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Because of its paramount importance in the successful industrial control strategy of a given heat exchanger network (HEN), the control structure designs for providing appropriate manipulated variable (MV) and controlled variable (CV) pairings have received considerable attention. However, quite frequently HENs with such control structures face the problem of hard constraints, typically holding the HENs at less controlled operating space. So both the MV pairings and the above control pairings should be considered to design a control structure. This paper investigates the systematic incorporation of the two pairings, and presents a methodology for designing such two-tier control structure. This is developed based on the sequential strategy, coupling an indirect-tier with direct-tier control structure design, wherein the intention is realized in the former stage and the latter is implemented for further optimization. The MV identification and pairing are achieved through variations in heat load of heat exchangers to design the indirect-tier control structure. Then the direct-tier control structure is followed the relative gain array (RGA) pairing rules. With the proposed methodology, on the one hand, it generates an explicit connection between the MV pairings and the HEN configuration, and the quantitative interaction measure is improved to avoid the multiple solutions to break the relationship among all the control pairings into individuals; on the other hand, a two-tier control structure reveals control potentials and control system design requirements, this may avoid complex and economically unfavourable control and HEN structures. The application of proposed framework is illustrated with two cases involving the dynamic simulation analysis, the quantitative assessment and the random test.

A surrogate model for dynamical behavior of dielectric elastomer actuators was proposed, the reduced-order framework was based on long short-term memory (LSTM) networks, and the combination of prop...

Squeak and rattle (S&R) are nonstationary annoying sounds inside the car cabin that impose high warranty costs on car manufacturers. The need for taking S&R preventing measures and the maturity level and cost considerations of the physical prototypes during the pre-design-freeze stages justifies the use of virtual simulation methods. Squeak is a friction-induced high-frequency sound that is attributed to the stick-slip friction phenomenon. The importance of the friction parameters in the squeak severity prognosis is analytically and experimentally mentioned in the literature. However, studying the variation of these parameters respecting the changes in loading and driving conditions with the aim of application in virtual simulations has remained limited or too simplistic. In this work, the rate weakening effect of the friction coefficient curve was involved in the nonlinear finite element simulation of stick-slip events by an exponential decay formulation. The approximated squeak severity by the virtual simulations for selected material pairs agreed with the empirical results from a flexural stick-slip test bench. From the empirical stick-slip data, the dependence of the squeak severity on the friction decay coefficient and the difference of static and kinetic friction coefficients at low and high normal loads were observed, respectively. The relativity of friction parameters on the test conditions demands a dynamic updating of the friction model that can be achieved by polynomial or exponential approximations. Also, the observed polynomial relationship between the squeak severity and the operational conditions can be used to estimate the squeak severity from the linear dynamic simulation results. The outcome of this work can help to better understand the influence of the friction modelling parameters and their variation respecting the operational conditions. This can facilitate a more accurate prediction of squeak risk by employing virtual simulation tools in the pre-design-freeze stages of car development.

Measuring and quantifying the electromagnetic characteristics of switched reluctance motors (SRMs) are indispensable for advanced motor control and performance enhancement. This article reports on a novel method in obtaining the flux-linkage characteristics of an SRM without rotor clamping devices and position sensors. This approach combines measurement with data reconstruction. For the measuring step, flux-linkage samples at four torque-balanced positions were measured indirectly. Considering the magnetic coupling among phases, two different excitation forms were adopted to further increase accuracy. Then, for the reconstructing step, a fuzzy logic-based approach was applied to reconstruct the complete flux-linkage characteristics with measurement results. The construction results were compared to measurements results from the traditional rotor clamping method, and good agreements can be found, demonstrating the effectiveness of the proposed method. Furthermore, based on reconstructed electromagnetic characteristics, dynamic simulation of an SRM prototype under different control modes was carried out and analyzed in MATLAB. Comparison with dynamic experiments further verifies the accuracy and effectiveness of the proposed method.

Intensified interaction between electric power system (EPS) and district heating network (DHN) has raised an urgent requirement of security control to ensure the regular operation of the heat and electricity integrated energy system (HE-IES). However, the implicit expressions of thermal dynamics remain an obstacle to building the quantitative relationships between the EPS and the DHN. To solve this, this paper proposes a novel dynamic model of the district heating network, which contains the equivalent pipe model and the analytical thermal source-load function (TSLF). Then, the interaction between EPS and DHN is divided into the energy flow calculation at the control points and the dynamic simulation during the control intervals to investigate the coupling effect. On this basis, the dynamic characteristics in HE-IES are employed to quantitatively establish the security control strategy using the combined sensitivity analysis. Case studies verify the accuracy and efficiency of the proposed method.

In this article, a new torque sharing function (TSF) method is proposed for torque ripple reduction in switched reluctance machines (SRMs). The proposed TSF achieves lower current tracking error by establishing a new current reference generation strategy. The phase current reference is first derived from the torque command using offline calculations and also from the phase current response that is obtained from the dynamic model of the SRM. Then, an optimization problem is formulated to shape the current reference for the objective of minimizing the torque ripple and copper losses, while maintaining the required average output torque at the given operating speed. The dynamic simulation of the SRM model is also utilized in the optimization problem. Compared to the existing conventional and optimization-based TSFs, the proposed TSF exhibits lower current tracking error due to the consideration of the current dynamics. Better torque–speed performance with improved average torque and reduced torque ripple is also obtained, especially during commutation. Simulations and experiments under different operating conditions are carried out to verify the proposed TSF method.

The tether-net system is a promising technique for active debris removal. The capture process of a tether-net system for debris exhibits the nonlinear dynamics of very high dimensions and requires the dynamic simulation of high accuracy and efficiency in the design stage. This paper presents an integrated approach of both method of discrete elastic rods and algorithm of energy-conserving integration for the above purpose. The study shows that the method of discrete elastic rods is more suitable for modeling the extremely flexible threads of a woven net than the slender beam elements with C1 continuity. Besides, the energy-conserving integrator embedded in the present approach well conserves the total energy, and does not produce any numerical dissipations. The paper gives three numerical examples, including the capturing process of a hexagonal tether-net system for a space target, to demonstrate the advantages of the present approach, as well as the influence of some initial control parameters on the deployment phase of the tether-net system.

