Gear Assembly Research Articles

Impact of operator characteristics on landing gear ground manoeuvre occurrences

Abstract The variability in ground manoeuvre occurrences for aircraft landing gear is intrinsically linked to the airport geometries served by aircraft in-service and consequently, the cyclic loads that landing gear carry are driven by the route network and characteristics of aircraft operators. Currently, assumptions must be made when deriving fatigue load spectra for aircraft landing gear, which may fail to capture the operator characteristics, potentially leading to design conservatism. This paper presents the enhanced characterisation of ground turning manoeuvres within the Automatic Dependent Surveillance-Broadcast (ADS-B) trajectories for six narrow-body aircraft across a full-service carrier (FSC) and a low-cost carrier (LCC) fleet. The methodology presented within this paper employs ADS-B latitude and longitude information to overcome limitations of previous approaches, increasing the rate of correct manoeuvre identification within ADS-B trajectories to 77% of flights from the 50% rate achieved previously. When characterising the ground manoeuvres across 3,000 flights, significant differences in manoeuvre occurrences were observed between individual aircraft within the LCC fleet and between the FSC and LCC fleets. The occurrence of tight and pivot turns were shown to vary across the six aircraft with six and eight fatigue-critical turns being performed by the FSC and LCC fleet for every 10 flights performed. In addition, it was observed that the direction of fatigue critical turns is biased in specific directions, suggesting that individual main landing gear assemblies will accumulate fatigue damage at an increased rate, leading to greater justification for operator-specific spectra and structural health monitoring of aircraft landing gear.

Modelling width of the spectral component of a gas-turbine engine gearbox output shaft speed

Gearbox is the most stressed component in an aircraft gas-turbine engine. This implies the need for finding ways to monitor its technical condition. Practice shows that the most efficient method is vibration-based diagnostics. However, this method requires the use of sophisticated measurement systems and highly skilled personnel. This paper shows that errors of gear coupling manufacture and assembly, characteristics of machine operating mode, design factors, frequency modulation of the carrier of the engine rotor speed in the stationary mode of its operation, and wear of teeth flanks determine the width of the spectral component of the gearbox output shaft speed. Using the results obtained from the developed model of the width of gear tooth spectral component, ratios for width of the spectral component of the signal of the “standard” tachometric speed sensor of the gearbox output shaft speed and the corresponding spectral component of its vibration were obtained. Models for repaired and newly manufactured gearboxes and gearboxes with tooth flank wear were proposed. This allowed the development of a number of new diagnostic indicators of a defect. Several examples of the use of these new diagnostic indicators are given for the gearbox of one of turbo-prop engines. The results obtained provide an opportunity to assess the gearbox technical condition in operation.

Development of Mini Silk Screen Printing Machine

The research aims to develop and design a mini semi-automatic screen-printing system that can be easily controlled. The objectives of this project are to create a suitable design for the mini semi-auto screen printing system and to develop it accordingly. The type of study conducted is the development of a real project, which is the production of a mini silk screen printing machine. The development of this project involves 4 phases: design and fabrication phase, motor wiring system, mould production and testing process. In this project, a mechanical setup will be created to execute the printing process. This setup will include a conveyor mechanism to hold the paper, a lifting arrangement, a wiping setup, and cutters. To control the printing operation and semi-automate the screen-printing setup, a power panel will be utilized. The setup will encompass a control system and a motion system, which will consist of a gear assembly and servo motors. The testing conducted is the functional process of the system regarding machine operation. As a conclusion, the development of mini silk screen printing successfully develops for student in Mechanical Engineering Department in POLIMAS. Keywords: Silk screen printing, printing process, control system

Review On Evolution and Development of Electric Road Roller

The evolution and development of electric road rollers mark a significant advancement in the construction machinery industry, driven by the imperative of sustainable infrastructure development. This paper provides a comprehensive overview of the historical progression, technological innovations, and current trends shaping electric road rollers. Beginning with the early developments of steam-powered and diesel-driven road rollers, the transition towards electric propulsion systems is traced, highlighting the environmental benefits and operational efficiencies offered by electric models. An electric-applied road roller vehicle represents a sustainable and innovative solution for the construction industry. This eco-friendly equipment utilizes electric power to propel the roller, reducing carbon emissions and noise pollution compared to traditional fossil fuel-powered counterparts. The vehicle's design incorporates advanced technology, such as gear chain mechanism to maximize energy efficiency and extend battery life. With its quiet operation and reduced environmental impact, the electric road roller vehicle demonstrates a promising step towards greener construction practices, contributing to a cleaner and more sustainable future. Top of Form Keywords— Electric Road Roller, Battery, High torque dc motor, propulsion system, gear assembly, etc.

