共查询到20条相似文献,搜索用时 15 毫秒
1.
As the spring equation is limited to the accuracy of mill stiffness and the linearity of the mill spring curve, the traditional gaugemeter automatic gauge control (GM-AGC) system based on spring equation cannot meet the requirements of practical production. In allusion to this problem, a kind of novel GM-AGC system based on mill stretch characteristic curve was proposed. The error existing in calculating strip thickness by spring equation were analyzed first. And then the mill stretch characteristic curve which could effectively eliminate the influence of mill stiffness was described. The novel GM-AGC system has been applied successfully in a hot strip mill, the application results show that the thickness control precision is improved significantly, with the novel GM-AGC system, over 98.6% of the strip thickness deviation of 3.0 mm class can be controlled within the target tolerances of ±20 μm. 相似文献
2.
Adaptive Type-2 fuzzy control possesses control performance better than the traditional adaptive fuzzy control.However,heavy computation burden obviously blocks the utilization of adaptive Type-2 fuzzy control in industrial application.By adopting novel piecewise fuzzy sets and center-average type-reduction,a simplified adaptive interval Type-2 fuzzy controller involving less computation is developed for practical industrial application.In the proposed controller,the inputs are divided into several subintervals and then two piecewise fuzzy sets are used for each subinterval.With the manner of piecewise fuzzy sets and a novel fuzzy rules inference engine,only part of fuzzy rules are simultaneously activated in one control loop,which exponentially decreases the computation and makes the controller appropriate in industrial application.The simulation and experimental study,involving the popular magnetic levitation platform,shows the predicted system with theoretical stability and good tracking performance.The analysis indicates that there is far less computation of the proposed controller than the traditional adaptive interval Type-2 fuzzy controller,especially when the number of fuzzy rules and fuzzy sets is large,and the controller still maintains good control performance as the traditional one. 相似文献
3.
In order to achieve higher efficient cohesion match of procedure and equipment between ironmaking and steelmaking interface, the theory of multi-dimensional material flow control was applied to analyze torpedo ladle-iron ladle transportation process between blast furnace and basic oxygen furnace. Moreover, basic parameters of material flow were analyzed and optimized, such as time, temperature and material quantity. Based on operating principles of material flow, control methods were optimized, such as product organization mode, scheduling discipline and scheduling plan of hot metal ladle. Finally, the material flow control technology of ironmaking and steelmaking interface was integrated. Satisfactory effects are obtained after applying the technology in practice. The total turnover number of torpedo ladle decreases from 20 to 18, the hot metal temperature of 1# BF torpedo ladle decreases from 36 °C to 19.5 °C, the hot metal temperature of 2# BF torpedo ladle decreases from 36.6 °C to 19.8 °C, the temperature drop of desulfurization hot metal decreases by 4 °C, and the temperature drop of non-desulfurization hot metal decreases by 2.8 °C. Furthermore, the ironmaking and steelmaking interface system will realize high-efficiency control by using this control technology. 相似文献
4.
Inverse speed is a reversible maneuver.It is a characteristic of underwater vehicle at low speed.Maneuverability in the vertical plane at a speed lower than inverse speed is different from one at higher speed.In the process of underwater working for observation,AUV's cruise speed is always low.Therefore,the research on inverse speed is important to AUV's maneuverability.The mechanism of inverse speed was analyzed,and then the steady pitching equation was derived.The parameter expression of track angle in vertical plane was deduced.Furthermore,the formula to calculate the inverse speed was obtained.The typical inverse speed phenomenon of the flat body and the revolving body was analyzed.Then the conclusion depicts that,for a particular AUV with flat body,its inverse speed is lower than that of revolving body.After all the calculation and the analysis,a series of special experiments of inverse speed were carried out in the simulation program,in the tank and in the sea trial. 相似文献
5.
For multiple grid-connected inverters with active filter function, it makes sense to regulate every unit to output maximum active power from photovoltaic arrays, as well as eliminate the harmonic due to the non-linear loads connected to the electric networks. Naturally, a centralized control coordination strategy was proposed for the purpose of high facility utilization, good harmonic compensation ability and unwanted overcompensation condition. Based on a vector decoupling control scheme and generalized instantaneous reactive power theory, the solution was to allocate the harmonic eliminating task for every inverter according to the instantaneous power margin of each. The grid current always keeps sinusoidal in spite of non-linear load change and output active power change for any inverter. The simulation results validate the efficacy of the proposed coordination strategy. 相似文献
6.
