Abstract: This paper proposes an envelope control framework for four-wheel independently actuated autonomous ground vehicle (AGV) to regulate it on desired path and simultaneously control it to the driving limits. The envelope control framework is achieved based on the integrated control of active front-wheel steer and direct yaw-moment control. In a speed controller, the G-G diagram is used to describe the driving limits on each path segment. The desired traction and braking force is calculated according to the G-G diagram and desired path. In a path-following controller, a feedforward–feedback lateral controller is designed to calculate the desired steering angle to follow the desired path. In a yaw-moment controller, the β–r phase portraits are utilized to describe the handling limits. The yaw-moment controller aims at keeping the AGV from losing stability in limit driving, which is calculated through a sliding mode controller and provided by the independent motors actuation. Through an independent driving technique, the tyre cornering stiffness is estimated online based on the predefined Magic Formula model to improve the controller's robustness. An autonomous Formula Student racecar developed by the authors is used as testbed. The autonomous driving experiments on racetrack validate the efficiency of the proposed controller.

Abstract: Internal model control (IMC) with optimal H2 minimization framework is proposed in this paper for design of proportional-integral-derivative (PID) controllers. The controller design is addressed for integrating and double integrating time delay processes with right half plane (RHP) zeros. Blaschke product is used to derive the optimal controller. There is a single adjustable closed loop tuning parameter for controller design. Systematic guidelines are provided for selection of this tuning parameter based on maximum sensitivity. Simulation studies have been carried out on various integrating time delay processes to show the advantages of the proposed method. The proposed controller provides enhanced closed loop performances when compared to recently reported methods in the literature. Quantitative comparative analysis has been carried out using the performance indices, Integral Absolute Error (IAE) and Total Variation (TV).

Abstract: In this paper, a novel concept of an interval type-2 fractional order fuzzy PID (IT2FO-FPID) controller, which requires fractional order integrator and fractional order differentiator, is proposed. The incorporation of Takagi-Sugeno-Kang (TSK) type interval type-2 fuzzy logic controller (IT2FLC) with fractional controller of PID-type is investigated for time response measure due to both unit step response and unit load disturbance. The resulting IT2FO-FPID controller is examined on different delayed linear and nonlinear benchmark plants followed by robustness analysis. In order to design this controller, fractional order integrator-differentiator operators are considered as design variables including input-output scaling factors. A new hybridized algorithm named as artificial bee colony-genetic algorithm (ABC-GA) is used to optimize the parameters of the controller while minimizing weighted sum of integral of time absolute error (ITAE) and integral of square of control output (ISCO). To assess the comparative performance of the IT2FO-FPID, authors compared it against existing controllers, i.e., interval type-2 fuzzy PID (IT2-FPID), type-1 fractional order fuzzy PID (T1FO-FPID), type-1 fuzzy PID (T1-FPID), and conventional PID controllers. Furthermore, to show the effectiveness of the proposed controller, the perturbed processes along with the larger dead time are tested. Moreover, the proposed controllers are also implemented on multi input multi output (MIMO), coupled, and highly complex nonlinear two-link robot manipulator system in presence of un-modeled dynamics. Finally, the simulation results explicitly indicate that the performance of the proposed IT2FO-FPID controller is superior to its conventional counterparts in most of the cases.

Abstract: Fractional order PID (FOPID) controllers are introduced as a general form of classical PID controllers using fractional calculus. As this controller provides good disturbance rejection and is robust against plant uncertainties it is appropriate for the vibration mitigation in structures. In this paper, an FOPID controller is designed to adjust the contact force of piezoelectric friction dampers for semi-active control of base-isolated structures during far-field and near-field earthquake excitations. A multi-objective cuckoo search algorithm is employed to tune the controller parameters. Considering the resulting Pareto optimal front, the best input for the FOPID controller is selected. For seven pairs of earthquakes and nine performance indices, the performance of the proposed controller is compared with those provided by several well-known control techniques. According to the simulation results, the proposed controller performs better than other controllers in terms of simultaneous reduction of the maximum base displacement and story acceleration for various types of earthquakes. Also, it provides acceptable responses in terms of inter-story drifts, root mean square of base displacements and floor acceleration. In addition, the evaluation of robustness for a stiffness uncertainty of ±10% indicates that the proposed controller gives a robust performance against such modeling errors.

