Limitations of GM-AGC based on spring equation

Through theoretic analysis, it was proved that in GM-AGC based on spring equation, if there is deviation between calculated value and true value of mill modulus,not only actual thickness deviation of strip can not be eliminated completely,but also under some special conditions,negitive feedback control pro- cess of calculated thickness even will result in positive feedback phenomenon of actual thickness because of mistake of roll gap regulated direction.Thus,it will cause deterioration of control effect of GM-AGC based on spring equation.