Assessing the effects of interference fit assembly on gear tooth surface deviations

When shafts and gears are assembled with an interference fit, the tight connection between the two parts is achieved through deformation. To maximize the amount of torque the gear assembly can transmit, it becomes necessary to apply the maximum possible interference fit. However, this will cause areas of high stress in the gear root and deformations that adversely affect the contacting surfaces of the gears. In this work, the modified gear tooth surfaces that provide the desired meshing and contact conditions considering the deformations caused by the interference fit assembly will be established. For that, a finite element (FE) model will be developed to simulate gear-shaft interference fits by the finite element method. The FE model will comprise the entire gear along with the corresponding portion of the shaft, replicating the intended interference fit. Consequently, the model will enable the determination of the stresses at the root of the gear teeth as well as the deviations throughout the active gear tooth surfaces. With them, the deviated gear tooth surfaces will be reconstructed and virtually inspected by using the IGD computer program. Thus, the deviations caused by the interference fit will be assessed and the needed modifications of the gear tooth surfaces established to have these deviations compensated. A numerical example of design and compensation of deviations caused by interference fit assembly is presented.

Dynamic simulation of the differential gear in road vehicles

The differential gear is a mechanism that is part of the kinematic chain of the vehicle’s transmission. The differential gear has the role of dividing the self-propulsion power flow received from the main drive into two branches, each transmitted to a drive wheel, giving them the possibility to rotate with different angular velocities, depending on the driving conditions. The present work presents the possibilities of computer-aided design and 3D modeling of the main drive and differential gear, respectively the bevel pinion, the crown wheel, the planet pinions and the satellites, using Autodesk Inventor Professional. The 3D model of the main drive - differential gear assembly, considered as a mechanism, was subjected to a dynamic study, using the Dynamic Simulation module. This involves the modeling of the kinematic couplings, the definition of the drive movement parameters and the external loads, respectively the graphical visualization of the kinematic and kinetostatic results for the various components of the mechanism, in real operating conditions, during a kinematic cycle. At the same time, based on the obtained results, the analysis by the finite element method of the most critical component elements, under straight-line driving and turning conditions, is presented.

Material Selection for Differential Gearbox under Torque Conditions: A Simulation-Based Study

Abstract: This research paper conducts an in-depth exploration into the structural behaviors of three distinct materials—Cast Iron, Copper Alloy, and Magnesium Alloy—within the framework of a differential gearbox under varying torque loads. Employing finite element analysis through ANSYS, the investigation systematically scrutinizes critical parameters such as total deformations, equivalent stress (von Mises stress), and shear stress. The primary aim is to offer insights that guide material selection strategies and enhance the optimization of design processes in automotive applications. The results illuminate nuanced material responses when exposed to torque conditions, presenting implications for real-world gear assembly scenarios. This study significantly contributes to the evolving knowledge base in automotive engineering, providing a foundation for wellinformed decision-making in material selection and design optimization for differential gearboxes.

One-shot sim-to-real transfer policy for robotic assembly via reinforcement learning with visual demonstration

AbstractReinforcement learning (RL) has been successfully applied to a wealth of robot manipulation tasks and continuous control problems. However, it is still limited to industrial applications and suffers from three major challenges: sample inefficiency, real data collection, and the gap between simulator and reality. In this paper, we focus on the practical application of RL for robot assembly in the real world. We apply enlightenment learning to improve the proximal policy optimization, an on-policy model-free actor-critic reinforcement learning algorithm, to train an agent in Cartesian space using the proprioceptive information. We introduce enlightenment learning incorporated via pretraining, which is beneficial to reduce the cost of policy training and improve the effectiveness of the policy. A human-like assembly trajectory is generated through a two-step method with segmenting objects by locations and iterative closest point for pretraining. We also design a sim-to-real controller to correct the error while transferring to reality. We set up the environment in the MuJoCo simulator and demonstrated the proposed method on the recently established The National Institute of Standards and Technology (NIST) gear assembly benchmark. The paper introduces a unique framework that enables a robot to learn assembly tasks efficiently using limited real-world samples by leveraging simulations and visual demonstrations. The comparative experiment results indicate that our approach surpasses other baseline methods in terms of training speed, success rate, and efficiency.

