMA wire and a bias spring. Yuan [5] designed the compliant actuator with
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