Mechanical Transmission Research Articles

Application of On-Rotor Sensing in Planetary Gearbox Fault Diagnosis

Planetary gearbox is a crucial mechanical transmission component, widely used in various mechanical equipment and industrial fields. Its failure will not only cause significant economic losses, but also may bring threats to the life and health of workers. Therefore, the condition monitoring and fault diagnosis of planetary gearbox is of great significance. In this paper, a novel on-rotor sensing (ORS) technique based on a three-axis MEMS accelerometer is employed to collect vibration signals from planetary gearboxes, in which the accelerometer is mounted on the shaft near to the sun gear and rotates together with the shaft. The two orthogonal outputs of the collected vibration signals is used to construct an analytic signal and then demodulated to get the envelope spectrum, which is then used diagnose the fault in the planetary gearbox. Results show that the proposed method can effectively diagnose the sun gear crack fault, while conventional piezoelectric sensors placed on planetary gearbox casing are less capable of detecting such faults, demonstrating the superiority of ORS technology in the field of rotating machinery fault diagnosis.

Molecular phylogeny and secondary structure analysis of hop stunt viroid (HSVd) associated with Mulberry (Morus alba) in India.

Hop stunt viroid (HSVd), a small, single stranded, circular, non-coding infectious RNA known to cause infection in various economically important crop plants. In the present investigation, a study was conducted in the southern part of Karnataka districts of India to detect the possible association of HSVd infection in mulberry plants. A total of 41 mulberry plants showing typical viroid-like symptoms along with asymptomatic samples were collected and screened using conventional Reverse Transcriptase Polymerase Chain Reaction (RT-PCR) using a specific set of HSVd-Fw/ HSVd-Re primers. Out of 41 samples, the study confirmed the presence of HSVd in six samples of mulberry collected from Ramanagara (1 sample), Chikkaballapur (3 samples) and Doddaballapura (2 samples) regions with an expected HSVd amplicon size of ∼ 290-300 nucleotides. The mechanical transmission of HSVd was also confirmed on cucumber (cv. Suyo) seedlings through bioassay, which was reconfirmed by RT-PCR. The amplicons were cloned, sequenced, and the representative nucleotide sequences were deposited in the NCBI GenBank. Subsequently, molecular phylogenetic analysis showed that HSVd mulberry isolates from this study were most closely related to grapevine isolates, indicating a common origin. On the other hand, it was shown to belong to a different group from mulberry isolates so far reported from Iran, Italy, Lebanon, and China. The secondary structure analysis of HSVd mulberry Indian isolates exhibited substitutions in the terminal left, pathogenicity, and variable regions compared to those of the Indian grapevine isolates. As far as this study is concerned, HSVd was detected exclusively in some mulberry plants with viral-like symptoms, but the pathogenesis and symptom expression needs to be further investigated to establish the relationship between HSVd and the disease symptoms in the mulberry plants.

Computational Fluid Dynamics Methodology to Estimate the Drag Coefficient of Balls in Rolling Element Bearings

The emergence of electric vehicles has brought new issues such as the problem of rolling element bearings (REBs) operating at high speeds. Losses due to these components in mechanical transmissions are a key issue and must therefore be taken into account right from the design stage of these systems. Among these losses, the one induced by the motion of rolling elements, known as drag loss, becomes predominant in high-speed REBs. Although an experimental approach is still possible, it is difficult to isolate this loss in order to study it properly. A numerical approach based on CFD is therefore a possible way forward, even if other issues arise. The aim of this article is to study the ability of such an approach to correctly estimate the drag coefficient associated with the motion of rolling elements. The influence of the numerical domain extension, the mesh refinement, the simplification of the ring shape, and the presence of the cage on the values of the drag coefficient is presented. While it seems possible to compromise on the calculation domain and mesh size, it appears that the other parameters must be taken into account as much as possible to obtain realistic results.

Ultra-sensitive current bistability and light switching in a resonant tunneling superlattice transistor

Bistability in the current–voltage characteristics of semiconductor superlattices and quantum cascade laser structures has the potential for wide-ranging applications, particularly in sensing systems. However, the interdependency of applied bias and current injection in conventional two-terminal structures has led to complications in analysis and rendered the bistability phenomenon difficult to implement in practical applications. Here, we report a new kind of electronic bistability coupled to optical switching in a resonant tunneling bipolar superlattice transistor. This bistability manifests as sharp discontinuities in the collector current with extremely small variations of the applied voltage, which arise from unstable tunneling transmission across the hetero-barrier between the two-dimensional electron gas (2DEG) at the edge of the transistor base and the collector superlattice structure. The electronic transitions between high and low quantum mechanical transmissions are demonstrated to be caused by self-consistent variations of the internal electric field at the heterointerface between the 2DEG and the superlattice. They are also present in the base current of the three-terminal device and result in sharp switching of near-infrared spontaneous light emission output from an interband radiative recombination process with a peak emission wavelength of 1.58 μm. A comprehensive quantum mechanical theoretical model accounting for the self-consistent bistable tunneling transmission is in quantitative agreement with the experimental data. The measured peak transconductance sensitivity value of 6000 mS can be used in the highly sensitive detector and non-linear device applications.

