Accepted Manuscripts

Arkadiusz Mystkowski
J. Dyn. Sys., Meas., Control   doi: 10.1115/1.4041978
This study deals with sliding-mode nonlinear observers for a flux-controlled active magnetic bearing (AMB) operated with zero-bias flux. The Lyapunov sliding-mode observer (LSMO) feedback designs are performed for the nonlinear AMB dynamics due to control voltage saturation. The nonlinear observers are designed to estimate the magnetic flux and rotor mass velocity. The observer designs are incorporated in equivalence implementation of the nonlinear state-feedback controller. The main design tools such as sliding-mode control, Lyapunov-based control are used in this framework. The proposed observers are verified by means of numerical simulations, and stability and effectiveness of the proposed observer-based feedback designs are shown.
TOPICS: Magnetic bearings, Feedback, State feedback, Dynamics (Mechanics), Stability, Control equipment, Computer simulation, Magnetic flux, Design, Rotors
Technical Brief  
Haoran Tan, Zhiwu Huang and Min Wu
J. Dyn. Sys., Meas., Control   doi: 10.1115/1.4041977
This paper studies the design and implementation of an interactive real-time cloud supervisory control and data acquisition (SCADA) platform. The platform relying on C# and client/server architecture provides full support for data supervision of the cloud control system (CCS). Users are allowed to design supervisory interfaces by dynamically creating and customizing virtual instruments, which are seamlessly integrated into the platform by reconstructing it. Both the scalar and matrix data from different cloud nodes are supported for supervising simultaneously in real time through receiving data asynchronously. The user can tune the parameters of the CCS online via duplex channels based on the TCP/IP protocol. To overcome the disturbance of network delays to data display, a stable data and real-time data communication scheme is proposed. All the supervised data can be stored in separate files for further analysis. Finally, the online simulation and experiment are provided to demonstrate the feasibility of the designed SCADA platform.
TOPICS: Control systems, Virtual instrumentation, Carbon capture and storage, Design, Delays, Simulation, Data acquisition, Scalars
Douglas/J. Freese and Yunjun Xu
J. Dyn. Sys., Meas., Control   doi: 10.1115/1.4041850
Accurate path scouting control of an autonomous agricultural robot is substantially influenced by terrain variability, field patterns, and uncertainties in sensed information. Based on conventional farming techniques, the targeted test crop of strawberries grows in semistructured environments. Thus in this study, the proposed scouting control architecture comprises of three distinct portions and in each portion different sensors are used. Based on range finder information, the first region uses a proportional-integral-derivative (PID) controller with logic steps to account for undesirable pop-up events. In the other two portions, vision based robust controllers are developed, in which a new bound is derived for the focal length uncertainty in vision. Stabilities of the controllers are proven and the reachabilities are analyzed to guarantee that the final state of each portion is within a desired initial region of the next portion controller. The proposed multi-phase scouting control is successfully validated for our custom-designed robot in a commercial strawberry farm.
TOPICS: Robots, Control equipment, Uncertainty, Sensors
Vikram Banthia, Ali Maddahi, Kourosh Zareinia, Subramaniam Balakrishnan and Nariman Sepehri
J. Dyn. Sys., Meas., Control   doi: 10.1115/1.4041851
In this paper, a control scheme is developed and evaluated for stable bilateral haptic teleoperation of a single-rod hydraulic actuator subjected to base disturbance. The proposed controller, based on Lyapunov stability technique, is capable of reducing position errors at master and slave sides, and provides a feel of the contact force between the actuator and the task environment to the operator without a need for direct measurement. The controller requires only the measurements of the actuator line pressures and displacements of the master and slave. The system stability is insensitive to the uncertainties of the physical parameters and of the measurement of the base point motion. Stability of the proposed controller incorporating hydraulic nonlinearities and operator dynamics with an estimated upper value for the base disturbance is analytically proven. Simulation studies validate that the proposed control system is stable while interacting with a task environment. Experimental results demonstrate the effectiveness of control scheme in maintaining stability, while having good position tracking by the hydraulic actuator as well as providing a haptic feel to the operator without direct measurement of interaction force, while the hydraulic actuator is subjected to base disturbance.
