Abstract: A magnetic force model of a capsule robot in three-dimensional spatial rotating magnetic field with gradient is proposed. The magnitude and direction of the magnetic force are investigated employing the section across the spatial rotating magnetic field, and the influence on the motion of the robot originated from the magnetic force is analyzed. The directivity of the magnetic force is verified using a permanent magnet, and the quantity of the magnetic force is tested using a spiral robot. Experimental results show that the magnitude and direction of the magnetic force are related to different location of the magnetic field. The experimental phenomena such as stagnation, retrogression and vibration happens to the capsule robot can be explained by the experimental results, the characteristics of the magnetic force generated by the spatial rotating magnetic field with gradient may have reference value for further improving the drive performance of the robot.

Key words: capsule robot;universal rotating magnetic field;gradient magnetic field;characteristics of magnetic force