Aiming at the sudden change of path curvature in traditional bi-arc parking trajectory planning, an improved bi-arc parking trajectory fitting method is proposed to meet the requirements of curvature and steering angular velocity of parking path. The minimum parking space size and feasible parking starting area are obtained by calculation. Then, parking path tracking is controlled based on adaptive algorithm, and the adaptive algorithm is optimized and compensated, so that the path tracking error is controlled in a small range. Two kinds of parking conditions are designed according to the limit position of the feasible parking starting area. The proposed method is verified by simulation in MATLAB, and dynamic simulation is carried out in CARSIM software. The practical driving of the intelligent experimental vehicle is used to verify whether the relevant methods and functions of the proposed parallel parking system can meet the design requirements. The results show that the proposed method can be applied to parking path planning at any location in the feasible parking starting area.

Dynamic analysis is an essential task in the geometry design of suspension systems. Whereas the dynamic simulation based on numerical software like Adams is quite slowly and the existing analytical models of the nonlinear suspension geometry are mostly based on small displacement hypothesis, this paper aims to propose a whole-range dynamic model with high computational efficiency for planar double wishbone suspensions and further achieve the fast optimal design of suspension geometry. Selection of the new generalized coordinate and explicit solutions of the basic four-bar mechanism dramatically reduce the complexity of suspension geometry representation and provide analytical solutions for all of the time varying dimensions. By this means, the running speed and computational accuracy of the new model are guaranteed simultaneously. Furthermore, an original Matlab/Simulink implementation is given to maintain the geometric nonlinearity in the solving process of dynamic differential equations. After verifying its accuracy with an ADAMS prototype, the presented whole-range model is used in the vast-parameter optimization of suspension geometry. Since both kinematic and dynamic performances are evaluated in the objective function, the optimization is qualified to give a comprehensive suggestion to the design of suspension geometry.

The lateral vibration coupling mechanism is the basic law describing the current vibration behavior of a high-speed train. The main reason is that there are design defects in the ICE3 bogie prototype. Therefore, the passenger dedicated line is not a necessary and sufficient technical condition for ensuring the stability and safety of high-speed railway operation. Based on the previous research, this article further develops theoretical demonstration and experimental verification of the lateral vibration coupling mechanism of the high-speed train. According to the concept of system stiffness and the statistical characteristics of Gaussian process, a new concept of singular coefficient is proposed to describe non-stationary and non-Gaussian processes. Combined with the quality vibration tracking test of a high-altitude vehicle, the conclusions obtained are in good agreement through the experimental testing and the dynamic simulation. The application of the singular coefficient further gives three conditions for determining the lateral vibration coupling mechanism of the high-speed train, namely, sufficient excitation energy, vibration transmission medium, and possibility of coupling resonance. Aiming at the influence of high-order modal interception and residual force of flexible body, the new concept of singular coefficient is applied. The rigid-flexible coupling simulation reflects the main statistical characteristics of non-stationary and non-Gaussian processes and reveals the current lateral vibration coupling mechanism of the high-speed train.

The dynamics of the Long Reach Manipulators create disturbances in its supporting base structure. This causes positional and attitude inaccuracies of the end-effector, thwarting the accomplishment of the desired mission task. Hence the base disturbance problem has been a subject of research since long time bringing solutions from varied domains. This paper analyzes the balance link concept for compensating the disturbances. The LRM system is modelled as a two-link serial chain with payload, and the balance arm, as a single link with tip mass that is dynamically varied by controlling the quantity of the hydraulic fluid in the bellows-like reservoir at the tip. The supporting base is modelled as a half car. Simultaneous constraint matrices are set up for the arrangement, and dynamic simulation is performed using SIMULINK. The pitch and bounce motions of the base are studied along with the torque error during compensation. The simulation plots are obtained for two conditions of compensating arm¾with fixed tip mass and with varying tip mass. The results confirm the suitability of the suggested compensating arrangement in controlling base disturbances.

In the present paper, an attempt has been made to introduce a new Stability Index (SI) for induction motors (IMs) three-phase fault recovery in industrial networks. The proposed SI is based on the steady-state model of induction machine as well as the usage of concepts related to stable and unstable equilibrium points. This index is evaluated by estimating the post-fault slip and is a function of the maximum slip and slips related to the induction motor operating point in pre-fault and post-fault torque-slip characteristics. Moreover, this index quantifies the amount of stability in addition to the stability state determination. The method is validated through comparison between the analytical and dynamic simulation results. Sensitivity analysis has also been used to describe the proposed index completely. This paper also presents a novel objective function by which the fault recovery process can be done optimally. The proposed method presented in this paper has also been applied to two industrial networks, one of which is the modified IEEE 9-bus system.

This letter proposes an analytical expression on transient overvoltage peak value caused by DC blocking (DCB) and commutation failure (CF). The proposed method can obtain the transient overvoltage risk without modeling the complex AC/DC hybrid system. The method only requires the equivalent parameters of the AC system and the operation parameters of the DC system to effectively calculate the overvoltage without using the dynamic simulation software. The simulation results verify the effectiveness and correctness of the proposed method.

