Rui Ding

On a Bio-inspired Amphibious Robot Capable of Multimodal Motion

This paper addresses the system design and locomotion control for a versatile amphibious robot, AmphiRobot-II, inspired by various amphibian principles in the animal kingdom. In terms of the propulsion features of existing amphibians, a novel hybrid propulsive mechanism coupled with wheel-propeller-fin movements is proposed that integrates fish- or dolphin-like swimming and wheel-based crawling. The robot is able not only to implement flexible wheel-based movements on land, but also to perform steady and efficient fish- or dolphin-like swimming under water and can further switch between these two patterns via a specialized swivel device. To achieve multimodal motions, a body deformation steering approach is proposed for the turning locomotion on land with minimum turning radius obtained accordingly. A central pattern generator inspired underwater locomotion control is also implemented and tested on the physical robot. Based on the aforementioned design, the AmphiRobot-II prototype has been built and has successfully demonstrated to confirm the effectiveness of the hybrid propulsive scheme and the amphibious control approaches.

Amphibious Pattern Design of a Robotic Fish with Wheel-propeller-fin Mechanisms

He article focuses on the underwater and terrestrial locomotion aspects of an amphibious robotic fish propelled bymodular fish-like propelling units and a pair of hybridwheel-propeller-fin mechanisms. The life forms have evolved over millions of years and shaped dexterous structures and locomotion patterns, which are well adapted to underwater, terrestrial, and aerial environments. These locomotor skills can provide useful insight into the implementation of robotic tasks in unpredictable environments. Successful parameter tuning in each project indicated that the CPG-inspired nonlinear system was dynamically rich enough to generate the expected locomotor behaviors. Although swimming and crawling governed by the artificial CPGs have been extensively investigated, the generation and transition of multiple amphibious behaviors within the CPG control framework were rarely tackled.

CPG-based dynamics modeling and simulation for a biomimetic amphibious robot

This paper deals with the motion control and dynamics modeling of an amphibious biomimetic robot capable of multi-mode motion. A robust gait control for steady swimming using a central pattern generator (CPG) is proposed and has been successfully applied to the robot, with coordinated movements of a pair of pectoral fins and multiple modular fish-like propelling units. Combined with the hydrodynamic forces acting on the robot, a dynamics modeling based on the Lagrangian function has been established. Then some simulations are conducted with the CPG control imported into the model. By varying the input drive of the CPG model, different activities of swimming mode can be induced with the velocity, direction and type of gaits modulated accordingly. Physical tests verify the feasibility of the dynamics model coupling of the CPG control for efficient propulsion.

Dynamic Modelling of a CPG-Controlled Amphibious Biomimetic Swimming Robot

This paper focuses on the modelling and control problems of a self-propelled, multimodal amphibious robot. Inspired by the undulatory body motions of fish and dolphins, the amphibious robot propels itself underwater by oscillations of several modular fish-like propelling units coupled with a pair of pectoral fins capable of non-continuous 360 degree rotation. In order to mimic fish-like undulating propulsion, a control architecture based on Central Pattern Generator (CPG) is applied to the amphibious robot for robust swimming gaits, including forward and backward swimming and turning, etc. With the simplification of the robot as a multi-link serial mechanism, a Lagrangian function is employed to establish the hydrodynamic model for steady swimming. The CPG motion control law is then imported into the Lagrangian-based dynamic model, where an associated system of kinematics and dynamics is formed to solve real-time movements and, further, to guide the exploration of the CPG parameters and steady locomotion gaits. Finally, comparative results between the simulations and experiments are provided to show the effectiveness of the built control models.

