Investigators: Jeff Ahrens, Jim Reynolds, Omar Bennani

Collaborator: Dr. Hassan K. Khalil, Michigan State University

Select publications:

• X. Tan, O. Bennani, "Fast Inverse Compensation of Preisach-Type Hysteresis Operators Using Field-Programmable Gate Arrays," ACC'08
• J. Ahrens, X. Tan, H. Khalil, "Multirate Sampled-Data Output Feedback Control of Smart Material Actuated Systems," ACC'07 (invited)
• X. Tan, J. S. Baras, "Adaptive Identification and Control of Hysteresis in Smart Materials," IEEE Trans. Automatic Control  (2005)
• X. Tan, J. S. Baras, P. S. Krishnaprasad, "Control of Hysteresis in Smart Actuators with Application to Micropositioning," Systems & Control Letters (2005)
• R. V. Iyer, X. Tan, P. S. Krishnaprasad, "Approximate Inversion of the Preisach Hysteresis Operator with Application to Control of Smart Actuators," IEEE Trans. Automatic Control (2005)
• X. Tan, J. S. Baras, "Modeling and Control of Hysteresis in Magnetostrictive Actuators," Automatica (2004)

In this project we investigate control of smart material-actuated systems targeting hysteresis, nonlinearity, and uncertainty in these systems. The development of related control theory is closely tied to experimental verification on smart material systems (magnetostrictives, piezoelectrics, shape memory alloys, and electroactive polymers). One such experimental platform is shown below. A robotic arm (only the shaft is shown in the photo), actuated by a pair of shape memory alloy (SMA) wires, is taken as an example system. This system exhibits interesting coupling of dynamics (heating dynamics, inertia dynamics) with the hysteresis nonlinearity inherent in SMA actuation. Tools from hysteresis inversion, high-gain observer, and hybrid systems are brought together for the controller design to achieve fast and accurate tracking control of the robotic arm.