Shusheng Bi

Development and design of a robotic manta ray featuring flexible pectoral fins

This paper showed our preliminary work in probing into fish robot with pectoral fin propulsion. The aim of this project is to develop a fish robot mimicking manta rays that swim with flexible pectoral fins in oscillation motion. Based on the analysis of motion feature and skeletal structure of pectoral fin of manta rays, a kind of flexible pectoral fin made of silicone rubber was designed. Experiments on the propulsion of fin prototype were carried out in tank. Experiment results showed that flexible pectoral fin in oscillation motion could generate great thrust and the thrust would increase with fin-beat frequency and amplitude increasing. In the end, a robot fish with flexible pectoral fins was built. The speed of robot fish could reach the maximum of 1.4 times BL (body length) per second. Experiments proved that it was feasible to develop a robot fish featuring flexible pectoral fins in oscillation motion and the method to mimic manta rays was a great idea to improve performance of underwater vehicles.

Design of a robotic fish propelled by oscillating flexible pectoral foils

This paper proposed a new method of designing a flexible biomimetic fish propelled by oscillating flexible pectoral fins. The molding soft body is adopted in the robotic fish. Pneumatic artificial muscles are utilized as driving sources and two ribs with distributed flexibility as main parts of the propulsive mechanism. The leading edge locomotion profile of the flexible pectoral fin in air is studied experimentally, and the flapping locomotion in water is observed too. Finally, the effectiveness of the proposed method is illustrated by the experiment. It shows that the robotic fish can realize self-driven, and it can swim at a speed of 0.18m/s∼0.20m/s after optimization.

A bio-inspired swimming robot for marine aquaculture applications: From concept-design to simulation

This paper presents the development of a bio-inspired swimming robot from concept design to simulation for marine aquaculture applications. Based on investigation of several fish motions, the Manta ray is found to be the most suitable mock object since the flapping pectoral fin features long-endurance, low noise, high payload capacity, good stability and maneuverability. Through a comprehensive analysis of the structure of Manta ray, the shape proportional relationship between the body and the pectoral fins is obtained. Even though the concept design simplifies the structure, major functional components are retained. By applying two degrees of freedoms to each segment of the pectoral fin, the propulsion mechanism allow the robotic fish to swim in 3D. In addition, a thrust analysis is performed for a good understanding of the fishs aquatic locomotion principle. The flapping motion is decomposed into two orthogonal waves and realized on the robotic fish, taking advantages of sine generators. Simulation experiments including motion comparison, speed and turning tests verify the correctness of the robotic fishs structure and its propulsion mechanisms.

Design and implication of a bionic pectoral fin imitating cow-nosed ray

Pectoral foil structure and motion discipline of cow-nosed ray as nature prototype is analyzed. A bionic pectoral fin is designed according to the analysis results. Propulsion performance of the bionic fin at sinusoidal motion law is studied experimentally on a towing platform, at the oscillating frequency from 0.2 Hz to 2 Hz and amplitude from 2.5° to 30°. Well driving ability is obtained, and maximal average thrust of 2.75N is achieved by a single bionic fin expressed at towing speed of 10 cm/s. A biomimetic fish utilizing the kind of bionic fin is developed, and swimming speed of 0.9BL (body length) in maximum can be reached.

Design and motion analysis of tetrahedral rolling robot

A novel robot mechanism-tetrahedral rolling robot is introduced in the paper. The robot comprises of six extension struts and four node flats. When the COG of tetrahedron exceeds the stability region, the robot will roll. The structure of the tetrahedral rolling robot is described. Designing method of the robot is given, and it is proved correct and feasible through experiment. Kinematic model in different motion phase is analyzed in the paper, and the rolling critical condition is formulated. The effectiveness of the method is testified through simulation. The study of the paper will provide important reference for the dynamic analysis, optimization design and control of the tetrahedral rolling robot.