Hysteresis Stress, Strain and Penetration Analysis of Spur Gear Assembly for Various Sustainable Design

This paper considers and compares the hysteresis stress and strain and the penetration property of spur gear assemblies based on three unique designs. Spur gear plays an important part in mechanical structures, and any mechanical setup should consider the execution of such a mechanical component under distinct designs to improve its mechanical productivity and sustainability. To explore the ways in which the mechanical behaviour of the designs varies with the design configurations, we integrate simulation analysis with an experimental study. The outcomes of this paper indicate considerable differences in both hysteresis stress, strain distribution, and penetration behavior measurements between three designs. The paper explains the stated disparities by the unique geometric layouts and material characteristics of each design. Furthermore, it emphasizes that some of the examined designs have lower hysteresis losses and favourable stress and strain distributions, which positively affects the long-term performance of gear systems. Other designs, however, exhibit severe penetration and stress concentrations leading to rapid gear wear and likely premature failure. In distinguishing these events, the present study offers a valuable approach to the parameters that influence the performance of gear systems and aids in the improvement of the design methodology.

Large gear structure assembly method based on uncalibrated image visual servo guidance.

The reliability of the transmission system hinges significantly on the assembly quality of its main component, the large gear structures. However, the traditional approach of employing manual lifting presents a host of challenges, such as high assembly complexity and lowered efficiency, rendering the overall assembly process notably arduous. In this study, a large gear structure assembly method based on uncalibrated image visual servo guidance is proposed. Comprising three modules, the approach involves constructing a task function for projective homography, estimating the image Jacobian matrix, and designing an adaptive servo controller. This methodology facilitates the mapping of changes in gear images to the motion of the end-effector in the parallel mechanism. Consequently, the system dynamically guides the end-effector to achieve the required attitude adjustments in the gear assembly in response to changes in the image features. Experimental results demonstrate that the method proposed surpasses alternative approaches, simultaneously exhibiting a significant enhancement in assembly efficiency. The method has a wide application prospect in the field of automated assembly of large gear structures.

A Motion Planning Method for Visual Servoing Using Deep Reinforcement Learning in Autonomous Robotic Assembly

Assembly positioning by visual servoing (VS) is a basis for autonomous robotic assembly. In practice, VS control suffers potential stability and convergence problems due to image and physical constraints, e.g., field of view constraints, image local minima, obstacle collisions, and occlusion. Therefore, this article proposes a novel deep reinforcement learning-based hybrid visual servoing (DRL-HVS) controller for motion planning of VS tasks. DRL-HVS controller takes current observed image features and camera pose as inputs, and the core parameters of hybrid VS are dynamically optimized using a deep deterministic policy gradient (DDPG) algorithm to obtain an optimal motion scheme, considering image/physical constraints and robot motion performance. In addition, an adaptive exploration strategy is proposed to further improve the training efficiency by adaptively tuning the exploration noise parameters. In this way, the offline pretrained DRL-HVS controller in the virtual environment, where the DDPG actor–critic network is continuously optimized, can be quickly deployed to a real robot system for real-time control. Experiments based on an eye-in-hand VS system are conducted with a calibrated HIKVISION RGB camera mounted on the end-effector of a GSK-RB03A1 six degree-of-freedom (6-DoF) robot. Basic VS task experiments show that the proposed controller achieves better performance than the existing methods: the servoing time is 24% smaller than that of the five-dimensional VS method, a 100% success rate with the perturbed ranges of the initial position within 25 mm for translation and 20° for rotation, and a 48% efficiency improvement. Moreover, a planetary gear component assembly process case study, where the robot aims to automatically put the gears on the gear shafts, is conducted to demonstrate the applicability of the proposed method in practice.

Influence of assembly errors on meshing characteristics of spiral bevel gear and compensation approach of misalignment

Based on the spatial position relationship of spiral bevel gear, mathematical model and mesh model applied with finite element analysis (FEA) approach has been established. The influence of axial position errors of pinion and wheel, offset error, and shaft angle error on the meshing characteristics has been investigated. A method has been proposed to compensate the gear assembly errors by the axial displacement of the pinion and wheel, and the correctness of this method verified by numerical examples. The performed results indicate that the existence of assembly errors can cause contact pattern on the tooth surface to deviate from its design position, resulting in poor meshing quality and having a certain impact on transmission error (TE) and peak-to-peak transmission error (PPTE). The pinion and wheel’s axial positioning errors can be offset by each other, whereas the offset error and shaft angle error can be mitigated by the interplay between the axial positioning of the pinion and wheel. By compensating for assembly errors with axial displacement, the position of the contact pattern can be precisely controlled, and TE will not significant changes.

