Recent Patents on Mechanical Engineering - Volume 11, Issue 2, 2018

Background: Wrist activity is very frequent in our daily routine, and is under heavy load during the movement such as supporting and push-pull. So wrist can get damaged very easily in daily life. Based on the rehabilitation medicine and ergonomics, the particularity and complexity of human limbs should be considered in the design process. During the treatment process, the wrist joint rehabilitation equipment can provide stable, accurate, safe and comfortable repeated rehabilitation training for patients. The use of rehabilitation training equipment can greatly reduce the cost of treatment and improve the rehabilitation efficiency. Objective: The related patents of rehabilitation training equipment for wrist joint will be reviewed, and the structure and working principle of these equipments will be illustrated. The results of the analysis provide some meaningful reference for the optimal design of the wrist joint. Methods: Based on the comparative analysis of the latest patents related to wrist rehabilitation equipment, the key problems and future development of the rehabilitation equipment are put forward. Results: The patents of the rehabilitation training equipment for the wrist are classified in the paper. Studies show that remarkable improvements have been achieved in the invention of the wrist rehabilitation equipment. Conclusion: In the future, the mechanical design, control system and rehabilitation strategy of wrist rehabilitation equipment should be further studied.

Background: Electrical Discharge Machining (EDM) technology is an effective and practical method of the manufacturing of holes. The electro-discharge machine tool, which is mainly made up of machine tool, impulse power, and automatic feed adjustment device, etc., is the carrier of the machining technology of holes. Objective: To meet the increasing requirement of machining accuracy and machining efficiency of EDM of holes, the mechanical structures and machining methods of EDM of holes are constantly being enhanced. Methods: This paper retraces varieties of representative patents relevant to the electrical discharge machining technology. Results: Through retracing the characteristics of different types of electrical discharge machining technology, the main problems existing in the current development such as the low machining efficiency are concluded and analyzed. Development of patents on mechanical structures and machining methods of EDM of holes in future is discussed. Conclusion: The optimization and development of mechanical structures and machining methods of EDM of holes are beneficial to improve accuracy. More related patents on mechanical structures and machining methods of EDM of holes will be invented.

Background: In the hydrodynamic lubricated step bearing with a small ratio of the outlet zone width to the inlet zone width, the boundary slippage frequently occurs on both the contact surfaces in the outlet zone and on the moving contact surface in the inlet zone in the condition of heavy loads and high sliding speeds. Thus, the load-carrying capacity of the bearing is greatly reduced but the friction coefficient of the bearing is significantly increased, as compared to the calculation results from conventional hydrodynamic lubrication theory. The boundary slippage in this bearing is thus very harmful. Objective: The study aimed to introduce the hydrodynamic step bearings in these operating conditions with high load-carrying capacities and low friction coefficients by preventing the boundary slippage on the bearing surfaces as registered in the patent. Methods: The analytical results are presented for the carried load and friction coefficient of this kind of bearing with natural contact surfaces by considering the contact-fluid interfacial slippage. The calculated carried load and friction coefficient of the bearing are compared with those calculated from the conventional hydrodynamic lubrication theory for the same operating conditions. The invented bearing is then proposed by preventing the boundary slippage for significantly improving the overall performance of the bearing. Results: It is shown that due to the occurrence of the boundary slippage, the performance of the studied bearing with natural contact surfaces is overall severely deteriorated including the drop of its loadcarrying capacity and the significant increase in its friction coefficient. The bearing thus works in a bad condition. The invented bearing by preventing the occurrence of the boundary slippage thus has overall improved performances. Conclusion: The overall performance of the studied bearing can be greatly improved by eliminating the boundary slippage occurrence. The working condition of the bearing can thus be significantly bettered.

Background: Nanoporous filtration membranes are important for ultimate purification. An optimized cylindrical-shaped nanoporous filtration membrane with two different pores across the membrane thickness registered in the patent is introduced. It has significantly improved performances in purification. Objective: To introduce an optimized cylindrical-shaped nanoporous filtration membrane with improved performances. Methods: An analysis was carried out for the minimum flow resistance of the proposed membrane by using the flow equation for a nanoscale fluid flow. The optimal parameters of the membrane were found. Results: The analytical results show that there exists an optimal ratio between the radii of the two nanopores across the membrane thickness for yielding the highest flux of the membrane. Conclusion: The invented membrane is advantageous over conventional membranes with single cylindrical pores across the membrane thickness in the overall performances including the flux and the mechanical strength of the membrane.