A waypoint-tracking controller for a bionic autonomous underwater vehicle with two pectoral fins

This study aims to develop a waypoint-tracking control system for a biomimetic underwater vehicle (BUV). The BUV is propelled by wide paired pectoral foils, and each pectoral foil is driven by three independent fin rays. To simplify the control strategy, the maximum flapping amplitude of the pectoral fin is used to control the forward velocity, and a turning factor is defined for the manoeuvre control. Several swimming experiments are carried out to investigate the influence of the control parameters on the swimming performance of the prototype. Based on the results of the swimming experiments, a waypoint-tracking control system is proposed, which contains two layers: the velocity control layer and the heading angle control layer. A subdivision control method is adopted by the velocity control layer to get the maximum flapping amplitude. The fuzzy control method is employed by the heading angle control layer to obtain the turning factor for steering motion. Several waypoint-tracking experiments are carried out to verify effectiveness of the control system. The results show that the prototype can automatically reach the target area with the designed control system, even though the waypoints are arranged or randomly given. Graphical Abstract

Applying coupled nonlinear oscillators to imitate swimming modes of cow-nosed rays

Cow-nosed rays can perform diversified swimming modes including linear cruise, pitching, yawing, and gliding. This paper focuses on the realization of these swimming modes. Furthermore, the role of tail fins are taken into account. The phase oscillators with controlled amplitudes have been adopted to build a new central pattern generator (CPG) network that includes six pectoral fin ray oscillators and two tail fin ray oscillators. Meanwhile the coupling connections are analyzed. The swimming modes of asymmetric oscillations in time, asymmetric oscillations in spatial, yawing based on the amplitudes, turning on the spot, and pitching based on tail fins are achieved. The simulations and experiments demonstrated that the CPGs are effective for controlling multi-fin actuated robotic fish to imitate the swimming modes of cow-nose rays and enable the robotic fish to achieve more complex movements by controlling the coordination of the pectoral fins and the tail fins.

Locomotion Analysis Of A Modular Pentapedal Walking Robot.

In this paper, the configuration of a five-limbed modular robot is introduced. A specialised locomotion gait is designed to allow for omni-directional mobility. Due to the large diversity resulting from various gait sequences, a criteria for selecting the best gaits based on their stability characteristics is proposed. A series of simulations is then performed to evaluate the various gaits in different walking directions. A gait arrangement scheme toward omni-directional locomotion is finally derived. Lastly, Experiments are also carried out on our pentapedal robot prototype in order to validate the results of simulation. The experiments confirm the gait analysis and selection is highly accurate in the evaluation of gait stability.

Design and analysis of a novel variable stiffness actuator based on parallel-assembled-folded serial leaf springs

Abstract Variable stiffness actuator (VSA) can significantly improve the dynamic performance of robots and ensure safety in human robot interaction. In this paper, a novel structure-controlled VSA which achieves a lower minimal stiffness while the size and load capacity remain unchanged is introduced. Stiffness variation is implemented by changing the effective length of parallel-assembled-folded serial leaf springs presented in this paper, which makes the adjustment of stiffness easier and driven by an independent motor. A modified analytical model of joint stiffness is built, which takes the gap between leaf springs and rollers into consideration. Experiments prove that the modified model is more accurate comparing with the ideal model which ignores the gap. Further analyses show that the gap can even make serious impacts on leaf spring-based structure-controlled VSA in other performances such as deformability and energy capacity. Graphical Abstract

Kinematic analysis and design of a robotic fish using flapping and flexional pectoral fins for propulsion

Compared with Autonomous Underwater Vehicle driven by traditional screw propellers, robotic fish is characterized by some desired features as high maneuverability and low noise. The research on bionic robotic fish which is propelled by paired pectoral fins has been gradually becoming hotspot in the field of biomimetics and robotics. Based on the research of cownose ray, the profile curve of pectoral fins for the kinematic analysis is established in this paper. We present that the dynamic foil deformation is composed of spanwise flapping and chordwise flexion. A novel bionic fish, Cownose Ray V, with multi-propulsion sources used in pectoral fins is designed, including the mechanical structure and the electronic control system. A towing platform is developed in order to test the propulsion performance of Cownose Ray V. According to the experimental results, the deformation and motion of pectoral fins obtained from Cownose Ray V imitate that of its natural sample to a great extent, which indicates that it can reach the desired propulsion performance.