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Showing papers in "IEEE Transactions on Control Systems and Technology in 2009"


Journal ArticleDOI
TL;DR: The proposed algorithm was at the core of the planning and control software for Team MIT's entry for the 2007 DARPA Urban Challenge, where the vehicle demonstrated the ability to complete a 60 mile simulated military supply mission, while safely interacting with other autonomous and human driven vehicles.
Abstract: This paper describes a real-time motion planning algorithm, based on the rapidly-exploring random tree (RRT) approach, applicable to autonomous vehicles operating in an urban environment. Extensions to the standard RRT are predominantly motivated by: 1) the need to generate dynamically feasible plans in real-time; 2) safety requirements; 3) the constraints dictated by the uncertain operating (urban) environment. The primary novelty is in the use of closed-loop prediction in the framework of RRT. The proposed algorithm was at the core of the planning and control software for Team MIT's entry for the 2007 DARPA Urban Challenge, where the vehicle demonstrated the ability to complete a 60 mile simulated military supply mission, while safely interacting with other autonomous and human driven vehicles.

802 citations


Journal ArticleDOI
TL;DR: Simulation and experimental results demonstrate that the proposed control method not only drives the drive axis to vibrate along the desired trajectory but also compensates for manufacture imperfections in a robust fashion that is insensitive to parameter variations and noises.
Abstract: A new control method is presented to drive the drive axis of a Micro-Electro-Mechanical Systems (MEMS) gyroscope to resonance and to regulate the output amplitude of the axis to a fixed level. It is based on a unique active disturbance rejection control (ADRC) strategy, which actively estimates and compensates for internal dynamic changes of the drive axis and external disturbances in real time. The stability analysis shows that both the estimation error and the tracking error of the drive axis output are bounded and that the upper bounds of the errors monotonously decrease with the increase of the controller bandwidth. The control system is simulated and tested using a field-programmable-gate-array-based digital implementation on a piezoelectric vibrational gyroscope. Both simulation and experimental results demonstrate that the proposed controller not only drives the drive axis to vibrate along the desired trajectory but also compensates for manufacture imperfections in a robust fashion that makes the performance of the gyroscope insensitive to parameter variations and noises. Such robustness, the fact that the control design does not require an accurate plant model, and the ease of implementation make the proposed solution practical and economic for industrial applications.

311 citations


Journal ArticleDOI
TL;DR: A real-time algorithm for estimation of slip angle using inexpensive sensors normally available for yaw stability control applications that compensates for the presence of road bank angle and variations in tire-road characteristics is developed.
Abstract: Real-time knowledge of the slip angle in a vehicle is useful in many active vehicle safety applications, including yaw stability control, rollover prevention, and lane departure avoidance. Sensors to measure slip angle, including two-antenna GPS systems and optical sensors, are too expensive for ordinary automotive applications. This paper develops a real-time algorithm for estimation of slip angle using inexpensive sensors normally available for yaw stability control applications. The algorithm utilizes a combination of model-based estimation and kinematics-based estimation. Compared with previously published results on slip angle estimation, this present paper compensates for the presence of road bank angle and variations in tire-road characteristics. The developed algorithm is evaluated through experimental tests on a Volvo XC90 sport utility vehicle. Detailed experimental results show that the developed system can reliably estimate slip angle for a variety of test maneuvers.

292 citations


Journal ArticleDOI
TL;DR: Comparison with several other vehicle control system approaches shows how the system operational envelope for CRVDC is significantly expanded in terms of vehicle global trajectory and planar motion responses.
Abstract: A coordinated reconfigurable vehicle dynamics control (CRVDC) system is achieved by high-level control of generalized forces/moment, distributed to the slip and slip angle of each tire by an innovative control allocation (CA) scheme. Utilizing control of individual tire slip and slip angles helps resolve the inherent tire force nonlinear constraints that otherwise may make the system more complex and computationally expensive. This in turn enables a real-time adaptable, computationally efficient accelerated fixed-point (AFP) method to improve the CA convergence rate when actuation saturates. Evaluation of the overall system is accomplished by simulation testing with a full-vehicle CarSim model under various adverse driving conditions, including scenarios where vehicle actuator failures occur. Comparison with several other vehicle control system approaches shows how the system operational envelope for CRVDC is significantly expanded in terms of vehicle global trajectory and planar motion responses.

