Bounded Inputs Total Energy Shaping for Mechanical Systems
MRJ Harandi, A Molaei, HD Taghirad, JG Romero
arXiv preprint arXiv:2104.02337 | Abstract: Designing control systems with bounded input is a practical consideration since realizable physical systems are limited by the saturation of actuators. The actuators' saturation degrades the performance of the control system, and in extreme cases, the stability of the closed-loop system may be lost. However, actuator saturation is typically neglected in the design of control systems, with compensation being made in the form of over-designing the actuator or by post-analyzing the resulting system to ensure acceptable performance.. | 2021 | Preprint | PDF | Dynamical Systems Analysis and Control |
On the Matching Equations of Kinetic Energy Shaping in IDA-PBC
M. Reza J. Harandi, Hamid D. Taghirad
arXiv preprint arXiv:2011.14958 | Abstract: Interconnection and damping assignment passivity-based control scheme has been used to stabilize many physical systems such as underactuated mechanical systems through total energy shaping. In this method, some partial differential equations (PDEs) arisen by kinetic and potential energy shaping, shall be solved analytically. Finding a suitable desired inertia matrix as the solution of nonlinear PDEs related to kinetic energy shaping is a challenging problem. In this paper, a systematic approach to solve this matching equation for systems with one degree of underactuation is proposed. A special structure for desired inertia matrix is proposed to simplify the solution of the corresponding PDE. It is shown that the proposed method is more general than that of some reported methods in the literature. In order to derive a suitable desired inertia matrix, a necessary condition is also derived. The proposed method is applied to three examples, including VTOL aircraft, pendubot and 2D SpiderCrane system. | 2020 | Preprint | PDF | Dynamical Systems Analysis and Control |
Solution to IDA-PBC PDEs by Pfaffian Differential Equations
M. Reza J. Harandi, Hamid. D. Taghirad arXiv:2006.14983 | Abstract: Finding the general solution of partial differential equations (PDEs) is essential for controller design in some methods. Interconnection and damping assignment passivity based control (IDA-PBC) is one of such methods in which the solution to corresponding PDEs is needed to apply it in practice. In this paper, such PDEs are transformed to corresponding Pfaffian differential equations. Furthermore, it is shown that upon satisfaction of the integrability condition, the solution to the corresponding third order Pfaffian differential equation may be obtained quite easily. The method is applied to the PDEs of IDA-PBC in some benchmark problems such as Magnetic levitation system, Pendubot and underactuated cable driven robot to verify its applicability. | 2020 | Preprint | PDF | Dynamical Systems Analysis and Control |
Coverage Control of Multi-Robot System for Dynamic Cleaning of Oil Spills
Samane Kaviri, Ahmadreza Tahsiri and Hamid D. Taghirad
International Conference on Robotics and Mechatronics | This paper addressed the dynamic cleaning of
oil spills using a multi-robot system. The cleaning process is
performed using a group of aerial agents adaptively covering
an oil spill considering its advection and spreading on the sea
surface. The concept of Voronoi Tessellation is employed to
command the autonomous vehicles on how to adapt its
configuration with the dynamic oil spill. Once the spill tracking
error reduces to the desired value, all of the agents spray
dispersant on the oil spill. This solution prevents wasting the
excess amount of dispersant that is often being sprayed in
conventional methods by aircraft. A distributed sliding mode
control scheme is proposed to navigate the agents to the nearoptimal Centroidal Voronoi Tessellation (CVT) by targeting
the thick layers. Simulation results demonstrate that the
proposed strategy can efficiently track the trajectory of the
polluted area, and adaptively cover the time-varying shape of
the oil spill. | 2019 | Conference | PDF | Dynamical Systems Analysis and Control |
Two PID-Based Controllers for a tethered Segway on Dome Shaped Structures
Mohammad H. Salehpour Hamid D. Taghirad and Hadi Moradi