Background: Guideway is one of the most important parts for precision and force transferring on whole machine tools due to its sliding joint interfaces. Recent researches have found that the stiffness and damping of a guideway joint interface play a very significant role in precision and heavyduty machine tools. The guideway with high stiffness and damping prompts the development of modern CNC machine tools. Recently, various papers and patents have studied different methods and forms to improve the dynamic characteristics of guideway for machine tools. Objective: The purpose of this study was to design a sliding guideway for machine tools with oilyporous joint interface, and then the experimental setup was introduced in detail to test and verify its mechanical properties. The measuring method ESDOF was also given in the paper. Methods: In this study, firstly, a novel sliding guideway was designed and introduced in detail. The proportions of the ingredients for the selected iron-based porous material were also given in the paper. Secondly, a measuring method named ESDOF (equivalent single degree of freedom) was adopted to verify the mechanical properties of the designed guideway. The experiments proved that the designed guide has higher stiffness and damping than traditional 45 steel ones. Thirdly, the results of lubrication and low-speed stability of the designed guideway were also proved by experiment. Results: The designed guide way has more suitable properties for precision and heavy-duty machine tools than rolling guide. The research showed that the oily-porous joint interface had better dynamic characteristics than conventional 45 steel ones, the normal stiffness of the former increased about 50% and the damping increased about 5-6 times. From this study, the guideway with the high stiffness and damping coefficient, better low-speed stability, and lower critical creeping velocity was introduced in details. Conclusion: In this paper, a proposed sliding guideway for machine tools with the oily-porous joint interface was introduced in detail. Meanwhile, an experimental setup about the designed guideway was also proposed to test and verify its mechanical properties. It was concluded that in static situation, the normal stiffness and damping coefficient increased along with the normal load increased, and the normal stiffness increased obviously due to more lubricant exuded from the porous base. It was also concluded that the designed guideway had better low-speed stability and lower critical creeping velocity than conventional sliding guideway. In general, the sliding guideway with oily-porous joint interface is a novel and beneficial exploration for machine tools and it can be used in heavy-duty machine tools due to its high stiffness and damping merits.

Background: For life, cars have brought convenience to people, besides causing environmental pollution, traffic congestion, and road safety. One of the main reasons for traffic accidents is that drivers cannot respond to road state and information timely. Intelligent vehicle and safety driving assistance technology are one of the ways to reduce traffic accidents. Many papers and patents are studying how to reduce the rate of traffic accidents. Objective: Traffic sign recognition is an important part of the intelligent vehicle system and advanced driver assistance system. To reduce the rate of traffic accidents in weak illumination, this paper proposes a detection and recognition method for intelligent vehicle traffic sign based on machine vision. Methods: Firstly, the traffic signs are reclassified from the color and shape characteristics of traffic signs. Then, the concept of color shape pairs is put forward, and the color-geometric model is established. To achieve the enhancement effect, the image is preprocessed by the uniformity of the histogram. We mainly use the fast algorithm of invariant moments and Zernike moments to extract the sign features. Finally, template matching and support vector machine are used to traffic sign image recognition. Results: The experimental results show that the technology has good robustness in complex environments such as weak light, occlusion and shadow and it can improve the image recognition rate effectively. Conclusion: Compared with the traditional method, it provides a method for intelligent vehicle traffic sign identification under weak illumination conditions.

Background: The tire is the only part of a vehicle that makes contact with the road, and the tire's rolling resistance certainly affects the fuel consumption of the vehicle. In previous researches, Scholars have studied the influence of some parts of the tire structure on rolling resistance and available patents have used varying methods to design low rolling resistance tires. Objective: The aim of this research is to explore the relationship between region energy losses and rolling resistance, based on which, an optimize tire structure is proposed to reduce the rolling resistance. Methods: In this paper, the 2-D cross-section of radial tire 205/55R16 was divided into two region: the crown and the non-crown. Then, a model of the tire was established for the Finite Element Analysis (FEA). And finally, with various structural changes in different regions, a sensitivity analysis was conducted. Results: The results show that in either region where the structure is changed, the energy loss in the considered region is consistent with the rolling resistance. In the crown area, the contribution of tread structure to energy loss is nearly up to 69%, and the 2# belt width is more sensitive than 1# belt width. In the non-crown area, abrasion, carcass, apex and sidewall have the same effect on energy loss, which is about 30%. Compared with the abrasion height, the apex height shows higher sensitivity to energy loss in the non-crown region. Apex and sidewall energy loss increased with decreasing abrasion height, and with increasing apex height. Conclusion: For the energy loss in the crown region, tire tread plays a crucial role. Reducing the width of tire belt and height of the apex can effectively reduce energy loss, and appropriately increasing abrasion height can also reduce the rolling resistance. By carefully combining all the design methods mentioned, a final tire structure which can optimize the rolling resistance is proposed.

