Coupling Between the Spin and Gravitational Field and the Equation of   Motion of the Spin
  In general relativity, the equation of motion of the spin is given by the equation of parallel transport, which is a result of the space-time geometry. Any result of the space-time geometry can not be directly applied to gauge theory of gravity. In gauge theory of gravity, based on the viewpoint of the coupling between the spin and gravitational field, an equation of motion of the spin is deduced. In the post Newtonian approximation, it is proved that this equation gives out the same result as that of the equation of parallel transport. So, in the post Newtonian approximation, gauge theory of gravity gives out the same prediction on the precession of orbiting gyroscope as that of general relativity. 
Ning Wu