Bidirection modeling and experimental analysis of underwater snake robot

Snakes have dedicate body and can maneuver in challenging environments. In this work, a soft snake-like robot is designed to locomote like a biological snake that can be used in search and rescue operation. The soft snake-like for underwater use has advantages of low inertia, high buoyancy, and more structural flexibility. Currently, the use of multi-redundant thin McKibben actuators for soft snake-like robot was not yet explored. Addressing this gap, a soft snake robot model using Finite Element (FE) will be developed. The FE model will be developed and used to investigate the snake bending motions in Matlab Simulink with Simscape Multibody Library (SML). Next, the actual fabrication of the robot will be validated with the simulated FE model using redundant mechanism of 10 McKibben actuators attached on a plastic plate. The structure of this robot uses 32 cm of a thin non-rigid plastic plate with five thin muscles at both sides of the body. Each thin muscle has 2.0 mm outer diameter with internal 1.3 mm silicone tube. The manipulator will be tested with different pressure and frequencies to perform various bending motions. Tracker application will capture every phase of the bending body and movements for analysis of the robot’s movement. It is expected that the snake-like robot can move and the errors of bending angle between simulation and experiment are less than 5%

Design and Modeling of a Soft, Pressurised, Spherical Robot

In the world of spherical robots groundbreaking innovations with regards to the sensory system and driving mechanism have taken place in last few decades. The motivation in this thesis is to integrate these innovations and develop a spherical robot, “RoboBall”, with a novel elastic spherical shell. This thesis reports on the design of the elastic shell, the modeling of robot’s dynamics and comparison of the analytics with experimental results. In addition to the electric motor-powered motion of the ball, the robot is also able to adjust its air pressure with an embedded pneumatic control system, and this thesis shows how that causes changes in the ball’s dynamics. The design of the internal driving mechanism, prior history, and a taxonomy of the spherical robots is also outlined. A non-trivial feature of the robot is its soft and pressure controlled elastic shell, which presented numerous design challenges. The rigid endplates and elastic exterior together form the skin of the robot, and different elastic-rigid interfaces for an air-tight robot are explored. The development of the internal pressure control system and its components are discussed. The “RoboBall” has an internal pendulum driven mechanism. The pendulum has two degrees of freedom; rolling and steering. A motion in the third direction i.e., oscillation in the vertical direction, is not actively controlled by the pendulum or any other mechanism but is governed by the system’s dynamics. This study focuses on the third degree of freedom, the bouncing of the “RoboBall”, which can be affected by varying the pressure inside the ball. The bouncing of the ball is modeled as a simplified spring-mass damper system and the effect of variation of pressure on different parameters. The thesis concludes with an experimental evaluation of a mass equivalent system, and comparison of these results to the formulated dynamic model