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# Accepted Manuscripts

BASIC VIEW  |  EXPANDED VIEW
research-article
J. Dyn. Sys., Meas., Control   doi: 10.1115/1.4036237
This paper investigates the problem of robust stabilization for a class of discrete-time TS fuzzy systems via input random delays in control input. The main objective of this paper is to design a state feedback H¥ controller. Linear matrix inequality approach together with the construction of proper Lyapunov-Krasovskii functional is employed for obtaining delay dependent sufficient conditions for the existence of robust H¥ controller. In particular, the effect of both variation range and distribution probability of the time delay are taken into account in the control input. The key feature of the proposed results in this paper is that the time-varying delay in the control input not only dependent on the bound but also the distribution probability of the time delay. The obtained results are formulated in terms of linear matrix inequalities (LMIs) which can be easily solved by using the standard optimization algorithms. Finally, a numerical example with simulation result is provided to illustrate the effectiveness of the obtained control law and less conservativeness of the proposed result.
TOPICS: Fuzzy logic, Delays, State feedback, Probability, Linear matrix inequalities, Control equipment, Optimization algorithms, Construction, Design, Simulation results, Takagi–Sugeno fuzzy models
research-article
J. Dyn. Sys., Meas., Control   doi: 10.1115/1.4036232
This paper describes a model-based feedback control method to transition from spark ignition (SI) to homogeneous charge compression ignition (HCCI) combustion in gasoline engines. The purpose of the control structure is to improve robustness and reduce calibration complexity by incorporating feedback of the engine variables into nonlinear model-based calculations which inherently generalize across operating points. This type of structure is sought as an alternative to prior SI-HCCI transition approaches which involve open-loop calibration of input command sequences which must be scheduled by operating condition. The control architecture is designed for cam switching type SI-HCCI mode transition strategies with practical two-stage cam profile hardware, which previously have only been investigated in a purely open-loop framework. Experimental results on a prototype engine show that the control architecture is able to carry out SI-HCCI transitions across the HCCI load range at 2000 RPM engine speed while requiring variation of only one major set point and three minor set points with operating condition. These results suggest a noteworthy improvement in controller generality and ease of calibration relative to previous SI-HCCI transition approaches.
TOPICS: Homogeneous charge compression ignition engines, Engines, Calibration, Feedback, Ignition, Robustness, Gasoline engines, Hardware, Stress, Engineering prototypes, Combustion, Control equipment
research-article
Elham Javidmanesh
J. Dyn. Sys., Meas., Control   doi: 10.1115/1.4036229
In this paper, delayed BAM neural networks, which consist of one neuron in the X-layer and other neurons in the Y-layer, will be studied. Hopf bifurcation analysis of these systems will be discussed by proposing a general method. In fact, a general n-neuron BAM neural network model is considered and the associated characteristic equation is studied by classification according to n. Here, n can be chosen arbitrarily. Moreover, we find an appropriate Lyapunov function that under a hypothesis, results in global stability. Numerical examples are also presented.
TOPICS: Stability, Artificial neural networks, Bifurcation, Neural network models
research-article
J. Dyn. Sys., Meas., Control   doi: 10.1115/1.4036228
In the framework of wave based method, we have examined swing motion control for double pendulum and load hoist models, respectively. Emphases are placed on wave scattering by the middle load mass in the double pendulum model and on time-varying configuration in the load hoist model. By analyzing wave transmission and reflection, trolley’s motion to alleviate swing is designed by absorbing reflected wave through adjusting the velocity of trolley. Simulation and experiment are also conducted to validate the proposed control method. The results show that with the designed trolley’s motion swings of load can be significantly reduced for both double pendulum model, suspended rod model which is demonstrated a special case of double pendulum model, and load hoist model. Simulation results agree well with the experimental measurement. Launch velocity profiles may have important impact on motion design, especially on force necessary to displace trolley. Finally, a wave based feedback control is also discussed to demonstrate the flexibility of method.
