Snake Robots

Abstract

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Multi-objective optimization for efficient motion of underwater snake robots

“…The heading (or orientation)θ ∈ R of the snake is defined as the average of the link angles, i.e. asθ = 1 n ∑ n i=1 θ i [22]. The global frame position p CM ∈ R 2 of the CM (center of mass) of the robot is given by…”

“…It is interesting to note that if, in the dynamic model (4) and (5), we set the fluid parameters to zero and replace the drag forces in x and y direction with ground friction models [22], then the model reduces exactly to the dynamic model of a ground snake robot described in [22]. The underwater snake robot model is thus an extension of the land snake robot model, and may be used for amphibious snake robots moving both on land and in water.…”

“…In this paper, we will use a general sinusoidal motion pattern that describes a broader class of motion patterns including lateral undulation and eel-like motion [8]. Lateral undulation [22], which is the fastest and most common form of ground snake locomotion, can be achieved by creating continuous body waves, with a constant amplitude, that are propagated backwards from head to tail. In order to achieve lateral undulation, the snake robot is commanded to follow the serpenoid curve as proposed in [7].…”

“…For instance, g(i, n) = 1 gives lateral undulation, while g(i, n) = (n − i)/(n + 1) gives eellike motion [11]. The parameter γ is a joint offset coordinate responsible for the direction control [22].…”

Waypoint guidance control for underwater snake robots exposed to ocean currents

“…A popular guidance strategy for marine systems, that extends straight line path-following, is waypoint guidance (WPG) [12]. For land-based snake robots, WPG was proposed in [13]. WPG can also be applied for underwater bio-mimetic E. Kelasidi robots: A control system for a three-linked robotic fish was developed in [14], and in [15] WPG was applied to achieve obstacle avoidance of a USR.…”