Comparative Analysis of the Characteristics of Asynchro- nous Drives with Vector Control and Direct Torque Control

Active development of electric drive theory in recent decades has led to the emergence of various methods for asynchronous three-phase motors control, promoted by leading drive development companies, the competition between which inevitably gives rise to false preconceptions about the real capabilities and characteristics of these methods. Additionally, literary sources often bypass positional drives, focusing on speed control, and the same can be said about the preference for synchronous drives over asynchronous ones. This study solves the problem of a comprehensive comparison of the characteristics of classical vector control based drives and direct torque control schemes at the levels of theoretical description and computer simulation. To solve this problem mathematical descriptions and functional diagrams of asynchronous motors with indicated control systems are given and analyzed and models of considered systems are developed in the Simulink environment of the Matlab program, considering flexibility of mechanical transmission and various resistance moments and allowing to form a quantitative assessment of considered characteristics. The results of numerical modeling are presented on example of a specific induction motor with a squirrel-cage rotor DMChTs 80-2-8OM2 for each system variant in several operating modes, which are of interest for various options of such drives practical application and identifying considered control methods individual features. Advantages and disadvantages formulated as a result, as well as recommendations for the use of the compared drive systems, are quite universal and can be used in design of various drives with both asynchro-nous and synchronous motors.

Lightweight design of steel sprocket for roller chain drive using explicit dynamic simulation

Roller chain drives are frequently applied in a variety of machinery for mechanical motion and power transmission. The roller engagement location on the sprocket tooth contour and the resulted contact behavior is governed by the wear of components and pretension of the chain. Therefore, the influence of extension of chain resulted from wear and pretension of chain on contact behavior was investigated numerically using explicit dynamics module of ABAQUS software. The contact angles evaluated from the numerical simulation were assessed relative to those obtained from the basic rigid body analytical formulation. The chain elongation of 3% increased the maximum contact force up to 52% during engagement with the driver sprocket. The contact force raised to 400% when the pretension in the chain drive was increased from 200 to 1000 N, leaving the force distribution pattern unaltered. The optimal design of a steel sprocket is realized through equivalent static finite element contact analysis of a sprocket engaged with 3% extended roller chain. The dynamic finite element analysis in conjunction with topology optimization reduced the weight of the sprocket by 24%.

Analysis of technical solutions for a high-power drive of a pumping unit intended for hydraulic fracturing of reservoir bridges in oil and gas isolated cavities

In order to simplify the design and increase the reliability of a high-power drive, the possibilities of using various high-speed two-shaft double-flow mechanical gear shift transmissions in a pumping unit designed for hydraulic fracturing of reservoir bridges in oil and gas isolated cavities are considered. Keywords:power drive, gear shift transmission, friction device, planetary gearbox, hydraulic pump, power flow au@vstu.ru

Recent Research on Magnetic Machinery

Background: As a clean energy source, magnetic energy is a significant power source of mechanical equipment, which affects the direction of control mode and mechanical structure of mechanical equipment. Magnetic machinery is widely used in industrial power systems and automatic control systems as the power source of mechanical equipment transmission parts or actuators. Magnetic machinery is essential to make mechanical equipment easy to control, energy saving and environmental protection, simple structure, and so on. In order to innovate the control mode of mechanical equipment and optimize the types of traditional mechanical systems, magnetic machinery developed magnetic coupling, magnetic gear, magnetic spring, and other magnetic machinery. The characteristics of magnetic machines with different functions are analyzed based on the types of magnetic machines. Therefore, this aspect's development and application are getting more attention in recent years. To innovate the control mode of mechanical equipment and optimize the types of traditional mechanical structures, magnetic types of machinery, such as magnetic coupling, magnetic gear, and magnetic spring, are making continuous progress. New magnetic machines are also being developed. This paper summarizes the typical patents on three kinds of magnetic machinery: magnetic coupling, magnetic gear and magnetic spring. In addition, the advantages of existing magnetic machinery are summarized, the current situation of magnetic machinery is analyzed, and the development of magnetic machinery is summarized. Through the analysis of enormous patents of magnetic coupling, magnetic gear, and magnetic spring, it is concluded that although there are many kinds of magnetic machinery, there are no systematic and mature design theories and methods. The development trend of magnetic machinery is also discussed. The research on magnetic machinery helps innovate mechanical equipment's control mode and optimize the types of traditional mechanical structures. As a result, more patents will be invented in the future.