2018 6th RSI International Conference on Robotics and Mechatronics (IcRoM) | Abstract: The UTDTR Robot is a human inspired robotic platform based on a two-wheeled mobile robot. This robot is designed for the purpose of dome shaped structures inspection and maintenance, and it is a tethered robot to stably climb steep surfaces on the top of dome structures. In this paper analysis and controller design of this robot modelled as a MIMO system is represented in order to provide the desired performance on the operating surface with minimum control effort and complexity. Two PID-based controllers are designed such that the stability and desired performance conditions are obtained. In the first design a fuzzy PID controller with self-tuning scale factors is designed to tune the controller gains is forwarded, while in the second approach a multi model gain scheduling controller based on conventional PID controller is considered. Finally, the effectiveness and simplicity of the proposed controller is verified through simulation, comparing the resulting closed loop transient and steady-state response to that of the previously proposed controllers. | 2018 | Conference | PDF | Dynamical Systems Analysis and Control |
Brain Computer Interface Control of a Virtual Robotic System based on SSVEP and EEG Signal
Fatemeh Akrami, Ebrahim Abedloo and Hamid D. Taghirad | Abstract: In brain computer interface (BCI) systems the brain patterns for a certain type of behaviour is extracted and the corresponding control commands are produced in order to control an external apparatus. SSVEP is a specific type of such control signal which is produced at the occipital lobe of the brain in response to an external oscillating stimulus. As the brain signals in SSVEP based BCI are the neurological reaction of the individuals to the presented stimulus, it is crucial to design a suitable stimulus system as well as investigation of its effectiveness. In this paper a suitable visual stimulus is designed and implemented, and its effectiveness to control the motion of a robot on a virtual robotic system is verified based on experiments. An online integrated system comprising of a virtual industrial robotic manipulator, an EEG deployment and statistical feature extraction method is developed and real time experiments to verify its accuracy and effectiveness is experimented on different subjects. The experiments shows the promising features of the developed systems for further applications. | 2017 | Conference | PDF | Dynamical Systems Analysis and Control |
Two PID-Based Controllers for a tethered Segway on Dome Shaped Structures
Mohammad H. Salehpour Hamid D. Taghirad and Hadi Moradi
2018 6th RSI International Conference on Robotics and Mechatronics (IcRoM) | Abstract: The UTDTR Robot is a human inspired robotic platform based on a two-wheeled mobile robot. This robot is designed for the purpose of dome shaped structures inspection and maintenance, and it is a tethered robot to stably climb steep surfaces on the top of dome structures. In this paper analysis and controller design of this robot modelled as a MIMO system is represented in order to provide the desired performance on the operating surface with minimum control effort and complexity. Two PID-based controllers are designed such that the stability and desired performance conditions are obtained. In the first design a fuzzy PID controller with self-tuning scale factors is designed to tune the controller gains is forwarded, while in the second approach a multi model gain scheduling controller based on conventional PID controller is considered. Finally, the effectiveness and simplicity of the proposed controller is verified through simulation, comparing the resulting closed loop transient and steady-state response to that of the previously proposed controllers. | 2017 | Conference | PDF | Dynamical Systems Analysis and Control |
Comment on: "Centers of quasi-homogeneous polynomial planar systems"
A. Rahimabadi, H.D. Taghirad
Nonlinear Analysis: Real World Applications | Abstract: We describe a counter-example which shows that of theorem in Algaba et al. (2012) is not correct. This part of the theorem, pinpoints whether the origin of quasi-homogeneous system in Algaba et al. (2012) is a center or not. It is shown in this note that the given necessary and sufficient conditions of theorem, in Algaba et al. (2012) are not complete. | 2017 | Journal | PDF | Dynamical Systems Analysis and Control |
Design of a Robust Controller for a Tethered Segway on Dome-Shaped Structures
Mohammad H. Salehpour Hamid D. Taghirad and Hadi Moradi
2016 4th International Conference on Robotics and Mechatronics (ICROM) | Abstract: Tethered Segway is a robotic platform inspired by human climbers. It is a two-wheeled mobile platform tethered to the top of a structure in order to climb steep surfaces with varying slopes, such as domes. The unstructured environment may cause uncertainties in the dynamic behavior of the robot while operating on different parts of the dome. In this paper analysis and synthesis of a robust controller for a tethered Segway is presented in order to provide desired performance in the presence of uncertainties. To design the robust controller, structured and unstructured uncertainties of the model are encapsulated into a structured singular perturbation. A linear robust controller is designed such that the robust stability of the closed loop system is preserved in the presence of modeling uncertainties. Finally, the effectiveness of the proposed controller is verified through simulation by comparing its closed loop transient response and sufficiently suitable steady-state performance to that of a previously proposed LQR controller for the robot. | 2016 | Conference | PDF | Dynamical Systems Analysis and Control |
