Lightweight Dual-Mode Soft Actuator Fabricated from Bellows and Foam Material

Abstract

Foam-based soft actuators are lightweight and highly compressible, which make them an attractive option for soft robotics. A negative pressure drive would complement the advantages of foam actuators and improve the durability of the soft robotic system. In this study, a foam actuator was designed with a negative pressure pneumatic drive comprising bellows air chambers, a polyurethane foam body, and sealing layers at the head and tail. Experiments were performed to test the bending and contraction performances of the actuator with the foaming multiplier and air chamber length as variables. At air pressures of 0–90 kPa, the bending angle and contraction of the actuator increased with the foaming multiplier and number of air chamber sections. The designed actuator achieved a bending angle of 56.2° and contraction distance of 34 mm (47.9% of the total length) at 90 kPa, and the bending and contraction output forces were 3.5 and 7.2 N, respectively. A control system was built, and four soft robots were constructed with different numbers of actuators. In experiments, the robots successfully completed operations such as lifting, gripping, walking, and gesturing. The designed actuator is potentially applicable to debris capture, field rescue, and teaching in classrooms.