ELECTRIC VEHICLE PERFORMANCE ANALYSIS USING MULTI-MOTOR PROPULSION SYSTEM

Developing powertrains for Electric Vehicles requires first to evaluate thetarget vehicle. From vehicle data, the resistant forces appearing duringvehicle movement can be determined. The requiredpower and torque for the propulsion system depend onvehicle speed and road slope angle. To reduce the losses on mechanical transmissions in-wheel motors are used. The motors are limited by thetorque, power,and speed capabilities.In the present paper, the vehicle performance isanalyzed fromthis perspective including nominal and maximum supported values by the powertrain motors.

A digital twin library of mechanical transmission system for the application of small sample fault diagnosis problem

Timely and accurate fault diagnosis of transmission systems is crucial to ensuring the systems’ reliability, safety, and economic viability. However, intelligent fault diagnosis algorithms require a lot of labeled data for training, which may not be available and accessible, especially for many critical devices. This hinders the application of some excellent diagnosis methods in real industry. Digital twin (DT), as an advanced cyber-physical integration method, can be utilized to generate rich fidelity data with virtual models to overcome the dilemma of insufficient data, especially for the small sample problem. We propose the DT library to model the mechanical transmission system with various faults for the data augmentation of the small sample problem. In the library, common components in mechanical transmission systems are modular and digitalized into several differential equations. They can compose a mechanical transmission system digital twin (TSDT) and be injected with various faults to simulate the transmission signal, and even replace the physical experimental platform. The simulation data is used as a pre-training dataset, which can be imported into the transfer learning method for the fault diagnosis. After several verifications, it can be concluded that the simulation data from TSDT is effective in transfer ability and fault feature learning, which significantly improves fault recognition accuracy in the small sample problem.

Design and multimodal locomotion plan of a hexapod robot with improved knee joints

AbstractHexapod robots represent complex and highly redundant robotic systems capable of handling various tasks in extreme environments, such as planetary exploration and disaster response. To enhance the terrain adaptability and maneuverability of hexapod robots, we present a novel multimodal hexapod robot in this research. Our multimodal hexapod robot design incorporates knee joints with an improved multiparallel quadrilateral transmission mechanism, addressing singularity issues commonly encountered in legged robots. This enhancement not only improves the mechanical transmission characteristics of the knee joints but also increases the workspace of a single leg to achieve leg‐arm reuse functionality. In the presence of flat and structured terrain, the robot seamlessly switches to a wheeled locomotion mode, enabling swift traversal. Conversely, when faced with rough and unstructured terrain, it transitions into a legged mode, employing adaptive gait stability to navigate effectively. A novel operational mode in which the hexapod robot utilizes four legs for body support, while the remaining two legs are repurposed as arms is proposed. This innovative approach empowers the hexapod robot to perform dual‐arm manipulation without the need for additional degrees of freedom for the manipulator. To validate the effectiveness of our designed hexapod robot and multimodal motion planning algorithm, comprehensive experimental testing has been conducted, demonstrating the practicality and versatility of our system.

Wheel slip ratio control considering time delay characteristic for electro-mechanical braking system

Electro-mechanical braking (EMB) system is a novel brake-by-wire (BBW) system which is the development direction of the electrification and intelligent vehicle braking system. However, as the EMB contains a mechanical transmission mechanism, there is an inevitable time delay in the braking process, which will cause problems of the wheel slip ratio control. To address this issue, this paper proposes a novel wheel slip ratio control system based on a hierarchical control framework, comprising a slip ratio control layer and a clamping force control layer. Firstly, an EMB actuator model considering the stiffness and damping characteristics of the ball screw is constructed and the correspondence between the model and the EMB object is verified. Subsequently, a model-based compensate active disturbance rejection control (MCADRC) algorithm based on the EMB actuator model is designed to compensate the uncertainty of the EMB and improve the tracking accuracy of the clamping force. Furthermore, the influence of time delay on slip ratio control is analyzed and a slip ratio controller considering time delay characteristic is developed to improve the slip ratio control quality. Finally, the HiL test results show that the proposed controller can effectively reduce the jitter of slip ratio by 1.2% and improve the response speed of slip ratio control 7.8%, which prove the real-time and effectiveness of the controller.