262 citations


Journal ArticleDOI
TL;DR: This brief proposes an adaptive neural sliding mode control method for trajectory tracking of nonholonomic wheeled mobile robots with model uncertainties and external disturbances and derives online tuning algorithms for all weights of SRWNNs and proves that all signals of a closed-loop system are uniformly ultimately bounded.
Abstract: This brief proposes an adaptive neural sliding mode control method for trajectory tracking of nonholonomic wheeled mobile robots with model uncertainties and external disturbances. The dynamic model with model uncertainties and the kinematic model represented by polar coordinates are considered to design a robust control system. Self recurrent wavelet neural networks (SRWNNs) are used for approximating arbitrary model uncertainties and external disturbances in dynamics of the mobile robot. From the Lyapunov stability theory, we derive online tuning algorithms for all weights of SRWNNs and prove that all signals of a closed-loop system are uniformly ultimately bounded. Finally, we perform computer simulations to demonstrate the robustness and performance of the proposed control system.

257 citations


Journal ArticleDOI
TL;DR: This paper investigates the tracking control of an electrically driven nonholonomic mobile robot with model uncertainties in the robot kinematics, the robot dynamics, and the wheel actuator dynamics with a robust adaptive controller proposed with the utilization of adaptive control, backstepping and fuzzy logic techniques.
Abstract: This paper investigates the tracking control of an electrically driven nonholonomic mobile robot with model uncertainties in the robot kinematics, the robot dynamics, and the wheel actuator dynamics. A robust adaptive controller is proposed with the utilization of adaptive control, backstepping and fuzzy logic techniques. The proposed control scheme employs the adaptive control approach to design an auxiliary wheel velocity controller to make the tracking error as small as possible in consideration of uncertainties in the kinematics of the robot, and makes use of the fuzzy logic systems to learn the behaviors of the unknown dynamics of the robot and the wheel actuators. The approximation errors and external disturbances can be efficiently counteracted by employing smooth robust compensators. A major advantage of the proposed method is that previous knowledge of the robot kinematics and the dynamics of the robot and wheel actuators is no longer necessary. This is because the controller learns both the robot kinematics and the robot and wheel actuator dynamics online. Most importantly, all signals in the closed-loop system can be guaranteed to be uniformly ultimately bounded. For the dynamic uncertainties of robot and actuator, the assumption of ldquolinearity in the unknown parametersrdquo and tedious analysis of determining the ldquoregression matricesrdquo in the standard adaptive robust controllers are no longer necessary. The performance of the proposed approach is demonstrated through a simulation example.

208 citations


Journal ArticleDOI
TL;DR: A tracking controller is presented to stabilize the attitude of a micro satellite via integrator backstepping and quaternion feedback and is shown to render the equilibrium points in the closed-loop system uniformly asymptotically stable.
Abstract: In this brief, a tracking controller is presented to stabilize the attitude of a micro satellite via integrator backstepping and quaternion feedback. The controller is shown to render the equilibrium points in the closed-loop system uniformly asymptotically stable. Simulations are performed using satellite parameters from the ESEO mission under the European Space Agency's SSETI project.

208 citations


Journal ArticleDOI
TL;DR: Based on the relative motion dynamic model illustrated by C-W equations, the problem of robust Hinfin control for a class of spacecraft rendezvous systems is investigated, which contains parametric uncertainties, external disturbances and input constraints.
Abstract: Based on the relative motion dynamic model illustrated by C-W equations, the problem of robust Hinfin control for a class of spacecraft rendezvous systems is investigated, which contains parametric uncertainties, external disturbances and input constraints. An Hinfin state-feedback controller is designed via a Lyapunov approach, which guarantees the closed-loop system to meet the multi-objective design requirements. The existence conditions for admissible controllers are formulated in the form of linear matrix inequalities (LMIs), and the controller design is cast into a convex optimization problem subject to LMI constraints. An illustrative example is provided to show the effectiveness of the proposed control design method.

