F. FotoohiNia

Bio: F. FotoohiNia is an academic researcher from K.N.Toosi University of Technology. The author has contributed to research in topics: Multivariable calculus & Model predictive control. The author has an hindex of 2, co-authored 3 publications receiving 21 citations.

Robust nonlinear model predictive sliding mode control algorithm for saturated uncertain multivariable mechanical systems

Abstract: In this paper, robust stabilization and predictive tracking control for a class of nonlinear uncertain multivariable systems is presented. The control scheme is built by incorporating nonlinear model predictive control in discrete sliding mode control to obtain optimal results while satisfying hard constraints and closed-loop robustness in the presence of external disturbance (matched or unmatched) and parametric uncertainty. Additionally, the control input domain limitation is involved in construction of the model predictive control scheme by employing sliding functions admissible bounds. The problem of cost minimization is solved through optimal selection of terminal cost gain and allocation of system dynamics with respect to sliding surfaces while robust stabilization and feasibility are ensured through the prediction horizon.

Tracking control of moving flexible system by incorporation of feedback-based vibrational energy sink in model predictive control algorithm

Abstract: This paper proposes a new approach towards the nonlinear problem of tracking control for mobile multivariable vibrational structure featuring an Euler-Bernoulli vibrational beam. The control scheme involves obtaining interactions between flexural and rigid motions of the multivariable continuum mechanics system with actuator force limitation both regarding domain and frequency bandwidth. To this end, the boundary control inputs are selected prioritizing two tasks, satisfying actuator limitations and obtaining minimum possible tracking error. The former is employed as hard constraint in model predictive control (MPC) scheme while the latter is considered as soft constraint. The control scheme is adjusted such that when actuator limits are exceeded, the soft constraints are relaxed to maintain stability. In order to provide smooth tracking, Euler-Bernoulli transverse vibration is attenuated by incorporating Feedback Vibrational Energy Sink (FVES) method in obtaining control law. Hence, actuators are manipulated such that total vibrational energy of flexible beam is damped without using passive or conventional active dampers. The accuracy of the proposed method has been verified via FEA-based simulations.

FEA-based tracking control of flexible body switching dynamic structure

Abstract: In dynamically switched systems with unknown switching signal, the control system is conventionally designed based on the worst switching scenario to ensure system stability. Such conservative design demands excessive control effort in less critical switching configurations. In the case of continuum mechanics systems, such excessive control inputs result in increased structural deformations and resultant modeling uncertainties. These deformations alter differential equations of motion which cripple the task of control. In this paper, a new approach for tracking control of uncertain continuum mechanics multivariable systems undergoing switching dynamics and unknown time delay has been proposed. Control algorithm is constructed based on the mathematical rigid model of the plant and a Common Lyapunov Function (CLF) is proposed upon sliding hyperplane regarding all switching configurations. Considering the model-based nature of sliding mode control (SMC) and inevitable uncertainties induced from modeling simplifications of continuum system or parameter evaluation errors, Finite Element Analysis (FEA) is utilized to approximate total model uncertainties. To obtain robust stability, instead of conventional switching functions in the construction of control law, the control inputs are selected such that system dynamics reside within stability bounds which are calculated based on the Lyapunov asymptotic stability criterion. Therefore, the unwanted chattering issue caused by continuous switching is not observed in control input signals. Eventually, the accuracy of the proposed method has been verified through the student version of ANSYS® mechanical APDL-based simulations and its effectiveness has been demonstrated in multiple operating conditions.

Two-sided linear matrix inequality solution of affine input matrix for feasible discrete finite-time sliding mode control of uncertain nonlinear mechanical machines:

Abstract: In this article, a new control method is proposed based on finite-time discrete sliding mode control for uncertain multi-input multi-output systems which are affine to their inputs considering unce...

Friction-Tracker-Embedded Discrete Finite-Time Sliding Mode Control Algorithm for Precise Motion Control of Worm-Gear Reducers Under Unknown Switched Assistive/Resistive Loading

Abstract: This paper proposes a novel method for simultaneous estimation of unknown switched external disturbance and precise position control of dynamical systems which employ worm gear drive reducers. This algorithm is based on an improved discrete sliding mode control (DSMC) design which ensures convergence to the desired sliding set without introducing chattering effects to the dynamical system. In order to improve the performance of DSMC and to obtain an accurate estimation of gearbox model, a new method for incorporation of switched friction is proposed in the presence of external disturbance. To this end, the dynamical response of worm gear drive reducer is investigated in distinct switched disturbance modes of resistive disturbances, assistive disturbances and no disturbance to obtain approximate functions describing system dynamics in aforementioned configurations. In comparison with the feedback data, the obtained models permit appropriate incorporation of friction into the improved DSMC scheme. Based on multiple common Lyapunov functions and calculation of virtual reference signals for armature currents, the feasibility of control algorithm is ensured in all modes of switched dynamics. The effectiveness of the proposed estimation and control schemes has been verified using an experimental setup employing a worm gear drive reducer on which multiple permanent magnet DC motors are installed, and improvements resulted from incorporation of friction estimation algorithm are analyzed.