Key Engineering Materials Vols. 467-469

Abstract: As the electrical source of hearts, sino-atrial node (SAN) plays a significant role in rhythmic firing. The aim of this study is to determine effects of atrium on the electrical activity of SAN. Based on a mathematical model considering central and peripheral SAN cells as well as an atrial model, one-dimensional fiber with a gradual heterogeneity of SANC was developed. The forth-order Runge-Kutta and three-point centered difference methods were used to integrate the conduction model. The results demonstrated that as a load of SAN, atrium decreased the spontaneous sinus rate casing a shift of leading pacemaker site from the periphery to the center. If the ectopic beat produced by a premature stimulation was late after the end of the atrial refractory, the pause following it was compensatory. Otherwise, the pause was non-compensatory. In this case, the peripheral SANC excited earlier than the central SANC. During multiple premature beats, at short intervals the propagation could block in SAN due to a long refractory period of the action potential close to the central SANC. Leading pacemaker site shift was observed during the following several spontaneous SANC excitation. Therefore, the existence of atrium is suggested affecting not only sinus rates, but also the mode of electrical propagation and the site of the earliest excitation.

Abstract: In an ideal situation, good measuring system can be designed if exact information is known concerning performance and structures involved during the lifetime of the measuring object. But in the real world uncertainties of object exist in this information as well as in the method of measurement. To account for these uncertainties, concept of active measurement has been presented in this paper. Nowadays, scale transform and smart sensor have been applied for realizing elementary active measurement technique, the objective herein is to present measuring method of actively adjusting structure based on these factors. The practicality of this concept is illustrated with an engineering system using wire rope nondestructive testing device, double-point measurement device with eddy current probe as sensors is designed. Mathematical model of the rope’s characteristics and real-time quantity to trim of measure device is established according to relative spacing between sensors and rope. The idea of active control is introduced here, adjusting instrument structure timely based on mathematical relationships and feedback information will achieve the active measurement.

Abstract: Mechatronics system is widely used in computer numerical control, robots, medical equipment, and automatic production etc. Whereas the frequency responses of sensors and actuators in mechatronics system vary greatly, and then sampling time is also different among some links of mechatronics systems. This paper presents the multirate nature of mechatronics systems based on the characteristic of sensors and actuators. Then mechatronics system is described as a multirate discrete control system. Mathematical model of the system is established using lifting technique. Finally, a kind of motion control system that includes multirate controller is analysed and simulated with the different three sampling rates separately. The results show that the presented multirate discrete control system really exists in mechatronics system, and the performance is also influenced in a certain extent under traditional control method.

Abstract: Removed due to author request.

Abstract: Systems with large variable delay, traditional control methods can’t performance well. In this paper, a controller combined with the human-simulated intelligent controller (HSIC) and newly dynamic anti-saturation integral controller, is used in the time-varying delay motor speed control. Simulation studies show, there is no chatter in this controller which is always in norm variable structure controller and this method reaches good performance in the time-varying delay system.

Abstract: For the scroll wrap in small-parameter scroll compressor, its temperatures under stable operating condition are analyzed and the simulations for thermal deformation of scroll wrap height are performed. By fitting the simulations, a formula for simplified calculation of thermal deformation of scroll wrap height is proposed. The maximum deviations between simplified calculations for thermal deformation of orbiting scroll wrap height in a scroll compressor and simulations by FEM are no more than 5%, so the simplified calculation for thermal deformation of scroll wrap height is feasible. The experiment for the scroll compressor in which the orbiting scroll wrap is modified based on simplified calculation shows the modification for scroll wrap considering deformation of scroll wrap height can improve obviously the performances of scroll compressor. At the same time, reducing the temperature differences between the discharge and suction temperatures, limiting scroll wrap height, using the material having lower thermal expansion coefficient, and selecting a larger thickness of scroll wrap are other several effective means to reduce the influence of thermal deformation of scroll wrap height and to improve the performance of scroll compressor in engineering practice.

Abstract: This paper proposes a new method for assessing the degree of the cumulative fatigue crack initiation damage of the joint welds at the guyed mast earplate. Based on the multi-scale wind-induced stress analysis of the guyed mast earplate joint, and considering the welding residual stress in earplate joint, the critical plane approach is used for the calculation of cumulative strain fatigue damage due to the combined actions of the welding residual stress and the wind load.

Abstract: The trajectory planning of redundant manipulator is key areas of research, which require efficient optimization algorithms. This paper presents a new method that combines multiple objectives for trajectory planning and generation for redundant manipulators. The algorithm combines collision detection, finding target and optimizing trajectory using Genetic algorithm. In order to optimize the path, an evaluation function is defined based on multiple criteria, including the total displacement of the end-effector, the total angular displacement of all the joints, as well as the uniformity of Cartesian and joint space velocities. These criteria result in minimized, smooth end-effector motions. These algorithm yields solutions instantaneously and generate the path. The proposed algorithm is analyzed and its performance is demonstrated through simulation and the results are compared with the other methods.

Abstract: This paper is motivated by works done in the area of robot-assisted stroke rehabilitation. To map the EMG to joint torque, evolutionary techniques with suitable mathematical models are proposed. These models have unknown adjustable parameters, and the values of these parameters are obtained using nonlinear regression methods such as GA and SA. Five subjects took part in the experiments and they were asked to perform non-fatiguing and variable force maximal voluntary contractions and sub-maximal voluntary contractions. The recorded EMG signals data of various joints are entered to the model, to estimate the best fit values for the unknown parameters. Once these values of the parameters are obtained they are applied into the model and thus the joint torque is estimated. Predictions made by the proposed techniques are well correlated with experimental data.

Abstract: In this paper, a sensor data fusion technique is proposed to develop the effective robot navigation and optimize the navigation rules using a Modified Fuzzy Associative Memory (MFAM). MFAM provides good flexibility to use multiple input space and reduction of rule base for robot navigation. The behavior rules obtained from MFAM model are tested using the experimental studies and results are discussed and compared with the existing methods.