TOPICS: Cranes, Stress, Waves, Pendulums, Hoists, Scattering (Physics), Simulation results, Design, Feedback, Reflection, Simulation, Motion control
Technical Brief
Patricio Ordaz-Oliver
J. Dyn. Sys., Meas., Control   doi: 10.1115/1.4036227
This paper addresses to demonstrate the Uniform-Ultimately Bounded Stability (UUB-Stability) of the PD+ compensator where the joint velocity is not available to be measured but rather it is estimated. The proposed stabilization control strategy is developed for a “n” degree of freedom Robotic Manipulator process where the joint speed is not available to be measured, furthermore, the external disturbances and/or uncertain dynamics are considered in the system dynamics. To conclude the closed-loop robust stabilization, the proposed feedback strategy is based on nonlinear state estimation with a Luenberger-like observer and the classical PD+ used in robot manipulators.
TOPICS: Dynamics (Mechanics), Stability, Control equipment, System dynamics, Degrees of freedom, Feedback, Manipulators, State estimation
research-article
J. Dyn. Sys., Meas., Control   doi: 10.1115/1.4036236
The Udwadia-Kalaba methodology is a possible way of explicitly obtaining the equations of motion of constrained systems. From these equations of motion, one can estimate the necessary forces in the constraint to keep the system in a given motion. Hence, the Udwadia-Kalaba methodology can also apply to active tracking control of sub-systems or the control of points of a structure. In this work, one investigates experimentally the benefits and drawbacks of such control strategy by applying it to the control of out-of-plane vibrations of a cantilever beam. The beam is excited by a shaker mounted near the clamped-end of the beam. A second shaker applies the control forces in the free-end of the beam, where an accelerometer is used for feedback. The vibration behavior of the beam under excitation/control is measured by a laser vibrometer. Results show that, the methodology changes the dynamic behavior of the structure by changing its boundary conditions at the point of control, thus shifting natural frequencies and mode shapes. Results also show that the successful implementation of the method experimentally is sensitive to the quality of modeling of the structure.
TOPICS: Cantilever beams, Kaolin, Trajectories (Physics), Equations of motion, Vibration, Boundary-value problems, Feedback, Tracking control, Laser Doppler vibrometers, Mode shapes, Excitation, Accelerometers, Modeling
research-article
J. Dyn. Sys., Meas., Control   doi: 10.1115/1.4036233
This paper investigates the problem of decentralized model reference adaptive control (MRAC) for a class of large scale systems with time varying delays in the interconnected terms and state and input delays. The upper bounds of interconnection terms with time-varying delays and external disturbances are assumed to be completely unknown. By integrators inclusion a dynamic input delay compensator is established for input delay compensation and it is used as a practical method for state calculation x(t+R). Also, a method is presented for a class of decentralized feedback controllers, which can evolve the closed-loop system error uniformly bounded stable. As a numerical example, the proposed technique is applied to an unstable open loop system to show the feasibility and effectiveness of the method.
TOPICS: Delays, Errors, Feedback, Open loop systems, Control equipment, Adaptive control, Closed loop systems
research-article
J. Dyn. Sys., Meas., Control   doi: 10.1115/1.4036230
This paper presents a new switching anti-windup compensation design to maximize the domain of attraction for a supercavitating vehicle subject to actuator saturation. The dive-plane dynamics of the vehicle are considered. By applying the linear differential inclusion expression of saturated feedbacks, conditions under which the compensator locally stabilizes the closed-loop system are then derived. The design of anti-windup gains on maximizing the system's domain of attraction is finally formulated and solved as an iterative optimization problem with linear matrix inequality (LMI) constraints. Simulations are conducted for systems with magnitude and rate limits to evaluate the effectiveness of the proposed method.
TOPICS: Actuators, Design, Vehicles, Closed loop systems, Linear matrix inequalities, Dynamics (Mechanics), Simulation, Engineering simulation, Optimization
research-article
J. Dyn. Sys., Meas., Control   doi: 10.1115/1.4036231
A run-to-run optimization controller uses a reduced set of measurement parameters, in comparison to more general feedback controllers, to converge to the best control point for a repetitive process. A new run-to-run optimization controller is presented for the scanning fiber device used for image acquisition and display. This controller utilizes very sparse measurements to estimate a system energy measure and updates the input parameterizations iteratively within a feedforward with exact-inversion framework. Analysis, simulation and experimental investigations on the scanning fiber device demonstrate improved scan accuracy over previous methods and automatic controller adaptation to changing operating temperature. A specific application example and quantitative error analyses are provided of a scanning fiber endoscope that maintains high image quality continuously across a 20°C temperature rise without interruption of the 56 Hz video.
