Worm Gear Mechanism Research Articles

Design and Characteristic Research on Variable Displacement Mechanism of Two-Dimensional (2D) Bivariable Pump

In a hydraulic system, a micro variable pump is required to be high pressure and high speed, and this work presents a new type of 2D bivariable pump structure in which the worm gear and worm mechanism are used to rotate the cylinder block to change the flow distribution state of the cylinder window and the piston groove to change the displacement of the 2D pump. The flow–pressure mathematical model of the 2D variable pump is established to analyze the relationship between pump displacement and the pump cylinder rotation angle and the effects of variable displacement on pump pressure characteristics, flow characteristics, and volume efficiency in Matlab. During the experiment, we tested the change in the corresponding pump output flow when the cylinder rotation angle is 0~12°, which verifies the correctness of the variable calculation model. The experimental results indicate that the volume efficiency and mechanical efficiency of the single-piston 2D pump are reduced to different degrees after variable displacement, the volume efficiency is reduced by approximately 3% at most, and the mechanical efficiency is reduced by approximately 5% at most.

Optimal Design of Planetary Reducer of Electric Actuator base on NSGA-II

To solve the problem of equipment installation space shortage in industrial automation sites, a set of hybrid transmission schemes was designed with a two-stage 2K-H(NGW) planetary reducer as the main transmission mechanism combined with a fixed shaft gear train and worm gear and worm mechanism. At the same time, to obtain the design parameters of the electric actuator more quickly and accurately, with the minimum volume and maximum efficiency of the main transmission mechanism as the design objectives, the multi-objective function mathematical model is established under the conditions of meeting the gear matching, displacement coefficient, strength, and overlap degree, and the non-dominated sorting genetic algorithm II (NSGA-II) is used to solve the mathematical model. The research results show that the volume of the main transmission mechanism is reduced by 13.6%, the transmission ratio is increased by 1.54%, but the transmission efficiency is reduced by 3.32% when the strength and life of the gear are equal.

Systematic design of snake arm maintainer in nuclear industry

This paper develops a remote handling system with a Snake Arm Maintainer (SAM) as the end effector, which aims to meet the maintenance needs of various narrow working spaces of the Chinese Fusion Engineering Test Reactor (CFETR). The multi-joint snake-arm is designed with the principle of layered drive to realie the angle synchronisation of adjacent joints, which reduces the complexity of the drive control system, and reduces the volume and weight while ensuring a high spatial curvature. The drive box is connected to the Multi-Purpose Overload Robot (CMOR) through a quick-change connector. The worm gear mechanism realies the reverse folding of the SAM and close to the CMOR, enabling access to the narrow vacuum chamber. Two working methods of SAM are designed based on trajectory planning and trajectory tracking. Finally, based on the actual environment of the CFETR vacuum chamber, simulation experiments were carried out on the rationality of the structural design of the SAM and the correctness of the working methods, which verified the feasibility of working in a narrow vacuum chamber.

Building of Inmoov Robotic Arm for Performing Various Operations

Abstract: ‘Automation is the key in reducing the repetitive and banal tasks of everyday life’, the oft-quoted aphorism best portrays our effort at making a humanoid hand for tasks that require dexterity of fingers in situations where time and effort are of importance. The cost of human labor, quality of processes or products, time, and safety make this project a need of the hour. The research paper showcases our efforts of making a humanoid robotic arm. The body of the arm is composed of 3D printed parts. Servo Motors with nylon strings were used to control the fingers and the wrist. InMoov Nervo Board was used to control the servos. Worm Gear Mechanism was implemented to control the bicep movement and Worm Wheel is used for shoulder rotation. Machines can perform a wide range of functions without a considerable amount of human intervention. The future scope of Robotics and Automation would be to make a diverse and positive impact in industrial as well as research applications. Keywords: 3D Print, Build Challenges, Electronics, Humanoid, Inmoov, MyRobotLab, Robotic Arm, Robotics

Effect of Ankle Torque on the Ankle-Foot Orthosis Joint Design Sustainability.

The ankle joint of a powered ankle–foot orthosis (PAFO) is a prominent component, as it must withstand the dynamic loading conditions during its service time, while delivering all the functional requirements such as reducing the metabolic effort during walking, minimizing the stress on the user’s joint, and improving the gait stability of the impaired subjects. More often, the life of an AFO is limited by the performance of its joint; hence, a careful design consideration and material selection are required to increase the AFO’s service life. In the present work, a compact AFO joint was designed based on a worm gear mechanism with steel and brass counterparts due to the fact of its large torque transfer capability in a single stage, enabling a compact joint. Further, it provided an added advantage of self-locking due to the large friction that prevents backdrive, which is beneficial for drop-foot recovery. The design was verified using nonlinear finite element analysis for maximum torque situations at the ankle joint during normal walking. The results indicate stress levels within its design performance; however, it is recommended to select high-grade structural steel for the ankle shaft as the highest stresses in AFO were located on it.

