Recent Patents on Mechanical Engineering - Volume 14, Issue 4, 2021

Background: Search and rescue in high-risk situations and searches in unknown environments pose certain threats to human life. The development of mobile robots with exploratory capabilities that can be adapted to complex sites with high mobility and high obstacle-crossing capabilities is, therefore, a research trend. Existing wheeled and tracked mobile robots have excellent locomotion, but they are less adaptable and less efficient when faced with complex terrain or outer space environments. Therefore, how to increase the obstacle-crossing ability and improve the movement efficiency of mobile robots have become a research hotspot in the field of mobile robotics. Objective: To introduce the classification, characteristics, and the development of the existing hopping robots. Methods: The various products and patents of hopping robots are summarized, and the structural features, differences, and applications of typical hopping robots are introduced. Results: By analyzing a variety of hopping robots, the typical characteristics and the current problems of hopping robots are analyzed, the development trend of hopping robots is prospected, the current research status of hopping robots is discussed, and the future prospects are carried out. Conclusion: Hopping robots can be divided into mechanical energy driven, combustion energy driven and new energy-driven according to the drive energy sources. Depending on the drive energy used, jumping robots can achieve a jump height 0.5-30 times higher than their own size, and when combined with a specific mechanical structure design, they are highly explosive, have high mobility and can solve interstellar exploration, terrain exploration and rescue problems. Compared to mechanical energy driven technique, combustion energy-driven technique is two orders of magnitude more energy-intensive than even the highest performing batteries. The use of recycled, renewable energy solves the energy self-loading problem of combustion energy driven drives and is more environmentally friendly than the two previous types of new energy drives. Therefore, such products should be invented and patented in the future.

Background: Angular contact ball bearings are the most popular bearing type used in the high speed spindle for machining centers. The performance of the bearing directly affects the machining efficiency of the machine tool, obtaining a higher dm136;™n value is the direction of its research and development. Objective: By analyzing the research achievements and patents of electric spindle angular contact bearings, summarizing the development trend provides a reference for the development of electric spindle bearings. Methods: Through the analysis of the relevant technology of the electric spindle angular contact ball bearing, the advantages and disadvantages of the angular contact ball bearing are introduced, and the research results are combined with the patent analysis. Results: With the rapid development of high-speed cutting and numerical control technology and the need for practical applications, the spindle requires higher and higher speeds for bearings. In order to meet the requirements of use, it is necessary to improve the bearing performance by optimizing the structure size and improving the lubrication conditions. Meanwhile, reasonable processing and assembly methods will also have a beneficial effect on bearing performance. Conclusion: With the continuous deepening of bearing technology research and the use of new structures and ceramic materials has made the bearing's limit speed repeatedly reach new highs. The future development trend of high-speed bearings for electric spindles is environmental protection, intelligence, high speed, high precision and long life.

Background: Completing the transition from a sitting position to a standing position is a major activity in people’s daily lives and is crucial for independent living. Lower limb dysfunction will bring many inconveniences into a person’s life and greatly affect their quality of life. Patients with lower limb dysfunction are a specialized group, and nursing problems for this group are becoming increasingly serious. Helping patients with lower limb dysfunction restore their lower limb mobility or assisting them to walk is a social problem necessary to be solved. Objective: To review the recent sit-to-stand assistive devices based on hip support, classify them systematically and introduce their characteristics, including the mechanisms and the types of patients for which such mechanisms are applicable; to help patients with lower limb dysfunction or doctors (therapists) understand and choose a reasonable sit-to-stand assist device based on hip support. Methods: This paper summarizes literatures and patents about sit-to-stand assistive devices. From the aspects of structural characteristics, drive type and support modes based on the hip and applications situation, the advantages and disadvantages of the typical sit-to-stand assist devices are represented. Results: Current and future development trends on the structural characteristics, drive type and support modes based on the hip and applications situation of sit-to-stand assist devices are discussed to improve the humanization, modularization and applicability of sit-to-stand assist devices. Conclusion: Sit-to-stand assistive devices based on hip support can help patients improve the quality of their life, assist patients carrying out rehabilitation training, and delay the decline of lower limb function. However, the existing sit-to-stand assistive devices based on hip support need further improvement in the aspects of motion mechanism, new technology application and ergonomics design.

Background: The overflow valve, as an essential pressure control element, is widely applied in various hydraulic transmission systems because of its characteristics of constant pressure overflow, stable pressure, system’s unloading and safety protection. The research on the structure and working principle of the overflow valve is beneficial to improve the working efficiency and operating stability of pressure control of the hydraulic transmission. Therefore, the development trend of the overflow valve for pressure control has been paid more and more attention. Objective: To meet the growing demands for the working efficiency and operating stability of hydraulic transmission, the structure of the overflow valve for pressure control such as direct-acting overflow valve and pilot-operated overflow valve is being improved continuously. Methods: This paper retraces various current representative patents relative to the structural device of direct-acting overflow valve and pilot-operated overflow valve for pressure control. Results: Through investigating a large number of patents on the overflow valve for pressure control, the main existing problems, such as low working efficiency and poor operating stability are summarized and analyzed. Moreover, the development tendency of the overflow valve for pressure control in the future is also discussed. Conclusion: The optimization of the structure of the overflow valve for pressure control is conducive to improve working efficiency and operating stability. More correlative patents will be invented in the future.