Robust gait control in biomimetic amphibious robot using central pattern generator

This paper presents a control architecture for the underwater locomotion control of a biomimetic amphibious robot with multi-mobility mechanism. In view of both hydrodynamic problem and engineering approach, we develop a robotic prototype capable of multi-mode motion. A robust gait control for steady swimming using the central pattern generator (CPG) is proposed and has been successfully applied to the robot. The CPG can produce coordinated patterns of rhythmic activity while being simply modulated by control parameters including input drive, frequency, amplitude, threshold, etc., which will be suitable for manually interactive modulation. Using the CPG model, the robot is capable of performing and switching between various locomotion modes such as swimming forwards and backwards, turning and pitching, with the speed, direction and gait types modulated accordingly. A test-bed is provided and results are presented demonstrating interesting properties of the CPG-based control approach and feasibility of the CPG control for efficient propulsion.

Bio-inspired design and realization of a novel multimode amphibious robot

This paper deals with an improved design scheme for an amphibious robot inspired by various amphibian principles in animal kingdom. Considering the propulsive features of existing amphibian modes synthetically, a novel hybrid propulsive mechanism that integrates fish-like swimming with wheel-paddle-fin movements is proposed. The robot is able to implement speedy and efficient fish-like or dolphin-like swimming and to perform flexible wheel-like terrestrial movements, which can switch between these two patterns by a specialized swivelling device. Critical engineering realization issues involving morphological optimization, buoyancy calculation and waterproof sealing are discussed. In particular, the design philosophy of modularity has been incorporated into the development of the robotic prototype. Preliminary testing partially validates the feasibility of multimode gaits both on land and in water.

Fuzzy Logic PID Based Control Design for Permanent Magnet Synchronous Motor Servo System

This paper mainly deals with a fuzzy logic proportional-integral-derivative (PID) based controller for a permanent magnet synchronous motor (PMSM) system. To greatly improve the dynamic characteristics of the PMSM and refrain from undesired disturbance due to parameter diversification and load disturbance, a novel fuzzy switching algorithm is created and a combined fuzzy PID controller is further developed to ensure smooth transition over a wide range of speeds. Numerical simulation and physical experiments on the PMSM servo system confirm that the proposed controller has been endowed with the advantage of both fuzzy logic controller and PID controller, which yields enhanced dynamic feats and stability.

Platform-level design for a biomimetic amphibious robot

This paper addresses a platform-based design for a bio-inspired amphibious robot well-suited for multi-mode motion both on ground and under water. It concerns mechanical design, hardware implementation, software design, as well as ADAMS-based modeling. By introducing well-established software and hardware architectures, an ARM+uC/OS-II centered embedded control system is formed. With the sensor subsystem processing the gathered robotic and environmental information effectively, different motion modes will be adopted under dynamically changing environments. Preliminary testing partly verifies the feasibility of the platform-oriented, amphibious robotic prototype.

Body-Deformation Steering Approach to Guide a Multi-mode Amphibious Robot on Land

This paper addresses the locomotion control for a biomimetic amphibious robot capable of multi-mode motion both in water and on land. Currently, a wheel-like device named wheel-paddle is employed as the primary driving mode. Depending on the deflections of rear propelling units, a body-deformation based steering approach is proposed, and an optimal realization is explored through geometrical analysis. Furthermore, the kinematic models as well as corresponding simulation results are outlined and the error between two models is also summarized. The experimental results demonstrate the validity, stability and maneuverability of the formed steering, satisfying robots operation requirements on land.

CPG-based behavior design and implementation for a biomimetic amphibious robot

This paper presents the behavior design and multimodal locomotion control of a biomimetic amphibious robot based on a bio-inspired CPG (central pattern generator). A set of four key parameters are introduced serving as external stimuli to shape the CPG rhythmic activities where necessary speed and orientation modulation as well as 3-D locomotion can be obtained. In terms of the built parameter set, a library of movement primitives based on finite state machine is established to facilitate rapid and smooth gait transitions. To enhance adaptive behaviors, well-integrated sensory feedback by means of two liquid-level detectors enables the gait transition between ground and water autonomously. Simulations and experiments are also conducted to demonstrate the feasibility of a behavior-based control architecture governed by CPGs.