Biologically inspired swimming robotic frog based on pneumatic soft actuators

Abstract

Research on soft robots and swimming robots has been widely reported and demonstrated. However, none of these soft swimming robots can swim flexibly and efficiently using legs, just like a frog. This paper demonstrates a self-contained, untethered swimming robotic frog actuated by 12 pneumatic soft actuators, which can swim in the water for dozens of minutes by mimicking the paddling gait of the natural frog. We designed two kinds of pneumatic soft actuators as the joints on the robotic frog’s legs, which allows the legs to be lighter and more compact. It is found that such soft actuators have great potential in developing amphibious bionic robots, because they are fast-responding, inherently watertight and simple in structural design. The kinematic analysis in swimming locomotion was conducted for the prototype robotic frog, and the locomotion trajectory of each leg was planned based on the analysis of the paddling gait of frogs. Combined with the deformation model of the soft actuators, the robotic frog’s legs are controlled by coordinating the air pressure of each joint actuator. The robotic frog’s body is compact and the total mass is 1.29 kg. Different paddling gaits were tested to investigate swimming performance. The results show that the robotic frog has agile swimming ability and high environmental adaptability. The robotic frog can swim forward more than 0.6 m (3.4 times the body length) in one paddling gait cycle(6 s), whose average swimming velocity is about 0.1 m s−1, and the minimum turning radius is about 0.15 m (less than 1 body length).

Soft Robotics: A Systematic Review and Bibliometric Analysis

“…Instead, Hu et al developed two actuator configurations, one with tilted cameras 3D-printed on the whole actuator surface and one with a hybrid actuator with tilted and non-tilted cameras that can be configured according to the specific application [ 40 ]. Jizhuang et al developed a soft robot based on frog locomotion that is driven by fluid actuators, and the robot is capable of linear displacements and rotations [ 41 ]. Tang et al were inspired by the kinematics of cheetahs’ spines during galloping and created a bio-inspired robot based on this principle.…”

“…Jizhuang et al approached the control of the frog robot through an open-loop control system that connected an HC-12 module to the robot microcontroller, which allowed the robot to be controlled from a PC. The drive system is specific to pneumatic actuators and the robot has high autonomy while not being tied to an external power source [ 41 ].…”

Research status and development trend of frog-inspired robots

“…The use of the soft drive unit promotes the development of the frog-inspired robot in the direction of miniaturization, light weight, and flexibility. To realize stable and controllable explosion drive, Qi [75] proposed a high-precision gas flow control method based on air pressure sensor, which integrates solenoid valve and air pump to realize quantitative generation and high-precision delivery of gas fuel. Meanwhile, a structural design scheme combining the soft explosive drive unit and the rigid hindlimb drive is also proposed (Fig.…”

“…(e) Explosive jumping experiment[74]. (f) Model of a Frog-inspired jumping robot based on explosion and linkage drive[75].…”

A Shift from Efficiency to Adaptability: Recent Progress in Biomimetic Interactive Soft Robotics in Wet Environments

“…Top photo by Joel Henry on Unsplash, bottom reproduced with permission. [ 350 ] Copyright 2020, IOP Publishing. h) eel.…”