208 citations


Journal ArticleDOI
TL;DR: A nonlinear model predictive control (NMPC) is used to design a high-level controller for a fixed-wing unmanned aerial vehicle (UAV) and the control objective is extended to track adjoined multiple line segments.
Abstract: In this paper, a nonlinear model predictive control (NMPC) is used to design a high-level controller for a fixed-wing unmanned aerial vehicle (UAV). Given the kinematic model of the UAV dynamics, which is used as a model of the UAV with low-level autopilot avionics, the control objective of the NMPC is determined to track a desired line. After the error dynamics are derived, the problem of tracking a desired line is transformed into a problem of regulating the error from the desired line. A stability analysis follows to provide the conditions that can assure the closed-loop stability of the designed high-level NMPC. Furthermore, the control objective is extended to track adjoined multiple line segments. The simulation results demonstrate that the UAV controlled by the NMPC converged rapidly with a small overshoot. The performance of the NMPC was also verified through realistic ?hardware in the loop simulation.?

199 citations


Journal ArticleDOI
TL;DR: In this paper, adaptive control is presented for a class of single-degree-of-freedom (1DOF) electrostatic microactuator systems which can be actively driven bidirectionally.
Abstract: In this paper, adaptive control is presented for a class of single-degree-of-freedom (1DOF) electrostatic microactuator systems which can be actively driven bidirectionally. The control objective is to track a reference trajectory within the air gap without knowledge of the plant parameters. Both full-state feedback and output feedback schemes are developed, the latter being motivated by practical difficulties in measuring velocity of the moving plate. For the full-state feedback scheme, the system is transformed to the parametric strict feedback form, for which adaptive backstepping is performed to achieve asymptotic output tracking. Analogously, the output feedback design involved transformation to the parametric output feedback form, followed by the use of adaptive observer backstepping to achieve asymptotic output tracking. To prevent contact between the movable and fixed electrodes, special barrier functions are employed in Lyapunov synthesis. All closed-loop signals are ensured to be bounded. Extensive simulation studies illustrate the performance of the proposed control.

188 citations


Journal ArticleDOI
TL;DR: A second-order sliding mode strategy to control the breathing subsystem of a polymer electrolyte membrane fuel cell stack for transportation applications is presented and exhibits good dynamic characteristics, being robust to uncertainties and disturbances.
Abstract: A second-order sliding mode strategy to control the breathing subsystem of a polymer electrolyte membrane fuel cell stack for transportation applications is presented. The controller is developed from a design model of the plant derived from open literature, and well suited for the design of second-order sliding mode strategies. Stability issues are solved using a super twisting algorithm. The resulting approach exhibits good dynamic characteristics, being robust to uncertainties and disturbances. Simulations results are provided, showing the feasibility of the approach.

Journal ArticleDOI
TL;DR: A new design scheme of PID controllers based on a data-driven (DD) technique is proposed for nonlinear systems that can adjust the PID parameters in an online manner even if the system has nonlinear properties and/or time-variant system parameters.
Abstract: Since most processes have nonlinearities, controller design schemes to deal with such systems are required. On the other hand, proportional-integral-derivative (PID) controllers have been widely used for process systems. Therefore, in this paper, a new design scheme of PID controllers based on a data-driven (DD) technique is proposed for nonlinear systems. According to the DD technique, a suitable set of PID parameters is automatically generated based on input/output data pairs of the controlled object stored in the database. This scheme can adjust the PID parameters in an online manner even if the system has nonlinear properties and/or time-variant system parameters. Finally, the effectiveness of the newly proposed control scheme is evaluated on some simulation examples, and a pilot-scale temperature control system.

