Fractional Order Controller Design for A Flexible Link Manipulator Robot

Fixed wing Unmanned Aerial Vehicles (FWUAVs) are widely utilized in both military and civilian sectors due to their ability to perform risky, inaccessible operations. The mathematical model of FWUAVs is complex, incorporating physical laws and coordinate systems with transformation matrices. In addition, controlling FWUAVs is challenging due to their nonlinear and coupled dynamics. This paper focuses on tracking trajectories for fixed wing unmanned aerial vehicles (FWUAVs) using a Robust Fractional Order Sliding Mode Controller (RFOSMC). An RFOSMC, which combines a conventional Sliding Mode Controller (SMC) with flexible fractional calculus, is proposed in this paper. Particle Swarm Optimization (PSO) is used to tune the control gains of RFOSMC. External disturbances and parameter variation are added to evaluate the controller’s performance. Comparative studies have been done with Linear Quadratic Regulator (LQR), Fractional Order PID (FOPID), SMC, and robust FOSMC. RFOSMC performs better than LQR, FOPID, and SMC in tracking accuracy, response speed, and overshoot. In addition, the performance comparison of RFOSMC and conventional SMC has been done based on performance index values of errors (ITAE), and RFOSMC showed a 76.5918% improvement. For a step input, RFOSMC showed the smallest settling time of 0.835s compared with 2.724s for SMC and 4.8573s for FOPID. Open-loop model verification and overall control system of FWUAV are done using MATLAB/Simulink software.

Fractional order sliding mode control is studied in this paper. The control objectives are achieved by adopting the reaching law approach of sliding mode control. The main contribution of this work is to show that the philosophy of integer order sliding mode control is valid also for the systems represented by fractional order operators. A sufficient condition and its implications for stability are given. Matched and unmatched uncertainties are studied. The attractor nature of the switching manifold is analyzed together with a stable sliding subspace design condition. The claims are justified through a set of simulations and the results obtained are found promising.

In this paper, an industrial grade adaptive control scheme is proposed for a micro-grid integrated dual active bridge driven battery management system (DIBMS). A benchmark industrial grade adaptive control scheme depends on two factors namely robustness and computational resource utilization when such controllers are implemented over processors. The mathematical model of DIBMS system is nonlinear, thus for desired response, non-linear controllers based on sliding mode variable structure control theory suits it well for the state regulation problem of DIBMS, however such controllers utilize high computational resources when practically implemented over processors. Keeping in view the above performance indices, this paper proposes an industrial grade computationally efficient and finite time adaptive robust convergent control for DIBMS system. A proportional integral (PI) scheme is used as central control unit and Hebbian algorithm with double integration of the state error is introduced for online tuning the gains of central control unit. The robustness and computational resource efficiency of the proposed control paradigm is validated using a laboratory scale test bench through TI Launchpad (TMS320F28379D). The superiority of the proposed AI based PI control paradigm is compared with classical PI, integer order sliding mode control (SMC), and fractional order SMC (FOSMC) in terms of computational resource utilization and robustness under all test conditions.

Fractional order neural sliding mode control based on the FO-Hammerstein model of piezoelectric actuator

Fractional order sliding mode control of a pneumatic position servo system

Adaptive fractional order sliding mode controller with neural estimator

This work suggests an optimized improved power rate sliding mode control (PRSMC) to control a 4-degrees of freedom (DOF) manipulator in joint space as well as workspace. The proposed sliding mode control (SMC) aims to improve the reaching mode and to employ an optimization method to tune the control parameters that operate the robotic manipulator adaptively. Inverse kinematics is used to obtain the joint desired angles from the end effector desired position, while forward kinematics is used to obtain the real Cartesian position and orientation of the end effector from the real joint angles. The proposed enhancements to the SMC involve the use of the hyperbolic tangent function in the control law to improve the reaching mode. Added to that, particle swarm optimization (PSO) is used to tune the parameters of the improved SMC. Furthermore, the Lyapunov function is utilized to analyze the stability of the closed-loop system. The proposed enhanced sliding mode combined with the optimization method is applied experimentally on a 4-DOF manipulator to prove the feasibility and efficiency of the proposed controller. Finally, the performance of the suggested control scheme is compared with the conventional power rate SMC in order to demonstrate the enhanced performance of the suggested method.

In this paper, a hybrid system that combines the advantages in terms of robustness of the fractional control and the Sliding Mode Control (SMC) will be proposed. The proposed fractional order SMC is applied to a level control in a nonlinear coupled tank, as a case study. To investigate the capability of the method, a Sliding Mode Controller is alternatively designed. Primarily a sliding surface based on linear compensation networks PD or PID is designed. The work is followed by designation of a fractional form of these networks, PDμ or PIλDμ. Finally, the performance of the proposed technique is also investigated under disturbance and variation in parameters of system. The simulation results indicate the significance of the fractional order sliding mode controllers.