Autonomous on-orbit servicing, such as capture, refuel, repair and refurbishment of on-orbit satellites using a robotic arm mounted on servicing satellite is one of the important components of future’s space missions. Space robots increase reliability, safety, and ease of execution of space operations, but pose a novel challenge due to micro-gravity and space environments. While capturing high speed orbiting objects, robotic arms undergo impact and require appropriate modeling of the system. In this paper, a unified framework is provided for modeling impact dynamics, post-capture stabilization and target maneuvering of a multi-arm robotic system mounted on a servicing satellite while capturing orbiting objects. The dynamic model of multi-arm space robot is obtained using the Decoupled Natural Orthogonal Complement (DeNOC) based formulation and closed-loop constraint equations. All three phases of the capturing operation, namely, approach, impact, and post-impact are modeled using Impulse-momentum approach and conservation of momentum. In the approach phase, robot arms are planned to move from its initial configuration to the desired capture configuration. In the impact phase, a framework is developed to estimate the impulse forces and changes in the generalized velocities caused by the impact. In post-impact phase, these velocities are used as initial conditions for the post-impact dynamics simulations. The uncontrolled dynamics during post-impact will result in an undesirable motion, thus post-impact reactionless control (minimum base disturbance) strategy is used to maneuver the space robot’s arms and target object. As such, the robotic arms can be used to maneuver an astronaut for repair of satellite. Most of the times the parameters of target object are not known. Hence, an adaptive reactionless control strategy has been devised for capturing object with unknown parameters. The effectiveness of the framework is shown using a dual-arm robot mounted on a servicing satellite performing capturing operation for multiple objects. The effects of relative velocity and angle of approach on the impact forces are also investigated.

The use of mechanical energy in daily life including industries and transport applications are increasing rapidly. Induction motor has special advantages because of less cost, reliable, robust and less maintenance when compared to other motors. It also has special features which satisfies all the requirements. On the whole 3-phase IM (Induction motor) plays major role in several applications (i.e. industrial, mechanical). The meticulous behavior of induction motor modeling and speed control can aid for controlling of machine application where flawless results can be obtained. The major faults in the IM effect the air gap flux, where the mathematical modeling can helpful to estimating the errors obtain while designing the motor. The paper represents the bit by bit implementation of 3-phase induction motor modeling and speed control using MATLAB simulation.

Purpose This paper aims to develope a novel fractional hybrid impedance control (FHIC) approach for high-sensitive contact stress force tracking control of the series elastic muscle-tendon actuator (SEM-TA) in uncertain environments. Design/methodology/approach In three different cases, the fractional parameters of the FHIC were optimized with the particle swarm optimization algorithm. Its adaptability to the pressure of the sole of the foot on real environments such as grass (soft), carpet (medium) and solid floors (hard) is far superior to traditional impedance control. The main aim of this paper is to derive the dynamic simulation models of the SEM-TA, to develop a control architecture allowing for high-sensitive contact stress force control in three cases and to verify the simulation models and the proposed controller with experimental results. The performance of the optimized controllers was evaluated according to these parameters, namely, maximum overshoot, steady-state error, settling time and root mean squared errors of the positions. Moreover, the frequency robustness analysis of the controllers was made in three cases. Findings Different simulations and experimental results were conducted to verify the control performance of the controllers. According to the comparative results of the performance, the responses of the proposed controller in simulation and experimental works are very similar. Originality/value Origin approach and origin experiment.

Conventionally, researchers conducted field tests and modeling works for the Variable Refrigerant Flow system separately. In this study, we used the compressor model as a case study to illustrate a novel approach to integrate field tests and modeling works. Field tests in an office building were conducted to collect data. For mass flow rate prediction, three traditional models, including the 20-coefficient model, the efficiency-based model, and the efficiency-based 20-coefficient model, and three machine-learning-based models including Support Vector Regression, Neural Network, and Random Forest, were investigated and compared. We found that the efficiency-based 20-coefficient model and the Support Vector Regression model had a higher accuracy (the mean relative errors were 0.11% and 0.15%, and the coefficient of variation of the root mean-square-error were 0.20 and 0.23) and lower uncertainty within 0.2 g•s−1 for steady-state operation prediction. However, all six models failed to predict accurately the beginning part of the transient process. A tens-of-seconds delay existed between the predicted values and the experiment values. We applied the Convolutional-Neural-Network-based model to address this problem. The mean relative error of this model is reduced to 2% for dynamic simulation. In summary, we recommend the efficiency-based 20-coefficient model, and the Support Vector Regression model for the steady-state compressor model development, while the Convolutional-Neural-Network-based model is recommended for transient model development. For the power consumption prediction, 20-coefficient and Neural Network models can predict transient data well. The process of predicting the capacity is the same as the process of mass flow rate prediction.

Existing generator parameterization methods, typically developed for large turbine generator units, are difficult to apply to small kW-level diesel generators in microgrid applications. This paper presents a model parameterization method that estimates a complete set of kW-level diesel generator parameters simultaneously using only load-step-change tests with limited measurement points. This method provides a more cost-efficient and robust approach to achieve high-fidelity modeling of diesel generators for microgrid dynamic simulation. A two-stage hybrid box-constrained Levenberg-Marquardt (H-BCLM) algorithm is developed to search the optimal parameter set given the parameter bounds. A heuristic algorithm, namely Generalized Opposition-based Learning Genetic Algorithm (GOL-GA), is applied to identify proper initial estimates at the first stage, followed by a modified Levenberg-Marquardt algorithm designed to fine tune the solution based on the first-stage result. The proposed method is validated against dynamic simulation of a diesel generator model and field measurements from a 16kW diesel generator unit., Comment: 9 pages, 9 figures, accepted by IEEE Transactions on Smart Grids

The aim of this study is to propose a new three-degree-of-freedom linear-rotational resonant actuator and its controller. To realize all of the resonant motion, four-phase coils and three sets of the permanent magnet are arranged symmetrically. In addition, in order to control the proposed actuator, inverter topology with six-switches is presented. Parameter characteristics obtained through finite-element analysis support the validity of the proposed actuator. Finally, dynamic simulation is performed to verify the effectiveness of the proposed actuator.

This paper deals with a four-wheel-steering four-wheel-driving (4WS4WD) vehicle under the path-following control. Focuses are placed on the motion control of the vehicle, and the drive forces and steering angles for achieving accurate path-following by the vehicle are determined. In this research, a nonlinear vehicle model of three degrees of freedom (DOFs) is used. The vehicle path-following dynamics are modeled using the classical mass-damper-spring vibration theory, which is described by three ordinary differential equations of second order with lateral, heading and velocity deviations, and control parameters. Combined with the vehicle path-following dynamic model, the nonlinear vehicle dynamic model is decoupled in generalized coordinate space. The required drive forces and steering angles for the vehicle path-following controllers are thus calculated and control models are obtained. Theoretical analysis for steering and driving control models is also carried out. It discloses that control models can maintain good performance against uncertainties. The vehicle path-following control is exhibited by dynamic simulation in CarSim with consideration of a complex vehicle model and a variable-curvature planned path. Numerical results obtained are analyzed and show control models have capable of dealing with a complex path-following problem. This paper provides a new insight into understanding path-following control of a 4WS4WD vehicle at the generalized vibration level.