Eccentric device for varying the gear ratio

In the paper is presented the working principle of the device as well as the constructive-functional scheme for its realization. The use of such a device allows variable gear ratios to be obtained in a very wide range. It has the advantage of a compact construction relative to other mechanisms with varying transmission ratios, such as the crank mechanism. The device contains a worm gear that allows for the eccentricity of a toothed wheel in relation to the cone wheel. The worm gear mechanism also ensures that it is self-locking while it is in operation without the need for other insurance items. The device can be used in the control of actuators in the field of machining or packaging in an automated process.

Worm gear mechanism with switchable backdrivability

A worm gear has the advantages of a large reduction ratio and non-backdrivability. Because of this non-backdrivability, it can maintain a joint angle without energy consumption. Today, many robots have large workspaces that extend into the living spaces of humans, and they are required to work cooperatively with humans. In such cases, backdrivability is necessary to achieve high compliance for robots. Compliance helps robots perform cooperative tasks with humans, and protects its mechanisms and humans in the case of a collision. However, a worm gear cannot be backdriven because of the friction between tooth surfaces. Therefore, we have developed a worm gear mechanism that can switch its backdrivability using vibration that reduces friction. In this paper, we present a dynamic model of the worm gear to analyze the friction-reduction phenomenon caused by vibrations. We discuss the change in the effectiveness of the backdrivability with the change in the vibration direction. Finally, we experimentally confirm the certainty of the analysis.

Design optimization of worm gear drive with reduced power loss

In worm gear mechanism, power loss is one of the critical issues, which requires attention from gear designers and researchers. This is due to power loss; the overall efficiency of worm gear drive gets reduced. In this article, Simulated Annealing (SA) is used to minimize the power loss of worm gear drives within the prescribed set of design constraints. Various design constraints included in the design optimization problem are linear pressure, bending strength and deflection of worm. Gear tooth number, coefficient of friction and helix angle are the design variables considered. Results obtained are compared and validated with the results obtained in previous research work found in the literature. It shows that SA is more efficient in attaining optimal design values for worm gear drive for reducing power loss.

가위쌍 구조의 소형 CMG 모듈의 0.4 Nm 출력 토크에 대한 실험적 검증

In this paper, a mini control moment gyroscopic (CMG) actuator with a scissored-pair is designed and implemented. Two single gimbal CMGs form a double gimbal CMG mechanically to generate the double torque in the desired direction. The mechanical design of the worm gear mechanism allows the scissored-pair configuration. Experimental studies for measuring the induced torque using a force sensor are conducted. The estimated design torque and the measured torque are compared. We actually obtain a 0.4 Nm induced torque.

Development of a Self-Propelled Colonoscope Robot with a Conical Worm Gear Mechanism

Development of a Self-Propelled Colonoscope Robot with a Conical Worm Gear Mechanism

Positon Control of an Electric Clutch Actuator for 2-Speed I-AMT

A novel kind of I-AMTs is adopted for pure electric vehicle, which uses overrunning clutch to replace the sleeve to realize smooth shift without power interruption. A nonlinear-feedward-feedback controller is designed for its electric clutch actuator that includes a dc motor, a set of worm gear, worm and linkage mechanism to implement the motion control. However, the nonlinear load force and the nonlinear characteristics of linkage mechanism increase the difficulty of controller design. The designed controller includes two parts: the feedforward controller was designed to settle system nonlinearities and the feedback controller was designed to guarantee the reliability of the controller. Experiments result shows that, compared with PID controller, the designed controller can provide better performance and keep the system stable at the same time.

フリー/駆動切替機能を持つ補助機の機構と制御

This paper proposes an upper limb power assist exoskeleton with passive rotation mechanism in order to realize user's free motion when the power supply is cut off. The mechanism makes it possible to reduce power consumption while the user does not need power assist. The exoskeleton comprises a DC motor, a worm gear mechanism and two pressure sensors. This exoskeleton keeps its posture even if the power supply cut off because the worm gear mechanism has a self-lock function. We adapted high robustness control method, the simple adaptive control (SAC) to control the exoskeleton and verified the effect of the power assist using EMG measurement.

Dual-mode variable stiffness actuator using two-stage worm gear transmission for safe robotic manipulators

In this paper, we propose a new type of active variable stiffness actuator (VSA) by using a unique differential worm gear mechanism where a set of compressible coil springs are installed. The stiffness of the VSA is varied depending on the compressed amount of the coil springs; large compression results in an effectively stiff joint, and vice versa (compliant mode). Interestingly, an ideal rigid joint is also realizable if the springs’ reactive force is made larger than the external load (rigid mode). The VSA is characterized to become compliant rapidly if the external load exceeds the springs’ reactive force, so such a VSA can protect itself in an unexpected overloading condition. Conducted experiments confirm the effectiveness of the proposed VSA.

3P1-B03 中心静脈穿刺支援マニピュレータの開発(医療ロボティクス・メカトロニクス(2))

We are developing a robotic needle insertion system for assist of central venous catheterization that relieves the difficulties of manual procedure and reduce the complications. In this paper, we propose a new design prototype manipulator which weight is reduced and which is integrated with a display of ultrasonography to progress in the operability of our robotic needle insertion system. The new version manipulator weighs lighter than 500[g] using a worm gear mechanism in exchange of a RCM mechanism, and the new version manipulator has a display of ultrasonography placed in the field of operator's view during manipulation of this system. Additionally, it was suggested that the new version manipulator kept the same positioning precision as the old version of manipulator by an evaluation experiment.