Journal ArticleDOI
TL;DR: This paper develops a passivity-based distributed velocity input law and establishes a connection between the speed of convergence and the structure of the interconnection graph and proves attitude synchronization in the leader-follower case and in the cases of communication delay and temporary communication failures.
Abstract: This paper addresses passivity-based motion coordination of rigid bodies in the special Euclidean group SE(3) under the assumption that the agents exchange information over strongly connected graphs. In this paper, we especially focus on one of the motion coordination problems on SE(3) called attitude synchronization. We first develop a passivity-based distributed velocity input law to achieve attitude synchronization. Using the notion of algebraic connectivity, we then establish a connection between the speed of convergence and the structure of the interconnection graph. We also prove attitude synchronization in the leader-follower case and in the cases of communication delay and temporary communication failures. Finally, the performance of our developed control laws is demonstrated through both numerical simulation and experiments on a planar (2D) test bed.

Journal ArticleDOI
TL;DR: A leader-follower flocking system where few members are group leaders who have global knowledge (a desired trajectory), while majority of theMembers are group followers who can communicate with neighbors but do not have globalknowledge.
Abstract: In this paper, we investigate a leader-follower flocking system where few members are group leaders who have global knowledge (a desired trajectory), while majority of the members are group followers who can communicate with neighbors but do not have global knowledge. The followers do not even know who the leaders are in the group. The flocking group is able to track a specific trajectory led by group leaders. In this system, all group members estimate the position of flocking center by using a consensus algorithm via local communication in order to keep the flocking group connected. Based on the estimated position of flocking center, a leader-follower flocking algorithm is proposed, and its stability is proved. A group of real robots ldquowifibotsrdquo are used to test the feasibility of the algorithm. Experiments show that this leader-follower flocking system can track the desired trajectory led by group leaders.

Journal ArticleDOI
TL;DR: The experimental validation of a behavior-based technique for multirobot systems (MRSs) namely, the Null-Space-based Behavioral (NSB) control is presented and achieved by performing different experimental missions, in presence of static and dynamic obstacles.
Abstract: In this paper, the experimental validation of a behavior-based technique for multirobot systems (MRSs), namely, the Null-Space-based Behavioral (NSB) control, is presented. The NSB strategy, inherited from the singularity-robust task-priority inverse kinematics for industrial manipulators, has been recently proposed for the execution of different formation-control missions with MRSs. In this paper, focusing on the experimental details, the validation of the approach is achieved by performing different experimental missions, in presence of static and dynamic obstacles, with a team of grounded mobile robots available at the Laboratorio di Automazione Industriale of the Universita degli Studi di Cassino.

Journal ArticleDOI
TL;DR: A novel model for NCSs is proposed which can deal with network-induced delay, data packet dropout and data packet disorder in N CSs simultaneously and a receding horizon controller is also designed to implement the packet-based control approach.
Abstract: A packet-based control framework is proposed for networked control systems (NCSs). This framework takes advantage of the characteristic of the packet-based transmission in a networked control environment, which enables a sequence of control signals to be sent over the network simultaneously, thus making it possible to actively compensate for the communication constraints in NCSs. Under this control framework and a deriving delay-dependent feedback gain scheme, a novel model for NCSs is proposed which can deal with network-induced delay, data packet dropout and data packet disorder in NCSs simultaneously and a receding horizon controller is also designed to implement the packet-based control approach. This approach is then verified by a numerical example and furthermore an Internet-based test rig which illustrates the effectiveness of the proposed approach.

