Startle reaction is an alarm behavior observed in animal groups during anti-predatory response or fear-inducing stimulation. This behavior is characterized by spontaneous change in heading direction and increasing speed that can drastically affect group coordination. In this work, we leverage a mathematical model of fish social behavior to recreate startle reaction. Specifically, we model startle reaction through a biased jump diffusion process, where the jumps process captures sudden and fast changes of heading direction observed during this escaping behavior. Then, using extensive numerical simulations, we test their effects on group of fish including an informed individual prescribing the direction of motion and several followers by systematically varying the frequency and intensity of the sudden and fast turns introduced in the heading direction of a single individual. We demonstrate the emergence of novel form of leadership and phase transition between complete ordered states and disorganized states. In addition, we evidence that at specific range of frequencies and amplitudes, the initiation of this behavior might be utilized to divert group followers from their reference trajectory while keeping them in a synchronized state with the startling individual. Our findings offer a new paradigm to recreate the emergence of leadership applicable to divert or contain multi-vehicle systems.

Drop formation models are essential for the control of drop-on-demand (DoD) inkjet printing process. Traditional numerical models are difficult to implement in real-time control. In this paper, an equivalent circuit model (ECM) is developed to motivate the implementation of a data-driven ARX model combined with a drop volume adjuster to estimate drop volume. Drop pinch-off instants and drop velocities are modeled in polynomials with respect to the parameters of the drive waveform. All models are validated through 10-fold cross validation. The simulation of the drop volume model shows good agreement with experimental results.

Drifters are energy-efficient platforms for monitoring rivers and oceans. Prior work largely focused on free-floating drifters that drift passively with flow and have little or no controllability. In this paper we propose steerable drifters that use multiple rudders for modulating the hydrodynamic forces and thus maneuvering. A dynamic model for drifters with multiple rudders is presented. Simulation is conducted to examine the behavior of the drifter in two different flow conditions, uniform flow and parabolic flow. When there is no difference in relative flow between the rudders, as in uniform flow, the drifter can only be controlled until its velocity approaches that of the water. However, when present, local flow differentials can be exploited to initiate motion lateral to the ambient flow and control the trajectory of the drifter to some degree. The motion of the drifter is further classified as belonging to one of three major modes, rotational, oscillatory, and stable. The behavior of the drifter in a simulated river was mapped for different rudder angles. Identifying the parameters that induce each mode lays the groundwork for developing a feedback control scheme for the drifter.

This paper questions whether the controller properties for a given rigid body mechanical system still apply as the given system is changed. As a first attempt in this investigation, the controller for the underactuated rotary pendulum is investigated as the system morphs into an underactuated inverted pendulum cart. As the limiting condition of the inverted pendulum cart is approached, the investigation allows the controller to also morph. The authors show that, as the pendulum base radius grows, the rotary pendulum equations of motion morph into the inverted pendulum cart dynamics. The paper presents necessary conditions for the successful morphing of the dynamic equations. The morphing process for the controller tests the idea whether the control law also satisfies the same continuum basis as the motion equations. The paper presents a framework for the class of controllers investigated for providing insight into when the controller morphing may be successful. This paper presents dimensionless quantities that render the equations of motion and controller for the inverted pendulum cart and rotary pendulum into dimensionless form. These dimensionless quantities allow comparison of controllers and systems that are not possible through simple inspection. This comparison ability is especially useful for quantifying the nonlinearities of a given system and controller compared to another system and controller having different parameter sizes, a comparison rarely seen in the control literature.

In this paper, we derive a dynamical model for a controllable flexible membrane which is point-actuated by distributed voice coil motors (VCM) connected to it. Besides the modal analysis of the membrane motion, which is the only dynamics discussed in most of related published works treating external pressures as inputs, we integrate the dynamics of the voice coil motors including mechanics and electrical dynamics into the whole system, leaving the electrical signals as inputs to the VCM-actuated membrane system, which is useful for practical application. Also, the multiple-input-multiple-output (MIMO) system is simplified by transforming the dynamics equations into Laplace domain and into a matrix form, which makes the derived transfer functions concise and easier for analysis. It is demonstrated that the eigenmodes of an undamped free-vibration model can be used for approximating the deflection of a forced damping membrane. Furthermore, a reduced-order model is constructed for the flexible membrane system with two voice coil motors symmetrically located on the diameter of the membrane, which is subsequently validated with experimental results obtained on a 2-by-1-VCM-actuated membrane prototype.

