Assisted Passive Snake Robots:Conception and Dynamic Modeling Using Kane’s Method

Abstract

In this paper conception and dynamic modeling of a snakelike robot with passive wheels and compliant joints is investigated. The proposed robot has the ability to follow a so-called Serpenoid curve passively by using an appropriate set of initial conditions. Introduction of a unique structure at each joint enables the robot to achieve passive motion. A torsional spring is used in series with an actuator between each two consecutive links. Using wheels at the middle of each link imposes many non-holonomic constraints to the system. These constraints reduce the degrees of freedom of the system to only two. Due to the existence of these non-holonomic constraints, dynamic equations governing the locomotion of the articulated robot are obtained using Kane’s method. This technique is highly effective in reducing the complexity of the dynamic equations and results in significant reduction of the simulation time. Comparing the number of mathematical operations and the simulation time needed in the Kane’s and Lagrange’s methods illustrates the considerable difference.