The main goal of vehicle active suspension system is to upgrade the ride quality and stability of heavy duty vehicle (HDV) regardless of road surface. The mathematical modelling of HDV with two degrees of freedom is developed and simulated in MATLAB/Simulink environment. The simple and effective control techniques such as proportional integral and derivative (PID) controller, sliding mode controller (SMC) and fractional order sliding mode controller (FOSMC) are designed to detach the vibration from the passenger under step, sinusoidal and random road profile. Literature reveals that the FOSMC can eliminate steady state error and chattering effect unlike SMC and PID. The dynamic analysis of designed controllers is examined in terms of time domain, frequency domain and ride comfort analysis as per ISO 2631. The stability of SMC and FOSMC is confirmed by Lyapunouv stability for three different road profiles. The FOSMC shows satisfactory simulation results than SMC, PID and passive suspension system in reducing suspension deflection and body acceleration of HDV to upgrade the ride quality. Further, the efficacy of proposed FOSMC is proved by comparing the simulation results against existing results of PID controller.

In this paper, the vehicle's dynamical behaviour is first described through a bifurcation analysis to give some insights for its robust control synthesis. Then a novel adaptive fractional-order sliding mode controller (AFOSMC) is designed to effectively control the uncertain supercavitating vehicle against payload changes, nonlinear planing force and external disturbances. The control scheme utilises the fractional calculus and the adaptive law for the sliding mode control (SMC) to provide active control actions. The fractional calculus can guarantee more flexibility and more freedom for tuning active control synthesis than the integer-order counterpart. The adaptation law has been presented to directly handle the payload change effects. The dynamic performance of the proposed controller is verified through extensive simulation results, which demonstrate faster responses than existing integer order controllers. Furthermore, the fractional order controller shows its effectiveness in dealing with external disturbance, when eliminating most of the uncertainty effect.

<p>This paper presents a new approach of fractional order sliding mode <br />controllers (FOSMC) for a class of nonlinear systems which have a single input and two outputs (SITO). Firstly, two fractional order sliding surfaces S1 and S2 were proposed with an intermediate variable z transferred from S2 to S1 in order to hierarchy the two sliding surfaces. Secondly, a control law was determined in order to control the two outputs. A sliding control stability condition was obtained by using the properties of the fractional order calculus. Finally, the effectiveness and robustness of the proposed approach were demonstrated by comparing its performance with the one of the conventional sliding mode controller (SMC), which is based on integer order derivatives. Simulation results were provided for the cases of controlling a ball-beam and inverted pendulum systems.</p>

Fractional Order Sliding Mode Controller (FOSMC) is a hybrid one and has been integrated to escalate low voltage ride through (LVRT) during faults in a modular multilevel converter (MMC) based doubly fed induction generator (DFIG) connected wind energy conversion system (WECS). Voltage sag at grid directly affects stator of DFIG, due to its immediate connection. The machine’s rotor is joined to power electronic converters i.e. a rectifier (MSC) and an inverter (GSC) via a DC link. A Fractional Order Sliding Mode controller is used at Grid Side Converter to mitigate fault current and ameliorate parameters at stator, rotor terminals. This paper infers that proposed Fractional Order Super Twisting Algorithm (FOSTA) deployed Sliding Mode Controller (FOSMC) is the exceptional in dealing with symmetrical and asymmetrical faults by refining power quality parameters, LVRT problem. The fault ride capability with FOSMC is good compared to FOPI and SMC controllers.

In this paper, a robust Fractional order sliding mode controller (FOSMC) is proposed for the speed control of a permanent magnet synchronous motor (PMSM). The sliding mode controller (SMC), which is insensitive to uncertainties, is studied widely in the application of PMSM drive. Furthermore, it is remarkable to see the increasing number of studies related to the theory and application of fractional order controller (FOC), especially PIλDμ controller, in many areas of science and engineering. Research activities are focused on developing new analysis and design methods for fractional order controllers as an extension of classical control theory. In this study, with the exponent reaching law, a fractional order sliding surface is introduced and a FOSMC is designed and applied to a speed control of PMSM, which is typical nonlinear multivariable coupled system. The performance and robustness of the proposed method are tested for nonlinear load torque disturbance, and simulation results show the effectiveness of the proposed algorithm.

Fractional order sliding mode control has been applied for speed control of PMSM. However, in many previous works, the effects of the controller's parameters have not been studied. This paper investigates the effects of fractional order on performance of FOSMC speed control of PMSM. In this work, fractional order, α and β of FOSMS-PID were varied, and their performances were compared. The simulation and experimental results show that variation of order of fractional order integration, α and order of fractional order differentiation, β can affect the performance of the FOSMC-PID controller. Selection of α and β values determines balancing strategies between integral and differentiation portion of the controller. Proper value selection and combination of these variables can further contribute to obtain optimum speed tracking, disturbance rejection and chattering reduction abilities.

In this paper, designing of Fractional Order Sliding Mode Controller (FOSMC) for Twin Rotor MIMO System (TRMS) is done. The sliding surface in fractional order for TRMS is formulated, and control input of TRMS is derived by decoupling the system, i.e., neglecting the inter dependency between both (horizontal and vertical) planes. The stability and the convergence of the decoupled control input in finite time is verified through Lyapunov’s criteria for stability. The parameters like angle error, sliding surface, control law for horizontal plane and the vertical plane are separately matched with the Sliding Mode Control (SMC) in MATLAB/Simulation. Overall controlled trajectory after combining trajectory of vertical plane and horizontal plane respectively is obtained, and the chattering effect due to SMC is dampened out to considerable rate.