Convertible staircase lift

The present work investigates the design and analysis of a staircase lift, which can be used as a Material Handling System. A staircase lift is a mechanical device for lifting people and wheelchairs up and down the stairs, who may find difficulty in doing so themselves. For sufficiently wide stairs, a rail is mounted to the treads of the stairs. A chair or lifting platform is attached to the rail. A person on the chair or platform is lifted as the chair or platform moves along the rail, old age and goods are to be carried across the staircase. A staircase lift is a type of lift that can be mounted on the staircase without altering civil structure. Not only altering, but the person need not change the seat from the wheelchair to the staircase lift, there is a foldable supporting rod for the staircase lift which directly attaches to the wheelchair. This lift runs on electric power and consists of a motor, reduction gearbox, rope drive, two rails and a sliding chair. In this system, we use a DC motor for changing the polarity of the power supply which will make the motor run in reverse direction. Advantages over the conventional hydraulic lift are no civil structure and alteration is required, low cost, less bulkiness, less power, less maintenance required. Easy design, easy installations can be of industrial use too. Moreover, considering some drawbacks due to weight carrying capacity completely depends upon the capacity of the motor. There is a lot of scope for further modification in the project as using a monorail instead of two, using a belt drive or chain drive instead of a rope drive. Incorporation and automation/timer unit will ease the use of the device. Rack and carrier arrangement for using the device for a curved staircase and use of work & roller reduction gear assembly.

Design of a nature-inspired sun-tracking device in context of rural India

The efficiency of the photovoltaic system is traditionally being increased with the help of solar concentrators. The concentrators based on biomimetic structures of various flowers have proven to be effective in increasing performance efficiency. The present study proposes the design of a nature-inspired, novel and passive, single-axis solar tracker that operates on the principle of variable coefficients of thermal expansions of different metals in a bimetallic plate. The proposition mimics the heliotropism mechanism of Sunflowers to achieve acceptable results. It involves the use of a solar PV panel mounted on a gear assembly, connected to a bimetallic plate via connecting linkage and a concave mirror to reflect the incident sun rays on the plates during the day. The resultant deflection in the plates rotates the mounted solar PV panel to follow the sun throughout its diurnal course. There were certain conditions that were determined mathematically to ensure correct working of the proposed design. CAD modelling was adopted to better study the functioning of the envisioned contraption as a whole. The proposed design is easy to construct; thereby making it an efficient, promising and economical alternative to other passive and fixed ones.

Research on Tolerance Optimization of High Precision Equipment Assembly Based on Error Transfer Prediction Model

In this paper, the assembly error transfer prediction model was established based on the error transfer attribute and the error transfer path of the assembly process. The assembly accuracy prediction was realized by combining error variation inequality, constraint inequality and mathematical statistics method. Aiming at the lowest processing cost of high-precision equipment assembly, the assembly accuracy required the reliability of index, the value interval of tolerance item and the principle of tolerance selection as constraints, the tolerance optimization model was established. The tolerance optimization of high-precision equipment assembly was carried out by combining the penalty function method and the improved genetic algorithm. Finally, taking gear oil pump assembly as an example, according to the reliability calculation formula of assembly accuracy, the reliability is 97.35%. Compared with the processing cost before and after optimization, the processing cost decreased by 12.13% after optimization, and the assembly accuracy reliability increased by 1.65%. The correctness and effectiveness of assembly accuracy prediction and tolerance optimization are verified.

