Abstract

Systems continue to grow in complexity to meet the demands of today’s society. To control severe nonlinearities and protect against errors in the system model, control methods with wider stability margins are necessary. However, most robust control methods require an increased energy cost to guarantee stability with wider margins. Furthermore, most current control methods are derived using system models, which are difficult to develop for complex systems. Model-Free Sliding Mode Control is promising in overcoming the aforementioned difficulties; the control output is only determined by the system order, previous control values, and state measurements. The control scheme’s characteristics have been mathematically derived but may have important unexplored practical implications. Originally, Model-Free Controllers were only partially model-free due to assumptions on the control influence matrix. More recent controllers relaxed the assumption using a real-time estimator. In the present work, a model-free control implementation is developed exploiting the characteristic. The new implementation allows for quicker and easier model-free controller development. Additionally, model-free control’s current estimator is validated. A new estimator, which approximates the boundaries of the influence matrix (rather than the matrix itself) is proposed and tested in a sliding mode control setting. The new estimator allowed for stability in the reaching phase and comparable tracking performance in the sliding phase as a normal sliding mode controller. The tracking performance was a result of a lower control input, though this is not guaranteed in all circumstances. If the new estimator is added to the new model-free control implementation, the controller may perform better and more efficiently. In the first part of this work, the model-free controller and real-time estimator are derived. Next, a simulation study was performed to prove the feasibility of the new approach. Finally, recommendations for next steps of the research are outlined.

Publication Date

7-23-2024

Document Type

Thesis

Student Type

Graduate

Degree Name

Mechanical Engineering (MS)

Department, Program, or Center

Mechanical Engineering

College

Kate Gleason College of Engineering

Advisor

Jason Kolodziej

Advisor/Committee Member

Kathleen Lamkin-Kennard

Advisor/Committee Member

Sarilyn Ivancic

Campus

RIT – Main Campus

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