TOPICS: Control equipment, Haptics, Hydraulic actuators, Actuators, Stability, Control systems, Simulation, Dynamics (Mechanics), Errors, Uncertainty
Wafa Boukadida, Anouar Benamor and Hassani Messaoud
J. Dyn. Sys., Meas., Control   doi: 10.1115/1.4041852
This article focuses on Robust Optimal Sliding Mode Control (ROSMC) law for uncertain discrete robotic systems, which are known by their highly nonlinearities, unmodeled dynamics and uncertainties. The main results of this paper are divided into three phases. In the first phase, in order to design an optimal control law, based on the Linear Quadratic Regulator (LQR), the robotic system is described as a Linear Time Varying (LTV) model. In the second phase, as the performances of the Sliding Mode Control (SMC) greatly depends on the choice of the sliding surface, a novel method based on the resolution of a Sylvester equation is proposed. The compensation of both disturbances and uncertainties is ensured by the Integral Sliding Mode Control (ISMC). Finally, to solve the problem accompanying the LQR synthesis, Genetic Algorithm (GA) is used as an off-line tool to search the two weighting matrices. The main contribution of this paper is to consider a multi-objective optimization problem, which aims to minimize not only the chattering phenomenon but as well other control performances. A novel dynamically aggregated objective function is proposed in such a way the designer is provided, once the optimization is achieved, by a set of non-dominated solutions and then he selects the most preferable alternative}. To demonstrate the efficacy and to show complete performance of the new controller, a Selective Compliance Assembly Robot Arm robot (SCARA) is considered. The results show that the manipulator tracing performance is considerably improved with the proposed control scheme.
TOPICS: Robots, Trajectories (Physics), Sliding mode control, Design, Genetic algorithms, Robotics, Uncertainty, Manipulators, Pareto optimization, Optimal control, Optimization, Manufacturing, Resolution (Optics), Dynamics (Mechanics), Control equipment
Eric Magarotto, Jean-francois Massieu, Philippe Dorleans and Amrane Oukaour
J. Dyn. Sys., Meas., Control   doi: 10.1115/1.4041812
In this paper, a new aging detection method of a supercapacitor is proposed through the study of the charge process. Good indicators to describe this aging are Equivalent Series Resistance and capacitance evolution, which are online unmeasurable parameters of the component model. The proposed model belongs to the class of state and parameter affine nonlinear system. A new adaptive nonlinear observer is designed to estimate, under different aging phases, both states and parameters using measurements only available at each sampling instant. This unusual observer contains an adaptive gain, an unknown parameter into the measured output equation and the control signal into state matrix. This discrete-continuous observer is proved to be globally exponentially convergent under some sufficient conditions. Theoretical results are implemented for two cases of study, the first one through some simulations and the second one applied on real data for different sampling times and different values of observer gain. Results highlight good performances of the observer in online parameter estimation, thus the component aging is clearly shown.
TOPICS: Ultracapacitors, Design, Engineering simulation, Nonlinear systems, Parameter estimation, Signals, Capacitance, Simulation
Technical Brief  
Bingyao Lei, Peng Shi, Changxuan Wen and Yushan Zhao
J. Dyn. Sys., Meas., Control   doi: 10.1115/1.4041752
In this paper, a robust gain-scheduling attitude control scheme for spacecrafts with large rotational appendages is proposed. First, by introducing the higher order singular value decomposition (HOSVD) method, a polytopic linear parameter varying (LPV) model with a family of weighting coefficients is developed based on the kinetics of a flexible spacecraft. This model eliminates the need of verifying all the gridding points, which is required in conventional controller synthesis process, and reduces the calculation complexity. Secondly, a generalized plant is derived to guarantee both the system robust stability and the tracking performances. Based on the LPV control theory, a less conservative controller synthesis condition for the polytopic LPV system is deduced. With an online tuning unit, the convex combination of every vertex controller is obtained. For control implementation, the present scheduling parameter is taken as an input for the tuning unit. Numerical results demonstrate the effectiveness and efficiency of the proposed control scheme.
TOPICS: Gain scheduling, Space vehicles, Control equipment, Stability, Control theory
Leiying He, Qinchuan Li, Xubiao Zhu and Chuan-yu Wu
J. Dyn. Sys., Meas., Control   doi: 10.1115/1.4041749
Kinematic calibration is commonly used to improve the accuracy of a parallel mechanism. This paper presents an effective method for calibrating the three-degree-of-freedom parallel manipulator employing a direct kinematic model. An error-mapping function can be formulated from the differential geometry using a kinematic model with the error of the parallel manipulator established with a vector chain. To simplify the measurement of error, the positioning and orientation error of the moving platform is replaced by the positioning error of the tool center point, which can be measured by a laser tracker accurately. Three objective functions F1, F2, and F8 respectively representing 1-norm, 2-norm, and inf-norm of the error vector are used to identify parameters. Through computer simulation, evaluation of three objective functions showed that kinematic calibration with objective function F2 is highly accurate and efficient. An actual calibration experiment was carried out to verify the effectiveness of the method. The positioning error of calibration points reduced greatly from 3.904 to 0.256 mm during calibration procedure. The positioning error of points that were located in the space surrounded by the calibration points is smaller than 0.4 mm after error compensation.
