3D Magnetic Manipulation System For Actuation Of Magnetic Microrobot

As an important branch of robotics,microrobot has gained wide attention in many fields because it can carry out special operations in a narrow environment and overcome the size limitation.Among the numerous propulsion strategies of microrobot,the magnetic actuation has received great attention from researchers at home and abroad due to its superior performance in propulsion efficiency,the abundance of magnetic material,biological compatibility,medical safety,and other aspects.The magnetic actuation has progressed from the original uniform magnetic field and gradient magnetic field to the combined 2D magnetic field and three-dimensional magnetic field;from the original single degree of freedom control to multiple degrees of freedom control;from the original solenoid magnetic field to a magnetic field driven by the synchronized operation of permanent magnets,electromagnets,and robotic arms.However,there are still many limitations in the magnetic actuation,such as the magnetic flux intensity and magnetic gradient does not meet the requirements;the uniformity in the working area is not good enough.Although it can realize the multi-degree of freedom control,the magnetic control is only appliable to a narrow space.This paper aims to solve the problems of insufficient magnetic flux intensity and magnetic gradient and insufficient uniformity of the control area.To study the strategy of magnetic actuation,the force and torque of magnetic material are studied,and the relationship between current and force and torque of magnetic material is established.Based on the solenoid magnetic field,a method to calculate the solenoid based magnetic field is derived.To improve the magnetic field strength and gradient,solenoid and iron core are used to condense the magnetic flux lines.COMSOL is used to analyze the electromagnet with iron core,and the influences of current,solenoid distribution,relative magnetic conductivity of iron core and shape of iron core on the magnetic field distribution are obtained.In order to solve the problem of uneven magnetic field,the characteristic of gradient peak point is found,and the paired electromagnets is compared with Helmholtz coils and Maxwell coils.According to the property of gradient peak point of hollow core electromagnet,a planar magnetic field control system is designed and verified.A 3d magnetic field control system is designed by replacing a hollow core with a pair of cores.According to the requirements of 3d magnetic control system,the hardware of the magnetic control system is designed and fabricated.A power control system is designed,which is composed of upper computer,lower computer and power amplifier module to provide enough energy for electromagnet.