Turn-Taking Prediction for Human–Robot Collaborative Assembly Considering Human Uncertainty

Abstract Human–robot collaboration (HRC) combines the repeatability and strength of robots and human’s ability of cognition and planning to enable a flexible and efficient production mode. The ideal HRC process is that robots can smoothly assist workers in complex environments. This means that robots need to know the process’s turn-taking earlier, adapt to the operating habits of different workers, and make reasonable plans in advance to improve the fluency of HRC. However, many of the current HRC systems ignore the fluent turn-taking between robots and humans, which results in unsatisfactory HRC and affects productivity. Moreover, there are uncertainties in humans as different humans have different operating proficiency, resulting in different operating speeds. This requires the robots to be able to make early predictions of turn-taking even when human is uncertain. Therefore, in this paper, an early turn-taking prediction method in HRC assembly tasks with Izhi neuron model-based spiking neural networks (SNNs) is proposed. On this basis, dynamic motion primitives (DMP) are used to establish trajectory templates at different operating speeds. The length of the sequence sent to the SNN network is judged by the matching degree between the observed data and the template, so as to adjust to human uncertainty. The proposed method is verified by the gear assembly case. The results show that our method can shorten the human–robot turn-taking recognition time under human uncertainty.

Study of Effect of Linear Tip Relief Modification in Power Transmission Efficiency of Spur Gears

This paper explores the influence of linear gear tip relief modification on power transmission efficiency. In real time applications gears experience transmission error (TE) during operation which increases noise and vibration and also results in increased tooth profile deformation during operation of the gear. By providing tip relief profile modification this TE can be decreased. Using MATLAB for computation and ANSYS for the simulation of deformation, stress, strain, life, and factor of safety results for the gear assemblies are obtained. Deformation results are used for the computation change in power transmission efficiency followed by the modal and harmonic analysis of the gears and gear assemblies to determine change in the first mode of natural frequency.

Finite element analysis of bevel gear tooth side clearance and fatigue characteristics under alternating torque

In this paper, the effect of different tooth side clearances on the fatigue characteristics of bevel gears under alternating torque is investigated using finite element analysis technology. The article first determines the structure form and main parameters of the bevel gear and completes the establishment of the three-dimensional model of bevel gear transmission. Then, based on the principle of finite element analysis, the fatigue characteristics of the bevel gear under different tooth side clearances are simulated by ANSYS workbench software. Next, according to the simulation results, the changes in service life and safety coefficient of bevel gear with tooth side clearances are analyzed, and the relevant conclusions are drawn. Finally, combined with the finite element analysis results, the axial adjustment amount of the bevel gear assembly of this project is guided, and the actual use effect is verified. The results show that when the tooth side clearance jn is taken in the range of 0.04·m∼0.08·m, the fatigue safety coefficient and service life of bevel gear gradually decrease with the increase of tooth side clearance jn.

The effect of center distance error on the service life of polymer gears

Gear assembly errors are an important contributor to a premature gearbox failure. This study investigates the effects of center distance deviation on polymer gearbox life. The main focus was on the influence on the stress state of the gear. Reference spur gears (m = 1 mm, z = 20, b = 6 mm) with a standard involute gear profile and a gear ratio of 1 (same pinion and gear) were studied. A combination of numerical and experimental methods was used to obtain the best insight into the gear meshing process. Simulations of the gear meshing process were performed using a verified finite element analysis model. Torques of 0.8 Nm and 1.0 Nm were applied and gear meshing was simulated at center distances of 20.00 mm, 20.05 mm, and 20.10 mm. It was found that, as the center distance increased, the contact ratio decreased, which consequently leads to an increase in tooth root stress. Experimental gears tests were additionally conducted on a dedicated gear testing machine. The gears were tested under the same conditions previously simulated using the FEM model. Steel/PA6 gear pairs were tested, with at least three test repetitions for each combination of load and center distance. A significant reduction in gear service life of more than 30% was identified for larger center distances, while no pronounced effects on operating temperature were observed.

Online measurement method for assembly pose of gear structure based on monocular vision

The gear structure is an important part of the transmission device. The majority of manual methods are currently used to complete the assembly of the large internal gear. Manual assembly is difficult and inefficient. Therefore, an online measurement method for the assembly pose of the gear structure based on monocular vision is proposed. After the critical features of the gear structure have been detected, a duality elimination method based on traversal mapping dots is proposed to obtain the correct solution for the spatial circle pose. Concurrently, the circle pose optimization model is established to enhance pose precision. Then, a new calibration board was designed to complete the hand-eye calibration of the parallel mechanism and camera. Finally, the correction amount required to complete the internal and external teeth assembly is calculated based on the iterative update of the pose measurement method. The experimental results show that the comprehensive accuracy of the pose measurement method exceeds 0.2 mm, the average assembly time is approximately 14 min and the assembly success rate is approximately 97%. It has been realized that simulated gear structure parts can be assembled automatically.