Research of Slider-Crank Massager Noise Fault Diagnosis and Treatment

The abnormal periodic noise from the slider-crank massager was complained by many consumers when it was under unilateral massage. By anglicizing the worm non-working surface stained with marking compound, the reason of the abnormal periodic noise which stemming from repeated mating of non-normal mating surfaces of the worm gear mechanism is founded. In order to solve the problem the overrunning clutch is used as it’s beyond separation functions. When the force is loaded to passive wheel, the clutch is linked; while the load becomes kinetic energy, the power will be separated immediately. The characteristic determines that the overrunning clutch is one of the best choices to separate the load on the slider-crank massager. And the results of the experiment indicate that the method has a significant effect to reduce noise. It also has a practical significance to the common problems of the mechanism and to the related scientific problems.

WORM GEAR ANALYSIS IN TERMS OF NUMERICAL MODELLING

A worm gear mechanism, widely used in numerous mechanical applications, is the essential component in energy ef­ficiency considerations. Compared to traditional gearboxes, worm gear is characterized by lower value of efficiency, provided by the manufacturers as 70-90%. However, the efficiency level can differ depending on the specific conditions of operation such as output torque, input rotational velocity, ambient temperature and type of lubrication. In order to analyse and simulate the worm gear mechanism in mechanical systems, it is essential to establish the actual efficiency value for specific conditions. The following article contains the description of efficiency test performed for the worm gear as a part of tram pantograph system studied in frame of ESTOMAD project. The aim of the experiment was to deter­mine the actual efficiency value of the transmission tested. The worm gear has been tested in an open loop configuration, therefore the efficiency has been determined basing on input and output torque and rotational velocity measurements. The tests have been performed for various output torques and input velocities to obtain view on losses in worm gear under different operational conditions, paying special attention to the velocity that drives the pantograph mechanism. The efficiency changes with the output torque variation, while the impact of rotational velocity level on the mentioned value is minimal. The results of measurements are used in modelling phase of worm gear component in 1D simulation environment, particularly creating new model and its correlation and validation.

Design and Implementation on a Novel of Solar Double-Direction Tracking-Device

The development of solar energy tracking technology has important practical significance for promoting solar energy application. In the paper, double-direction tracking-device was designed based on the theory of calendar check tracking and worm gear mechanism, gear transmission mechanism, cam push-rod mechanism was used to achieve the function of “single driving, double-direction tracking” . So, the function of tracking solar azimuth and solar altitude angles was cleverly realized through controlling a single power. In the paper, design and manufacture of the device were completed by Solidworks software. Through the debugging experiment, the device’s advantages were proved of low energy consumption, high reliability, strong anti-interference ability, easy maintenance and suitable for a variety of small solar installations.

Green Manufacturing: a Pumpless Mechanical-Hydraulic Clamping Device Based on Wormgear and Crank-Slider Mechanism

Hydraulic transmission clamping device may cause environmental pollution due to the existing of fluid pump and open oil tank. A new-concept clamping device based on high flexibility of hydraulic is introduced in this paper. Without any pump and open oil tank, environments pollution is reduced to a very low level. The driving piston is actuated by combined wormgear and crank-slider mechanism, the clamping piston is driven by sealed fluid in the two cylinders. The self-locking wormgear provides continuous clamping force during machining without any added energy, and a pressure switch guarantees the safety of operation. There are many choices when we considering the power sources, it could be electrical motor with proper speed reducer or just manpower, which provide a rotation movement. The working principle and mechanical calculation formulas are presented in this paper, which is instructive to the industrial field.

A mathematical model of a worm mechanism generated by a conical cutter

In this article, an imaginary conical cutter was used to determine the geometric models of the worm—gear mechanism including a worm and a gear. Mathematical models of the worm and the gear were derived using an imaginary conical cutter and gear theory. Based on the geometric relations between the worm and conical cutter surfaces and between the gear and conical cutter surfaces, the worm and the gear were regarded as an envelope to the family of conical cutter surfaces when they rotated for one cycle. Using the developed mathematical model, the stress analysis of the proposed mechanism was examined. The results show that the von Mises stress and volume of the proposed worm and gear were smaller than those of the conventional worm—gear mechanism. Lastly, a numerical example was used to illustrate the geometric model of a gear and a worm with a gear ratio of 30:1.

High Performance Rotary Table for Machine Tool Applications

The high performance rotary tables are immense necessary part for the multi-axis machines. These rotary tables are yet in the developing stage. In this report, a rotary table driven by roller drive is introduced and the characteristics of that are discussed by comparing them with the characteristics of rotary table driven by worm gear mechanism. As the characteristics, the positioning accuracy and repeatability, frequency response, rotational fluctuations and influence of unbalance mass on motion are measured. According to the measured results, it can be said that the rotary table driven by roller drive shows high performances and therefore it can be said that this type of rotary tables are well suited for machine tool applications.