A Soft, Centimeter‐Scaled, Thin‐Cable‐Crawling Robot for Narrow Space Inspection

Cables are critical in engineering structures for load‐bearing, electronic connection, and mechanical transmission. Various cable‐crawling robots (CCRs) have been developed to perform scheduled inspection or convey supplies. Most existing CCRs are often actuated by motors and used in large‐scaled engineering structures. The heavy bodies of these CCRs can cause damage or even casualties once slippage or drop occurs. A small and lightweight CCR that can crawl on thin cables is highly demanded for safety inspection in narrow and confined inner spaces of engineering structures. Herein, a soft CCR (weight, 2.1 g; length, 43 mm) is developed by utilizing multilayered dielectric elastomer actuators. Compared with existing solutions, this CCR achieves crawling on thin cables (diameter: <1 mm) while crawling fastest (horizontal: 0.72 body length per second). The CCR is also capable of transporting objects (horizontal: 3.69 times its own weight; vertical: 0.76 times its own weight), climbing upward on a vertical cable, and locomoting across the water–air interface. The CCR is also demonstrated to crawl on a slack cable and circular/spiral cables. Finally, the soft robot, equipped with an endoscope, demonstrates inspections on a tensegrity structure as well as in an airplane wing model with a preplaced cable.

Incidence, transmission, host range and population dynamics of aphids transmitting bean common mosaic virus of cowpea

Cowpea [Vigna unguiculata (Linn.) Wilczek] is an important pulse crop which belongs to family Fabaceae. Bean Common Mosaic is a major viral disease in cowpea resulting in significant yield losses to a tune of 70 per cent. The results showed that disease was widespread in all the surveyed areas, with the highest average per cent disease incidence being observed in Bagalkote (29.82%) followed by Vijayapur (27.41%), Dharwad (25.47%) and Belagavi district (18.89%). The disease incidence varied from 3.25 per cent to 69.56 per cent among the villages and from 12.94 per cent to 44.80 per cent among the taluks. The host range and transmission studies revealed that BCMV infecting cowpea is readily transmissible by sap, aphids and through seeds. The mechanical transmission was 71.43 per cent, aphid transmission was found to an extent of 54.42 per cent and the seed transmission of BCMV infecting cowpea was 64.00 per cent. The population of aphid (Aphis craccivora) was maximum during the 38th and 39th Standard Meteorological Weeks (SMWs) with the mean value of 92.70 and 81.20, respectively. The aphid population varied at different crop stages. Aphid population build up showed a strong significant negative correlation with rainfall. There was a significant negative correlation with minimum temperature and morning RH.

Degradation modeling and reliability estimation for mechanical transmission mechanism considering the clearance between kinematic pairs

The mechanical transmission mechanism is the core component of electromechanical systems, of which the health state can affect the accuracy and stability of the entire system. Due to machining errors and thermal deformation, clearance often exists between the kinematic pairs, which leads to irregular collision- separation during the operation. The clearance size and the surface quality of pairs change during the service life, leading to the time-varying damage and degradation state of the mechanism. Therefore, the kinematic pairs suffer from not only natural deterioration process such as wear, fatigue, etc., but also the collision-separation process caused by the clearance. In this paper, a degradation and shock model for the mechanical transmission mechanism is proposed considering the influence of clearance between the kinematic pairs. The degradation process is divided into running-in stage, stable degradation stage, and fast degradation stage according to the health states, and is modeled by a transformed gamma process to account for the dependency between service time and health state. Random shocks caused by the collision-separation process are classified into different zones in terms of their sizes, and the arrival rate of the shocks also change with the health state of the mechanism. The closed-form reliability function is derived and verified by the experiment of rotating pair of the crank and rocker mechanism. Results show that the proposed degradation and shock model can obtain a more realistic and reasonable reliability of the transmission mechanism.

Design of a Novel Linkage for Electronic Parking Brake Transmission Systems

Abstract This paper presents a novel mechanical transmission for pulling-cable electronic parking brakes (EPBs). The system is interposed between the brake electric actuator and the brake pads, and it exploits a 2DOF planar linkage to provide the requested brake force and ensure the correct vehicle standstill. This paper describes the working principles and main component of the adopted architecture, and compares it with the EPB state of the art. Thereafter, the paper focuses on the system requirements and consequent functional design. A first prototype of the presented mechanical transmission is then presented to discuss the role of a mechanical engagement within the system to ensure its proper behavior. In conclusion, the EPB drive motor assessment is discussed on the basis of a simplified drive chain dynamic model.

