The following report is created by Eric Falcon as his masters thesis for the study program of Electro-Mechanical System Design at Aalborg University. The thesis project handles the modeling, analysis, and design of controllers for a reluctance magnetic lead screw linear actuator. The actuator consists of a permanent magnet motor, the rotor of which drives a magnetic nut, which then applies force to the linear translator. The intent of the project is to determine the control characteristics of the system and to investigate the maximum performance achievable by the machine.

The first portion of the report investigates the magnetic lead screw system and related previous works as well as handles the nonlinear and linear modeling of the motor and mechanical system. Additionally, testing of the model in comparison to the expected behavior is conducted in simulation. The model is then analysed with linear analysis methods and the change of behavior over the nonlinear operating region inspected.

The second portion of the report considers the development of controllers for the system. Based on the hardware expected to be used for the implementation of the project, a desired controller architecture is developed and, based on this, linear current controllers and three methods of position control are designed. The position control methods include a cascaded linear slip controller, a cascaded controller where the current necessary for a desired force is calculated, and a traditional LQR with feed forward of the discontinuous frictions in the system. Additionally, as the system has no position sensor, the sensor capabilities necessary for effective control are investigated as well as various methods for estimating the translator state without any sensor feedback.

In an ideal case, the developed controllers would have been implemented on the physical system, however as this was not completed, there are many possibilities for future work. Despite this, the control considerations for developing a control system for such a machine have been considered and a fairly high performance has been seen in simulated testing of the control in many scenarios.