Background: The collection of temperature is very important in life. Thermistor temperature sensors are an important part of the temperature acquisition system. Thermistor temperature sensors can convert the temperature signal into an electrical signal for output. Due to the different application fields and technical requirements, the shape, function, and structure of thermistor temperature sensors are very different. Objective: The purpose of this study is to summarize and analyze the advantages and disadvantages of various devices from a large number of documents and patents. Methods: In this paper, the patents and the latest research of thermistor temperature sensors are reviewed. Results: By summarizing the characteristics of a large number of thermistor temperature sensors and analyzing the problems, the development of thermistor temperature sensors is expected. Conclusion: Thermistor temperature sensors are widely used. Therefore, it is necessary to carry out special structural design and technical research for thermistor temperature sensors in different application fields. Simultaneously, with the development of technology, intelligent sensors and multifunctional sensors are an inevitable development trend.

Background: With the rapid development of automobile technology, the problem of abnormal door-closing noise has attracted more and more attention. The abnormal door-closing noise is an important factor for judging the quality of a car, so accurate identification of abnormal noise is the premise of fundamentally solving the abnormal noise. Objective: To accurately identify the abnormal sound of car closing through the image processing method. Methods: To accurately identify the abnormal noise of car closing%the method to recognize and classify images using Support Vector Machine (SVM) is proposed. This method extracts Histogram of Oriented Gradient (HOG), texture and Speed Up Robust Features (SURF). The three extracted feature vectors are combined and used as the input of SVM. The classifiers obtained by different kernel functions are used to predict the labels of the test set, respectively. Results: Calculating the ratio of the value on the diagonal of the confusion matrix to the total number of each row, and this ratio is the classification accuracy rate. Test accuracy rate is 85%, the results indicate that the accuracy is high. Conclusion: This paper uses image processing methods to extract HOG, GLCM, SURF features and merge them together as a new feature vector. The experimental results show that the SVM classifier using the Gaussian kernel function optimized by hyperparameters has a high accuracy rate and can be used to identify whether the door is closed with abnormal noise.

Background: Shock absorbers are the main damping component of vehicle suspension system, whose excellent passive characteristics can greatly improve and guarantee the ride comfort and handling stability of vehicles. Therefore, it is of great significance to research and develop a shock absorber with excellent passive characteristics. Objective: The purpose of this paper is to propose and design a bionic three-link tube shock absorber with good buffering and vibration reduction performance and bionic adaptive characteristics. In addition, the passive characteristics of the purposed shock absorber are studied. Methods: The bionics idea is applied to the development of vehicle shock absorbers. A three-link mechanism with dampers and springs is abstracted and designed according to the structure and the function of kangaroo legs. A bionic three-link tube shock absorber is constructed based on the traditional tube shock absorber structures and the three-link mechanism. Three-dimensional modeling and three-dimensional dynamic simulation of the shock absorber are carried out by CATIA and ADAMS. Results: The body acceleration are greatly reduced relative to excitations; the dynamic displacement decreases sharply under greater excitation, but there is slight increase under smaller excitation; the motion function and joint change characteristics of the proposed shock absorber are similar to those of kangaroo legs to a certain degree. Conclusion: The results show that the structure design of the bionic three-link tube shock absorber is reasonable and workable, the shock absorber presents good buffering and damping performance and some bionic adaptive characteristics, however, there is still room for further optimization of the structure design.

Background: Demands for Precise positioning systems are dramatically increasing in various fields. So, it is crucial to find and address their issues in order to improve their performances. In this regard, scholars have tried to detect the challenges with which these systems are faced. Some most important problems introduced by scholars are short stroke, low dexterity, complicated structure, lack of compact size, low output force, low response, low resolution, etc. Methods: This paper presents an XY precision positioning system that the Impact Drive Mechanism (IDM) is used as the positioning system itself. This system is designed based on microscale steps of IDM whose Piezoelectric Actuator (PEA) is driven by saw-tooth shaped voltage pulses. Although IDM can solve aforementioned problems, it has nonlinear equations which may make a big challenge in its control. Therefore, this study also presents a fuzzy controller that is capable to work well in such complex systems. Using fuzzy controllers is very useful in this application, but it requires more computation time and cost. Thus, a square root controller is proposed in order to reduce them. Results: Results show that although the square root controller gives the same result, it needs less computation time and cost than the fuzzy controller does. Conclusion: In conclusion, in this new design of the positioner, using a square root controller is more efficient and economical than the fuzzy one.