Reigon of Convergence Expansion of a Robust Model Predictive Controller
Mojgan Rostami and Hamid D. Taghirad
2015 23rd Iranian Conference on Electrical Engineering | Abstract: In this paper a gain scheduling method is proposed for robust model predictive control of a useful class of nonlinear discrete-time systems. The system is composed of a linear model perturbed by an additive state-dependent nonlinear term. Robust model predictive controllers are designed in the literature to compensate for the uncertainty of the system. In order to enlarge the region of convergence it is assumed that system has several equilibrium points and multiple robust controllers are designed. By switching between the controllers it is verified that the region of convergence shall be enlarged, while the overall stability of the system is preserved. In the proposed method, the stability analysis based on Lyapunov functions for each level set is performed, while state feedback control law is designed by minimization of a desired cost function formed in linear matrix inequalities. The simulation results show the applicability of the proposed method. | 2015 | Conference | PDF | Dynamical Systems Analysis and Control |
Corner stability in nonlinear autonomous systems
Arsalan Rahimabadi, H. D. Taghirad
Nonlinear Dynamics | Abstract: In most practical applications, studying the asymptotic stability of equilibrium points of a system is of utmost importance. Furthermore, in many cases, the response is restricted to only a sector of the state space. For example, positive systems that are common in chemical processes have nonnegative state variables. For such systems, stability analysis of the system using Lyapunov stability is not advised, since this stability is defined for all the points within a neighborhood of the equilibrium point. In this paper, a new notion of stability, called corner stability, is defined as more suitable for studying asymptotic stability of equilibrium points in such systems. In order to derive sufficient conditions of corner stability, a theorem is stated and proven in this paper, and corner stability of three case studies is analyzed and verified. | 2015 | Journal | PDF | Dynamical Systems Analysis and Control |
Robust Control of a Steam Turbine Power Based on a Precise Nonlinear Model
S.A. Salamati, H.D. Taghirad, Ali Chaibakhsh
2014 5th Conference on Thermal Power Plants (CTPP) | Abstract: In this paper, a precise and nonlinear model is developed for Nekka power plant turbine from its experimental data and documents. It is proposed to use boiler-turbine coordinated control system to increase effective efficiency of the steam unit. Identification procedures have been performed to obtain continuous time models of Nekka steam turbine at various loads. After determining the upper bound for uncertainty and choosing a good performance weighting function, a robust controller has been designed and implemented in closed loop for the turbine nonlinear model. Since the closed loop performance was not as required, a cascade controller structure is proposed, in which the turbine loop is closed by a PI controller in order to significantly reduce the uncertainty. Simulation results demonstrate the suitable performance of the closed loop in terms of tracking, speed of response, and damping of oscillations. | 2014 | Conference | PDF | Dynamical Systems Analysis and Control |
A neutral system approach to H-Infinity PD/PI controller design of processes with uncertain input delay
A. Shariati, H.D. Taghirad, A. Fatehi
Journal of Process Control | Abstract: This paper presents a neutral system approach to the design of an H? controller for input delay systems in presence of uncertain time-invariant delay. It is shown that when proportional derivative (PD) controller is applied to a time-delay system, the resulting closed loop system is generally a time-delay system of neutral type with delay term coefficients depending on the controller parameters. A descriptor model transformation is used to derive an advantageous bounded real lemma representation for the system. Furthermore, new delay-dependent sufficient conditions for the existence of an H? PD and PI controller in presence of uncertain delay are derived in terms of matrix inequalities. Some case studies and numerical examples are given in order to illustrate the advantages of the proposed method. | 2014 | Journal | PDF | Dynamical Systems Analysis and Control |
PD Controller Design with H-Infinity Performance for Linear Systems with Input Delay
