The Research On Dynamic Modeling, Optimal Design And Control For Hybrid Linkage Mechanism System

With the rapid development of science and technology, and uninterrupted progress of society, demand on performance of modern mechanisms is more and more highness, especially for the better flexible output. Hybrid mechanism is a new type mechanism with good flexible output. A hybrid mechanism is a configuration that combines the motions of two characteristically different electric motors by means of a mechanism to produce programmable output. Where one of the motions coming from a constant speed motor provides the main power, a small servo-motor introduces programmability to the resultant actuator. Such machines will introduce to users greater flexibility with programmability option, and energy utilization will be realized at maximum. Hybrid mechanisms are products of combination of theory of modern mechanisms, sensor technology, microelectronics technology, modern control theory, computer and information science, and artificial intelligence etc. It is one of the trends of modern mechanism. Based on theory of traditional mechanisms, modern control theory, modern dynamics analysis theory, modern optimization theory, statistics analysis and advance composite mechanics, systemic studies on hybrid linkage mechanism are performed with an example of hybrid five-bar mechanism in this paper. The contributions achieved are suitable for the other types of hybrid linkage mechanism.Hybrid mechanism takes on the characteristic with multiple degree-of-freedom and multi-bar. Using classical techniques to derive the dynamics equations of hybrid mechanism can be a tedious and error-prone task. In this paper, dynamic analysis of hybrid five-bar mechanism was studied based on power bond graph for the first time. The kinematics and dynamics of the mechanism are represented in a form by compact graphics mode and concise notation. Thus, the understanding of the complex static and dynamic interactions within a hybrid mechanism is enhanced. The analyst may view the mechanism-dynamics problem from a fresh perspective-a point of view that often provides new insights into the complex behavior of hybrid mechanism. The unified formula of mechanism dynamics equations derived here is a regularized one. The bond graph method lead to a form suitable for automatic derivation and computation. The procedure does not have to analyze acceleration of hybrid mechanism. In terms of physical parameters of hybrid five bar mechanism and necessary input matrix, the bond graph-based computer programs can automatically derive and solve the dynamic equations of mechanism-dynamics problem on a computer, obviously enhancing efficiency and reliability of dynamics analysis for hybrid five bar mechanism.Hybrid mechanism is highly nonlinear and strong coupling flexible devices. From a point of view of system, the potential law in itself can be just opened out. In this paper, a global coupling dynamic model of a hybrid five-bar mechanism system is established by using power bond graph and power topo-bond graph for the first time. The hybrid system including multi-energy field is represented in a form by compact graphics mode. The coupling properties are depicted and its effect are analysed from this model. The results of simulation show that a global coupling dynamic model of a hybrid five-bar mechanism is correct. The study shows that simulation results of global mathematical model are much closer to experimental results than that of isolated mathematical model. The proposed method may be commonly applied to modeling and analysis of other controllable mechanism systems.By the combination of modern chaos optimization algorithm and the optimization Toolbox of MATLAB6.5 programming language, hybrid optimization algorithm for nonlinear optimization design of hybrid mechanism is proposed. The better capability of the global search is acquired by using the algorithm proposed. Using the hybrid optimization algorithm, kinematics, dynamics and multi objective optimization design for hybrid five-bar mechanism are performed respectively on the base of the analysis of kinematics and dynamics. The results of optimization show that the better integrative performance of mechanism can be obtained by using multi objective optimization design which kinematic, dynamic characteristics and sensitivity of dimensions of links act as objective function.Hybrid mechanism remains with position control following system. Position control accuracy of system determines the profile accuracy of hybrid actuator. Incorporating the grey prediction, repetitive control and the conventional PID control, a design method of the grey prediction repetitive PID control algorithm is presented for the first time. This control algorithm can be divided into three steps: to estimate unsure parameters and disturbance of system using grey prediction, to compensate PID control in terms of the prediction results, and then to add repetitive control for controlling cyclical motion. The simulation results show that this algorithm has better performances than that of the conventional repetitive control system. The control method has better application value for hybrid linkage mechanism taking on a characteristic of cyclical motion. In addition, The CMAC neural network control system is used in this paper. By means of the control system of hybrid driving linkage mechanism, following motion of high tracking precision can be obtained. Simulation results show that this method has better dynamic performance, robustness and anti-disturbance than the traditional PID control.Whereas the better performance and the development of 3-D braided composite, the damping and stiffness analysis of 2-step hollow-box-section 3-D braidedcomposite were performed in this paper. Then, the mathematical model for optimization of the damping and stiffness of bar were proposed. The results of numeral examples show that the better damping and stiffness characteristic could be obtained by using optimal design, contenting the determinate restriction. The method proposed here is useful for the design and engineering application of the kind of member.According to the theoretical model proposed, the experimental equipments of the hybrid actuator realizing flexible output motions were set up. The correlative experiment examinations were made. The results of experiment tallies with simulative results of theories comparatively, which proves that theories of this paper are correct. In addition, the comparison experiments were performed for hybrid five-bar mechanism with components of six kinds of materials respectively. The materials examined were carbon constructional quality steel, aluminum alloy, nylon plastics, phenolic cotton cloth laminated, 3-D braided composite and so on. The results of experiment show that the performance of system is improved obviously with the 3-D braided composites. It is an available approach improving dynamic performance of hybrid mechanism to use 3-D braided composite component. It is important for optimization of the material selection for hybrid mechanism components.There exists connatural effect to output error, from manufacturing error of component of hybrid linkage mechanism. In this paper, the sensitivity analysis of dimensions of links is made for hybrid five-bar mechanism. According to the effect of dimension error of each component for output error, the choice principia for dimension tolerance of each bar are given. In order to open out effect of input kinematic parameters for output error of system, the analysis of statistical dependence is made for hybrid five-bar mechanism in terms of experimental data for the first time. As can been seen, matching up reasonably input kinematic parameters can reduce output error availably. It has practical significance for design of hybrid mechanism.