Dynamic Analysis of a Novel Wormly-Structured Snake Robot Abstract: Nowadays snake robots play incredible roles in robotics. Despite the wide range of use, they suffer from some main disadvantages; Not only they are not flexible enough, but also large diameter and utilizing unsuitable joints increase the probability of getting stuck in curvy paths. Additionally, they are usually designed for special tasks not for general issues, for example they will face dynamic limitations in working freely. In this work the prepared robot has overcome the above disadvantages, through the use of high density covered pipes as its frame. Our robot claims high flexibility due to the use of a sophisticated joint for movement in tight curvy routs. Furthermore, there is no need to any extra space for movement despite the robots introduced in prior works. It is designed to be used in various sites such as pipelines and gearboxes as a problem recognizer under predefined circumstances. Here, the special movement in three phases is proposed for making the robot act like a worm. Within this work the dynamic movements of the robot is first modelled in state-space, then the movement is analyzed in three recognized phases mentioned above added by illustrative block diagrams and figures. Keywords: Snake robot, dynamic, wormy movement, state-space 1. Introduction Snake robots can be used in Industry [1], security and defence [2], medical research [3- 4]. There were previous works on this phenomenon. For instance, various types of models have been developed by Miler [5]. In [6] the movement force is applied via wheels on snake robot with specific characteristics and for different challenging environmental situation. Serpentine robots were become more well-liked for overcoming the earlier robots disadvantages [7]. CPG (Distributed Central Pattern) control was proposed in prior mobile robots for making optimized algorithms [8]. In 2003, a snake robot was proposed to be utilized in small pipelines whose movement algorithm suffered from being wavy [9]. Being dependent on pipeline body properties, makes it so limited and feeble in wide range applications. Furthermore, having a wire connection between the robot and outside for power supply and controlling the process, there was high threat of being locked in the pipes. Another robot was invented with high flexibility, which had got many controlling motors to be capable enough in most of cases particularly in pipelines. Nevertheless it was suffering from being controlled with wire, moreover, it needed to have considerable extra space for crawling inside pipelines [10]. Robotic systems MRINSPECT series were presented in pipelines by analyzing dynamics in realistic conditions in 2007, even though; it needed to be adaptable to characteristic of pipelines [11]. Fig.1: The Wireless Wormly-Structured Snake robot. An essential requirement of the considered robot is flexibility. Utilizing the special joints, the proposed robot is 270 degree flexible with, allowing us to use it in curvy spaces as it is shown in Fig.1. Because of small diameter it is capable of being used in tight paths, so as a problem recognizer, it can crawl inside the pipelines, gearboxes and even inside the human body, if decreased in size. Regarding all these, this robot can be used in the fields of industry and medical research. Maryam Kouzehgar (1) , Seyed Amir Tafrishi (2) , and Atabak Maleki (2) (1) Faculty of Electrical & Computer Engineering, Control Engineering Department, University of Tabriz, Tabriz, Iran , mkouzehgar@tabrizu.ac.ir (2) Faculty of Engineering, Islamic Azad University of Tabriz, Tabriz, Iran , {amirtafrishi , atabak_92m}@yahoo.com