In this paper, a novel mechanical flux-adjusting interior permanent magnet (MFA-IPM) motor is proposed. The key is to employ an additional mechanical flux-adjusting (MFA) device attached to one side of the rotor, which can achieve flexible adjustment of the air-gap flux and obtain a wide speed range. This system with appropriate gears uses centrifugal force to set the cylindrical PMs in a required position. The topology and working principle of the MFA-IPM motor are introduced. Then, the dynamic performance prediction between the deformation length of spring and the rotation angles of PMs is obtained by the dynamic simulation. Moreover, the electromagnetic characteristics of the proposed MFA-IPM motor and a conventional IPM motor are analysed and compared based on finite element analysis, including no-load performances, inductances, electromagnetic torque, flux-weakening ability and speed range, as well as demagnetization evaluation. Finally, a prototype MFA-IPM motor is fabricated and tested. Both the simulation and experimental results indicate the validity and feasibility of the MFA-IPM motor.

This paper presents a controller model of asymmetric current injection for converter-interfaced generators suitable for root-mean-square (RMS) phasor-domain, fundamental-frequency, three-phase, and dynamic simulation tools. The effectiveness of the proposed controller is assessed with simulations in test systems with high percentage of converter-interfaced generation. The simulations focus on the operation of protection relays that use negative-sequence quantities in their directional elements. This paper also presents and compares two strategies to limit reactive negative-sequence currents, and active and reactive positive-sequence currents. A tutorial test system and a regional system part of the actual Brazilian Interconnected Power System are used to assess the correctness of the proposed controller in three-phase fundamental-frequency RMS dynamic simulations.

Conventional transmission line distance protection approaches are subject to malfunction under reverse fault-induced current transformer (CT) saturation for the typically employed breaker-and-a-half configuration. This paper addresses this issue by proposing a new distance protection approach that combines the blocking and unblocking criteria of distance protection based on the values of incomplete differential current, operation voltage, and current harmonic content. The proposed approach is verified by theoretical analysis, dynamic simulation testing, and field operation to ensure that the obtained distance protection is reliable and refrains from operating unnecessarily under reverse fault-induced CT saturation in the breaker-and-a-half configuration. Meanwhile, the proposed approach is demonstrated can operate reliably when forward faults occur or various reverse faults are converted to forward faults.

Since gas turbine plays a key role in electricity power generating, the requirements on the safety and reliability of this classical thermal system are becoming gradually strict. With a large amount of renewable energy being integrated into the power grid, the request of deep peak load regulation for satisfying the varying demand of users and maintaining the stability of the whole power grid leads to more unstable working conditions of gas turbines. The startup, shutdown, and load fluctuation are dominating the operating condition of gas turbines. Hence simulating and analyzing the dynamic behavior of the engines under such instable working conditions are important in improving their design, operation, and maintenance. However, conventional dynamic simulation methods based on the physic differential equations is unable to tackle the uncertainty and noise when faced with variant real-world operations. Although data-driven simulating methods, to some extent, can mitigate the problem, it is impossible to perform simulations with insufficient data. To tackle the issue, a novel transfer learning framework is proposed to transfer the knowledge from the physics equation domain to the real-world application domain to compensate for the lack of data. A strong dynamic operating data set with steep slope signals is created based on physics equations and then a feature similarity-based learning model with an encoder and a decoder is built and trained to achieve feature adaptive knowledge transferring. The simulation accuracy is significantly increased by 24.6% and the predicting error reduced by 63.6% compared with the baseline model. Moreover, compared with the other classical transfer learning modes, the method proposed has the best simulating performance on field testing data set. Furthermore, the effect study on the hyper parameters indicates that the method proposed is able to adaptively balance the weight of learning knowledge from the physical theory domain or from the real-world operation domain.

This paper treats numerical methods for an efficient prediction of the rotorcraft emergency procedures after engine failures. The analytical means of compliance for the Category-A requirements can be used for the type certification of the transport-category rotorcraft when their fidelities are approved by the civil airworthiness authority. However, the most promising trajectory optimization approaches to the Category-A maneuver analyses typically suffer from a dimensionality problem when a high-fidelity math model is adopted. To cope with such difficulties, the paper proposes new techniques, where the system states except the initial ones and all dynamic constraints are removed from the resultant nonlinear programming problem. For these proposes, the controls are parameterized using the Hermit splines with the local support and efficient recursive formulas to predict the constraint-function Jacobians are derived. The efficiency of the proposed techniques is compared with that using the pseudo-spectral collocation method. In addition to an autorotational descent maneuver, four Category-A procedures for the continued takeoff, rejected takeoff, continued landing, and balked landing maneuvers are analyzed with varying the engine-failure conditions and with a suitable consideration on the pilot-delay time to validate the usefulness of the proposed methods.