Journal ArticleDOI
TL;DR: A state-space mathematical model, based on a nonlinear equivalent circuit flow model, which represents the interaction of the pump with the left ventricle of the heart is presented and a feedback controller which adjusts the pump speed based on the slope of the minimum pump flow signal is discussed.
Abstract: The left ventricular assist device (LVAD) is a mechanical device that can assist an ailing heart in performing its functions. The latest generation of such devices is comprised of rotary pumps which are generally much smaller, lighter, and quieter than the conventional pulsatile pumps. The rotary pumps are controlled by varying the rotor (impeller) speed. If the patient is in a health care facility, the pump speed can be adjusted manually by a trained clinician to meet the patient's blood needs. However, an important challenge facing the increased use of these LVADs is the desire to allow the patient to return home. The development of an appropriate feedback controller for the pump speed is therefore crucial to meet this challenge. In addition to being able to adapt to changes in the patient's daily activities by automatically regulating the pump speed, the controller must also be able to prevent the occurrence of excessive pumping (known as suction) which may cause collapse of the ventricle. In this paper we will discuss some theoretical and practical issues associated with the development of such a controller. As a first step, we present and validate a state-space mathematical model, based on a nonlinear equivalent circuit flow model, which represents the interaction of the pump with the left ventricle of the heart. The associated model is a six-dimensional vector of time varying nonlinear differential equations. The time variation occurs over four consecutive intervals representing the contraction, ejection, relaxation, and filling phases of the left ventricle. The pump in the model is represented by a nonlinear differential equation which relates the pump rotational speed and the pump flow to the pressure difference across the pump. Using this model, we discuss a feedback controller which adjusts the pump speed based on the slope of the minimum pump flow signal, which is one of the model state variables that can be measured. The objective of the controller is to increase the speed until the envelope of the minimum pump flow signal reaches an extreme point and maintain it afterwards. Simulation results using the model equipped with this feedback controller are presented for two different scenarios of patient activities. Performance of the controller when measurement noise is added to the pump flow signal is also investigated.

Journal ArticleDOI
TL;DR: This paper addresses the problem of combining automatic lane-keeping and driver's steering for either obstacle avoidance or lane-change maneuvers for passing purposes or any other desired maneuvers, through a closed-loop control strategy.
Abstract: In this paper, we address the problem of combining automatic lane-keeping and driver's steering for either obstacle avoidance or lane-change maneuvers for passing purposes or any other desired maneuvers, through a closed-loop control strategy. The automatic lane-keeping control loop is never opened, and no on/off switching strategy is used. During the driver's maneuver, the vehicle lateral dynamics are controlled by the driver himself through the vehicle steering system. When there is no driver's steering action, the vehicle center of gravity tracks the center of the traveling lane thanks to the automatic lane-keeping system. At the beginning (end) of the maneuver, the lane-keeping task is released (resumed) safely and smoothly. The performance of the proposed closed-loop structure is shown both by means of simulations and through experimental results obtained along Italian highways.

Journal ArticleDOI
TL;DR: A simple but innovative algorithm is proposed that is capable of providing quasi-optimal performance using a single accelerometer and pays a small price in terms of performance with respect to the mix SH-ADD algorithm, while guaranteeing cost reduction and augmented reliability.
Abstract: The topic of this brief is the design and analysis of a control strategy for semi-active suspensions in road vehicles. Currently used closed-loop control strategies (like the Sky-Hook damping) require two sensors for each suspension. Typically, two accelerometers or an accelerometer combined with a stroke sensor are used. In this brief, a simple but innovative algorithm is proposed that is capable of providing quasi-optimal performance using a single accelerometer. The starting point of this work is the Mix-SH-ADD control algorithm, which has been recently developed and proposed. Starting from that idea, the single-sensor algorithm is derived. This algorithm pays a small price in terms of performance with respect to the mix SH-ADD algorithm, while guaranteeing cost reduction and augmented reliability.

Journal ArticleDOI
TL;DR: The proposed path generation algorithm allows us to find a path satisfying arbitrary initial and final conditions, specified in terms of position and velocity, and guarantees that the tracking error, both in position and in attitude, asymptotically tends to zero.
Abstract: In this brief, we consider the problem of 3-D path generation and tracking for unmanned air vehicles (UAVs). The proposed path generation algorithm allows us to find a path satisfying arbitrary initial and final conditions, specified in terms of position and velocity. Our method assumes that aircraft structural and dynamic limitations can be translated in a turn radius constraint; therefore, the generated paths satisfy a constraint on the minimum admissible turning radius. The proposed algorithm for the path tracking guarantees, under specified assumptions, that the tracking error, both in position and in attitude, asymptotically tends to zero. The work has been carried out with reference to the UAV of the Italian Aerospace Research Center (CIRA). Simulation results for both the path generation and the tracking algorithms are presented; the latter have been obtained using a detailed 6-degree-of-freedom model of the CIRA UAV in the presence of wind and turbulence.