In this paper, we investigate finite amplitude torsional oscillations of a shape-morphing plate submerged in a quiescent, Newtonian, incompressible fluid. To address this problem, we focus on a two-dimensional cross section of the plate and para-metrically study hydrodynamic moments and power dissipation during the plate oscillation as a function of the shape-morphing deformation intensity and the oscillation amplitude. This fluid-structure interaction problem is tackled within the framework of a computational fluid dynamics model where the fluid flow is described via the Navier-Stokes equations and the deformations of the structure are prescribed. The results demonstrate a gradual reduction of hydrodynamic moment and nonmonotonic power dissipation behavior as the imposed shape-morphing becomes more aggressive. In addition, power dissipation can be minimized for an optimum value of the shape-morphing intensity. Results from this study are relevant in underwater systems subjected to torsional oscillations and demonstrate an avenue for hydrodynamic moment control and reduction of energy losses.

One of the current technologies widely used to extract the earth’s renewable energy is solar modules, which harness energy from the sun; however, their operating conditions and their energy storage capacities vary greatly under different weather conditions. The high-speed Flywheel Energy Storage System (FESS) presents a promising prospective solution for solar energy storage and utilization. Accurately modeling FESS can lead to its efficient design and control. In this paper, a fully integrated FESS, with comprehensive photovoltaic (PV) system, has been modeled to simulate the overall energy harvesting capabilities, power output, and efficiency. The solar module has been modeled using the one-diode solar cell model technique to predict the overall system efficiency and determine the most efficient time of day for switching between the FESS’s charging (morning time) and discharging mode (night time). To validate the developed model using experimental data, four 250 Wp Ankara Solar PV modules and a Balance of System (BOS) were installed. The solar irradiance, wind speed, cell temperature, solar module, FESS output voltage and current were logged during the system’s operation. The theoretical model predicted that the energy output for the test day was 4.80 kWh, while the experimental analysis showed that the solar modules produced 4.68 kWh, only 2.5% percentage difference. The theoretical and experimental power curves followed the same trends throughout the day, which assures that the model could accurately predict the daily energy output of the solar array. The efficiency of the solar module was determined to be 15.3%. The solar module simulation serves as a repeatable replication of the actual solar module source, which enables convenient, low-cost estimation of the solar module-FESS system under different environmental conditions. The developed solar module was integrated with a brushless DC motor and flywheel models to simulate the FESS response. Relative to the input solar energy input of 4.68 kWh, the daily energy stored in a flywheel was 3.51 kWh, giving the overall solar-module-FESS system an efficiency of 74.7%. After the experimental setup completion of FESS, the integrated solar module-FESS model will be tested for its overall power output and efficiency against the traditional solar module-battery-system.

In this paper, we introduce an agent-based model of lost person behavior that may be used to improve current methods for wilderness search and rescue (SAR). The model defines agents moving on a landscape with behavior considered as a random variable. The behavior uses a distribution of four known lost person behavior strategies in order to simulate possible trajectories for the agent. We simulate all possible distributions of behaviors in the model and compute distributions of horizontal distances traveled in a fixed time. By comparing these results to analogous data from a database of lost person cases, we explore the model’s validity with respect to real-world data.

This paper proposes a height profile model for drop-on-demand printing of UV curable ink. Existing models include superposition of single drops, numerical models, and graphic-based model. They are either too complicated or over simplified. Graphic model intends to find a sweet spot in between, however, accuracy is marginally improved from superposition model while it demands more computation. The proposed model aims to achieve the same as graphic model by introducing volume and area propagation matrices to reflect the localized ink flow from higher location to the lower, while avoiding the detailed physics behind it. This model assumes a constant volume and area propagation of subsequent drop due to height profile difference. It is validated with experiments on single drop, 2-drop and 3-drop line printing. Stability of this model is analyzed.. Using root mean square (RMS) error as benchmark, proposed model achieves 6.6% along the center row and 7.4% overall, better than existing models.

The kinetic energy of a mass traveling in the horizontal direction can be fully transformed into potential energy using an elastica as a temporary storage element. This problem, which resembles the sport of pole-vaulting, is investigated using a non-dimensional framework and by solving the ensuing two-point boundary problem. Dimensional studies are conducted with the objective of better understanding the role of the mass of the vaulter, modeled here as the mass attached to the elastica, and torque applied by the vaulter, modeled here as external torque on the elastica, on vaulting performance. Simulation results indicate better vaulting performance, as indicated by higher non-dimensional potential energy, for lower mass and higher torque.

This paper presents a dynamic model of a three-pressure-stage Heat Recovery Steam Generator (HRSG) system. It is developed on the Siemens T3000 plant monitoring environment. The multi-physics mathematical model captures essential physical phenomena of the HRSG system such as thermodynamics, heat transfer, phase change, fluid dynamics, etc. as well as their couplings. Fast simulation of the dynamic model is achieved and real-time execution is feasible. Aside from heat exchange elements such as economizers and superheaters, the critical components of the model are the high, intermediate, and low pressure boilers. Here, phase transitions and widely different operating pressures pose unique computational challenges and demand accurate modeling of mass and energy balance during unsteady conditions. A two-mode dynamics has been implemented in modeling the boilers. The model switches between these modes during transients. Through collaboration with Siemens Energy Inc., the model’s transient behavior and steady values have been validated with selected transient startup-data from a real HRSG.

