| As a high-tech underwater detector,bio-mimetic robot fish has great advantages in the exploration and development of marine environment,such as marine resource exploration,water quality monitoring,maritime detection and underwater archaeology,etc.Until now,the motion control methods of robot fish mainly include the method of curve fitting of fish body wave,the method of sinusoidal controller and the method based on the central pattern generator(CPG).Designing a modularized bio-mimetic robot fish based on black carp,which is assembled by various functional modules and each functional module can be packaged separately without affecting to each other.In addition to basic swimming models such as linear movement and turning,a series of complex underwater swimming models such as swimming suspension and snorkeling can be realized.The CPG control method is used to realize the basic swimming models of the robot fish,and realize the flexible control of the robot fish through parameter adjustment combining with the closed-loop swimming suspension controller,which has the characteristics of strong flexibility and maneuverability.The details are as follows:(1)Black carp as a bionic object,designing a bio-mimetic robot fish based on the modular idea that can realize swimming snorkeling.The modularize design of the robot fish have the characteristics of strong expansion,convenient disassembly and good sealing performance,and can be equipped with different functional compartments to meet different environmental requirements.The main body of the robot fish is consist of a sinking module,a pectoral fins module,a hardware module and a caudal fin module,and each module is sealed as a whole separately.The pectoral fins module and the caudal fin module of the robot fish provide Propelling force and the hardware module bears the package of hardware and power,the sinking and floating module consists of a weight compartment and a water absorption and drainage mechanism which can realize the weight adjustment and suspension control of the robot fish.The robot fish shells are also designed in a block-assembled structure,which is connected to the main structure by 12 shells.Water can fill the space between the shell and the main structure which is exposed to the outside water,to reduce the quality of the fish body and achieve the purpose of reducing the mass of robot fish,and to save power and increasing the ability of battery life.(2)Establishing a CPG kinematic model of bio-mimetic robot fish,Which combined the characteristics of MPF and BCF swimming models,the swimming models of the pectoral and caudal fins were analyzed.With the CPG control method,the robot fish has realized the basic linear movement and the basic turning movement and the switching of each swimming models by controlling the swimming models of 2DOF(degree-of-freedom)pectoral fins and the single joint caudal fin,which include linear movement and radius turning under the pectoral and caudal fins,and the in-situ turning and swimming backward under the pectoral fins,and the switching between linear movement and radius turning.Changing the CPG control method enables smooth switching of swimming models and better swimming stability.Change the CPG related parameters such as turning radius,swimming speed,etc.(3)Through hydrodynamic analysis,to adjust and improv the CPG control parameters of robot fish.The design of the closed motion controller of the swimming suspension to realize the swimming suspension of the robot fish and the robotic fish can be suspended in the water,and on this basis,the swimming suspension can be realized by changing the angle of attack of the pectoral fins.The experimental results show that the robotic fish can perform complex and flexible movements in the water and has good maneuverability. |
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