The goals of this work are to compare and analyze the use of PI conventional and Cascade control configuration in heater-plug-flow-reactor-series (Heater-PFR-series) to produce benzene through the reaction of hydrodealkylation of toluene (HDA).The two control configurations were rigorously examined in UniSim dynamic simulation environment. The PI control parameters were tuned by using “autotuner” mode of UniSim. As shown in dynamic simulation study, the two control configurations with its tuning parameters gave the fast and stable responses. This study revealed that the Cascade control acted very well and its responses were better and faster than those in PI-conventional.Keywords: cascade control; dynamic simulation; PFR; PI conventional; UniSim

Nowadays power transmission losses in multi-terminal high-voltage DC (MT-HVDC) systems of large offshore wind farms are the main concerns to wind farm operators. Maintaining the DC voltages and currents within pre-specified limits and simultaneously optimising DC power flows of MT-HVDC systems using optimum droop control settings becomes a complex optimisation problem. This droop control scheme was less explored with power loss minimisation applications due to the difficulties in the optimisation of these droop gain settings. This study presents a new mathematical programming plus meta-heuristic-based optimisation approach to solve this optimisation problem. This hybrid optimisation methodology is also termed as 'matheuristic approach'. The proposed matheuristic method optimises the droop control settings for different operating conditions of offshore wind farms and simultaneously minimises the DC power losses in the MT-HVDC system. The proposed optimisation method has been tested upon a six-terminal HVDC system connected with large offshore wind farms. The superiority of the proposed optimisation method is demonstrated using the steady state as well as dynamic simulation studies. The simulation results show that DC power losses could be reduced significantly by adopting the proposed method to facilitate optimal power flows in the MT-HVDC system of large offshore wind farms.

How to effectively improve the behavior decision ability in unknown environment is a great challenge for mobile robots. Traditional methods suffer from the low efficiency and large computation load. Motivated by the regulation effect of serotonin and dopamine on human behavior, a novel adaptive behavior decision model for mobile robot is proposed in this work. This model integrates two kinds of adjustment factors that mimic the effects of two neuromodulators, serotonin and dopamine, to regulate the behavior decision of a mobile robot in unknown environment. Adjustment factor $$\mathbf {p}$$ is designed to simulate the function of the serotonin and make the robot avoid obstacles effectively, while the adjustment factor $$\mathbf {r}$$ is designed to simulate the function of the dopamine and make the robot approach the target quickly. Both of the adjustment functions can be adaptively regulated with the robot’s movement. Static and dynamic simulation results show that this neuromodulatory model has excellent collision avoidance capacity which can avoid the obstacles fluently, and the trajectory obtained tends to be optimal. Moreover, it is relatively simple, thus can effectively reduce the computation time and the load capacity, and greatly improve the running efficiency of the mobile robot in unknown environment.

The design of a vehicle frame is largely dependent on the loads applied on the suspension and heavy parts mounting points. These loads can either be estimated through full analytical multibody dynamic simulations, or from semi-analytical simulations in which tire and road sub-models are not included and external vehicle loads, recorded during field testing, are used as inputs to the wheel hubs. Several semi-analytical methods exist, with various modeling architectures, yet, it is unclear how one method over another improves frame loads prediction accuracy.This study shows that a semi-analytical method that constrains the vehicle frame center of gravity movement along a recorded trajectory, using a control algorithm, leads to an accuracy within 1% for predicting frame loads, when compared to reference loads from a full analytical model. The control algorithm computes six degrees of freedom forces and moments applied at the vehicle center of gravity to closely follow the recorded vehicle trajectory. It is also shown that modeling the flexibility of the suspension arms and controlling wheel hub angular velocity both contribute in improving frame loads accuracy, while an acquisition frequency of 200 Hz appears to be sufficient to capture load dynamics for several maneuvers. Knowledge of these loads helps engineers perform appropriate dimensioning of vehicle structural components therefore ensuring their reliability under various driving conditions.

The test signal of multistage gear transmission system is complex. When coupling faults occur in the system, it is often difficult to accurately extract all kinds of fault features. In the past studies, we found that the fault signals have modulation and coupling effects. The failure of a gear is often reflected in the power spectrum in the form of associated changes in the meshing frequency of other stages. The separation of these features will facilitate the analysis of the coupling effects of multiple faults. The transfer characteristic method provides an effective method for decomposing such signal features. In this paper, through the analysis of transfer characteristics, the coupling fault transfer characteristics and the associated influence relationship of fixed-axis gear crack and planetary gear missing tooth are revealed. The contact force signals of each pair of gears with the coupling fault are obtained by dynamic simulation. The test signals of the fixed-axis gearbox and planetary gearbox are obtained under normal and coupling fault states. According to the method of system identification, the corresponding transfer function model of each path is established. The transfer process is revealed by the analysis of transfer characteristics. The association between two kinds of faults is found, which does not exist in a single fault and is difficult to obtain by signal analysis. This study reveals the association and vibration mechanism of the coupled fault, which provides a theoretical basis for fault diagnosis of multistage gears.

In this work, based on nonlinear robust control theory and computer virtual simulation technology with driving environment identification, we propose a robust controller and design a dynamic simulation analysis system for tractor-semitrailer with interference on rainy slippery road, and this work’s purpose is to solve the virtual simulation analysis problem nonlinear vehicle systems and improve those vehicles safety under harsh environment. Firstly, a verified 6DOF vehicle model with nonlinear tire based on vehicle simulation and analysis data was proposed with external interferences. Jacobian matrix eigenvalues criterion and 3D phase space portrait method were employed for investigating vehicle bifurcations, with crosswind and pavement interferences. Then, the nonlinear bifurcation of the vehicle is analyzed. And, based on robust control theory, taken the tractor yaw rate and joint angle as control objects, a MIMO H ∞ dual feedback synthetic controller with strategy for active front wheel steering (AFS) and direct yaw moment control (DYC) was designed. Furthermore, we have built a new computer dynamic virtual simulation and analyzing system prototype. Finally, the simulation results reveal that Hopf bifurcations are identified with interferences, various equilibrium forms of stability are visualized as well. And the designed controller has good effect on eliminating bifurcations and improving robust stability of tractor-semitrailer with crosswind interference and parameter perturbation on lower adhesion road. It is a valuable reference for tractor-semitrailer safety design and nonlinear analysis under harsh environment, and it also give a useful reference to future intelligent logistics truck platoon design and nonlinear dynamic control.