Background: Three-dimensional (3D) printing is an emerging technology, capable of manufacturing a solid layer by layer. With the advancements of materials for 3D printing, this technology is applicable in almost every sector. But in accordance with the product requirements, we need to modify the mechanical properties of the material. To achieve a good surface finishing we require coating of filament. For this purpose, an apparatus is designed for the coating a material over a filament, which is capable of coating filaments uniformly and with an automated process. Objective: The objective of the present invention is directed to a filament feeding device for applying uniform coating on a filament in order to make 3D solid objects with good quality finishing, thereby eliminating the chances of strains and imperfect coating on the filament. Methods: The present invention relates to a filament feeding device, comprising a container equipped within the device for storing a chemical solution in a liquefied form. An inlet port is fabricated on the container for inserting a filament inside the container, and a number of relief valves are placed at a bottom portion of the container for controlling the leakage of the filaments during insertion of the filaments. A stepper motor in association with a blade is equipped within the container to rotate the main extruder of a 3D printer, and an outlet port is designed opposite to the inlet port for discharging the filament from the container for 3D printing of the filament in order to manufacture the solid object. Results: The apparatus makes it easy for coating and coloration of materials to make the reinforced composite filaments. As this apparatus provides a uniform coating of material on the filaments, the product printed by filaments has a good surface finishing. Conclusion: The proposed method can reduce coating time and printing time. This work provides meaningful implication to researchers who are doing research in the domain of additive manufacturing.

Aim: The aim of this study is to develop machine learning models for the performance of refrigerator and air-conditioning system. Background: The Coefficient Of Performance (COP) of Refrigerator and Air-Conditioning (RAC) is a complex function of evaporative temperature and concentration of nanoparticles in lubricants. In recent years, researchers have focused on experimental studies for the improvement of COP. Further, few researchers have applied simulation techniques such as fuzzy system, Artificial Neural Network (ANN), simulated annealing, etc. to Vapour Compression Refrigeration (VCR) cycle. Though, there is a scarcity of modeling research work for the performance of RAC system. Objective: The study aims to develop the machine learning predictive models for the performance of refrigerator and air-conditioning system using experimental data. Methods: The experiment was performed on VCR system to determine COP. Three different concentrations of lubricants (added 0.5, 1.0 and 1.5g nano-TiO2 particle on 1 liter of Polyolester (POE) oil) were used. The experimentally calculated COP was used to train and test the machine learning models. Gaussian Process Regression (GPR) and Support Vector Regression (SVR) methods were applied to develop the models. Results: The experimental result reveals that the COP increases with increasing the concentration (of nano particles) at a given temperature. The addition of 0.5 and 1.0g TiO2 in the POE oil shows better rate of increment in the COP in comparison to addition of 1.5g TiO2 in the POE oil. Machine learning models using GPR and SVR with RBF kernel function is the most appropriate machine learning model for the nonlinear relationship between the output parameter (COP) and the input parameter (evaporative temperature and concentration of TiO2). Conclusion: The present study was conducted to investigate the machine learning approaches for the performance of RAC system using experimental data sets. The experimental result shows that R134a and TiO2-POE nano-lubricants work efficiently and the coefficient of performance of VCR system increases with concentration of nanoparticles. The developed model performance is compared using coefficient of correlation and RSME values. After comparison, it is concluded that RBF based GPR model is the best fit machine learning model to predict the COP in the context of any other model for this data set.

Background: The increased global obesity rate presents a major public health issue for people of every age group belonging to all regions. Obesity increases health risks, such as cardiovascular disease, cancer, diabetes, osteoarthritis, and chronic kidney diseases. At present, we have all faced the impact of the damage caused by COVID-19. All past researches and traditional weight machines were found to be either plate-loaded or weight-stack-loaded. The plate-loaded machine requires the location of various load plates and manual adjustment of the load. Machines based on such techniques always have chances for user injury. Objective: The objective of developing a new innovative gym machine provides a load lifting apparatus which does not require weight stacks or weight plates for the user to exercise and is adapted to adjust user of various height and weight, requiring lower maintenance cost, providing user safety, and easy handling nature; this machine offers a cost-effective alternative for the existing devices. Methods: The present paper provides an innovation approach in developing multi exercise selfweight gym machine. The machine includes a unique design with new features for holding the handle during load lifting exercise, an input shaft having one or more first pulleys coupled to the handle for rotating the input shaft. An intermediate shaft having the first set of gears is configured for selective engagement with the input shaft. The output shaft includes a second set of gears which are configured for selective engagement with the intermediate shaft, and one or more second pulleys coupled for lifting one or more loads. A weight-based exercise machine that depends on user weight will add to its independence for adding or withdrawing weights, which makes the designed machine more cost-effective. The addition of parallelogram linkages in its design benefitted in providing a non-swing motion. The concept of maintaining proper resistance has also been an important factor during the design of the machine. Patents: The paper presents the idea of designing multi self-weight exercise machine as an innovation, involving a gear change mechanism for the users, having different weights and height. Results: The results concerning the gear ratio for the first and second lever are computed for the respective machine. Effective gear ratio and standardized load values calculation have been obtained for the user having less or more than 78 KG weight. Conclusion: The designed machine has been proved to be efficient by involving innovative ideas and design consisting of engagement configuration of the input shaft and intermediate shaft that further provide different gear ratio between the input, output & intermediate shaft. The concept of movable chairs along with the change of weight through gear mechanism and the use of this machine in different exercises have proved it to be effective and beneficial for users and the manufacturer due to its easy handling nature.