This chapter presents an overview of the work on the RoboSalmon prototype biomimetic underwater vehicle carried out at the University of Glasgow. This work includes the development of the mathematical model that covers the kinematics and dynamics of the RoboSalmon vehicle to assist with the understanding of the dynamics of the swimming process. Details of the method used to model the tendon drive propulsion system are presented along with details of the modelling of the recoil motion. Experimental surge results are presented, which show a number of trends in the data including an increase in surge velocity with increasing tail-beat frequency. The maximum surge velocity obtainable from the vehicle before actuator saturation occurred was 0.18 m/s, which was achieved at a tail-beat frequency 0.61 Hz and a nominal tail-beat amplitude 0.15 m. From the surge data collected, the relationship between tail-beat frequency and surge velocity appeared to be linear. The range of surge velocities obtained for the RoboSalmon was then compared to the swimming performance of a real Salmon, which showed that the swimming speed of the RoboSalmon obtained for a particular beat frequency was lower than that achievable by a real Salmon by around a factor of 3.2. This difference in performance is due to the mechanical nature of the RoboSalmon system. Overall, the work completed on the RoboSalmon has shown that a biomimetic fish-like propulsion system is potentially viable as a form of propulsion for an AUV. The experimental results show that the biomimetic system used on the RoboSalmon may have advantages over a conventional propeller- and rudder-based system in terms of improved propulsive efficiencies and increased vehicle manoeuvrability. Further investigation and development of this technology could lead to the development of AUVs with significantly increased efficiencies and manoeuvrability thus allowing longer and more challenging missions to be undertaken.

Chapter Contents:

• 15.1 Introduction
• 15.1.1 Biomimetics and biologically inspired design
• 15.1.2 Biological AUV design
• 15.2 Biological swimming
• 15.2.1 Types of aquatic swimming
• 15.2.2 Fish swimming
• 15.2.2.1 Genera of fish
• 15.2.2.2 Swimming gait
• 15.2.3 Method of biomimicry: RoboSalmon
• 15.3 Mathematical modelling of a biologically inspired AUV
• 15.3.1 Vehicle dynamics
• 15.3.1.1 Rigid body dynamics
• 15.3.1.2 Hydrodynamic added mass terms
• 15.3.1.3 Restoring forces and moments
• 15.3.1.4 Hydrodynamic damping terms
• 15.3.1.5 Tail manoeuvring capability
• 15.3.1.6 Recoil motion
• 15.3.1.7 Tendon drive system: input forces and moments
• 15.3.2 Vehicle hull kinematics
• 15.3.3 State space form
• 15.3.4 Model results
• 15.4 Forward propulsion analysis
• 15.4.1 Tail-beat frequency and amplitude
• 15.4.2 Power
• 15.5 Open-loop manoeuvring analysis
• 15.5.1 Turning from stationary
• 15.5.2 Turning at speed
• 15.5.3 Turning circle
• 15.5.4 Power consumption
• 15.6 Conclusion
• References

Inspec keywords: propellers; biomimetics; robot dynamics; autonomous underwater vehicles; mobile robots; design engineering; robot kinematics

Other keywords: RoboSalmon prototype; recoil motion modelling; surge velocity; autonomous underwater vehicle; mathematical model; biomimetic underwater vehicle design concept; tendon drive propulsion system; rudder-based system; biomimetic fish-like propulsion system; swimming process; RoboSalmon vehicle kinematics; propeller-based system; RoboSalmon vehicle dynamics; tail-beat frequency; University of Glasgow; AUV

Subjects: Design; Robot and manipulator mechanics; Mechanical components