Aiming at the group of autonomous agents consisting of multiple leader agents and multiple follower ones, a flocking behavior method with multiple leaders and a global trajectory was proposed. In this flocking method, the group leaders can attain the information of the global trajectory, while each follower can communicate with its neighbors and corresponding leader but does not have global knowledge. Being to a distributed control method, the proposed method firstly sets a movable imaginary point on the global trajectory to ensure that the center and average velocity of the leader agents satisfy the constraints of the global trajectory. Secondly, a two-stage strategy was proposed to make the whole group satisfy the constraints of the global trajectory. Moreover, the distance between the center of the group and the desired trajectory was analyzed in detail according to the number ratio of the followers to the leaders. In this way, on one hand, the agents of the group emerge a basic flocking behavior; on the other hand, the center of the group satisfies the constraints of global trajectory. Simulation results demonstrate the effectiveness of the proposed method. 相似文献
7.
Traffic jam in signalized road network简 总被引:1,自引:0,他引:1
Traffic jam in large signalized road network presents a complex nature.In order to reveal the jam characteristics,two indexes,SVS(speed of virtual signal) and VOS(velocity of spillover),were proposed respectively.SVS described the propagation of queue within a link while VOS reflected the spillover velocity of vehicle queue.Based on the two indexes,network jam simulation was carried out on a regular signalized road network.The simulation results show that:1) The propagation of traffic congestion on a signalized road network can be classified into two stages:virtual split driven stage and flow rate driven stage.The former stage is characterized by decreasing virtual split while the latter only depends on flow rate; 2) The jam propagation rate and direction are dependent on traffic demand distribution and other network parameters.The direction with higher demand gets more chance to be jammed.Our findings can serve as the basis of the prevention of the formation and propagation of network traffic jam. 相似文献
8.
Abstract: Two-tier heterogeneous networks (HetNets), where the current cellular networks, i.e., macrocells, are overlapped with a large number of randomly distributed femtocells, can potentially bring significant benefits to spectral utilization and system capacity. The interference management and access control for open and closed femtocells in two-tier HetNets were focused. The contributions consist of two parts. Firstly, in order to reduce the uplink interference caused by MUEs (macrocell user equipments) at closed femtocells, an incentive mechanism to implement interference mitigation was proposed. It encourages femtoeells that work with closed-subscriber-group (CSG) to allow the interfering MUEs access in but only via uplink, which can reduce the interference significantly and also benefit the marco-tier. The interference issue was then studied in open-subscriber-group (OSG) femtocells from the perspective of handover and mobility prediction. Inbound handover provides an alternative solution for open femtocells when interference turns up, while this accompanies with PCI (physical cell identity) confusion during inbound handover. To reduce the PCI confusion, a dynamic PCI allocation scheme was proposed, by which the high handin femtocells have the dedicated PCI while the others share the reuse PCIs. A Markov chain based mobility prediction algorithm was designed to decide whether the femtoeell status is with high handover requests. Numerical analysis reveals that the UL interference is managed well for the CSG femtocell and the PCI confusion issue is mitigated greatly in OSG femtocell compared to the conventional approaches. 相似文献
9.
High-accuracy motion trajectory tracking control of a pneumatic cylinder driven by a proportional directional control valve was considered. A mathematical model of the system was developed firstly. Due to the time-varying friction force in the cylinder, unmodeled dynamics, and unknown disturbances, there exist large extent of parametric uncertainties and rather severe uncertain nonlinearities in the pneumatic system. To deal with these uncertainties effectively, an adaptive robust controller was constructed in this work. The proposed controller employs on-line recursive least squares estimation (RLSE) to reduce the extent of parametric uncertainties, and utilizes the sliding mode control method to attenuate the effects of parameter estimation errors, unmodeled dynamics and disturbances. Therefore, a prescribed motion tracking transient performance and final tracking accuracy can be guaranteed. Since the system model uncertainties are unmatched, the recursive backstepping design technology was applied. In order to solve the conflicts between the sliding mode control design and the adaptive control design, the projection mapping was used to condition the RLSE algorithm so that the parameter estimates are kept within a known bounded convex set. Extensive experimental results were presented to illustrate the excellent achievable performance of the proposed controller and performance robustness to the load variation and sudden disturbance. 相似文献
10.