Journal ArticleDOI
TL;DR: This paper shows the effective use of feedforward dynamic inversion, coupled with reference trajectory yd generation, to achieve high performance settle time in single-track hard disk drive (HDD) seek performance, and concludes that the zero-order Taylor series stable NMP approximation matches the best performance of the exact inversion techniques in this application.
Abstract: Single-track hard disk drive (HDD) seek performance is measured by settle time, ts. In this paper, we show the effective use of feedforward dynamic inversion, coupled with reference trajectory yd generation, to achieve high performance ts. Models of HDD dynamics are typically nonminimum phase (NMP), and it is well known that the exact tracking solution for NMP systems requires noncausal preactuation to maintain bounded internal signals. In the specific HDD operating modes of interest, anticipation of a seek command is unrealistic, and thus preactuation adds to the overall computation of settle time. Unlike many dynamic inversion tracking applications, this negative effect of preactuation leads to interesting trade-offs between preactuation delay, yd tracking accuracy, and achievable settle performance. We investigate multiple single-input single-output (SISO) inversion architectures, and we show that the feedforward closed-loop inverse (FFCLI) achieves superior settle performance to the feedforward plant inverse (FFPI) in our application because FFCLI does not excite the closed-loop dynamics. Using the FFCLI architecture, we further investigate numerous NMP inversion algorithms, including both exact inversion schemes with initial condition preloading and stable approximate NMP inverse techniques. We conclude that the settle performance of the zero-order Taylor series stable NMP approximation matches the best performance of the exact inversion techniques in our application, and does so without the high frequency excitation required by the zero magnitude error tracking controller (ZMETC), or the excessive preactuation required by the zero phase error tracking controller (ZPETC). Minimum energy optimal trajectory generation methods show that the system order n is a limiting factor in settle performance. This confirms that the zero-order series method, which is capable of producing settle times in less than n samples, is on par with optimal approaches yet much simpler to implement. Multiple NMP inversion algorithms are experimentally validated on a servo track writer (STW), which reinforces the general trends observed in ideal simulations.

Journal ArticleDOI
TL;DR: This brief addresses the optimal-stabilization problem for networked control systems (NCSs) with time delays and packet losses, and a controller design method with both system stability and control performance taken into account is proposed.
Abstract: This brief addresses the optimal-stabilization problem for networked control systems (NCSs) with time delays and packet losses. The closed-loop NCS is modeled as a discrete-time switched system, and the stability conditions are derived in terms of linear matrix inequality. A controller design method with both system stability and control performance taken into account is proposed, and estimation of distribution algorithm is used to select the optimal stabilizing gain. The proposed method can be easily implemented to various applications, since it has simple structure and has no assumptions on time-delay and packet-loss models. Simulation and experimental results are given to demonstrate the effectiveness of the proposed approach.

Journal ArticleDOI
TL;DR: A one degree of freedom piezoelectric cantilever is studied where the hysteresis curve is approximated by a quadrilateral and the creep is considered to be a disturbance, making it possible to achieve the performances required in micromanipulation tasks.
Abstract: Piezocantilevers are commonly used for the actuation of micromechatronic systems. These systems are generally used to perform micromanipulation tasks which require high positioning accuracy. However, the nonlinearities, i.e., the hysteresis and the creep, of piezoelectric materials and the influence of the environment (vibrations, temperature change, etc.) create difficulties for such a performance to be achieved. Various models have been used to take into account the nonlinearities but they are often complex. In this paper, we study a one degree of freedom piezoelectric cantilever. For that, we propose a simple new model where the hysteresis curve is approximated by a quadrilateral and the creep is considered to be a disturbance. To facilitate the modelling, we first demonstrate that the dynamic hysteresis of the piezocantilever is equivalent to a static hysteresis, i.e., a varying gain, in series with a linear dynamic part. The obtained model is used to synthesize a linear robust controller, making it possible to achieve the performances required in micromanipulation tasks. The experimental results show the relevance of the combination of the developed model and the synthesized robust H infin controller.