It is important that automotive engineers understand the interactions between active human maneuvering motions and vehicle dynamics, and how vehicle control affects the physical sensations of the human driver. This paper proposes a new system framework, the human model-based active driving system (HuMADS) for simulating human driver-vehicle interactions. HuMADS integrates the vehicle controller with models of vehicle dynamics and human biomechanics. It has an hierarchical closed-loop architecture for driver-vehicle control systems, including structures and contact interfaces of human and vehicle bodies. HuMADS is based on the OpenSim simulation platform. The developed system regulates the human model dynamics, such that the human model can react realistically to vehicle maneuver motions. The usability of the HuMADS is demonstrated through the simulation of coordinated gas/brake pedal operation and wheel-steering in highway driving tasks. The simulated vehicle dynamics and vehicle maneuvers are comparable with previously published experimental data of car-following driving. In addition, the proposed controllers successfully maintain the human body’s balance inside the vehicle during vehicle maneuvers. We are convinced that the HuMADS has potential as a tool for the development of intelligent transportation systems and investigation of integrated safety.

This paper presents a quantitative analysis of the operations of shared-ride automated mobility-on-demand services (SRAMODS). The study identifies (i) operational benefits of SRAMODS including improved service quality and/or lower operational costs relative to automated mobility-on-demand services (AMODS) without shared rides; and (ii) challenges associated with operating SRAMODS. The study employs an agent-based stochastic dynamic simulation framework to model the operational problems of AMODS. The agents include automated vehicles (AVs), on-demand user requests, and a central AV fleet controller that can dynamically change the plans (i.e. routes and AV-user assignments) of AVs in real-time using optimization-based control policies. The agent-based simulation tool and AV fleet control policies are used to test the operational performance of AMODS under a variety of scenarios. The first set of scenarios vary user demand and a parameter constraining the maximum user detour distance. Results indicate that even with a small maximum user detour distance parameter value, allowing shared rides significantly improves the operational efficiency of the AV fleet, where the efficiency gains stem from economies of demand density and network effects. The second set of scenarios vary the mean and coefficient of variation of the curbside pickup time parameter; i.e. how long an AV must wait curbside at a user’s pickup location before the user gets inside the AV. Results indicate that increases in mean curbside pickup time significantly degrade operational performance in terms of user in-vehicle travel time and user wait time. The study quantifies the total system (user plus fleet controller) cost as a function of mean curbside pickup time. Finally, the paper provides an extensive discussion of the implications of the quantitative analysis for public-sector transportation planners and policy-makers as well as for mobility service providers.

The ability of wheeled mobile robots to overcome steps is often limited by wheel size. Enhancing the ability of mobile robots to overcome obstacles is essential for extending their operation area, and many previous attempts have been made by using transformable wheels, a linkage mechanism, and a spoke-type wheel-leg mechanism. In this study, we propose a shape-morphing wheel mechanism for step climbing at high speed. In the general case of low speed locomotion, a robot's wheels can be used normally. However, to overcome relatively large obstacles, the robot's wheels can extend its shape by using the proposed morphing mechanism with centrifugal force at high speed locomotion. Two modes of step climbing are analyzed that use kinetic energy conversion or impact on the steps. Detail design issues with comprehensive analyses results are presented. Results demonstrate that a robot with morphing wheels can climb a 46.67 mm obstacle at 1.82 m/s, which is 1.33 times larger than the wheel radius. We expect that this method can be applied to other locomotion modes of wheeled mobile robots.

Mechanics and control of innovative gyroscopic structural systems are detailed in the paper. By adding controllable spinning wheels to a network of controllable, axially loaded strings and bars, it is shown that the mobility and manipulation of the structural system are enhanced. Using principles of mechanics, a nonlinear dynamic model is presented to modulate the torque produced by the network of spatially distributed gyroscopes. Equations of motion, formulated as a second-order matrix differential equation, provide a trajectory for the nodal displacement of the bars, along with the wheel's spin degree of freedom. While the gyroscopic robotics concept is scalable to an arbitrarily large network, this research aims to identify elemental modules to override fundamental design principles of the innovative structural systems. Dynamic simulation and experimental verification on a planar D-bar tensegrity structure are used to demonstrate the utility of one such fundamental building block of the gyroscopic robotic system.

The World Health Organization reports that approximately 15% of the world’s population is disabled. Physiotherapy helps promote functional recovery in upper and lower extremity impairment. An exoskeleton robot-based exercise tool for neurorehabilitation is an appealing solution to treat many disabled people. Knowledge of anatomical characteristics and anthropometrical properties are equally important for mechanical design, as well as modeling, and control of exoskeleton robots. However, most of the anthropometrical data is not readily available from a single source. Additionally, eight degrees of freedom human lower extremity kinematic and dynamic models are also not available. This paper presents dynamic modeling and simulation of the human lower extremity (HLE). A comprehensive review of HLE anatomical characteristics, degrees of freedom, and range of motion of various joints are presented. The Lagrange energy method is used for developing the dynamic model. The developed model includes both linear and rotational displacements of the knee joint. The dynamic simulation uses a sliding mode controller. Simulation results show the performance of the controller, joint torque, and power requirements for tracking specified trajectories. It is also shown that sliding mode control (SMC) is a robust control scheme that works effectively even in the presence of external disturbances and parameter variations. The simulation results indicate that SMC is a suitable choice for controlling a physical exoskeleton robot.

Dynamic simulation is vitally important in power system analysis, but traditional approaches based on numerical integration over small time steps are time-consuming. Also, the Newton-Raphson method suffers from difficulty in convergence when solving nonlinear algebraic equations. This paper proposes a novel dynamic simulation approach based on holomorphic embedding. By obtaining a high-order approximation of system dynamics, it achieves a much larger time step and thus enhances the computational efficiency significantly. In addition, the new approach avoids non-convergence issues in solving algebraic equations, which improves robustness. The approach includes flexible modeling of synchronous generators and controllers, and we propose a method for modeling generator coordinate transformations. The approach is tested on the IEEE 39-bus, 10-generator system and a Polish 2383-bus, 327-generator system. The results demonstrate promising computational efficiency and satisfactory numerical robustness for the analysis of large-scale power systems.

