Recent Patents on Mechanical Engineering - Volume 15, Issue 1, 2022

Background: As the basis of mechanical manufacturing, large-scale machine tools are being developed for improving processing accuracy, load-bearing capacity and rigidity. Hydrostatic thrust bearing, hydrostatic guide and hydrostatic ram are important components of large machine tools; with the continuous improvement of product accuracy requirements, the research on the hydrostatic thrust bearing, hydrostatic guide and hydrostatic ram has become more important. Objective: This paper presents the current research on hydrostatic thrust bearing, hydrostatic guide and hydrostatic ram to highlight the importance of hydrostatic ram in improving the machining accuracy of machine tools. The study aims to lay a foundation for research and development of hydrostatic ram in the future. Methods: Firstly, the hydrostatic bearing technology is introduced. Secondly, the research status of hydrostatic thrust bearing, hydrostatic guide and hydrostatic ram is presented to provide theoretical basis for improving the processing performance of rest ram. Results: Deformation compensation and thermal deformation compensation of hydrostatic ram have been studied more. Most of the research study focuses on the accuracy of hydrostatic ram, but less on the bearing performance of hydrostatic ram. Conclusion: Breakthroughs have been made in the research on precision control and structural form of the hydrostatic bearing at home and abroad. Most scholars take the ram of Computer Numerically Control (CNC) boring and milling machines as the research object, but there is less research on the ram of vertical lathes. Therefore, the academic circle should pay more attention to the bearing performance of the hydrostatic ram of vertical lathes.

Background: In machine vision, 3D reconstruction is widely used in the medical system, autonomous navigation, aviation and remote sensing measurement, industrial automation, and other fields, and the demand for reconstruction precision is significantly highlighted. Therefore, 3D reconstruction is of great research value and will be an important research direction in the future. Objective: By reviewing the latest development and patent on 3D reconstruction, this paper provides references to researchers in related fields. Methods: Machine vision-based 3D reconstruction patents and articles were analyzed from the aspects of the algorithm, innovation, and application. Among them, there are over 30 patents and nearly 30 articles that have been published in the past ten years. Results: Researches on machine vision-based 3D reconstruction in the recent 10 years were reviewed, and the typical characteristics were concluded. The main problems in its development were analyzed, the development trend was foreseen, and the current and future research on the productions and patents related to machine vision-based 3D reconstruction was discussed. Conclusion: The reconstruction result of binocular vision and multi-vision is better than monocular vision in most cases. Current researches of 3D reconstruction focus on robot vision navigation, intelligent vehicle environment sensing system and virtual reality. The aspects that need to be improved in the future include improving robustness, reducing computational complexity, and reducing operating equipment requirements, etc. Furthermore, more patents on machine vision-based 3D reconstruction should also be invented.

Background: With the continuous pursuit of high-quality and high-precision bearings in industrial production, the processing accuracy of bearing balls is increasing, and high surface quality has become the most basic requirement for high-quality bearing balls. Studying the working principle of the detection devices for surface defects on bearing balls is beneficial to improve the surface accuracy of bearing balls and the quality of bearings. Objective: The objective of this study was to provide an overview of recent patents and methods on the detection device for surface defects on bearing balls. Methods: This paper reviews various representative patents related to the detection devices for surface defects on bearing balls. The advantages and disadvantages of the patents are also analyzed. Results: By tracing the characteristics of different types of the detection devices for surface defects on bearing balls, the currently existing problems are concluded and analyzed, such as low detection accuracy, low detection efficiency, and limited scope of application, etc. The future development of patents on detection devices for surface defects on bearing balls is discussed. Conclusion: The optimization and development of detection devices for surface defects on bearing balls are beneficial to improve the detection accuracy and efficiency of surface defects on bearing balls, and are conducive to expanding the scope of application of the detection devices. More related patents on detection devices of surface defects on bearing balls will be invented.

