Robust Control of Temperature During Local Hyperthermia of Cancerous Tumors Regardless of Uncertainty on All Model Parameters

Abstract

Local hyperthermia is one of the most prevalent thermal therapies for cancerous tumors, near the skin surface or natural body orifices. Due to the requisiteness of temperature control during local hyperthermia, first, the heat conduction process during the mentioned therapy is analytically modeled via a fractional-order transfer function with time delay. Since the influence of the heat source and the patient`s physiological reaction may vary the patient body temperature and affect all of the model parameters, robust control of temperature during the treatment is necessary. Hereupon, this study suggests a novel robustness criterion to achieve the phase margin invariance despite concurrent uncertainty on different parameters of the process model. Afterward, an analytical method is presented to tune a Fractional-Order Proportional-Integral-Derivative (FO-PID) controller for desirably adjusting the values of phase margin and gaining crossover frequency, such that the proposed robustness feature is also satisfied. Finally, a numerical simulation is presented to evaluate the efficiency of the paper`s achievements, using practical parameters.

Keywords

• hyperthermia
• cancerous tumor
• robustness criterion
• fractional-order pid controller
• phase margin
• gain crossover frequency