Due to the maturity of wide area measurement technology, phasor measurement unit (PMU)-based dynamic equivalent modeling method (PDM) has been wildly used in large-scale power system modeling. However, traditional “event-based” PDM equivalent model may face serious robustness issues, such as although derived equivalent models show the good ability on reproduction of the system behaviors under recorded events where they derived from, they may not work well for other possible disturbances. In this article, to improve the robustness of equivalent model, a novel method on dynamic equivalent modeling of power system is proposed. Based on the result of coherency identification, generators inside the equivalent system can be aggregated into different coherent subgroups and represented by multimachine equivalent model. Key parameter selection, which can shrink the scale of identified parameters, is designed to avoid multiple solutions of the equivalent model. Moreover, a multiobjective parameter identification algorithm is developed to fully consider the PMU measurements in different system events. In addition, hybrid dynamic simulation is performed so that each equivalent submodel can be identified separately. Finally, the effectiveness of the proposed method is verified in an actual power grids in China.

In this study, an unsymmetrical bistable multi-magnetic circuit permanent magnetic actuator is proposed. The operating principle and mathematical model of the high-voltage circuit breaker with the proposed machine are analysed. Additionally, the static and dynamic characteristics of the high-voltage circuit breaker with the presented machine are investigated and evaluated using numerical finite element analysis methods. Furthermore, the influence of the length of the middle gap and the additional coil in the proposed machine are studied. The advantages of the presented machine, such as less magnet volume, low cost, high force density, and short starting time, are discussed. Finally, a prototype is created and tested, followed by the retrieval of the characteristic curves of the holding force to confirm the proposed design.

The wide application of large inertia loads in space drive mechanisms is relatively rare in theoretical research. An 8-degree-of-freedom nonlinear dynamic model is established for the time-varying and nonlinear perturbation problems of a large inertia load space drive mechanism. The model is a two-stage spur gear model in which the effects of backlash and time-varying stiffness are considered. The 3D model was imported into ADAMS, and the nonlinear dynamic response of the system was studied by motion simulation. This paper sets up a large inertia experimental device to collect and process data. Comparing experimental results with Adams results, the correctness of the numerical model was verified, and the reasons for the differences between the two were explained. A comparative analysis of the load response under different inertia was performed to illustrate the importance of studying large inertia loads. The simulation results show that the output shaft has a great influence on the dynamic response. Changing the material of the gear can improve the transmission precision of the gear system. The analysis results in this paper enrich the research on the dynamic response of gear system, and provide a theoretical basis for the subsequent design of large inertia load gear system and improve vibration and noise during operation.

Ankle injury and dysfunction are always accompanied by abnormal peripheral tissues. In order to achieve a more comprehensive rehabilitation training, this article firstly studies the movement characteristics of the surrounding muscles of the ankle-foot. The human musculoskeletal model in OpenSim is used for human exercise experiment. And the relationship between different muscles around the ankle-foot and the direction of the ankle-foot movement are measured respectively, so as to formulate ankle-foot static/dynamic rehabilitation strategies related to the auxiliary training of the ankle-foot muscle. In order to implement the established rehabilitation exercise strategy and to reduce the control difficulty of rehabilitation robot, a new type of decoupling series-parallel mechanism with three rotations and one movement is proposed. After analyzing the degree of freedom and the positive kinematics solution, it is proved that it is completely decoupled in kinematics, can realize the independence of motion control, and there is no singular space. Then, under the premise of meeting the space required for the implementation of the rehabilitation strategy, the proposed new ankle-foot rehabilitation robot is optimized in terms of structure and component size, which improves its space utilization and optimizes the overall mechanical performance. Finally, the dynamic simulation experiment is carried out with the dynamic rehabilitation strategy as the goal, which proves that the robot can realize the normal gait simulation movement in sitting posture, and the motion control of the robot is independent of each other and shows good dynamic performance. Through investigation, the ankle-foot rehabilitation robot designed in this article is cost-effective.

Voltage stability is a relevant part of power system stability analysis ever since many voltage collapse incidences have occurred at different regions of the world. In this paper we take up IEEE 118 bus system as it represents a close approximation of standard Grid system. This IEEE 118-bus system has fixed number of predefined generators, synchronous condensers, transmission lines, transformers and loads. In this work IEEE 118 bus system is simulated and load flow simulation is computed using the software PSS®E. The weak buses of the IEEE standard 118 bus network are predicted with the help of L-Index Algorithm in MATLAB. Further dynamic simulation is also performed in the weak buses obtained from L-Index as it opens up scope of more detail analysis of the system. An initial transient disturbance is then introduced in the weak buses and then the resultant maximum frequency deviation and the recovery time of the voltage is computed which finally helps to detect the weak areas in the transmission network. Further Critical Clearing time of the weakest bus is also computed.

This chapter focuses to develop positive‐sequence synchronous machine models suitable for dynamic simulation of power system disturbances. A synchronous machine subject to a 3‐phase fault exhibits a variety of time responses in different time scales, namely, the transient and subtransient effects, as it settles to a new steady state after the fault is cleared. The chapter discusses how to interface the detailed synchronous machine model to the power network, and how to develop a linearized synchronous machine model. The generator terminal voltages are developed using the states from the synchronous machine dynamic model. The linearization of power systems with subtransient generator models will increase the dimensions of the state variables and the system matrix. The chapter shows the systematic reduction of the 2‐axis model to simpler models, including the flux‐decay model and the electromechanical model. It should be noted that finite‐element methods have been proposed to compute the machine parameters.

This chapter discusses power system dynamics and simulation using the electromechanical model for generators and the constant impedance model for loads. It shows how generators and loads can be connected into the static power network to form a dynamic system. The chapter presents the impact of faults on power system stability by simulating the resulting power system dynamics. It discusses fault‐on and post‐fault electrical power computation for the single‐machine infinite‐bus system. The chapter analyses dynamic simulation and uses the electromechanical model of synchronous machines to illustrate the simulation of power systems subject to disturbance conditions. The Euler method requires one evaluation of vector at each integration step, and is straightforward to implement. The chapter also discusses several integration methods for numerically computing the time response of such dynamic power systems to disturbances.