TOPICS: Kinematics, Lasers, Calibration, Manipulators, Errors, Geometry, Error compensation, Computer simulation, Chain, Parallel mechanisms
Paul/Francis Curran
J. Dyn. Sys., Meas., Control   doi: 10.1115/1.4041754
The relatively new concept of wave-based control is extended to general finite-dimensional, linear, time-invariant systems, with or without damping. The new models offer an explanation for how systems of springs and masses although lumped and therefore technically having no delay appear to have delay nonetheless. The principle contribution is a fairly systematic, MIMO, multi-objective control design methodology. The method yields controllers which in general deliver good closed-loop tracking, good disturbance rejection and good stability robustness in the face of parameter uncertainty. In particular, but not exclusively, the method is applicable to the control of flexible structures as demonstrated by several examples including mitigation of sloshing of liquid-fuel in a simplified model of an upper-stage Vega rocket.
TOPICS: Waves, Flexible structures, Control modeling, Delays, Uncertainty, Time-invariant systems, Robustness, Rockets, Sloshing, Springs, Damping, Design methodology, Stability, Control equipment, Fuels
Jianfeng Huang, Jianlong Zhang, Wei Huang and Chengliang Yin
J. Dyn. Sys., Meas., Control   doi: 10.1115/1.4041757
Motor speed synchronization is important in gear shifting of emerging clutchless automated manual transmissions for electric vehicles and other kinds of parallel shaft-based powertrains for hybrid electric vehicles. This paper proposes a speed synchronization controller design for a kind of system integrating a traction motor and a dual clutch transmission (DCT), using optimal control and disturbances compensation. Based on the relativity between magnitudes of different system parameters, the optimal control law is simplified into the proportional (P) one to ease design and analysis. Relationship between the feedback gain and the duration of speed synchronization process is derived in an explicit way to facilitate model-based determination of controller parameters. To alleviate overshoot while maintaining predesigned performances, the explicit nominal speed trajectory rather than the fixed setpoint speed is chosen as the reference signal. To improve robustness of the controller, a time-domain disturbance observer is added to cancel effects from parameter drift, unmodeled dynamics and other exogenous disturbances. As a result, the proposed controller possesses merits of few controller parameters to be determined, good transient response and robustness. These features make it suitable for practical engineering use. Simulation and experiment results verify its effectiveness in attaining both a fast and small-overshoot speed synchronizing process.
TOPICS: Engines, Motors, Synchronization, Control equipment, Robustness, Optimal control, Design, Gears, Dynamics (Mechanics), Relativity (Physics), Simulation, Transients (Dynamics), Trajectories (Physics), Electric vehicles, Feedback, Hybrid electric vehicles, Signals, Traction, Manual transmissions
Asma Achnib, Tudor-Bogdan Airimitoaie, Patrick Lanusse, Sergey Abrashov, Mohamed Aoun and Manel Chetoui
J. Dyn. Sys., Meas., Control   doi: 10.1115/1.4041711
A discrete-time robust controller design method is proposed for optimal tracking of future references in preview systems. In the context of preview systems, it is supposed that future values of the reference signal are available a number of time steps ahead. The objective is to design a control algorithm that minimizes a quadratic error between the reference and the output of the system and at the same time achieves a good level of the control signal. The proposed solution combines a robust feedback controller with a feedforward anticipative filter. The feedback controller's purpose is to assure robustness of the closed-loop system to model uncertainties. Any robust control methodology can be used (such as ?-synthesis, QFT, or CRONE control). The focus of this paper will be on the design of the feedforward action in order to introduce the anticipative effect with respect to known future values of the reference signal without hindering the robustness achieved through the feedback controller. As such, the model uncertainties are taken into account also in the design of the feedforward anticipative filter. The proposed solution is validated in simulation and on an experimental water tank level control system.
