Innovation in Underwater Robots: Biologically Inspired Swimming Snake Robots

Abstract

Abstract-Increasing efficiency by improving locomotion methods is a key issue for underwater robots. Moreover, a number of different control design challenges must be solved in order to realize operational swimming robots for underwater tasks. This paper proposes and experimentally validates a straight line path following controller for biologically inspired swimming snake robots. In particular, a line-of-sight (LOS) guidance law is presented, which is combined with a sinusoidal gait pattern and a directional controller that steers the robot towards and along the desired path. The performance of the path following controller is investigated through experiments with a physical underwater snake robot for both lateral undulation and eel-like motion. In addition, fluid parameter identification is performed and simulation results based on the identified fluid coefficients are presented to obtain back-to-back comparison with the motion of the physical robot during the experiments. The experimental results show that the proposed control strategy successfully steers the robot towards and along the desired path for both lateral undulation and eel-like motion patterns.Index Terms-Underwater snake robots, modeling of swimming robots, model identification, LOS path following controller.

Modeling and propulsion methods of underwater snake robots

“…In particular, different types of UUVs such as conventional work class remotely operated vehicles (ROVs), inspection class ROVs and autonomous underwater vehicles (AUVs) are now widely used for subsea inspection, maintenance, and repair (IMR) operations in the oil and gas industry, archaeology, oceanography and marine biology [1], [2], [3]. In addition, lately, research has been conducted on developing intervention AUVs (I-AUVs) [4], underwater snake robots (USRs) [5], [6] and underwater swimming manipulators (USMs) [2], [3] as alternative solutions for several tasks to be performed in the subsea environment, with an overall goal to overcome and extend the capabilities of existing UUVs in the future.…”

“…There are several models proposed for swimming snake-like robots. A discussion of the different modeling approaches proposed for USRs can be found in [5], [12]. This paper proposes a closed form model for USRs swimming in a 2D plane, which takes into account the extra propulsion forces acting along the body when the snake robot is equipped with different added effectors, such as a caudal tail, fins, stern propeller, and tunnel thrusters, in addition to the propulsion forces generated by the link angle motion together with the hydrodynamic forces.…”

Velocity and orientation control of underwater snake robots using absolute velocity feedback

“…Several motion control systems for snake robots in the literature (e. g. [2,5,17]) do not control the velocity of the robot, but propose to choose a constantλ to achieve some forward velocity, while controlling the orientation of the robot to follow the reference of a guidance system. We conjecture that making velocity control a higher priority than orientation control will provide a velocity controller that is a natural complement of motion control approaches such as in [2,5].…”

“…Research on snake robots started with land-based snake robots [1,2], and more recently broadened towards amphibious and swimming snake robots [3][4][5]. A closely related field is that of robotic fish, see for instance [6].…”

Kinematic singularity avoidance for robot manipulators using set-based manipulability tasks

“…The USM is essentially a crossover between an autonomous underwater vehicle (AUV) and an underwater snake robot (USR) [20], [21]. The USM is a multi-body articulated structure, but unlike conventional USRs, the USM is equipped with additional thrusters, thus enabling it to operate as a floating base robotic manipulator (see Figure 1).…”