Background: The Micro-Electro-Mechanical System (MEMS) resonator has been widely used in specific fields such as activity monitoring, robotics, accelerometers, gyroscopes and filters. Various relevant papers and patents have been reported in terms of behavior and modeling of the MEMS resonator under electrostatic excitation. However, some important issues are not well-studied for interdisciplinary research yet. How to achieve anti-oscillation control of the MEMS resonator with non-symmetric dead-zone input, immeasurable states and output constraint becomes a thorny question. Objective: To stabilize the MEMS resonator, an anti-oscillation control scheme of the MEMS resonator with non-symmetric dead-zone input, immeasurable states and output constraint is proposed in an oscillation state. Methods: Firstly, the mathematic model of the MEMS resonator is established, and the related oscillation is revealed for facilitating controller design. Secondly, a state observer is introduced to estimate immeasurable states, and an adaptive neural network is designed to approximate unknown nonlinear function. Thirdly, non-symmetric dead-zone characteristic existing in the control input is introduced, and a tangent barrier Lyapunov function is employed for the MEMS resonator to prevent constraint violation. Finally, an anti-oscillation control scheme fused with neural network, state observer and tangent barrier Lyapunov function is proposed without precise information of dead zone and model parameters in the framework of backstepping. Results: The proposed method can guarantee stability of the MEMS resonator in the sense of uniform ultimate boundedness. Chaos and oscillation of actual control input are completely suppressed in the MEMS resonator. Conclusion: The presented scheme can improve system performance and suppress high frequency chattering. The effectiveness and feasibility of the presented scheme are demonstrated by results.

Background: With the assistance of Nano-technology, many devices have been proposed which are capable of analyzing infinitesimal particles accurately. Objective: Nano-plates are the essential parts in Bio-Nano Electro Mechanical Systems (Bio-NEMS), such as Bio-sensors and Lap-on-Chips, and many systems are working based on oscillations of the Nano-plates. Methods: In this paper, Third-order Shear Deformation Nanoplates actuated by an electrostatic force is modeled with the nonlocal linear elasticity theory. Because of the high sensitivity of these nano-plates, a general model to study different complexities of these nanosystems is considered. In this modeling, the nano-plate is modeled with Finite Element Method (FEM) to solve mathematical equations accurately. The finite element formulation of TSDT plate has is presented. Results: The results are compared with Generalized Differential Quadrature Method (GDQM). The difference between TSDT and other simpler plate theories is studied. Furthermore, the influence of different parameters, such as electrostatic voltage, length scale and aspect of length to thickness of the plate, are assessed. Conclusions: In this paper, we found that calculated pull-in voltage based on TSDT is less than previous plate theories; therefore, to analyze the vibration behavior of thick plates in a Bio-MEMS device, TSDT theory should be used to present accurate information. In this article, various patents have been discussed.

Background: Micro-holes have been widely used in the fields of micro-accelerometer, micro flow sensor, micro reaction container, micro pump, and biological medicines. However, due to the properties of the non-conductive hard and brittle materials, it is very difficult to fabricate the microholes structure with the traditional method. Electrochemical discharging machining is put forward to fabricate micro-holes on such material. Various relevant papers and patents have studied different methods to improve the machining localization and stability. Objective: In order to improve the process localization of glass micro-holes and reduce the possibility of micro-holes outlet damage, the micro-electrochemical discharge machining was studied and optimized. Methods: Firstly, according to the principle of electrochemical discharge machining, the film forming mechanism and material removal mechanism were discussed. The influence of discharge energy on the micro-holes machining technology of glass was analyzed, and the energy control model of electrochemical discharge was established. Secondly, according to the experiment, the influence of pulse voltage, frequency and feed rate on the inlet diameter and outlet quality of micro-holes was analyzed. Results: Micro-holes are fabricated by suitable parameters on the glass workpiece with thickness 300μm. A 3 3 high-quality glass micro-holes array is machined successfully, the inlet diameter is 172μm and the outlet diameter is 167μm, and the taper of single micro-hole is less than 1°. Conclusion: It is proved that controlling the discharge energy can improve the process localization of glass micro-holes and reduce the possibility of micro-holes outlet damage.