Abstract: In this paper, we consider the problem of trajectory tracking of a multirotor Unmanned Aerial Vehicle carrying a suspended payload. The movement of the suspended payload influences the dynamics of the multirotor, which must be appropriately handled by the controller to achieve satisfactory tracking results. We derive a mathematical model of the interconnected multi-body system using Kane’s equations, and develop a non-linear tracking controller based on the backstepping technique. In addition to suppressing the effects of the swinging payload, the controller also compensates for an unknown constant wind disturbance. The origin of the tracking error is proven UGAS (Uniformly Globally Asymptotically Stable) and ULES (Uniformly Locally Exponentially Stable) through Lyapunov analysis. To reduce the swing motion of the suspended load, a nominal swing-free path is generated through open loop shaping filters, then further perturbed through a delayed feedback approach from measured load deflection angles to achieve robustness. The proposed controller structure is verified by simulations and experiments.

Abstract: Automatic voltage regulator (AVR) system is an important equipment in power system for maintaining the terminal voltage of the generator at a specific level. Recently, fractional order PID controller has been designed for AVR system. However, many fractional order PID controller designing methods need to calculate various performance indices in time domain and frequency domain in the process of parameter tuning, which is a tedious and complex process and satisfactory performance can not be obtained. In this paper, a new fractional order PID controller designing method is proposed AVR system based on Bodes reference model. The optimal parameters of FOPID controller is obtained through minimizing the integrated absolute error (IAE) between the output of the Bodes ideal reference model and that of the plant. Particle swarm optimization (PSO) is responsible to search the solution of the IAE criterion, i.e., the parameters of FOPID controller. Extensive simulations and comparisons show that the designed FOPID controller has more excellent performance. Meanwhile, PSO algorithm is effective for searching the optimal FOPID controller parameters.

Abstract: Recently, fractional-order proportional–integral–derivative (FOPID) controllers are demonstrated as a general form of the classical proportional–integral–derivative (PID) using fractional calculus In FOPID controller, the orders of the derivative and integral portions are not integers which offer more flexibility in succeeding control objectives This paper proposes a multi-objective genetic algorithm (MOGA) to optimize the FOPID controller gains to enhance the ride comfort of heavy vehicles The usage of magnetorheological (MR) damper in seat suspension system provides considerable benefits in this area The proposed semi-active control algorithm consists of a system controller that determines the desired damping force using a FOPID controller tuned using a MOGA, and a continuous state damper controller that calculates the input voltage to the damper coil A mathematical model of a six degrees–of–freedom seat suspension system incorporating human body model using an MR damper is derived and simulated us

Abstract: An adaptive robust controller that simultaneously rotates the tower and moves the trolley is proposed for a tower crane. The robust behavior of the controller is derived through the sliding mode technique, and its adaptive performance is obtained based on the adaptive model-reference approach. The controller operated well regardless of the significant variation of system parameters, internal noises, and external disturbances. Specifically, the controller did not require a priori knowledge of cargo mass and friction factors because an adaptation mechanism is integrated to estimate system parameters. Emulating experimental results showed that the proposed controller consistently stabilized all system responses.

Abstract: This paper presents intelligent controllers as a maximum power point tracking system for a switched reluctance generator (SRG) driven by a variable speed wind turbine to attain the maximum power. The intelligent controller systems are artificial neural network (ANN) controller and fuzzy logic (FL) controller. Both controllers manipulate the wind turbine rotational speed by changing turn-off angle of the SRG. The turn on angle is fixed. The wind plant is connected to the grid through a DC–AC inverter system and two step up power transformers. The systems are simulated in MATLAB/ Simulink environment. The results show that the ANN controller is more accurate and efficient than the FL controller.