Two adjustable compliant mechanism load deflection test benches are presented in this study. Both test bench mechanisms enable testing the deflection of flexible links or mechanisms. The modularity of the designs provides to test various link forms such as fixed-fixed and pinned-pinned joints. The load deflection test benches consist of a linear actuator, an amplifier rod, a linear rail and a sliding car. The measurement setup is equipped with force and displacement sensors for the linear actuator, various clamps to attach the compliant member, and machine vision software to measure member deflection. A displacement-controlled loading using a linear actuator, rack-pinion attached to a motor, or step loading with a pulley can be applied as an input to the system. There are several limitations involved in the design. First, the length of the test object should be kept between 5 cm to 30 cm. Second, a low cost linear actuator with a low extension velocity to obtain quasi static deflection curves of the compliant members is required. Finally, the design should also have the capability of providing various types of boundary conditions with interchangeable attachments. The force can be applied either parallel or perpendicular to the test object. Input load deflection is measured with the displacement sensor, and the resulting member displacement measured visually using machine vision software. This software synchronizes data from the displacement sensor and a calibrated camera image to automatically detect deflection using a pinhole camera model and known dimensions of the test apparatus. The purpose of this study is to design and fabricate a load deflection test setup capable of testing flexible links and compliant mechanisms. Two different designs are proposed and explored in this study. The first design is the modification of a commercially available ECP Model 210 educational turnkey system favorably utilized in undergraduate level vibrations and control labs. By attaching the designed clamps on two carts, fixed-fixed and U shaped compliant link load deflection can be obtained. Four cases such as fixed-fixed buckling beam, U shaped beam buckling with one end sliding, already buckled beam loaded at its upper midpoint, and inverse U-shaped beam loaded at its apex to form deflected M beam (with design 2) are considered. In order to achieve buckled beam experiments in which the load is applied at the midpoint of the already buckled links, a new test bench consisting of a linear actuator, rigid links, rail and two sliding cars is designed.

Lithium-ion battery cycle- and calendar-life remain to be one of the greatest uncertainties for the advanced energy storage systems. Accurate characterization of battery aging has been crucial for battery state-of-health (SOH) estimation and the remaining useful life (RUL) prediction. The formation-and-growth of the solid-electrolyte interphase (SEI) has been widely recognized as one of the most prominent battery degradation mechanisms. It consumes the cyclable lithium within the cell and ultimately leads to the capacity fade which cannot be measured directly onboard. This study evaluates the multi-scale multi-physics battery models and their respective aging mechanisms as well as the corresponding characterization metrics. Then the reduced order single particle model (SPM) is selected in this study, given its parametric dependence on both electrochemical and physical parameters as well as its compatibility to the available measurements in vehicle for aging characterization. n Li , the total moles of cyclable lithium within the cell, is identified as a valid aging parameter that can effectively characterize the capacity fade through the interpretation of experimental aging data. This study also investigates into the potentially optimal testing profile and the sufficient amount of data required for the accurate aging characterization. Then the method of brute force nearest neighbor search (NNS) is applied to derive the long-term evolution trend of the aging parameter n Li , which can serve as a key benchmark for validating the in-vehicle implementable algorithms for battery state-of-health (SOH) estimation and as an important foundation for predicting the remaining useful life (RUL) of battery.

This paper proposes a hybrid multibody dynamics formalism with a symbolical multibody toolbox developed in MATLAB Environment. The toolbox can generate the dynamic model of a multibody system with hybrid and nonholonomic dynamic properties. The framework and software structure of the toolbox are briefly demonstrated. The paper discusses the recursive kinematics and modular modeling theories that help improve the modeling performance and offer accessibility into the dynamic elements. The formalism that offers a symbolic solution to nonholonomic and constrained dynamics is explained in detail. The toolbox also provides design tools and auto-compilation of hybrid automata. Two exemplary models and their simulations are presented to verify the feasibility of the formalism and demonstrate the performance of the toolbox.

The Furuta pendulum is a two degree of freedom mechanical system that serves as an excellent and simple device to check control strategies applied for strongly nonlinear mechanical structures. Stability results related to certain stationary motions of the Furuta pendulum are compared to experimental observations, and conclusions are obtained regarding some essential mechanical phenomena that are present in the experimental rig, but still not properly described in the standard mathematical model of the pendulum. The results call the attention for the importance of the identification of the Coulomb friction in the structure, which effect the control strategies to be implemented.

