Development of a novel two-way 3D printed flexible spiral composite actuator based on shape memory alloy wire and its control

Abstract

Soft robotics find its applications across numerous of scientific and industrial fields, spanning from medicine and surgery to gripper technology, assistive devices, and exploration in underwater and space. The study introduces a soft actuator design for soft robotics, produced using 3D printing technology, offering an efficient alternative to traditional molding and curing methods. A shape memory alloy wire is integrated to the spiral body printed using a flexible filament. The spiral enhances the actuation stroke (AS) to 2 cm for a wire of 189 mm in length, while actuation in the literature is typically accomplished through an axial AS of 3%–5% of the wire’s length. Four types of spirals with increasing gaps are prepared to observe the cooling effect. Their performances are evaluated in terms of AS and time through image processing in order to determine the optimal configuration. An electrical current constraint is established to prevent potential damage, and spiral control is attained using a proportional–integral–derivative controller. Moreover, a pick and place operation showcases the spiral’s ability to autonomously lift a gripped object weighing 6.5 g, achieving a specific displacement of 6.5 mm. Subsequently, the object is lifted down to its initial position using a two-way actuator that utilizes the stored energy within the spiral’s structure and elastic effect. The proposed actuator has the potential to be widely applied across various soft robotic applications, including medical robots, delicate gripping robots, and bioinspired robots.