Programmable bioinspired robotic fish with fiber-based piezoelectric actuator array embedded in an elastomer

Macro-fiber composite (MFC) piezoelectric actuators employ piezo fibers with interdigitated electrodes, striking a balance between mechanical deformation and actuation force as we have shown our previous robotic fish concepts (e.g. Tan et al 2021 Bioinspir. Biomim., 16, 046024). In the present work, we explore a new class of piezoelectric-actuated robotic fish employing an array of MFC pairs embedded in silicone to emulate rattail-like swimming behavior. This array of MFC pairs is driven with programmable amplitude–frequency–phase schedules. The design is guided by multi-physics finite-element simulations which are then validated experimentally. We conduct geometry optimization (e.g. actuator spacing, substrate material and thickness, and tail dimensions) along with actuation-parameter studies (frequency, amplitude, phase). We explore standing waves (through the resonant frequencies) as well as propagating waves (for undulatory motions). Experiments are performed first in air to understand the modal behavior and mode sequence, and then in water tank to performance assessment. Measured outputs include time-averaged thrust, lateral force, fin kinematics, and electrical input power, which are used to compute power-specific thrust and—when submerged—effective propulsive efficiency.