Research On Sliding Mode Control Methods For Thermal Tactile Reappearance Device Based On Peltiers

Virtual reality technology is one of the most prominent achievements in the 21^st century which involves many fields and has a wide range of applications.Thermal tactile perception reappearance is an important branch of virtual reality technology and attracts the attentions of more and more researchers.In the fields of thermal tactile reappearance,the Peltier device is most commonly used because its dedicate size,safe and environmental design and not generating poisonous gas such as Freon.However,there are many nonlinear factors in Peltier device,what's more,the temperature is a sensitive physical quantity.It is of great theoretical and practical significance to study the Peltier temperature control algorithms of excellent dynamic characteristics.Sliding mode variable structure control has good dynamic response and strong robustness.The control methods of the temperature on Peltier thermal tactile reappearance surface are investigated in this paper.The Peltier is modeled precisely by thermal networks method and sliding mode control strategies are designed on it.On one hand,a finite-time disturbance observer is designed to evaluate the unknown external disturbance.By finite-time feed-forward compensation and sliding mode feedback control,the problem of Peltier temperature tracking control is dealt with and the influence of disturbances is dismissed.On the other hand,combing continuous sliding mode control and integral sliding mode control,an advanced continuous integral sliding mode control strategy is proposed based on finite-time observer.By simulation and experiment,the proposed continuous integral sliding mode control has continuous input and reduce chatting to a large extent.Furthermore,terminal sliding mode has a faster convengence speed than linear sliding mode.With the pratical demands increasing,the single-layer Peltier cannot reach a higher refrigeration temperature difference.To remedy this defect,a double-layer Peltier system is established which composed of two single-layer Peltier in parallel,enlarging the temperature difference successfully.In control algorithm,disturbance observers are applied to estimate the upper and lower layer perturbation respectively.A continuous terminal integral sliding mode control method for each subsystem is designed.Through finite-time Lyapunov stability theory,it is proved that this method can realize the rapid stabilization of temperature.Compared with finite-time non-smooth control,simulation and experiment are conducted to show that the continuous terminal integral sliding mode control has better disturbance rejection performace in the same condition of finite-time convergence.