| With the natural selection and evolution in billions of years,fishes owe the efficient and fast swimming ability.Fishes have strong mobility,good concealment and little influence on their surroundings.With the rapid development of computer technology and biological technology,bionics has begun to rise,and the field of bionic robotic fish has received extensive attention and research.The propulsion modes of robotic fish are mainly divided into the body and caudal fin(BCF)propulsion mode and the median and paired fin(MPF)propulsion mode.In this paper,an artificial muscle actuator based on shape memory alloy wire was developed.A control strategy combining the structure and the algorithm was proposed to realize the precise control of the amplitude and frequency of the artificial muscle actuator.Then the artificial muscle actuator was used as the actuating device to design two kinds of CARA-? and CARA-? bionic robotic fishes in the BCF swimming mode.The CARA-? robotic fish was used as a research object to study the characteristics of straight swimming and turning of robotic fish.The CARA-? robotic fish was used as the research object to study the underwater autonomous control of robotic fish.The main research content was as follows:(1)A new artificial muscle actuator based on shape memory alloy(SMA)was designed.By observing the movement mechanism of natural fish,the bionic structure of muscle-skeleton-spine was proposed.The artificial muscle actuator was designed with this structure as a bionic object.At the same time,two PCB boards were designed and manufactured to control the artificial muscle actuator.(2)The characteristics of artificial muscle actuator were analyzed.Based on the torque balance equation of the actuator and the SMA constitutive equation of Liang-Rogers,the bending motion model of the actuator was established.The bending amplitude characteristic of the actuator was analyzed experimentally.At the same time,the resistance change characteristics of SMA were experimentally studied.Based on the law of resistance,an adaptive heating strategy was proposed to control the bending angle of the actuator.In addition,the experiments was performed to analyze the response frequency and end output force of the actuator.Due to the effect of heat accumulation of SMA on the actuator,the control strategy of the actuator was determined by comparing the thermodynamic simulation of COMSOL and the amplitude bending ratio of the actuator.(3)Two robotic fish systems have been designed.The first robotic fish CARA-?was designed and produced by imitating the real carangiform fish.The robotic fish has a total length of 280 mm and a total weight of 210 g.It depended on the back of a third of the soft body for swinging.The robotic fish CARA-? was completed based on the CARA-?.The robotic fish has a total length of 340 mm and a weight of 376 g.The power supply and electronic control system are all integrated inside the fish body.(4)The control and swimming behavior of robotic fish were studied.Taking CARA-? robotic fish as the research object,the influence of the bending amplitude and the bending frequency on the speed of the robotic fish was studied.Aiming at the effect of SMA heat accumulation under high frequency,an adaptive round-robin heating control strategy was proposed,and the advantages of adaptive round-robin heating control strategy were experimentally analyzed.The speed and power ratio of robotic fish under two control strategies were theoretically calculated and compared.Then,according to the characteristics of four independent SMA output channels on each side of the actuator,10 kinds of heating combinations that can realize the turning of the robotic fish are proposed.The feasibility of these 10 combinations was experimentally verified.Finally taking the CARA-? robotic fish as the research object,the attitude of the robotic fish in the motion process was studied by using the 9-axis attitude sensor and the quaternion method. |
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