Ground testing of full-scale wind turbine nacelles has emerged as a highly favorable alternative to field testing of prototypes for design validation. Currently, there are several wind turbine nacelle test facilities with capabilities to perform repeated and accelerated testing of integrated turbine components under loads that the machine would experience during its nominal lifetime. To perform accurate and efficient testing, it is of significant interest to understand the interaction between coupled test rig/dynamometer and nacelle components, particularly when applying extreme loads. This paper presents a multi-body simulation model that is aimed at understanding the responses of a coupled test rig and nacelle system during specific tests. The validity of the model is demonstrated by comparing quasi-static and dynamic simulation responses of key components with experimental data obtained on an actual 7.5 MW test rig. A case study is conducted to analyze a transient grid-loss event; a Low Voltage Ride Through (LVRT) test on the dynamometer and drivetrain components. It is shown that the model provides an efficient way to predict responses of the coupled system during transient/dynamic tests before actual implementation. Recommendations for mitigating the impact of such tests on the test bench drive components are provided. Additionally, observations of differences between transient events in the field and ground based testing are made.

Developing controllers for powered prostheses is a daunting task that requires involvement from clinicians, patients and robotics experts. Difficulties arise for tuning prosthetic devices that perform in multiple conditions and provide more functionality to the user. For this reason, we propose the implementation of a simulation framework based on the open-source 3D simulation environment Gazebo, to reduce the burden of experimentation and aid in the early stages of development. In this study, we present a minimalist plugin for the simulator that allows the interfacing of a virtual model with the native prosthesis controller and renders the finding of impedance parameters as a pattern search problem. To demonstrate the functionality of this approach, we used the framework to obtain the parameters that offer the most similar joint trajectory to the respective biological counterpart during swing phase for ground level walking. The optimization results are compared against the response of a physical 2DOF knee-ankle prosthesis operating under the optimized parameters, showing congruence to our model-based results. We found that a simulation-based solution is capable of finding parameters that create an emerging behavior that approximates to the kinematic trajectory goals within a tolerance (mean absolute error ∼10%). This provides an appropriate method for development and evaluation of impedance-based controllers before deployment to the physical device.

A physics-based control-oriented combustion model is developed to accurately predict in-cylinder pressure and temperature of a diesel engine. The model is under the assumption that the combustion chamber consists of three zones: a liquid fuel zone, a reaction zone, and an unmixed zone. These zones are formulated to account for three key events in diesel combustion: fuel evaporation, chemical reaction, and fuel-air mixing, respectively. The liquid fuel zone is assumed to be of spherical shape. The evaporation of fuel is governed by Fick’s first law of diffusion. The reaction zone is modeled as a reactive system consisting of six species and two reaction steps. The burn rate is calculated based on species concentrations and reaction zone temperature. The unmixed zone contains only air and inert gas. The results of simulations are compared to the test data from a GM 6.7 L 8-cylinder Duramax diesel engine. The multi-zone model is shown to be capable of predicting in-cylinder pressure accurately with more degree of freedoms, compared to the singlezone reaction-based model.

Vapor compression systems are widely used as thermal management systems. To satisfy thermal demands, models are used to control and optimize the system’s performance, reliability, and efficiency. Significant effort has been made to model the condenser and evaporator, while there has been minimal focus on control-oriented modeling of the compressor. Initial work illustrates that during transient behavior, the working fluid exhibits a fast dynamic. However, during a startup and shutdown sequence, the working fluid follows a slower dynamic believed to be associated with heat transfer to the shell. To address both thermal dynamics, a graph-based modeling approach is used to incorporate the compressor shell’s thermal capacitance into the model. Experimental and simulation data are compared for a range of operating conditions including shutdown and startup dynamics.

A theoretical and computational model has been developed for the nonlinear motion of an inextensible beam undergoing large deflections for cantilevered and free-free boundary conditions. The inextensibility condition was enforced through a Lagrange multiplier which acted as a constraint force. The Rayleigh-Ritz method was used by expanding the deflections and the constraint force in modal series. Lagrange’s Equations were used to derive the equations of motion of the system, and a 4th order Runge-Kutta solver was used to solve them. Comparisons for the cantilevered beam were drawn to experimental and computational results previously published and show good agreement for responses to both static and dynamic point forces. Some physical insights into the cantilevered beam response at the 1st and 2nd resonant modes were obtained. The free-free beam condition was investigated at the 1st and 3rd resonant modes and the nonlinearity (primarily inertia) was shown to shift the resonant frequency significantly from the linear natural frequency and lead to hysteresis in both modes.