Journal ArticleDOI
TL;DR: It is demonstrated how ES can be used for the determination of an optimal combustion-timing setpoint on an experimental HCCI engine and the use of ES has the benefit of achieving both optimal setpoint (for maximizing the engine efficiency) and controller-parameter tuning tasks quickly.
Abstract: Homogenous-charge-compression-ignition (HCCI) engines have the benefit of high efficiency with low emissions of NOx and particulates. These benefits are due to the autoignition process of the dilute mixture of fuel and air during compression. However, because there is no direct-ignition trigger, control of ignition is inherently more difficult than in standard internal combustion engines. This difficulty necessitates that a feedback controller be used to keep the engine at a desired (efficient) setpoint in the face of disturbances. Because of the nonlinear autoignition process, the sensitivity of ignition changes with the operating point. Thus, gain scheduling is required to cover the entire operating range of the engine. Controller tuning can therefore be a time-intensive process. With the goal of reducing the time to tune the controller, we use extremum seeking (ES) to tune the parameters of various forms of combustion-timing controllers. In addition, in this paper, we demonstrate how ES can be used for the determination of an optimal combustion-timing setpoint on an experimental HCCI engine. The use of ES has the benefit of achieving both optimal setpoint (for maximizing the engine efficiency) and controller-parameter tuning tasks quickly.

Journal ArticleDOI
Dongkyoung Chwa1
TL;DR: A nonlinear tracking control method of 3-D overhead crane systems which works well even in the presence of the initial swing angle and the variation of payload weight, based on the feedback linearizing control by using the swing angular rate as well as the swing angle.
Abstract: In this brief, we propose a nonlinear tracking control method of 3-D overhead crane systems which works well even in the presence of the initial swing angle and the variation of payload weight. Besides the practical importance of the overhead cranes, this study is also theoretically interesting because four variables (trolley and girder positions, two swing angles) should be controlled using two control inputs (trolley and girder forces). To control such an underactuated system as cranes, a simple proportional-derivative (PD) controller has been normally used. Unlike the conventional regulation control, the newly proposed nonlinear tracking control law further improves the performance and robustness, which is based on the feedback linearizing control by using the swing angular rate as well as the swing angle. The proposed nonlinear tracking control law eliminates the nonlinear characteristics of the system and achieves the satisfactory position control and swing suppression, even when the initial swing angle and the variation of payload weight exist. We present the stability analysis and simulation results to demonstrate the practical application of our scheme.

Journal ArticleDOI
TL;DR: This paper presents the control of an electropneumatic system used for moving steering mechanism that needs a high-precision position control and high bandwidth and designs two kinds of controllers: a linear one based on gain scheduling feedback, and two high order sliding mode controllers ensuring finite-time convergence, high accuracy and robustness.
Abstract: This paper presents the control of an electropneumatic system used for moving steering mechanism. This aeronautic application needs a high-precision position control and high bandwidth. The structure of the experimental setup and the benchmark on which controllers are evaluated have been designed in order to precisely check the use of such actuator in aeronautics. Two kinds of controllers are designed: a linear one based on gain scheduling feedback, and two high order sliding mode controllers ensuring finite-time convergence, high accuracy and robustness. Experimental results display feasibility and high performance of each controller and a comparison study is done.

Journal ArticleDOI
TL;DR: A flatness-based tracking control for the VSC is proposed where the nonlinear model is directly compensated without a linear approximation, which leads to straightforward open-loop control design.
Abstract: In this brief, we consider reactive power and DC voltage tracking control of a three-phase voltage source converter (VSC). This control problem is important in many power system applications including power factor correction for a distribution static synchronous compensator (D-STATCOM). Traditional approaches to this problem are often based on a linearized model of the VSC and proportional-integral (PI) feedback. In order to improve performance, a flatness-based tracking control for the VSC is proposed where the nonlinear model is directly compensated without a linear approximation. Flatness leads to straightforward open-loop control design. A full experimental validation is given as well as a comparison with the industry-standard decoupled vector control. Robustness of the flatness-based control is investigated and setpoint regulation for unbalanced three-phase voltage is considered.

