Mechatronics

In this paper, a semi-active control of vehicle suspension system with magnetorheological (MR) damper is presented. At first a MR damper working in flow mode is designed. Performance testing is done for this damper with INSTRON machine. Then a mathematical model, Bouc–Wen model, is adopted to characterize the performance of the MR damper. With optimization method in MATLAB® and experimental results of MR damper, the coefficients of the model are determined. Finally, a scaled quarter car model is set up including the model of the MR damper and a semi-active control strategy is adopted to control the vibration of suspension system. Simulation results show that with the semi-active control the vibration of suspension system is well controlled.

The recent development of open-source 3-D printers makes scaling of distributed additive-based manufacturing of high-value objects technically feasible. These self-replicating rapid prototypers (RepRaps) can manufacture approximately half of their own parts from sequential fused deposition of polymer feedstocks. RepRaps have been proposed and demonstrated to be useful for conventional prototyping and engineering, customizing scientific equipment, and appropriate technology-related manufacturing for sustainable development. However, in order for this technology to proliferate like 2-D electronic printers have, it must be economically viable for a typical household. This study reports on the life-cycle economic analysis (LCEA) of RepRap technology for an average U.S. household. A new low-cost RepRap is described and the costs of materials and time to construct it are quantified. The economic costs of a selection of twenty open-source printable designs (representing less than 0.04% of those available), are typical of products that a household might purchase, are quantified for print time, energy, and filament consumption and compared to low and high Internet market prices for similar products without shipping costs. The results show that even making the extremely conservative assumption that the household would only use the printer to make the selected twenty products a year the avoided purchase cost savings would range from about $300 to $2000/year. Assuming the 25 hours of necessary printing for the selected products is evenly distributed throughout the year these savings provide a simple payback time for the RepRap in 4 months to 2 years and provide an ROI between >200% and >40%. As both upgrades and the components that are most likely to wear out in the RepRap can be printed and thus the lifetime of the distributing manufacturing can be substantially increased the unavoidable conclusion from this study is that the RepRap is an economically attractive investment for the average U.S. household already. It appears clear that as RepRaps improve in reliability, continue to decline in cost and both the number and assumed utility of open-source designs continues growing exponentially, open-source 3-D printers will become a mass-market mechatronic device.

ABSTRACT Nowadays the size and complexity of models is growing more and more, forcing modelers to face some problems that they were not accustomed to. Before trying to study ways to deal with complex models, a more important and primary question to explore is, is there any means to avoid the generation of complex models? The primary purpose of this paper is to discuss several issues regarding the complexity of simulation models, summarizing the findings in this area so far, and calling attention to this area that, despite its importance, appears to remain at the bottom of simulation research agendas. 1

Filled elastomers exhibit a number of peculiar features generally referred to as Mullins effect that include (i) large stress-softening (i.e. lower stress required to pull the sample to the same strain in second pull as compared to the first one), (ii) a dramatic drop in stress at the loading reversal point during the first cycle and, (iii) complete recovery of the virgin sample-like behavior when strain in second pull exceeds the previous maximum strain. Developing a constitutive model to describe these effects has proven a major challenge. One important reason for this, rectified by the present report, has been a dearth of experimental data performed on a well-characterized system where the potentially relevant parameters (temperature, deformation rate as well as the particulate loading, dispersion, particle size, surface area, and structure of carbon black) are systematically varied. We argue that the ``damage'' picture, which has been the only explanation for Mullins effect advanced in the literature, is inconsistent with the experimentally observed behavior.

