Electromechanical ballscrew force excitation system: dynamic modeling and control

Denizhan, Burak
Ball screws are components that are used to convert rotary motion into linear motion with relatively high mechanical efficiency. This property makes them an ideal choice for missile fin actuation systems where the demand for limited volume and high torque exists. Because of the structure of these systems, high torque demand comes with a high axial force on the ball screw, which consists of a nut, a shaft and balls in between. Especially, on high rotational speeds, the dynamic load capacity of ball screw plays an important role on the overall system performance. Hence, examining this property of the ball screw is critical. Since these application-specific ball screws have short strokes for accelerating the nut or shaft to the desired rotational speed, it is challenging to apply desired load to the nut in this limited period of time. In this study, a test rig is designed to test and verify the dynamic load capacity of ball screws with variable rotational speeds and load factors. Furthermore, mathematical modeling of the test rig is derived and the coefficients of the derived model are estimated through system identification principles by utilizing experimental data. Moreover, a robust force controller acting on the ball screws is synthesized and the mathematical model of the system with uncertainties is analyzed under the effect of the controller in simulation and test environment. Lastly, surplus force caused by the axial movement of the ball screws is decreased through a proposed feedforward controller. Simulation and experiment results show the efficiency of the designed robust feedback and the proposed feedforward controllers on the system.
Citation Formats
B. Denizhan, “Electromechanical ballscrew force excitation system: dynamic modeling and control,” Thesis (M.S.) -- Graduate School of Natural and Applied Sciences. Mechanical Engineering., Middle East Technical University, 2020.