Abstract: In this paper, DC motor speed is controlled using PID controller and fuzzy logic controller. PID controller requires a mathematical model of the system while fuzzy logic controller base on experience via rule-based knowledge. Design of fuzzy logic controller requires many design decisions, for example rule base and fuzzification. The FLC has two input, one of these inputs is the speed error and the second is the change in the speed error. There are 49 fuzzy rules which are designed for the fuzzy logic controller. The center of gravity method is used for the defuzzificztion. Fuzzy logic controller uses mamdani system which employs fuzzy sets in consequent part. PID controller chooses its parameters base on trial and error method. PID and FLC are investigated with the help of MATLAB / SIMULINK package program simulation. It is founded that FLC is more difficult in design comparing with PID controller, but it has an advance to be more suitable to satisfy non-linear characteristics of DC motor. The results shows that the fuzzy logic has minimum transient and steady state parameters, which shows that FLC is more efficiency and effectiveness than PID controller.

Abstract: When applying the permanent magnetic synchronous motors (PMSM) to refrigerant system, the suppression of speed ripples of the PMSM in low-feed range becomes the focus of consideration. The authors start with the generation mechanism and the periodical characteristics of the speed ripples to propose an adaptive control method. In the proposed method, the authors place a frequency variable resonance controller in parallel with the conditional proportion and integral (PI) controller to form a PI-resonance (PI-RES) controller. The compensation torque current generated by the resonance controller and the main reference current generated by the PI controller constitute the reference torque current. Because of the existence of the compensation torque current, the electromagnetic torque can follow the variation of the load torque much better, thus the speed ripples are suppressed. Performance indices of the conventional PI controller and the PI-RES controller are compared and evaluated through experimental investigations. The results validate the effectiveness of the proposed method.

Abstract: The increasing use of active front steering (AFS) technology for obstacle avoidance raises the question of drivers’ interaction with vehicle automation Mathematical models capable of representing such interaction are in demand for driver behavior study This paper presents the application of open-loop Stackelberg equilibrium to modeling a driver's interaction with vehicle AFS control in an obstacle avoidance scenario, where both the driver and the AFS controller are exerting steering control to the vehicle In this paper, such driver–AFS interactive steering control is modeled as a leader–follower game Mathematical expressions of the driver's and the AFS controller's steering control strategies are derived using the linear quadratic dynamic optimization approach and the distributed model predictive control (DMPC) approach These two approaches are found to give identical control gains, which suggest their equivalence in representing driver–AFS interaction The DMPC approach is found to consume far less computation time due to its numerical nature Mathematical modifications to the steering control strategies are then introduced to allow practical implementation for a future experimental study Simulation results including time histories of steering angles and vehicle responses are illustrated and discussed

Abstract: Experimental testing of an unmanned surface vehicle (USV) has been performed to evaluate the performance of two low-level controllers when displacement and drag properties are time-varying and uncertain. The USV is a 4.3 meter long, 150 kilogram wave adaptive modular vessel (WAM-V) with an inflatable twin hull configuration and waterjet propulsion. Open loop maneuvering tests were conducted to characterize the dynamics of the vehicle. The hydrodynamic coefficients of the vehicle were determined through system identification of the maneuvering data and were used for simulations during control system development. The resulting controllers were experimentally field tested on-water. Variable mass and drag tests show that the vehicle is best controlled by a model reference adaptive backstepping speed and heading controller. The backstepping controller developed by Liao et. al (2010) is modified to account for an overprediction of necessary control action and motor saturation. It is shown that when an adaptive algorithm is implemented for the surge control subsystem of the modified backstepping controller, the effects of variable mass and drag are mitigated.

