Design of Bio-manta Based on Continuously Programmable Soft Pneumatic Actuators (CPSPAs)

Bionic autonomous underwater vehicles (AUVs) have been prevalent in underwater equipment for their excel features. Manta rays have been widely studied due to their highly efficient and maneuverable pectoral fin propulsion. Traditional single-hinge actuation methods have impeded bionic pectoral fin achieving high bio-large-amplitude-continuous motion. To address the challenge and upgrade the performance of bionic propulsion, Continuously programmable soft pneumatic actuators (CPSPAs) were designed as bionic pectoral fins of a bio-manta robot fish. To achieve a high bio-similarity in motion and a comprehensive performance improvement, we propose analytical models to optimize the key parameters of the CPSPAs structure, where chamber wall thickness <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">t</i> = 1.5 mm, and chamber-void ratio <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">w/G</i> = 2:1 with a varying chamber height <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">h</i>. The pectoral fin locomotion profile of the bio-manta demonstrates maximum bending at 1/3 of the pectoral fin spanwise length and maximum amplitude of 55°, which is extremely similar to the fluttering motion of the manta, quantified with a similarity score of S = 0.9983. The proposed SPA bio-manta with a high bio-similarity and bio-affinity provide an innovative method to realize multi-muscle continuous actuation, which bring the bio-manta outstanding resilience and robustness. Such advantage has promised potential application in marine resource development and ocean database construction in the future.