Iris is one of the common biometrics used for identity authentication. It has the potential to recognize persons with a high degree of assurance. Extracting effective features is the most important stage in the iris recognition system. Different features have been used to perform iris recognition system. A lot of them are based on hand-crafted features designed by biometrics experts. According to the achievement of deep learning in object recognition problems, the features learned by the Convolutional Neural Network (CNN) have gained great attention to be used in the iris recognition system. In this paper, we proposed an effective iris recognition system by using transfer learning with Convolutional Neural Networks. The proposed system is implemented by fine-tuning a pre-trained convolutional neural network (VGG-16) for features extracting and classification. The performance of the iris recognition system is tested on four public databases IITD, iris databases CASIA-Iris-V1, CASIA-Iris-thousand and, CASIA-Iris-Interval. The results show that the proposed system is achieved a very high accuracy rate.

Simple 3-D printable open source hardware designs have proven to be effective scientific instruments at low costs. Further development in this area is coupling open source electronics with 3-D printable mechanical components to make fully functional distributedly-manufactured mechatronic tools for science. One research area where such low-cost technology is needed is to characterize thin film anti-reflective coatings and transparent conducting oxides (TCOs) for the glass, mirror and solar photovoltaic industry whose transmission properties are angle dependent. To meet this research need a low-cost 3-D printable open source dual axis gimbal system is presented in this study. An Arduino based microcontroller is used to move the sample holder to the user specified angle where two stepper motors control the motion providing two degrees of freedom. The sample holder is made in such a way that samples can easily be mounted on it by two movable latches. The system was validated and characterized for: i) unidirectional accuracy, 1 Preprint: Nupur Bihari, Smruti Prasad Dash, Karankumar C. Dhankani, Joshua M. Pearce. 3-D printable open source dual axis gimbal system for optoelectronic measurements. Mechatronics 56, 175-187 (2018). DOI: https://doi.org/10.1016/j.mechatronics.2018.07.005 ii) repeatability, iii) backlash, iv) speed resolution and v) microstep size. Finally, the mechatronic system is tested for the intended application using a halogen light source and a spectrometer to measure transmission through glass TCO samples through a hemisphere. The system performed as expected has a unidirectional accuracy of 2.827°, repeatability of 1.585°, backlash error of 1.237°, maximum speed of 35.156° and a verifiable microstep size of 0.33°. Despite the highest mean squared errors, the open source gimbal system performed adequately while measuring transmission of radiation through glass with TCO coatings. This open source system also represents a 96% cost in savings as compared to the least expensive commercial variant. The high mean squared errors are offset by the cost of the system coupled with its open source nature that promotes further collaboration and hence, development.

A methodology for the design of active car suspension systems is presented. The goal is to minimize vertical car body acceleration, for passenger comfort, and to avoid hitting suspension limits, for component lifetime preservation. A controller consisting of two control loops is proposed to attain this goal. The inner loop controls a nonlinear hydraulic actuator to achieve tracking of a desired actuation force. The outer loop implements a fuzzy logic controller which interpolates linear locally optimal controllers to provide the desired actuation force. Final controller parameters are computed via genetic algorithm-based optimization. A numerical example illustrates the design methodology.

A piezoelectric actuator consists of ceramic material that expands or contracts when a positive or a negative potential voltage signal is applied. The displacement of a piezoelectric actuator is commonly controlled using a voltage input due to its ease of implementation. However, driving a piezoelectric actuator using a voltage input leads to the non-linear hysteresis and creep. Hysteresis and creep are undesirable characteristics which lead to large errors when a piezoelectric actuator is used in positioning applications. The amount of hysteresis and creep could be minimized to a large extent when a piezoelectric actuator is driven using a charge input. Another method which substantially reduces hysteresis and creep involves the insertion of a capacitor in series with a piezoelectric actuator which is driven using a voltage input. A review of voltage, charge and capacitor insertion methods for driving piezoelectric actuators is presented in this paper. Experimental results, for a piezoelectric actuator driven using the above three methods, are presented to validate the facts presented in this review.

The paper describes the development of an electrically operated pneumatic fast-switching valve for pneumatic position control systems. The valve was designed and fabricated as an on–off valve with 2/2-way function and its characteristics were investigated. The detailed theoretical analysis and preliminary tests were carried out on the manufactured valve and showed that the switching time of the single stage valve