Abstract: This paper presents the design, implementation, and performance testing of a nonlinear proportional-integral (PI) predictive controller for a grid-tied inverter used in photovoltaic systems. A conventional cascade structure is adopted to design the proposed controller, where the outer loop is used to regulate the dc-link voltage, and the inner loop is designed as a current controller for adjusting the active and reactive powers injected into the grid. For each loop, the controller is derived based on combining a continuous-time nonlinear model predictive control and nonlinear disturbance observer techniques. It turns out that the composite controller reduces to a nonlinear PI controller with a predictive term that plays an important role in improving tracking performance. The salient feature of the proposed approach is its ability to approximately preserve the nominal tracking performance during the startup phase. Both simulation and experimental results are provided to demonstrate the effectiveness of the proposed approach in terms of nominal performance recovery, disturbance rejection, and current control.

Abstract: In order to achieve a desired control performance characterized by satisfying specifications in both frequency-domain and time-domain simultaneously, an optimal fractional order proportional integral derivative (PIλDμ) controller design strategy is proposed based on analytical calculation and Differential Evolution algorithm for a permanent magnet synchronous motor (PMSM) servo system in this paper. In this controller design, the frequency-domain specifications can guarantee the system stability with both gain margin and phase margin, and also the system robustness to loop gain variations. The time-domain specifications can ensure the desired step response performance with rapid rising curve, constrained overshoot, and proper power consuming. Compared with the PIλ controller and the traditional PID controller, PIλDμ controller can get obvious benefits from two more degrees of freedom of the fractional orders λ and μ on satisfying multiple constraints simultaneously and achieving better servo tracking performance for the PMSM servo system. PMSM speed tracking simulations and experiments are demonstrated to show the significant advantages of using the proposed optimal PIλDμ controller over the optimal fractional order PIλ controller and traditional integer order PID controller.

Abstract: Scalar control has been the most popular control method implemented in induction machine drive systems. This paper presents an enhanced open-loop Volts-per-Hertz (V/f) controller aimed at strengthening the magnetizing flux of an induction machine when operated below its rated frequency. Instead of using the traditional constant V/f based on the idealized approximate steady-state machine model and/or simple stator voltage drop compensation, this method derives a new V/f ratio from a more accurate steady-state model which takes core loss into consideration as well as the stator voltage drop. In addition, a frequency boost strategy is introduced with the proposed V/f ratio for slip compensation. The analytically derived V/f ratio under different frequencies at rated load is then compared to experimentally obtained data to verify its effectiveness.

Abstract: A new strategy based on Takagi–Sugeno fuzzy controller is proposed in this paper for wide-area power system. In this strategy, the proposed fuzzy controller is optimized by a new hybrid metaheurist...

Abstract: Summary This study presents a feedback control strategy for the regulation of a planar vertical takeoff and landing aircraft. To this end, two controllers that work simultaneously were designed. The first controller is devoted to stabilizing the vertical variable and is based on a simple feedback-linearization procedure in combination with a saturation function. The second controller – based on a combination of the traditionally PD-controller and a sliding mode controller – stabilizes both the horizontal and angular variables to the desired rest position. The performance of the closed-loop system is demonstrated through simulation results. Copyright © 2016 John Wiley & Sons, Ltd.

Abstract: This paper focuses on the observer-based methods for induction machine sensorless drive. It is well known that the use of speed observer is limited at a very low stator frequency due to speed unobservability. Some existing methods propose to avoid the zero-stator-frequency working points. These methods are nonetheless limited to high-torque operations. The first contribution of this paper is to analyze finely the speed observability, which leads to the definition of an observability index. The correlation between this index and the observer performance is analyzed and illustrated. The second contribution is to propose a control strategy that maximizes the observability index and improves the observer performance. The proposed strategy is tested first in open loop to evaluate the speed observer performance, and then, in closed loop to illustrate its pertinence for induction machine sensorless drive. All these results are validated by an experiment. The performed experimentation shows that the proposed control strategy gives better results than the existing method that avoid the zero-frequency working points. It offers a new path for induction machine sensorless drives.