Background: In the process of high-speed driving, there are many source signals that affect the ear noise of passengers in the car. It is important to obtain the reference signal of Active Noise Control (ANC) of the vehicle at high-speed conditions. Objective: This paper introduces a method to study the time-domain signal reconstruction of interior noise based on a data-driven method. Methods: Based on the noise signal collected in a car, the key point signals affecting the interior noise are determined by the acoustic transfer path analysis method. Considering the time-varying characteristics of the noise signal and the complex nonlinear relationship of interior noise, a noise reconstruction model based on wavelet decomposition Radial Basis Function (RBF) neural network is established. Furthermore, the BP neural network noise reconstruction model is set up to compare the reconstruction effect. Results: According to the reconstruction comparison, the average absolute error (0.0072) of the proposed algorithm model is smaller than the average absolute error of the noise reconstruction BP network model based on wavelet decomposition (0.0280), and the accuracy is improved by 74.29%. The average absolute error between the reconstructed value of the RBF neural network and the real value is smaller than that of the BP neural network, and the error of the proposed model is less than 0.01. The method proposed in this paper can reconstruct the interior noise signal of the vehicle accurately and effectively. Conclusion: This paper proposes a reconstruction model of vehicle interior noise signal based on wavelet decomposition RBF neural network algorithm driven by data-driven, and verifies the effectiveness of the algorithm with the real vehicle test data. The reconstruction method of RBF neural network based on data-driven wavelet decomposition provides a certain reference value for ANC to obtain a highprecision reference signal.

Background: Quadruped crawling robots face challenges when working in the raised terrain of a slope. The robot is affected by gravity and gait under this terrain. The ground reaction force on its hind legs is relatively large. This has strict requirements for the structure and gait planning of the quadruped crawling robot. Objective: Aimed at the problem of a large ground reaction force on the rear legs of the quadruped crawling robot when crawling on the raised terrain of a slope, a slope-triangular gait walking strategy for quadruped robots based on a layered CGP gait generation method is proposed. Methods: Three-dimensional model of the quadruped crawling robot is created in SOLIDWORKS. The kinematic model is established, and the foot position vector is obtained. Considering the characteristics of the raised terrain of a slope, slope tripod gait and hierarchical CPG slope tripod gait generator are proposed. Comparative simulation of sloped tripod gait and flat tripod gait, the slope tripod gait with and without the gait generator is carried out by Adams programming. Results: When the quadruped crawling robot adopts slope tripod gait and flat tripod gait respectively, the centroid displacement curve, foot speed curve and foot contact force curve are compared. When the quadruped crawling robot adopts the slope tripod gait and does not adopt the slope tripod gait, the body posture curves of the two are compared. The result proves that the tripod gait walking strategy is feasible. Conclusion: The slope tripod gait walking strategy can improve the impact resistance of the quadruped crawling robot on sloped high ground. The gait design and motion analysis process of the robot can provide a reference for other quadruped crawling robot devices.

Background: The vibration control loop is the key technology adopt to improve the control performance of the vibration table, which is set outside of the hydraulic vibration table servo control loop. However, the huge number of signal processing work prompts high demands on the calculation ability of the vibration controller. One kind of multi-CPU embedded vibration controller constructed by Digital Signal Processor (DSP) is proposed considering the working principle of the hydraulic vibration table and the Power Spectrum Density (PSD) reproduction process. The embedded controller consists of an acquisition unit, a calculation unit, and a monitoring unit distributes vibration control tasks to the different processing unit to realize distributed algorithm calculations. Every processing unit uses dual-port memory to accomplish data interaction between each other. The development of the embedded controller provides a benchmark engineering case for the design of the hydraulic vibration table vibration controller. Objective: This article focuses on the development of the multi-CPU embedded vibration controller and the distributed calculations. Meanwhile, the power spectrum density experiment is carried out to verify the performance of the hydraulic vibration embedded controller. Methods: 1) The structure of the hydraulic vibration table control system is given, that is, two closed-loop controls. The bandwidth of the system is further broadened by the vibration control of the outer loop. Besides, the accuracy of vibration control is also improved. Then, the development needs of the vibration controller are put forward according to the detailed process of the power spectrum density replication. 2) An arithmetic processing unit is formed by using TI C2000 series DSP to calculate a large number of signal processing and a signal acquisition unit at high speed. In order to improve signal processing efficiency, the signal acquisition unit is used to perform preprocessing calculations (data acquisition and filtering) and vibration control calculations in a distributed manner. 3) Processing speed is further improved by taking full advantage of DSP software sources include lots of library functions and optimized assembly library functions. 4) The friendly operation of the controller and the safety monitoring of the experiment process are realized by the industrial computer served as the human-computer interaction unit. 5) Multi-CPU data sharing is achieved through using dual-port RAM to realize. Results: Through experiments, the developed embedded controller is fully estimated. The experiment shows that the developed hydraulic vibration table can realize real-time vibration control. Concerning the acceleration power spectrum density reproduction experiment, 256 acceleration response samples are calculated, and the update time is 4ms. The tracking accuracy of the timedomain waveform is controlled within 0.3%. Conclusion: The use of the developed embedded controller with signal conditioning equipment can achieve real-time control of the hydraulic vibration table, but the performance of the embedded controller can be promoted in advance, and the performance improvement of the hydraulic vibration table embedded controller can be studied from the following aspects: 1) The Fourier calculation is executed by the acquisition unit to share the calculation workload of the calculation unit; 2) The computing unit uses a signal processor chip with better performance, although this will bring development difficulties; 3) The monitoring computer can use an embedded controller with superior performance instead of an industrial computer to reduce the size, improve the performance; 4) The DSP real-time operating system should be used, and the task scheduling of vibration control experiments should be optimized.