Learning control for gradually varying references in iteration domain was considered in this research, and a composite iterative learning control strategy was proposed to enable a plant to track unknown iteration-dependent trajectories. Specifically, by decoupling the current reference into the desired trajectory of the last trial and a disturbance signal with small magnitude, the learning and feedback parts were designed respectively to ensure fine tracking performance. After some theoretical analysis, the judging condition on whether the composite iterative learning control approach achieves better control results than pure feedback contro! was obtained for varying references. The convergence property of the closed-loop system was rigorously studied and the saturation problem was also addressed in the controller. The designed composite iterative learning control strategy is successfully employed in an atomic force microscope system, with both simulation and experimental results clearly demonstrating its superior performance. 相似文献
11.
As the sampling rates of the inner loop and the outer loop of the target tracking control system are different, a typical digital multi-rate control system was formed. If the traditional single-rate design method was applied, the low sampling rate loop will seriously impact the dynamical characteristic of the system. After analyzing and calculating the impact law of the low sampling rate loop to the bandwidth and the stability of the tracking system, a kind of multi-rate control system design method was introduced. Corresponding to the different sampling rates of the inner loop and the outer loop, the multi-rate control strategy was constituted by a high sampling rate sub-controller and a low sampling rate sub-controller. The two sub-controllers were designed separately and connected by means of the sampling rate converter. The low sampling rate controller determined the response rapidity of the system, while the high sampling rate controller applied additionally effective control outputs to the system during a sampling interval of the low sampling rate controller. With the introduced high and low sampling rates sub-controllers, the tracking control system can achieve the same performance as a single-rate controller with high sampling rate, yet it works under a much lower sampling rate. The simulation and experimental results show the effectiveness of the introduced multi-rate control design method. It reduces the settling time by 5 times and the over shoot by 4 times compared with the PID control. 相似文献
12.
A novel cooling system combining ultra fast cooling rigs with laminar cooling devices was investigated. Based on the different cooling mechanisms, a serial of mathematic models were established to describe the relationship between water flow and spraying pressure and the relationship between water spraying heat flux and layout of nozzles installed on the top and bottom cooling headers. Model parameters were validated by measured data. Heat transfer models including air convection model, heat radiation model and water cooling capacity model were detailedly introduced. In addition, effects on cooling capacity by water temperature and different valve patterns were also presented. Finally, the comparison results from UFC used or not have been provided with respect to temperature evolution and mechanical properties of Q235B steel grade with thickness of 7.8 mm. Since online application of the sophisticated CTC process control system based on these models, run-out table cooling control system has been running stably and reliably to produce resource-saving, low-cost steels with smaller grain size. 相似文献
13.
A simple control structure in servo system is occasionally needed for simple industrial application which precise and high control performance is not exessively important so that the cost production can be reduced efficiently. Simplified vector control, which has simple control structure, is utilized as the permanent magnet synchronous motor control algorithm and genetic algorithm is used to tune three PI controllers used in simplified vector control. The control performance is obtained from simulation and investigated to verify the feasibility of the algorithm to be applied in the real application. Simulation results show that the speed and torque responses of the system in both continuous time and discrete time can achieve good performances. Furthermore, simplified vector control combined with genetic algorithm has a similar perfofmance with conventional field oriented control algorithm and possible to be realized into the real simple application in the future. 相似文献
14.
With a focus on an industrial multivariable system, two subsystems including the flow and the level outputs are analysed and controlled, which have applicability in both real and academic environments. In such a case, at first, each subsystem is distinctively represented by its model, since the outcomes point out that the chosen models have the same behavior as corresponding ones. Then, the industrial multivariable system and its presentation are achieved in line with the integration of these subsystems, since the interaction between them can not actually be ignored. To analyze the interaction presented, the Gershgorin bands need to be acquired, where the results are used to modify the system parameters to appropriate values. Subsequently, in the view of modeling results, the control concept in two different techniques including sequential loop closing control (SLCC) scheme and diagonal dominance control (DDC) schemes is proposed to implement on the system through the Profibus network, as long as the OPC (OLE for process control) server is utilized to communicate between the control schemes presented and the multivariable system. The real test scenarios are carried out and the corresponding outcomes in their present forms are acquired. In the same way, the proposed control schemes results are compared with each other, where the real consequences verify the validity of them in the field of the presented industrial multivariable system control. 相似文献
15.
Guaranteed cost control of networked control systems under limited communication capacity and variable sampling简 总被引:1,自引:0,他引:1
The problem of guaranteed cost control for the networked control systems (NCSs) with time-varying delays, time-varying sampling intervals and signals quantization was investigated, wherein the physical plant was continuous-time one, and the control input was discrete-time one. By using an input delay approach and a sector bound method, the network induced delays, quantization parameter and sampling intervals were presented in one framework in the case of the state and the control input by quantized in a logarithmic form. A novel Lyapunov function with discontinuity, which took full advantages of the NCS characteristic information, was exploited. In addition, it was shown that Lyapunov function decreased at the jump instants. Furthermore, the Leibniz-Newton formula and free-weighting matrix methods were used to obtain the guaranteed cost controller design conditions which were dependent on the NCS characteristic information. A numerical example was used to illustrate the effectiveness of the proposed methods. 相似文献
16.