TOPICS: Optimization, Control equipment, Fibers, Temperature, Simulation, Endoscopes, Error analysis, Feedback, Feedforward control, Operating temperature
research-article
J. Dyn. Sys., Meas., Control   doi: 10.1115/1.4036234
In this paper, we pay attention to studying the switched model of the hydro-turbine governing system by introducing the concept of the switching of operational conditions. More specifically, utilizing the data of an existent hydropower station in China, we propose six nonlinear dynamic transfer coefficients of the hydro-turbine which can better describe the dynamic characteristics of the hydro-turbine governing system in the process of load rejection transient. Moreover, the elastic water hammer-impact of the penstock system and the nonlinearity of the generator for the process of load rejection transient are considered. Based on the combination of the different regulation modes of the governor and the corresponding running conditions of the hydroelectric generating unit, a novel nonlinear dynamic switched mathematical model of the hydro-turbine governing system is finally established. Meanwhile, the nonlinear dynamic behaviors of the governing system are exhaustively investigated using numerical simulations. These methods and analytical results will supply some theory bases for running a hydropower station.
TOPICS: Transients (Dynamics), Dynamic analysis, Stress, Hydraulic turbines, Hydroelectric power stations, Computer simulation, Water, Hydropower, Governors, Hammers, China, Generators
research-article
J. Dyn. Sys., Meas., Control   doi: 10.1115/1.4036235
This paper considers the problem of robust output regulation of nonlinear systems in semi strict-feedback form in the presence of model uncertainties and non-vanishing disturbances. In the proposed procedure, two exosystems are considered to generate the disturbance and reference signals. In order to reduce both the conservatism of the control law and also the chattering phenomena, a Disturbance Observer is designed for disturbance estimation instead of assuming the known upper bound for the disturbance. Moreover, a novel sliding surface is designed based on the tracking error to guarantee that the output of the system tracks the output of the exosystem. In this regard, some theorems are given and according to the Lyapunov approach, it is proved that the robust output regulation is guaranteed in the presence of model uncertainties and external disturbances. Finally, in order to show the applicability of the proposed controller, it is applied to the Van der Pol chaotic oscillator. Computer simulations verify the theoretical results and also show the effective performance of the proposed controller.
TOPICS: Theorems (Mathematics), Control equipment, Computer simulation, Sliding mode control, Nonlinear systems, Errors, Feedback, Signals, Uncertainty
research-article
J. Dyn. Sys., Meas., Control   doi: 10.1115/1.4036070
A method for distributed control of nonlinear flow equations is proposed. In this method, first, Takagi-Sugeno (T-S) fuzzy model is used to substitute the nonlinear partial differential equations governing the system by a set of linear partial differential equations; such that their fuzzy composition exactly recovers the original nonlinear equations. This is done to alleviate the mode-interaction phenomenon occurring in spectral treatment of nonlinear equations. Then, each of the so-obtained linear equations is converted to a set of ordinary differential equations using the fast Fourier transform (FFT) technique. Thus, the combination of T-S method and FFT technique leads to a number of ordinary differential equations for each grid point. For the stabilization of the dynamics of each grid point, the use is made of the parallel distributed compensation method. The stability of the proposed control method is proved using the second Lyapunov theorem for fuzzy systems. In order to solve the nonlinear flow equation, a combination of FFT and Runge-Kutta methodologies is implemented. Simulation studies show the performance of the proposed method, for example the smaller settling time and overshoot and also its relatively robustness with respect to the measurement noises.
