Movement modeling and control of precession mechanism for bonnet tool polishing large aixsymmetrical aspheric lenses

Movement modeling and control for bonnet tool polishing large axisymmetrical aspheric lenses is present. The intersection point of the spin axis and the bonnet is selected to be object, after analyzing the structure of bonnet tool and process feature of large axisymmetrical aspheric lenses polishing; a base coordinate is set up with the centre of bonnet to be its origin point. As the included angle of the spin axis of bonnet tool and the local normal is fixed in continuous precession polishing, a corresponding coordinate is set up to get the position parameters of the intersection point of the spin axis and the bonnet when polishing a random point, the position parameters of the intersection point of the spin axis and the bonnet in base coordinate are got according to space coordinate conversion; Movement model is obtained by space matrix transformation, based on the surface equation of large axisymmetrix aspheric lenses, processing control model and the position parameters got in last step; Finally, most efficiency algorithm is added to the movement model, and precession motion curve is got by simulation. The correctness of movement model and control algorithm is confirmed through simulating the trend of spin axis of bonnet follows the local normal and comparing the simulated value of precession angle with the actual value of precession angle.