The main characteristics of heavy forging manipulator is its powerful gripping weight and torque, the labor intensity can be reduced and the manufacturability of the forging equipments can be deeply developed by using it in forging workshops, therefore the reasarch and development of the heavy forging manipulator has important significance for the forging industry.

The forging sagging angle of deflection influences clamping stability of the large scale heavy clamping system directly.

It mainly contains the function overloading and operator overloading.

Distinguished from the existing AD-based OPF algorithms,the proposed algorithm applies operator overloading AD technique and explores the characteristics that most elements in Jacobian matrix and Hessian matrix of constraints in rectangular coordinates are constants,and adds a subroutine to identify all constant derivates to avoid repeated computations.