TOPICS: Simulation, Navier-Stokes equations, Differential equations, Flow (Dynamics), Nonlinear equations, Partial differential equations, Robustness, Fuzzy logic, Theorems (Mathematics), Dynamics (Mechanics), Stability, Fast Fourier transforms, Noise (Sound)
research-article
J. Dyn. Sys., Meas., Control   doi: 10.1115/1.4036074
Battery energy storage systems (BESS) have been integrated with wind turbines to mitigate wind intermittence and make wind power dispatchable as traditional power sources. This paper presents a new power dispatch and control methodology that allows an integrated wind turbine and BESS to provide the grid with consistent and optimal power within a predetermined dispatch interval. First, the desired battery state of charge (SOC) under each wind speed is determined by applying an offline probabilistic algorithm to historical wind speed and power data. With this information, a one-step ahead model predictive optimization approach is explored for scheduling the integrated system power output for the next dispatch interval. Then, a real-time controller is developed to make the actual system power output match the scheduled target. A wind turbine active power controller is proposed to track the reference power set point determined by a steady state optimization approach. By combining an internal integral torque control and a gain-scheduled pitch control, the proposed active power controller can operate in a desired rotor speed region without an accurate knowledge of wind turbine operating parameters. Compared to the conventional scheduling approaches and real-time controller, implementing the new methodology significantly reduces the ramp rate, generator torque changing rate, battery charging rate and the power output deviation from the scheduled target. BESS with various capacities and different wind profiles are considered to demonstrate the effectiveness of the proposed algorithms on battery sizing.
TOPICS: Wind turbines, Batteries, Control equipment, Wind velocity, Algorithms, Optimization, Wind, Wind power, Integrated systems, Torque, Rotors, Generators, Steady state, Torque control, Energy storage
research-article
K. D. Do
J. Dyn. Sys., Meas., Control   doi: 10.1115/1.4036071
This paper first derives equations of motion of extensible and shearable slender beams with large motions under both deterministic and stochastic external loads. Boundary feedback controllers are then proposed to achieve almost surely globally practically asymptotic stability. The control design, well-posedness, and stability analysis are based on a Lyapunov-type theorem developed for a class of stochastic evolution systems in Hilbert space.
TOPICS: Stress, Stability, Control equipment, Theorems (Mathematics), Equations of motion, Design, Feedback
research-article
J. Dyn. Sys., Meas., Control   doi: 10.1115/1.4036080
The paper presents the new way of identification of complex non-linear dynamic systems. The method has been explained with the use of a dynamic structure (degenerated one) with 1.5 degrees of freedom and some non-linear restitution force. The applied method allows for the assessment of the dynamic behavior of material in a wide range of dynamic loads. The equation of energy balance when oscillations are set harmonic is applicable to the solution. It is possible when the loading force is adjustable. The method has been computer verified using a system with cubic spring characteristic.
TOPICS: Nonlinear dynamical systems, Springs, Oscillations, Energy budget (Physics), Stress, Degrees of freedom, Computers
research-article
J. Dyn. Sys., Meas., Control   doi: 10.1115/1.4036072
Vehicle steering comfort is an important issue for steering control of Advanced Driver Assistance Systems (ADAS), especially the shared steering control systems. However, it is difficult to be evaluated objectively that is usually evaluated subjectively by the driver. This paper aims to develop an objective evaluation method of vehicle steering comfort, which is mainly based on steering efficiency of driver estimated by electromyography (EMG). First, driver steering efficiency, as key factor reflecting driver's maneuver energetics and some neurological control behaviors, is calculated in two steering conditions based on EMG. In this process, the subjective evaluation of vehicle steering comfort is obtained simultaneously else by test driver. Unlike traditional steering efficiency calculated from steering gear, driver steering efficiency does not only partly present the energy consumption of driver itself but also the driver-vehicle interaction. And then the relation between the steering efficiency and subjective evaluation is analyzed based on both linear regression and spearman correlation analyzing. This challenge work investigates the interaction between the quantitative energy consumption and driver metal feeling and builds bridge between them. At last, an objective evaluation method of vehicle steering comfort using steering efficiency is proposed, which providing a selection with quantitative evaluation. The proposed method is helpful to improve steering control by giving a quantitative index.
