Design and realization of a low-drive bionic frog robot

This paper presents the design and fabrication of a compact underdriven bionic frog robot, which is inspired by the locomotion stance of a frog. The robot's hind legs were ingeniously built using an underdriven associative 8-bar linkage mechanism with a single motor drive to mimic the swimming motion of a frog. To enhance the robot's biomechanics and locomotor capabilities, the robot's shell was designed to mimic biological features and adjust buoyancy. In addition, the body of the robot has three sealed chambers, which include a module for adjusting its center of gravity, an energy module, and a control and communication module. The robot is equipped with an integrated E30-170T27D transceiver chip specifically designed for wireless communication in shallow water. The Tensilica Xtensa LX6 microprocessor can perform sensor data acquisition and control robotic movements. Prototype experiments demonstrated that the frog robot is capable of achieving stable autonomous swimming and three-dimensional longitudinal movement. This is made possible by using two independently driven hind legs and a center-of-gravity adjustment mechanism. The robot exhibits an average speed of 100 mm s^-1. Furthermore, owing to its low drive, high bionic, and small design, the robot minimized perturbations to the water environment during underwater movement. This allows a stable water environment for underwater measurements and improves the overall endurance time. This study improves the overall endurance and provides a theoretical basis for the design of underdrive mechanisms for future bionic underwater robots.