Research On Novel Coil Array Drive Modeling And Control Strategy For Magnetic Microrobot

The small size and unconstrained characteristics of microrobot make it very suitable for working in relatively closed and narrow space.In recent years,it has shown great application potential in biology,medicine and other fields,such as blood vessel dredging,targeted drug delivery,gastrointestinal detection,etc.,so it has received extensive attention from researchers.As one of the most promising driving methods for microrobot,magnetic field has become a research hotspot because of its strong penetration,remote driving and nondestructive driving of living biological materials.After decades of development,from the construction of magnetic drive system to the precise control of microrobot to the design of functional microrobot,the research of magnetic drive microrobot has achieved fruitful results.Compared with a single microrobot,microrobot formation and cooperation can not only complete complex tasks,but also improve task throughput.At the same time,the miniaturization of robots limits the development of individual intelligence.The lack of individual intelligence can be compensated by the collective intelligence of multiple microrobots.However,since the microrobot group receives the same control input from the external magnetic field,the independent control of multiple microrobots is full of challenges.In addition,due to the magnetic interaction between microrobots,how to realize the group cooperative control of microrobots under physical constraints is also urgent to be solved.Starting from the design of the array coil magnetic drive system,this topic focuses on the independent control of the microrobot group and the cooperative control of the microrobot group.First,aiming at the problem that the existing electromagnetic coil system generates global magnetic field,which is difficult to realize the independent control of multiple magnetic microrobots,a local magnetic field generation system of array coils is designed.The number of layers,turns,current-carrying capacity and manufacturing process of the microcoil are comprehensively considered to optimize the structure of the microcoil.The material selection and structure design of the microrobot are carried out,and the dynamic model is established.The 3D simulation model is built by finite element method.The simulation results of single microcoil and combined microcoil verify the effectiveness of the designed local magnetic field generation system.Secondly,in order to achieve high-precision tracking and positioning of microrobot,a target tracking algorithm based on kernel correlation filter(KCF)and image contour detection fusion is proposed,with tracking accuracy of 1 pixel.In addition,the array coil drive circuit is designed,and the experimental platform of the magnetic microrobot independent drive closedloop control system is built.Based on visual feedback,the point-to-point discrete control strategy is adopted to carry out the independent control path tracking experiment of a single microrobot and multiple microrobots.The results show that the system has precise and flexible driving performance.Thirdly,considering the microrobot formation cooperative control requirements at the micro-scale,physical constraints are added to establish a multi-microrobot system model.Combined with the multi-agent path planning algorithm based on conflict search,a collisionfree path satisfying the distance constraint is planned for each microrobot.The path planning simulation of a single microrobot and multiple microrobots verifies the feasibility of the proposed method.Finally,build 12×12 expanded array experimental platform to carry out several experiments of microrobot cooperative control.It includes single microrobot executing sequential task experiment,multiple microrobots executing sequential task experiment,simulated micrologistics transportation experiment,microfluidic transportation and micro-assembly experiment to verify the comprehensive ability of the magnetic micro-robot group cooperative control system built in this paper.The experimental results show that the system can realize independent and cooperative control of multiple magnetic microrobots,and has great application potential in micro logistics and micro assembly.