Path planning and formation structure forming are two of the most important problems for autonomous underwater vehicles (AUVs) to collaborate with each other. In this work, a dynamic formation model was proposed, in which several algorithms were developed for the complex underwater environment. Dimension changeable particle swarm algorithm was used to find an optimized path by dynamically adjusting the number and the distribution of the path nodes. Position relationship based obstacle avoidance algorithm was designed to detour along the edges of obstacles. Virtual potential point based formation-keeping algorithm was employed by incorporating dynamic strategies which were decided by the current states of the formation. The virtual potential point was used to keep the formation structure when the AUV or the formation was deviated. Simulation results show that an optimal path can be dynamically planned with fewer path nodes and smaller fitness, even with a concave obstacle. It has been also proven that different formation-keeping strategies can be adaptively selected and the formation can change its structure in a narrow area and restore back after passing the obstacle. 相似文献
17.
To design a hyperchaotic generator and apply chaos into secure communication, a linear unidirectional coupling control is applied to two identical simplified Lorenz systems. The dynamical evolution process of the coupled system is investigated with variations of the system parameter and coupling coefficients. Particularly, the influence of coupling strength on dynamics of the coupled system is analyzed in detail. The range of the coupling strength in which the coupled system can generate hyperchaos or realize synchronization is determined, including phase portraits, Lyapunov exponents, and Poincare section. And the critical value of the system parameter between hyperchaos and synchronization is also found with fixed coupled strength. In addition, abundant dynamical behaviors such as four-wing hyperchaotic, two-wing chaotic, single-wing coexisting attractors and periodic orbits are observed and chaos synchronization error curves are also drawn by varying system parameter c. Numerical simulations are implemented to verify the results of these investigations. 相似文献
18.
A comprehensive predictive strategy was proposed for the neutral-point balancing control of back-to-back three-level converters. The phase currents at both sides and the DC-link capacitor voltages were measured for the prediction of the neutral-point current. A quality function was found to balance the neutral-point, and a metabolic on-times distribution factor was used as a predicator to minimize the quality function at each switching state. Simulation results show that the proposed method produces smaller ripples in tested signals compared with the established one, namely, 9.15% less in a total harmonic distortion(THD) of line-to-line voltage, 1.08% less in the THD of phase current, and 0.9 V less in the ripple of the neutral-point voltage. The obtained experimental results show that the main harmonics of the line-to-line voltage and the phase current in the proposed method are improved by 10 d B and 6 d B, respectively, and the ripple of neutral-point voltage is halved compared to the established one. 相似文献
19.
A nonlinear robust controller was presented to improve the tracking control performance of a flexible air-breathing hypersonic vehicle (AHV) which is subjected to system parametric uncertainties and unknown additive time-varying disturbances. The longitudinal dynamic model for the flexible AHV was used for the control development. High-gain observers were designed to compensate for the system uncertainties and additive disturbances. Small gain theorem and Lyapunov based stability analysis were utilized to prove the stability of the closed loop system. Locally uniformly ultimately bounded tracking of the vehicle's velocity, altitude and attack angle were achieved under aeroelastic effects, system parametric uncertainties and unknown additive disturbances. Matlab/Simulink simulation results were provided to validate the robustness of the proposed control design. The simulation results demonstrate that the tracking errors stay in a small region around zero. 相似文献
20.
A systematic method was proposed to estimate the occurrence probability of defective piles (OPDP) from a site according to quality assurance inspection. The OPDP was firstly suggested as the criterion to weight the performance of a pile foundation. Its prior distribution and updating distribution were deduced to follow Beta distributions. To calibrate the OPDP, a dynamic estimation model was established according to the relationships between prior mean and variance and updating mean and variance. Finally, a reliability-control method dealing with uncertainties arising from quality assurance inspection was formalized to judge whether all the bored piles from a site can be accepted. It is exemplified that the OPDP can be substantially improved when more definite prior information and sampling formation become available. For the example studied herein, the Bayesian estimator of updating variance for OPDP is reduced from 0.0037 to 0.0014 for the first inspection, from 0.0014 to 0.0009 for the second inspection, and with less uncertainty by incorporating experience information. 相似文献