Ala Shariati, Hamid D. Taghirad
AUR Journal of Electrical Engineering | Abstract: This paper considers H-Infinity control problem for input-delayed systems for time-varying delays. A proportional-derivative state feedback control law is used in this paper. By this means, the resulting closed-loop system turns into a specific time-delay system of neutral type. The significant specification of this neutral system is that its delayed term coefficients depend on the controller parameters. This condition provides new challenging issues in theoretical research as well as providing new applications. In the present paper, new delay-dependent sufficient condition is derived for the existence of H-Infinity controller in terms of matrix inequalities, in presence of varying time-delays. The resulting H-Infinity controller guarantees asymptotic stability of the closed-loop system as well as a guaranteed limited system induced norm smaller than a prescribed level. Numerical examples are presented to illustrate the effectiveness of the proposed method. | 2012 | Journal | PDF | Dynamical Systems Analysis and Control |
Delay-Dependent H-Infinity Control of Linear Systems with Uncertain Input Delay Using State-Derivative Feedback
A. Shariati, H. D. Taghirad
Control Engineering and Applied Informatics | Abstract: In some practical problems such as active vibration suppression systems, the state-derivative signals are easier to access than the state variables. This paper considers an H-Infinity -based state-derivative feedback control problem for input-delayed systems. Applying this control law, the resulting closed-loop system turns into a specific time-delay system of neutral type. The significant specification of this neutral system is that its delayed term coefficients depend on the controller parameters. The time-delay is considered as uncertain time-invariant with a known constant bound. In this paper, the delay-dependent sufficient conditions for the existence of an H-Infinity state-derivative feedback controller are derived in terms of matrix inequalities. The resulting H-Infinity controller stabilizes the closed-loop neutral system and assures that the H-Infinity -norm to be less than a prescribed level. An application example is presented to illustrate the effectiveness of the proposed method. | 2012 | Journal | PDF | Dynamical Systems Analysis and Control |
Delay-Independent Robust Stability Analysis of Teleoperation
Masoumeh Azadegan, Sadjaad Ozgoli, and Hamid Reza Taghirad
2011 Chinese Control and Decision Conference (CCDC) | Abstract: This paper considers the robust stability of uncertain teleoperation systems. Sufficient stability conditions are derived in terms of LMI by representing the teleoperation scheme in retarded form of time-delay systems. By choosing Lyapunov-Krasovski functional, a delay-independent robust stability criterion is presented. We show that the teleoperation system is stable and has good performance under specific LMI condition. With the given controller parameters, stability of system is guaranteed in the presence of any value of delay and admissible uncertainty. To evaluate the theoretical analysis, Numerical simulations are performed. | 2011 | Conference | PDF | Dynamical Systems Analysis and Control |
Delay-Independent Stability Analysis of Internet-based Tele-operation
Masoumeh Azadegan, Sadjaad Ozgoli, Hamid Reza Taghirad
2011 International Symposium on Computer Networks and Distributed Systems (CNDS) | Abstract: This paper presents a sufficient stability condition for internet-based tele-operation systems in terms of LMI. The tele-operation scheme is modeled in state-space as a time-delay system in retarded form and a delay-independent stability criterion is extracted. By choosing Lyapunov-Krasovski functional, we show that the internet-based tele-operation system is stable and has good performance under specific LMI condition. With the given controller design parameters, stability of system is guaranteed in the presence of any value of delay. Numerical simulations are performed to verify the theoretical results. | 2011 | Conference | PDF | Dynamical Systems Analysis and Control |
Robust Internal Model Control for Impulse Elimination of Singular Systems
M. M. Share Pasandand, H. D. Taghirad
International Journal of Control Science and Engineering | Abstract: In this paper the problem of model based internal control of singular systems is investigated. The limitations of directly extending the control schemes for normal systems to singular ones are thoroughly developed, and a robust approach is proposed in order to establish a control scheme for singular systems. The proposed method presents a general framework for robust control design of singular systems in presence of modeling uncertainties. Two simulation examples are given to how the proposed method can be implemented, and to show the effectiveness of such controllers in closed loop performance. | 2011 | Journal | PDF | Dynamical Systems Analysis and Control |