This chapter starts with a description of static load models, and with a discussion on incorporating such loads into the power system network solution process. It develops dynamic models of inductor motor models and discusses the motor initialization and simulation process. Two types of static load models are considered: the exponential load model and the polynomial load model, also known as the ZIP model. Induction motors of all sizes are used in factories and households, and can be a significant part of the total load. As an induction motor is a rotating machine with inertia and consumes both active and reactive power for its operation, its dynamics need to be captured in stability simulation programs. To incorporate induction motor models into a dynamic simulation program, the model parameters need to be put into per‐unit values. Induction machines have gained popularity with their application in variable‐speed wind turbine‐generators.

This paper presents a method for establishing a unified dynamics model of constrained metamorphic mechanisms. Based on the equivalent resistance, the influences of geometric constraints and/or force constraints on metamorphism are discussed, and the kinematic characteristics of metamorphic joints are described and analyzed in detail. On this basis, the metamorphic configurations of augmented Assur groups can be classified into three types, including non-collision, internal collision and external collision configurations, and the configuration complete dynamics models of augmented Assur groups are established. Then, the dynamics models of active parts, Assur groups and augmented Assur groups are summarized into a unified mathematical framework, and the unified dynamics model of constrained metamorphic mechanisms can be obtained. Based on the research mentioned above, the initial conditions of all components and the motion law of the active parts are given. The motion laws of all components, the driving force/torque of the active parts and the constraint force/torque of the metamorphic joints can be obtained by iteration and solution based on the theory that velocity and acceleration are same in an extremely brief period. Taking the planar double-folded metamorphic mechanism and the metamorphic nipper swing mechanism as examples, the computer numerical analysis and dynamic simulation are carried out to verify the correctness and effectiveness of the proposed theory and method.

A critical voltage-sag removal time (CVSRT), reflecting a duration from the beginning of voltage sags to the instant when speed of an induction motor reduces to the critical value, is important for maintaining the motor’s stable running. The CVSRT can be usually determined by time-domain dynamic simulation that always requires a full set of induction motor parameters. This approach is quite tedious since the simulation must be repeated until the correct CVSRT is found. Also, the motor equivalent-circuit parameter is often not readily available, particularly with the on-site motors. Thus, this paper presents an alternative analytical approach to determine the CVSRT under balanced and unbalanced sag conditions. A motor slip-torque curve mainly required for CVSRT calculation is analytically computed using manufacturer technical data instead of the equivalent-circuit parameters. The slip-torque curve is modified to take effects of voltage unbalance and feeder cable impedance into account. The obtained slip-torque curves are validated against the published data. The CVSRTs straightforwardly computed from the proposed analytical approach are compared against those from the time-domain simulation. A good agreement between them is observed in satisfactory manner.

Large-scale wind and solar power integration are likely to cause a short-term mismatch between generation and load demand because of the intermittent nature of the renewables. System frequency is therefore challenged. In recent years, it has been proposed that a part of the residential load can be controlled for frequency regulation with little impact on customer comfort. This paper proposes a thermostatic load control strategy for primary and secondary frequency regulation, in particular, using heating, ventilation, and air-conditioning units and electric water heaters. First, daily demand profile modeling indicates that these two loads are complementary in the daytime and can provide a relatively stable frequency reserve. Second, the progressive load recovery is specifically considered in the control scheme. The random switching and cycle recovery method is proposed for mitigating power rebound after switching the air conditioners on again. The proposed control strategy can organize a large population of thermostatic loads for the provision of a frequency reserve. Consequently, the requirement of a spinning reserve is reduced. Finally, the proposed control strategy is verified by the dynamic simulation of IEEE RTS 24-bus system.

PurposeThis paper aims to propose a double-sided switched reluctance linxear generator (DSRLG) exclusively for wave power generation. The initial dimensions are given through design experience and principles. To ameliorate comprehensive performance of the DSRLG, the multi-objective optimization design is processed.Design/methodology/approachThe multi-objective optimization design of the DSRLG is processed by adopting a modified entropy technique for order of preference by similarity to ideal solution (TOPSIS) algorithm. First, sensitivity analyzes on geometric parameters of the DSRLG are conducted to determine several pivotal geometric parameters as optimization variables. Then, the multi-objective optimization is conducted on the basis of initial dimensions. After determination of synthetical evaluation value of each structure parameter, the best dimension scheme of the DSRLG is concluded.FindingsAfter verification by finite element method simulation and dynamic simulation, the final dimension scheme proves to perform better than the initial scheme. Finally, experiments are conducted to verify the accuracy of both the stable finite element DSRLG model and dynamic simulation system model so that the conclusion of this paper proves to be reliable and compelling.Originality/valueThis paper proposes an improved structure of the DSRLG, which is superior for wave power generation. Meanwhile, a novel modified entropy TOPSIS algorithm is applied to the field of electrical machine multi-objective optimal design for the first time.

Purpose The effects of rotor blade design variables and their mutual interactions on aerodynamic efficiency of helicopters are investigated. The aerodynamic efficiency is defined based on figure of merit (FM) and lift-to-drag responses developed for hover and forward flight, respectively. Design/methodology/approach The approach is to couple a general flight dynamic simulation code, previously validated in the time domain, with design of experiment (DOE) required for the response surface development. DOE includes I-optimality criteria to preselect the data and improve data acquisition process. Desirability approach is also implemented for a better understanding of the optimum rotor blade planform in both hover and forward flight. Findings The resulting system provides a systematic manner to examine the rotor blade design variables and their interactions, thus reducing the time and cost of designing rotor blades. The obtained results show that the blade taper ratio of 0.3, the point of taper initiation of about 0.64 R within a SC1095R8 airfoil satisfy the maximum FM of 0.73 and the maximum lift-to-drag ratio of about 5.5 in hover and forward flight. Practical implications The work shows the practical possibility to implement the proposed optimization process that can be used for the advanced rotor blade design. Originality/value The work presents the rapid and reliable optimization process efficiently used for designing advanced rotor blades in hover and forward flight.