Applied Mechanics and Materials Vols. 365-366

Abstract: In this paper, the main factors which influence the current control performance of the Permanent Magnet Synchronous Motor are studied and analyzed. A method, which combines the fast terminal sliding mode control and the current feed forward control methods, is proposed to solve the problems of the cross-coupling of d-q current in field oriented control. Meanwhile, an adaptive control law is designed for the system uncertainties of system parameters perturbation and external disturbances and so on. The convergence of the proposed method is proved by Lyapunov theory. The proposed control method is testified by computer simulation and improves the robustness of the Permanent Magnet Synchronous Motor control system.

Abstract: S surface control is a simple and operative motion control algorithm for underwater vehicles, but it has two parameters requiring to be adjusted manually. In order to enhance the adaptability of S surface controller, the research of S surface controller parameter self-tuning methods based on rules and models is carried out. Firstly, combined with fuzzy control, parameter self-tuning method based on fuzzy rules is presented. Then by means of predictive control theory, model-based parameter self-tuning method is proposed. By introducing the nonlinear autoregressive moving average model, the prediction model of underwater vehicles is established using parallel Elman neural network, and the optimal parameters of S surface controller is obtained by constructing quadratic performance index function. The results of simulation experiments show that the response speed of S surface controller with parameter self-tuning modules is improved, and the parameter self-tuning methods is demonstrated feasible and effective.

Abstract: The focus of research of AUV is gradually moving towards multiple autonomous underwater vehicles (MAUV) in recent years. This paper describes an investigation into cooperative control of MAUV. Firstly, a distributed control architecture (MOOS) was applied to MAUV system. According to MOOS, functionalities of AUV were organized in a modular manner and a unified information exchange mechanism was used to ensure an efficient communication between different modules. Secondly, a behavior based control strategy was proposed to enable the AUV to cooperate with each other intelligently and adaptively. Interval programming algorithm was applied to make sure that behaviors of each AUV can be coordinated in a timely and optimal manner. Stability of behavior-based control of AUV was analyzed. Finally, a distributed simulation environment was established and a series of simulation were carried out to verify the feasibility of methods mentioned above.

Abstract: In this paper, we report an effective method for motion reliability analysis of the PUMA560 series mechanism. It firstly builds a Monte Carlo parameterized 3-D virtual model of this mechanism in ADAMS, and uses VC++ to program a pseudo-random number subroutine function that conforms to normal distribution and user defining function to simulate the stochastic error distribution of the mechanism, and a universal reliability analysis program of the PUMA560 series mechanism is then developed. After multiple virtual tests on this parameterized mechanism model, a large mount of test data are obtained and statistically analyzed to calculate the motion reliability; this can evaluate the influence of different stochastic errors on the mechanism dynamic characteristics. The advantages of this new method include simplicity (no need to solve complex mathematic model) and high accuracy which make it highly promising for application in mechanism design.

Abstract: In recent years, industrial sewing machine intelligence can be increased. Compared with the traditional equipment, the new generation of domestic equipment in the "high efficiency, energy saving, special" has realized great-leap-forward development. In the performance, will towards high precision, high efficiency, high performance, intelligent direction; in function, to the miniaturization, multi-function direction; in the program, to the systematic, integrated direction. The design and development of industrial sewing machine digitization design packaging platform are discussed.

Abstract: An automatic manufacturing system design must be optimized with a simulation including all the interacting devices. The simulation should be controlled by the real control system with a hardware in the loop approach. So the techniques for modeling the mechanisms must be effective for the model to be run without violating the real-time protocol. This paper reports a method to model the motor load by means of a reduced moment of inertia, where all the part downstream from the motor output shaft is transformed in function of the only one mechanism degree of freedom. The resulting model behaves as the real nonlinear mechanism, but it is computationally efficient since it is not ruled by the multibody 3D CAD mathematics.

Abstract: High pressure water jet flexible incremental sheet metal forming (HPWJFISMF), which is a new kind of sheet mental dieless forming with good flexibility, is quite suitable for the production of multi-varieties and small batch products and trial-manufacture of new products. We have designed a five-axis forming machine tool with three translational degrees of freedom of workbench and two rotational degrees of freedom of the nozzle .in order to study the technology of HPWJFISMF. This paper gives a detailed introduction for the hardware structure and software system of machine tool of HPWJFISMF, which adopts an open control system with PC and motion controller. The control system of HPWJFISMF is designed on the platform of VC++6.0 in object-oriented way. The working performance stability of the machine tool has been verified by machining experiments, which offers a good platform for the study of high pressure water jet forming.

Abstract: This paper addresses the stability and stabilization of discrete switched systems which can be used to describe manufacturing systems. A new sufficient and necessary condition in the use of parameter-dependent Lyapunov functions is proposed to guarantee the switched system stability under arbitrary switching. The control synthesis approach presented in this work reduces the conservatism by slack variables while investigating the static output feedback control issue. A cone complementarity linearization algorithm is applied to make the condition a minimization problem in the form of LMIs. By numerical evaluation, the new control design technique is illustrated to be more efficient.

Abstract: We proposed a constrained ruled surface approximation algorithm for 5-axis machining of aero structure. Ruled surface is widely used in the design of aero structure. In practical model process, the regular ruled surface is usually split into some small fragmentary surfaces. The segmentation of the original surface mainly comes from some iterative boolean operations on the ruled surface. The segmentation destroys original parameter lines and leads into complex curved boundaries. Furthermore, the obtained fragmentary surfaces deviate from the original ruled surface because of the accuracy loss in the boolean operations of 3D CAD software. Some gaps between the small surfaces often appear. In manufacturing process, it is difficult to generating high-quality tool path for the surface with disordered parameter lines, curved boundaries and gaps. The proposed ruled surface approximation algorithm provides an effective way to reconstruct the smooth ruled surface. The constraints of boundary and smoothness are both considered. The ruled surface for simultaneous 5-axis machining is finally obtained. This algorithm have been integrated into CATIA V5 system and applied in practical manufacturing planning of aero-structures.

Abstract: Visual navigation is extensively used in contemporary robotics. In particular, we can mention different systems of visual landmarks. In this paper, we consider one-dimensional color panoramas. Panoramas can be used for creating fingerprints. Fingerprints give us unique identifiers for visually distinct locations by recovering statistically significant features. Fingerprints can be used as visual landmarks for mobile robot navigation. In this paper, we consider a method for automatic generation of fingerprints. Since a fingerprint is a circular string, different string-matching algorithms can be used for selection of fingerprints. In particular, we consider the problem of finding the consensus of circular strings under the Hamming distance metric.