Adaptive Robust Controller Design For Non-minimum Phase Systems
M. Ataollahi and H. D. Taghirad | Abstract: Based on the synthesis algorithm of dynamical backstepping design procedure, in this paper a new adaptive robust approach for non-minimum phase systems is proposed. The proposed controller consists of two parts; a backstepping controller as the robust part and a model reference (MRAS) controller as the adaptive part. In this control scheme the daptive part acts not only as a medium to converge to suitable values for the unknown parameters and to reduce the uncertainty, but also provides a minimum-phase model for the robust controller to be well stabilized. A simulation case study is studied to show how to perform the proposed control law, and to illustrate the effectiveness of this method compared to that of conventional robust controllers. | 2011 | Conference | PDF | Dynamical Systems Analysis and Control |
Robust Internal Model Control For Impulse Elimination of Singular Systems
M. M. Share Pasand and H. D. Taghirad
International Journal of Control Science and Engineering | Abstract: In this paper the problem of model based internal control of singular systems is investigated. The limitations of directly extending the control schemes for normal systems to singular ones are thoroughly developed, and a robust approach is proposed in order to establish a control scheme for singular systems. The proposed method presents a general framework for robust control design of singular systems in presence of modeling uncertainties. Two simulation examples are given to how the proposed method can be implemented, and to show the effectiveness of such controllers in closed loop performance. | 2011 | Conference | PDF | Dynamical Systems Analysis and Control |
Descriptor Approach to Unknown Input PI Observer Design:application to fault detection
M.M. Share Pasand, H.D. Taghirad
Control Automation and Systems (ICCAS), 2010 | Abstract: The descriptor observer approach is improved further to a more suitable observer scheme which is applicable to a more general group of faults and systems. Also a disturbance decoupling scheme is added to the mentioned observer in order to enable the observer to distinguish faults from disturbances. | 2010 | Conference | PDF | Dynamical Systems Analysis and Control |
Unknown Input-Proportional Integral Observer for Singular Systems: Application to fault detection
M. M. Share Pasand, M. Aliyari Sh., and H. D. Taghirad
2010 18th Iranian Conference on Electrical Engineering | Abstract: A new approach to the observer design for descriptor continuous time systems is proposed and its application in the fault diagnosis problem is illustrated. In this observer, two features of disturbance decoupling and fault estimation are combined. Also a more general frame for fault estimation is used. Some numerical examples and simulation results are shown to justify the effectiveness of the algorithm. | 2010 | Conference | PDF | Dynamical Systems Analysis and Control |
Model predictive control of non-linear discrete time systems: a linear matrix inequality approach
N. Poursafar, H.D. Taghirad, M. Haeri
IET Control Theory & Applications | Abstract: Using a non-linear model in model predictive control (MPC) changes the control problem from a convex quadratic programme to a non-convex non-linear problem, which is much more challenging to solve. In this study, we introduce an MPC algorithm for non-linear discrete-time systems. The systems are composed of a linear constant part perturbed by an additive state-dependent non-linear term. The control objective is to design a state-feedback control law that minimises an infinite horizon cost function within the framework of linear matrix inequalities. In particular, it is shown that the solution of the optimisation problem can stabilise the non-linear plants. Three extensions, namely, application to systems with input delay, non-linear output tracking and using output-feedback, are followed naturally from the proposed formulation. The performance and effectiveness of the proposed controller is illustrated with numerical examples. | 2010 | Journal | PDF | Dynamical Systems Analysis and Control |
Disturbance Retrieving Unknown Input Proportional Integral Observer for Generalized Linear Systems
M.M. Share Pasand and H.D. Taghirad
ICCAS 2010 | Abstract: An unknown input retrieving observer scheme is proposed which not only decouples unknown inputs in estimation but also gives an estimation of the decoupled input. The provided method benefits from its low computational cost as well as its less restrictive existence conditions compared to existing ones. | 2010 | Conference | PDF | Dynamical Systems Analysis and Control |
