Papers by Keyword: State Space Model

Abstract: In order to control an unmanned helicopter accurately and reliably, it is necessary to have a precise mathematical model of its dynamics. This paper presents a new timedomain identification method and process for full state space model of small-scale unmanned helicopters. The identification method is called ISAcwPEM (Improved Simulated Annealing combined with Prediction Error Method), which is not sensitive to initial point selection and doesn’t require frequency-sweeping inputs. Firstly, the primary parameters to be identified are selected by model sensitivity analysis. After that, the improved simulated annealing algorithm runs in a distributed computing platform to figure out a 13-order state space model of the SJTU T-REX700E small-scale unmanned helicopter (consisting of a cruise modal and a hover modal). Then the iterative Prediction Error Method (PEM) is used to optimize the model. In addition, the time-delay term and the trim term are estimated and added to the model. Finally, the effectiveness of the identification method is well validated by real outdoor flight experimental results.

Abstract: The scope of this paper is to look beyond linear solutions and discuss briefly about the recent developments in nonlinear system control & controller tuning methods. An adaptive cruise control model is taken as case study to illustrate the practicality of implementation in the simulation environment in terms of modelling and control of non-linear process. Effort is made to analyse the nonlinear system control in MATLAB and PROTEUS environment.

Abstract: A dynamic simulation method of thermal environment was presented to evaluate the thermal performance of solar greenhouse. Solar greenhouse was firstly simplified into several components according to characteristics of its structure and materials, and then each component was divided into several temperature elements. For each element, heat balance equation was respectively built and integrated into a lumped model which was used to describe the thermal system of solar greenhouse. Consequently, a dynamic simulation based on state-space method was developed to calculate indoor temperature variations under the ambient conditions and structures of solar greenhouse. Experimental results show the presented method can simulate the long-term changes of indoor temperature, and are beneficial to evaluate and predict the thermal performance of solar greenhouses.

Abstract: The paper proposed a new systematic method to construct the functional relationship between product quality and tolerances. In the method, a unified user-defined tolerance model is designed to synthesize different kinds of tolerances using 3-D state space model; a deviation propagation model is proposed to analyze the quality-tolerance function. Particularly, the method is suitable for any kinds of tolerances and quality requirements. The method is successfully applied to the turbo-generator stator-core lamination auto-assembly project, and Monte Carlo method is used to simulate the quality performance and optimize the target tolerances.

Abstract: This article investigates how the scale and structure of energy production influence on sustainable economic development in China. First and foremost, the relationship between energy production and economic development was discussed in theory, and a time-varying parameter state space model was established. Then an empirical study based on the annual data from 1981 to 2012 was carried out by using method of Kalman filter. The results indicate that both the increasing scale of energy production and the increasing proportion of new energy have a positive and significant influence on Chinese economic growth. Finally, the thesis draws a conclusion that, expanding the scale of energy production and optimizing the structure of energy production will significantly promote China's sustainable economic growth.

Abstract: In order to simulate the dynamic trends of the influencing factors of water resources gap and periodic characteristics of the related factors, this paper establishes regional transition model and Error Correct Model as well as state-space model, whose parameters are used to measure the influences and trends. Empirical results implicit that these models fit sample data very well and some useful conclusions can be drawn from these parameters estimation. Different functions of influencing factors between periods of short and adequacy of water supply are showed. It is necessary to arrange consumption use rationally because of its greater percentage when water was scarce. The increasing consumption use becomes the main factor of water shortage.

Abstract: To improve the existing methods of identifying the key quality characteristics in multistage manufacturing process, the partial least squares regression (PLSR) method is combined with the state space model that a new method of identifying the key quality characteristics in multistage manufacturing process based on PLSR is proposed. According to the feature of multistage manufacturing process, the state space model is introduced to build the key quality characteristics identifying model for multistage manufacturing process, using the PLSR method to solve the problem of the quality characteristics such as multicollinearity, do model analyzing and identify the key quality characteristics. At last, the cigarette production process is presented as an example to introduce the application of this method. The result shows that this method can not only identify the key quality characteristics in multistage manufacturing process, but also establish the model of output quality effecting of all levels on the final product quality and its quality characteristics relationship, which reflect the structure of the multistage manufacturing process and causal relationship between quality characteristics at all process levels, provide the basis for quality analysis and control in multistage manufacturing process.

Abstract: Ship autopilots are usually designed based on PID controller because of the simplicity and the ease of construct. However its performance in various environmental conditions is not as good as desired. This disadvantage can be decreased by designing a linear state space feedback controller. This paper presents the utility of the state-space feedback controller to stabilize the system and shaping its response as desired. The simulation results for a 4DOF ship with real parameters show the effectiveness of the feedback controller in comparison with ordinary PID ship autopilots.

Abstract: A novel parameter estimation method for unknown static parameters of the state space model using particle filtering (PF) has proposed in this paper. Traditional methods enlarge state vector by treating the unknown parameter θ as a part of state vector (x_k,θ) . But this may cause the degeneration of θ, when some estimates become too small to continue as a result of the non-dynamic character of parameters if θ at time k is only determined by time k-1. Compared to traditional methods, this novel method assumes that the posterior distribution of θ is given by previous observation and state vectors, z_1:k and x_1:k. Obtain statistics at time k by using the integration of z_1:k and x_1:k, and solve parameter estimation problem by updating θ recursively. Good results are obtained when this method is used in different models.

Abstract: Based on stream of variation theory, parametric state space model of multi-station assembly process was built up. For problems of system-level evaluation index, the sensitivity evaluation index, soundness index as three methods of assembly system performance evaluation, the comprehensive stability index was presented. Parametric state space model was as a tool and the comprehensive stability index was as evaluation index to optimize the assembly lines, reduce the geometric deviation of product, improve the quality of product. Experiment verified comprehensive stability index can accurately evaluate the performance of assembly systems, improve the efficiency of optimizing assembly lines.