A comprehensive review of driving mechanisms in amphibian spherical robots

A spherical robot is based on the rolling concept inspired by the pangolins. This mode of locomotion is faster and safer as its spherical body becomes a protective shield. The mobility, adaptability, and concealment provided by a spherical robot can be used for terrestrial, aquatic, and amphibious applications such as harbour patrolling, defence tasks, rough terrains exploration, and agriculture. In designing the robot, priority on the centre of gravity position should be given as this will affect the robot’s stability, either while static or in motion. A proper driving principle can overcome this issue while ensuring that the robot can perform a given task. Therefore, this paper intends to identify the driving principle proposed for spherical amphibian robots by systematically reviewing existing driving methods and the mechanisms used. From the search, 159 titles were published since 2015. The review has identified that the driving mechanism of a spherical amphibian robot depends on the actuation method, which is the legged actuation, combined actuation, and linear actuation. Each driving principle has its trade-off in performing the terrestrial and underwater motion. Furthermore, the driving principle also affects the advantages of a spherical robot system. Hence, studies on the driving principle that are more agile and do not ignore the spherical robot’s main advantage need to be given emphasis

A comprehensive review of driving mechanisms in amphibian spherical robots

864-872A spherical robot is based on the rolling concept inspired by the pangolins. This mode of locomotion is faster and safer as its spherical body becomes a protective shield. The mobility, adaptability, and concealment provided by a spherical robot can be used for terrestrial, aquatic, and amphibious applications such as harbour patrolling, defence tasks, rough terrains exploration, and agriculture. In designing the robot, priority on the centre of gravity position should be given as this will affect the robot’s stability, either while static or in motion. A proper driving principle can overcome this issue while ensuring that the robot can perform a given task. Therefore, this paper intends to identify the driving principle proposed for spherical amphibian robots by systematically reviewing existing driving methods and the mechanisms used. From the search, 159 titles were published since 2015. The review has identified that the driving mechanism of a spherical amphibian robot depends on the actuation method, which is the legged actuation, combined actuation, and linear actuation. Each driving principle has its trade-off in performing the terrestrial and underwater motion. Furthermore, the driving principle also affects the advantages of a spherical robot system. Hence, studies on the driving principle that are more agile and do not ignore the spherical robot’s main advantage need to be given emphasis

Hydrodynamic Modelling for a Transportation System of Two Unmanned Underwater Vehicles: Semi-Empirical, Numerical and Experimental Analyses

Underwater transportation is an essential approach for scientific exploration, maritime construction and military operations. Determining the hydrodynamic coefficients for a complex underwater transportation system comprising multiple vehicles is challenging. Here, the suitability of a quick and less costly semi-empirical approach to obtain the hydrodynamic coefficients for a complex transportation system comprising two Unmanned Underwater Vehicles (UUVs) is investigated, where the interaction effects between UUVs are assumed to be negligible. The drag results were verified by Computational Fluid Dynamics (CFD) analysis at the steady state. The semi-empirical results agree with CFD in heave and sway; however, they were overpredicted in surge due to ignoring the wake effects. Furthermore, experiments were performed for the validation of the time-domain motion simulations with semi-empirical and CFD results. The simulations which were performed with the CFD drags were close to the experiments. The semi-empirical approach could be relied on once a correction parameter is included to account for the interactive effect between multiple UUVs. Overall, this work makes a contribution by deriving a semi-empirical approach for the dynamic and controlling system of dual UUVs, with CFD and experiments applied to ascertain its accuracy and potential improvement

Modeling and Control of Underwater Mine Explorer Robot UX-1

This paper presents the design and experimental assessment of the control system for the UX-1 robot, a novel spherical underwater vehicle for flooded mine tunnel exploration. Propulsion and maneuvering are based on an innovative manifold system. First, the overall design concepts of the robot are presented. Then, a theoretical six degree-of-freedom (DOF) dynamic model of the system is derived. Based on the dynamic model, two control systems have been developed and tested, one based on the principle of nonlinear state feedback linearization and another based on a finite horizon linear quadratic regulator (LQR). A series of experimental tests have been carried out in a controlled environment to experimentally identify the complex parameters of the dynamic model. Furthermore, the two proposed controllers have been tested in underwater path tracking experiments designed to simulate navigation in mine tunnel environments. The experimental results demonstrated the effectiveness of both the proposed controllers and showed that the state feedback linearization controller outperforms the finite horizon LQR controller in terms of robustness and response time, while the LQR appears to be superior in terms of fall time.This work was supported in part by the UNEXMIN Project through the European Union’s Horizon 2020 Research and Innovation Programme under Agreement 690008, in part by the RoboCity2030-DIH-CM Madrid Robotics Digital Innovation Hub (Robotica aplicada a la mejora de la calidad de vida de los ciudadanos. fase IV) through the Programas de Actividades I+D en la Comunidad de Madrid under Grant S2018/NMT-4331, and in part by the Structural Funds of the EU.Peer reviewe