Delay-Dependent H-Infinity Control of Linear Systems with input Delay Using Composite State-Derivative Feedback
A. Shariati, H. D Taghirad and B. Labibi
Iranian Conference on Electrical Engineering | Abstract: H-Infinity control problem for input-delayed systems is considered in this paper. A composite state-derivative control law is used, in which, a composition of the state variables and their derivatives appear in the control law. Thus, the resulting closed-loop system turns into a specific time-delay system of neutral type. The significant specification of this neutral system is that its delayed term coefficients depend on the control law parameters. This condition provides new challenging issues which has its own merits in theoretical research as well as application aspects. New delay-dependent sufficient condition for the existence of H ? controller in terms of matrix inequalities is derived in the present paper. The resulting H-Infinity controller guarantees asymptotic stability of the closed-loop system as well as a guaranteed limited H ? norm smaller than a prescribed level. Numerical examples are presented to illustrate the effectiveness of the proposed methods. | 2010 | Conference | PDF | Dynamical Systems Analysis and Control |
Delay-Dependent H-Infinity Control of Linear Systems with Time-Varying Delays Using Proportional-Derivative State Feedback
A. Shariati, H. D Taghirad and B. Labibi
Control & Automation (MED) | Abstract: This paper considers H-Infinity control problem for input-delayed systems for time-varying delays. A proportional-derivative state feedback control law is used in this paper. By this means, the resulting closed-loop system turns into a specific time-delay system of neutral type. The significant specification of this neutral system is that its delayed term coefficients depend on the controller parameters. This condition provides new challenging issues in theoretical research as well as providing new applications. In the present paper, new delay-dependent sufficient condition is derived for the existence of H-Infinity controller in terms of matrix inequalities, in presence of varying time-delays. The resulting H-Infinity controller guarantees asymptotic stability of the closed-loop system as well as a guaranteed limited system induced norm smaller than a prescribed level. Numerical examples are presented to illustrate the effectiveness of the proposed method. | 2010 | Conference | PDF | Dynamical Systems Analysis and Control |
Delay-Dependent Stabilization of Linear Input-Delayed Systems with Composite State-Derivative Feedback: Constant and Time-Varying Delays
A. Shariati, H.D Taghirad and B. Labibi
Iranian Conference on Electrical Engineering | Abstract: This paper considers stability problem for input- delayed systems for both constant and time-varying delay case. A new composite state-derivative control law is introduced, in which, a composition of the state variables and their derivatives appear in control law. By this means, the resulting closed-loop system becomes a particular time-delay system of neutral type. The significant specification of this neutral system is that its delayed term coefficients depend on the control law's parameters. This condition provides new challenging issues which has its own merits in theoretical as well as practical aspects. In the present paper, new delay-dependent sufficient conditions are derived in presence of both constant and varying time-delay in terms of matrix inequalities. The resulting controllers guarantee asymptotic stability of the closed-loop system. Simulation studies are presented to verify the stability conditions obtained within the theorems. | 2009 | Conference | PDF | Dynamical Systems Analysis and Control |
A New Sensorless Vector Control Method for Permanent Magnet Synchronus Motor Without Velocity Estimatior
H. D. Taghirad, N. Abedi, E. Noohi
7th International Workshop on Advanced Motion Control | Abstract: In this paper, a novel vector control method for permanent magnet synchronous motors is presented. In this method, the velocity estimation is completely removed and vector control is accomplished in a new coordinate system. In conventional vector control methods, the control effort is calculated in rotating coordinates with a synchronous speed of omega. However, in the proposed method, the control effort is calculated in rotating coordinates with reference speed omega. This change of coordinate decreases the calculation effort significantly. In order to verify the applicability of the proposed control law, a Lyapunov-based stability condition is derived and the performance of the controller is verified through simulations and experiments. The obtained results illustrate the effectiveness of the proposed method despite the simplicity of its implementation. | 2002 | Conference | PDF | Dynamical Systems Analysis and Control |