TOPICS: Robust control, Design, Control equipment, Feedback, Feedforward control, Signals, Uncertainty, Filters, Robustness, Water, Control algorithms, Simulation, Quantum field theory, Control systems, Design methodology, Closed loop systems, Errors
Wei Zhang, Younan Zhao, Masoud Abbaszadeh and Mingming Ji
J. Dyn. Sys., Meas., Control   doi: 10.1115/1.4041712
This paper considers the observer design problem for a class of discrete-time system whose nonlinear time-varying terms satisfying incremental quadratic constraints. We first construct a circle criterion based full-order observer by injecting output estimation error into the observer nonlinear terms. We also construct a reduced-order observer to estimate the unmeasured system state. The proposed observers guarantee exponential convergence of the state estimation error to zero. The design of the proposed observers is reduced to solving a set of linear matrix inequalities. It is proved that the conditions under which a full-order observer exists also guarantee the existence of a reduced-order observer. Compared to some previous results in the literature, this work considers a larger class of nonlinearities and unifies some related observer designs for discrete-time nonlinear systems. Finally, a numerical example is included to illustrate the effectiveness of the proposed design.
TOPICS: Nonlinear systems, Design, Errors, Linear matrix inequalities, State estimation, Discrete time systems
Noah Manring and Chris Williamson
J. Dyn. Sys., Meas., Control   doi: 10.1115/1.4041713
This paper has been written to develop closed-form equations for describing the theoretical displacement of a check-valve type, digital displacement pump. In theory, the digital displacement pump is used to alter the apparent volumetric displacement of the machine by short circuiting the flow path for reciprocating pistons within the machine that would ordinarily deliver a full volumetric flow-rate to the discharge side of the pump. The short circuiting for the pistons is achieved by opening and closing a digital valve connected to each piston chamber at a desired time during the kinematic cycle for each reciprocating piston. Experience with these machines has shown that the expected volumetric displacement for the machine tends to decrease with pressure. This paper presents a theoretical explanation for the reduced volumetric displacement of the pump and quantifies the expected behavior based upon the digital valve command, the residual volume of fluid within a single piston chamber, and the fluid bulk modulus-of-elasticity. In summary, it shown that the apparent volumetric displacement of the machine may be reduced by as much as 10% for high-displacement commands, and by as much as 30% for low-displacement commands.
TOPICS: Pumps, Valves, Displacement, Machinery, Pistons, Flow (Dynamics), Fluids, Kinematics, Pressure, Elastic moduli, Cycles
Pengpeng Zhang, Marcio de Queiroz, Milad Khaledyan and Tairan Liu
J. Dyn. Sys., Meas., Control   doi: 10.1115/1.4041703
This paper deals with the problem of rigid formation control using directed graphs in both 2D and 3D spaces. Directed graphs reduce the number of communication, sensing, and/or control channels of the multi-agent system. We show that the directed version of the gradient descent control law asymptotically stabilizes the inter-agent distance error dynamics of minimally persistent formation graphs. The control analysis begins with a (possibly cyclic) primitive formation that is grown consecutively by Henneberg-type insertions, resulting at each step in two interconnected nonlinear systems which are recursively analyzed using the stability of interconnected systems. Simulation and experimental results are presented for the directed formation controller in comparison to the standard undirected controller.
TOPICS: Stability, Control equipment, Simulation, Space, Nonlinear systems, Errors, Multi-agent systems, Dynamics (Mechanics)
Alan Whitman, G. M. Clayton and Hashem Ashrafiuon
J. Dyn. Sys., Meas., Control   doi: 10.1115/1.4041664
In this paper, we present a method to accurately predict the wheel speed limits at which mobile robots can operate without significant slipping. The method is based on an asymptotic solution of the nonlinear equations of motion. Using this approach, we can predict wheel slipping limits of both the inside and outside wheel when the robot is in a constant circular motion of any radius. The analytical results are supported by experiments which show that the inside wheel slipping limits for circular motions of various radii occur very close to the predicted values. The method is then applied to predict wheel speed profiles for general motion without slipping and experimentally verified for a sinusoidal path.
TOPICS: Mobile robots, Wheels, Robots, Nonlinear equations
Abdellah Benzaouia and Kenza Telbissi
J. Dyn. Sys., Meas., Control   doi: 10.1115/1.4041639
This paper presents a new approach of actuator fault estimation (FE) for discrete-time switched systems against unknown disturbance. The proposed fault estimation approach uses a new switching observer methodology which allows to obtain fast and exact fault information. Sufficient conditions are achieved by using multiple Lyapunov functional. These conditions are manipulated in a simple way in order to obtain a new LMI with slack variables and observer gains matrices. Finally, Two illustrative examples are performed to prove the effectiveness of the proposed method.
TOPICS: Actuators

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