Background: The thermal bubble-driven micro actuators have advantages of simple structure and low working voltage, which have broad prospects in the field of micro-fluidic systems. Methods: This paper presents a new type of micro-planar induction heater which can realize the fixed-point growth of thermal bubbles by adding some active cavities. The micro-planar induction heater is composed of a metal heating plate, a glass substrate, and a planar coil. Results: In the experiments, an alternating current of 80 kHz was applied to the micro-planar induction heater; both the heating time and the interruption time were 1 s controlled by a PLC. A CCD camera was used to record the generation process of thermal bubbles, including nucleation, growth, and shrinkage. The experimental results show that thermal bubbles can grow and contract periodically at the position of the cavities when the cavities diameter is 50 μm and 90 μm, respectively. The ideal thickness of the heating plate is between 6 μm and 13 μm. Conclusion: Here, the fixed-point growth of the thermal bubble with a micro-planar induction heater has been studied. This kind of fixed-point growth of thermal bubbles can be used in micro actuators, such as micro ejectors, micro mixers, and micro pumps.

Background: Stereo-vision-based three-dimensional coordinates measurement technology has been widely applied in the military or civil fields. There are two problems that need to be solved. The first problem is that each camera’s internal parameters and the two cameras' external parameters need to be calibrated. To increase the measurement range, usually, the turntable is used with the stereo vision system together. The second problem is the calibration of the turntable. Objective: The aim of the study is to construct and calibrate a stereo-vision-based coordinates measurement system via a two-axis turntable. Methods: Considering that the internal parameters of each camera do not change during the measurement process and the complicated optimization process of one-step self-calibration, a two-step stereo vision calibration method is proposed. In the first step, we calibrate the internal parameters of each camera through a specially designed planar target with circular points. In the second step, on the basis of the calibrated results of the internal parameters, the two cameras' external parameters are calibrated through a simple target which could be distributed in the measurement volume. For the calibration of the two-axis turntable, we calibrated the rotation axes of the turntable and the coordinates of points in the 3D space could be measured considering the non-orthogonality of the axes. Results: Some experiments are provided to examine the calibration methods we proposed. They are the plane target measurement experiments; the standard ball center coordinates measurement experiments and target pose measurement experiments. Experiment results demonstrate the superiority of the calibration method we proposed. Conclusion: We studied the calibration methods of the stereo-vision-based coordinates measurement system via a two-axis turntable. The experimental results show the measurement accuracy of our system is less than 0.1mm.

Background: Owing to the rising trend of agro wastes, efforts are being geared towards producing environmentally friendly welding flux. This project developed a nano-flux powder (MnO) from banana peel using nano-technology. For the first time, manganese was synthesized from banana peel ash. After that, the nano mixtures were centrifuged and calcinated to obtain nano flux powder. Methods: The surface morphology and physio-chemical properties of the nanopowder produced and control were determined using X-ray Powder Diffraction, Transmission Electron Microscopy, and Scanning Electron Microscopy along with Elemental Dispersive X-ray to analyze its composition. Also, the particle size was obtained using the Digmizer image. Results: The developed nano-flux powder has a mean area of 407.72 nm², a mean perimeter of 51.02 nm, and a length of 3.89 nm less than the commercial flux. The FTIR revealed the maximum peak of wave number 415z.00 cm^-1, which shows a broad high concentration than the control with wavenumber 3546 cm^-1. XRD result shows that manganese oxide is present in the powder with the highest intensity at MnO (110) with Quartz at 2θ = 26o, having a current of 9.26A and hematite at 2θ = 28% having a current 5.34A over the control. From the EDS of qualitative analysis of the powders, manganese and oxygen were present in high quantities in the developed flux with 29.45% and 38.70% than in control with 3.15% and 23.30%, which confirmed the nano-flux as Manganese Oxide (MnO). The results show that nano-flux powder can be produced from agrowaste with better properties and applications. Conclusion: From the results and discussion, banana peel was used to develop Manganese oxide flux powder, using nanotechnology, and it was characterized alongside commercial flux powder as a control.