An Analysis of Power Friction Losses in Gear Engagement with Intermediate Rolling Elements and a Free Cage

Currently, mechanical gears with cycloid engagement are increasingly used in mechanisms along with involute ones. In modern drive mechanisms, using pin gears and gears with intermediate rolling elements (IRE) is widespread, which simultaneously use cycloid gears. To a greater extent, pin gears are now being investigated, but IRE gears have their undeniable advantages. Many works are devoted to the study of cycloid toothing for certain gears, but the efficiency, especially that of IRE gears, has practically not been investigated. Therefore, the analysis of power losses in the engagement of a gear with IRE and a free cage (IREFC) is relevant. In this analysis, the authors of the work have used laws of mechanics, methods of energy flows and a secant normal. Mathematical expressions have been obtained to estimate slip speeds and power friction losses in the engagement of a gear with IREFC, and a formula has been derived to determine the efficiency of a mentioned mechanical transmission. The calculation of slip speeds and power losses at the points of contact of a rolling element with cycloid profiles of wheels for selected initial parameters of a gear with IREFC has been presented. The friction power and the overall efficiency of the entire gear engagement have also been calculated. This work shows that power friction losses at the points of contact of a rolling element with cycloid profiles of tooth wheels of a gear with IREFC are not the same. The friction power in the contact of a rolling element with a cycloid profile of a cam is an order of magnitude higher than the friction power in the contact of a rolling element with a cycloid profile of a crown.

Analysis of hydraulic drive circuit selection for a carrot collecting system

Compared to conventional mechanical transmissions, hydraulic transmission has the disadvantage of lower energy efficiency. However, it is widely employed in various working machines such as construction machines, off-road vehicles, forest logging machines, and especially agricultural machinery, owing to its flexibility in design, geometric arrangement, and simplicity in operation. In the development project for carrot harvesting machinery conjugate, hydraulic transmission is the optimal solution for the design and implementation of the carrot collecting roller system. This project is oriented towards achieving a practical result where the system structure is simple and effective, utilising hydraulic components available on the market in Vietnam. Given the myriad of hydraulic transmission circuits available, this paper undertakes an analysis based on numerical simulations of the functionality and energy efficiency of potential system design options and proposes a new practical speed control circuit. This suggested circuit uses a pressure-compensated flow control valve arranged parallel to the hydraulic motor. The study is carried out in the Matlab/Simulink simulation environment, where the circuit models are constructed using hydraulic components with practical parameter settings sourced from component suppliers. The analysis results indicate that the proposed circuit strikes a balance between functionality and economic efficiency.

Fuzzy algorithm-based active control method for vibration of a mechanical gear transmission system

The detached raft automatic frequency isolation system is a complicated system with high exceptionally nonlinear, high electromagnetic, and multi-source vibration modes. However, it generates a statistical method and it is hard to operate the organization. The fuzzy control algorithm, as an astute control method, can give a keen path to the active management of a complicated system of floating rafts. This study uses a system identification approach to construct mathematical models for a floating raft active vibration isolation system with discrete transfer work. The fuzzy model is used in tests and simulations controller is built using two contributions of acceleration and its variation, as well as a single result of control voltage. The control isolation system is a complicated system with many moving parts. A lot of moving parts profoundly nonlinear, high electromagnetic and multi-source vibration modes, generating a statistical method and it is hard to operate the organization. The fuzzy control algorithm, as a smart control method, can give a keen path to the active management of a sophisticated floating raft system. This research uses an identification strategy to construct a floating raft active vibration isolation technology discrete transfer work mathematical models. The fuzzy controller is then put together using two contributions: acceleration and variation, as well as a single outcome of control voltage for simulations and experiments research.

Femtosecond Laser Fabrication of Three-Dimensional Bubble-Propelled Microrotors for Multicomponent Mechanical Transmission.

Inspired by the reverse thrust generated by fuel injection, micromachines that are self-propelled by bubble ejection are developed, such as microrods, microtubes, and microspheres. However, controlling bubble ejection sites to build micromachines with programmable actuation and further enabling mechanical transmission remain challenging. Here, bubble-propelled mechanical microsystems are constructed by proposing a multimaterial femtosecond laser processing method, consisting of direct laser writing and selective laser metal reduction. The polymer frame of the microsystems is first printed, followed by the deposition of catalytic platinum into the desired local site of the microsystems by laser reduction. With this method, a variety of designable microrotors with selective bubble ejection sites are realized, which enable excellent mechanical transmission systems composed of single and multiple mechanical components, including a coupler, a crank slider, and a crank rocker system. We believe the presented bubble-propelled mechanical microsystems could be extended to applications in microrobotics, microfluidics, and microsensors.