Study on the stiffness of a 5-DOF hybrid machine tool with actuation redundancy

This paper deals with the stiffness of a 5-DOF hybrid machine tool with actuation redundancy. The revolute pair element and guideway-slider subsystem are proposed and their stiffness matrices are derived, respectively. After the stiffness matrices of all machine parts are deduced, an accurate stiffness model of the machine tool is derived by using the assembly method. The experiments are conducted to validate the stiffness model. Further, a few stiffness evaluation indices are presented to compare the stiffness of the redundant machine tool with that of the corresponding non-redundant one. Finally, the stiffness of the machine tool is improved by improving the stiffness of machine part with lowest stiffness.