Journal ArticleDOI
TL;DR: The problem of friction identification within the presliding and sliding regimes is addressed and three identification methods, designated as the LuGre method, the nonlinear regression (NLR) method, and dynamic non linear regression with direct application of the excitation (DNLRX) method are postulated.
Abstract: The problem of friction identification within the presliding and sliding regimes is addressed and three identification methods, designated as the LuGre (LG) method, the nonlinear regression (NLR) method, and dynamic nonlinear regression with direct application of the excitation (DNLRX) method, are postulated. The first employs the LG model structure, the second the basic Maxwell slip model structure, and the third an extended version of it. The Maxwell Slip model structure accounts for the presliding hysteresis with nonlocal memory, but is confined to providing constant sliding friction. This limitation is circumvented by the postulated extended version. In all methods identification is based upon signals obtained from a single experiment. The methods are successfully assessed via Monte Carlo experiments, as well as via a laboratory setup. The DNLRX is shown to achieve the best overall performance, followed by the NLR and LG methods. A simple DNLRX-based feedforward friction compensation scheme is also postulated and assessed. The results indicate that it is capable of yielding effective friction compensation.

Journal ArticleDOI
TL;DR: The proposed MPC architecture is implemented by means of a hardware description language and then prototyped and emulated on a field-programmable gate array and yields a small-in-size and energy-efficient implementation that is capable of solving the aforementioned problems on the order of milliseconds.
Abstract: This paper presents a hardware architecture for embedded real-time model predictive control (MPC). The computational cost of an MPC problem, which relies on the solution of an optimization problem at every time step, is dominated by operations on real matrices. In order to design an efficient and low-cost application-specific processor, we analyze the computational cost of MPC, and we propose a limited-resource host processor to be connected with an application-specific matrix coprocessor. The coprocessor uses a 16-b logarithmic number system arithmetic unit, which is designed using cotransformation, to carry out the required arithmetic operations. The proposed architecture is implemented by means of a hardware description language and then prototyped and emulated on a field-programmable gate array. Results on computation time and architecture area are presented and analyzed, and the functionality of the proposed architecture is verified using two case studies: a linear problem of a rotating antenna and a nonlinear glucose-regulation problem. The proposed MPC architecture yields a small-in-size and energy-efficient implementation that is capable of solving the aforementioned problems on the order of milliseconds, and we compare its performance and area requirements with other MPC designs that have appeared in the literature.

Journal ArticleDOI
TL;DR: In this work, two globally stabilizing bounded control schemes for the tracking control of robot manipulators with saturating inputs are proposed, seen as extensions of the so-called PD+ algorithm to the bounded input case.
Abstract: In this work, two globally stabilizing bounded control schemes for the tracking control of robot manipulators with saturating inputs are proposed. They may be seen as extensions of the so-called PD+ algorithm to the bounded input case. With respect to previous works on the topic, the proposed approaches give a global solution to the problem through static feedback. Moreover, they are not defined using a specific sigmoidal function, but any one on a set of saturation functions. Consequently, each of the proposed schemes actually constitutes a family of globally stabilizing bounded controllers. Furthermore, the bound of such saturation functions is explicitly considered in their definition. Hence, the control gains are not tied to satisfy any saturation-avoidance inequality and may consequently take any positive value, which may be considered beneficial for performance-adjustment/improvement purposes. Further, a class of desired trajectories that may be globally tracked avoiding input saturation is completely characterized. For both proposed control laws, global uniform asymptotic stabilization of the closed-loop system solutions towards the prespecified desired trajectory is proved through a strict Lyapunov function. The efficiency of the proposed schemes is corroborated through experimental results.