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Robust Integral Sliding Mode Control Design for Stability Enhancement of Under-actuated Quadcopter
Safeer Ullah,Adeel Mehmood,Qudrat Khan,Sakhi Rehman,Jamshed Iqbal 제어·로봇·시스템학회 2020 International Journal of Control, Automation, and Vol.18 No.7
In this paper, a robust backstepping integral sliding mode control (RBISMC) technique is designed for the flight control of a quadcopter, which is an under-actuated nonlinear system. First, the mathematical model of this highly coupled and under-actuated system is described in the presence of dissipative drag forces. Second, a robust control algorithm is designed for the derived model to accurately track the desired outputs while ensuring the stability of attitude, altitude and position of the quadcopter. A step by step mathematical analysis, based on the Lyapunov stability theory, is performed that endorses the stability of both the fully-actuated and under-actuated subsystems of the aforementioned model. The comparison of proposed RBISMC control algorithm, with fraction order integral sliding mode control (FOISMC), affirms the enhanced performance in terms of faster states convergence, improved chattering free tracking and more robustness against uncertainties in the system.
Safeer Ullah,Qudrat Khan,Adeel Mehmood,Aamer Iqbal Bhatti 대한전기학회 2020 Journal of Electrical Engineering & Technology Vol.15 No.4
This paper presents a backstepping sliding mode control (BSMC) scheme for uncertain underactuated nonlinear systems. Since, underactuated electro-mechanical nonlinear systems (UEMNS) operate under the fewer number of inputs than the degree of freedom, therefore, the control of such systems remains a complex task. In this work, a class of UEMNS is considered which can be transformed into the so-called regular form. In the design process, these UEMNS are frst transformed into regular form. In this form, the systems are properly subdivided into series cascaded blocks in which the one of the blocks is indirectly driven by the applied control input whereas the second block is directly controlled by the control input. This structure is apparently suitable for backstepping design. Hence, all the controller steps are designed via the proposed backstepping sliding mode technique. The step by step stability is proved rigorously by considering the Lyapunov approach. In term of benefts, this designed control law provides low-frequency vibration as compared to conventional SMC along with robust performance in the presence of matched uncertainties. This claim is verifed via the numerical simulation results of the cart-pendulum system. For further confrmation, these results are also compared with the standard literature results to demonstrate the benefts and efectiveness of the aforesaid control scheme for such class.
Distributed SDN Based Network State Aware Architecture for Flying Ad-hoc Network
Muhammad Saqib,Asif Mehmood,Adeel Rafiq,Afaq Muhammad,Wang-Cheol SONG 한국통신학회 2020 한국통신학회 APNOMS Vol.2020 No.09
Flying networks are resource constraints while the nature of nodes’ mobility is very dynamic and unpredicted. Therefore, these networks are very prone to link failure and performance degradation. By considering the existing limitations, this work proposes a new approach consists of proactive and reactive network failure mitigation techniques that have been named as a hybrid approach. In the proposed architecture, the SDN controllers are distributed where each one controls its local domain nodes. The controller node continuously monitors the network state information and proactively adjusts the near-future changes to the topology. Each local domain also contains a sink node that directly connects to the controller. The sink node is used to forward the network state information to the controller and keep the controller defined flow rules for local domain nodes. The sink node can also request a new path in case of any link failure or any topology updates cause by nodes’ movement. Besides, a distributed routing protocol also runs on domain nodes to establish connectivity toward the sink node.
Adaptive Backstepping Based Sensor and Actuator Fault Tolerant Control of a Manipulator
Zainab Shahid Awan,Khurram Ali,Jamshed Iqbal,Adeel Mehmood 대한전기학회 2019 Journal of Electrical Engineering & Technology Vol.14 No.6
The purpose of this research is to propose and design fault tolerant control (FTC) scheme for a robotic manipulator, to increase its reliability and performance in the presence of actuator and sensor faults. To achieve the said objectives, a hybrid control law relying on observer and hardware redundancy-based technique has been formulated in this paper. Non-linear observers are designed to estimate the unknown states. The comparison of actual states and observed states lead to fault identifcation, this is followed by fault tolerance accomplished with redundant sensors. For actuator fault tolerance, fault estimation and controller reconfguration techniques are applied in addition to nominal control law. Fault estimation is based on adaptive back-stepping technique and it is further used to construct actuator fault tolerant control. The proposed method is applied to a six degree of freedom (DOF) robotic manipulator model and the efectiveness of this technique is verifed by LabVIEW simulations. Simulation results witnessed the improved tracking performance in the presence of actuator and sensor failures