Kinematic Evaluation of a Series of Soft Actuators in Designing an Eel-inspired Robot

In this paper, we present the preliminary design of a soft robot inspired by the eel which swims by undulating its body in wavelike motion to generate thrust force. The robot body comprises of a series of soft pneumatic actuators controlled by Pulse-Width Modulation. A soft actuator was simulated and designed to be of suitable shape to mimic an eel. The robot eel body, was then, fabricated, incorporating pairs of soft actuators. In fish locomotion analysis, kinematics of the midline, which describes the path of the spine, is frequently studied to represent the whole body for the purpose of simplifying analysis. We investigated midline kinematics in a model angulliform swimmer. Typical kinematic parameters of the robot body during swimming were estimated to examine their change with variation of frequency. A kinematic model of the robot body was built to estimate the thrust force component. The results revealed good potential to develop our proposed design with midline robot body kinematic properties similar to those in natural long body fish, with movement in the robot body able to create thrust force.