TOPICS: Vehicles, Evaluation methods, Electromyography, Energy consumption, Nervous system, Metals, Bridges (Structures), Control systems, Energetics, Gears
Technical Brief
J. Dyn. Sys., Meas., Control   doi: 10.1115/1.4036073
Positive real constraints on the closed-loop of linear systems guarantee stable interaction with arbitrary passive environments. Two such methods of $\mathcal{H}_\infty$ optimal controller synthesis subject to a positive real constraint are presented and demonstrated on numerical examples. The first approach is based on an established multi-objective optimal control framework using linear matrix inequalities (LMIs) and is shown to be overly restrictive and ultimately infeasible. The second method employs a sector transformation to substitute the positive real constraint with an equivalent $\mathcal{H}_\infty$ constraint. In two examples this method is shown to be more reliable and displays little change in the achieved $\mathcal{H}_\infty$ norm compared to the unconstrained design, making it a promising tool for passivity based controller design.
TOPICS: Control equipment, Design, Optimal control, Linear matrix inequalities, Linear systems
research-article
J. Dyn. Sys., Meas., Control   doi: 10.1115/1.4036069
This paper deals with a new systematic multi-model controller design for nonlinear systems. The design of local controllers based on performance requirements is incorporated with the concept of local models selection as an optimization problem. Gap metric and stability margin are used as measuring tool and operation space dividing criterion, respectively. The developed method provides support to design a simple structured multi-PI controller which guarantees both robust stability and time-domain performance specifications. The main advantages of the proposed method are avoiding model redundancy, not needing a priori knowledge about system, having simple structure, and easing the implementation. To evaluate the presented multi-model controller design procedure, three benchmark nonlinear systems are studied. Both simulations and experimental results prove the effectiveness of the proposed method in set-point tracking and disturbance rejection.
TOPICS: Stability, Nonlinear systems, Design, Control equipment, Simulation, Redundancy (Engineering), Engineering simulation, Optimization
research-article
J. Dyn. Sys., Meas., Control   doi: 10.1115/1.4036083
Drillstring vibration is detrimental to drilling operations. It is crucial to understand the underlying mechanisms to circumvent these vibrations and to help improve drilling performance. This paper presents a six degree of freedom (DOF) finite element method (FEM) model to characterize the drillstring dynamics. In addition, a comprehensive bit-force model was developed and included as a boundary condition to the model, corresponding to the vibrations in axial, lateral, and torsional directions. This bit-force model considers the bottomhole assembly (BHA) eccentricity, mud damping, bit-rock interaction, and their coupling mechanisms. Simulation results have shown good agreement with field observations and experimental data in the literature. The utility of this modeling framework is demonstrated in the paper through case studies for normal operation, stick-slip vibration, and whirl vibration.
TOPICS: Finite element methods, Modeling, Vibration, Drill strings, Drilling, Boundary-value problems, Rocks, Simulation results, Stick-slip, Whirls, Degrees of freedom, Damping, Dynamics (Mechanics), Manufacturing
research-article
J. Dyn. Sys., Meas., Control   doi: 10.1115/1.4036034
This technical brief introduces a two-scale command shaping strategy for reducing vibrations in conventional and hybrid electric vehicle (HEV) powertrains during engine restart. The approach introduces no additional system components and thus few additional costs. The torque profile from an electric machine (EM) is tailored to start the ICE while minimizing residual vibrations. It is shown that the tailored EM torque profile, composed of a linear combination of constant and time-varying components, results in significant mitigation of powertrain vibrations and smoother ICE startup. The time-varying EM torque component is calculated using an analytical ICE model and a perturbation technique for separating scales, which isolates the ICE nonlinear response. Command shaping is then applied to the linear problem at the remaining scale. Simulation results suggest a promising and straightforward technique for reducing vibrations and improving drivability during ICE restart. Furthermore, two-scale command shaping may also be useful in mitigating other HEV-related drivability issues associated with powertrain mode changes (e.g., blending of hybrid power sources, engaging and disengaging of clutches, etc.).
TOPICS: Engines, Vibration, Torque, Machinery, Hybrid electric vehicles, Hybrid power systems, Simulation results