outer surfaces of the spherical shell shaped rotor body at two sides of the opening are provided with protective sliding sleeves 33 respectively one end of each sliding sleeve 33 close to the opening of the spherical shell shaped rotor body is provided with a positioning block 32 a spherical sealing block 31 is disposed between two positioning blocks 32 and the spherical sealing block 31 is fixedly disposed on a front end of the main axle 14 extending out of the opening of the spherical shell shaped rotor body a seal ring 35 is disposed between the sealing block 31 and each of the positioning blocks 32 in this example the protective sliding sleeves 33 are disposed on the sliding slots at the outer surface of the opening member 23 the spherical sealing block 31 is a spherical shell larger than or equal to 90 degrees when the spherical shell shaped rotor body rotates no opening occurs in the spherical stator body however when the spherical shell shaped rotor body steers the opening member 23 moves towards the left or the right at this moment the positioning blocks 32 pull the protective sliding sleeves 33 to move to the vacancy thus preventing the dust from entering the spherical stator body the seal ring 35 also has functions of protection and preventing dust as shown in fig1 and 4 a magnetic sensing device 41 and a magnetic sensing hall device 42 are disposed outside the spherical stator body the magnetic sensing device 41 and the magnetic sensing hall device 42 both operate to detect magnetic fluxes of the ndfeb permanent magnet 22 the.