scholarly journals Basic Theory and Design Method of Variable Shaft Angle Line Gear Mechanism

2021 ◽  
Vol 67 (7-8) ◽  
pp. 352-362
Author(s):  
Yang-zhi Chen ◽  
Chao He ◽  
Yue-ling Lyu
Keyword(s):  
Degrees Of Freedom ◽  
Design Method ◽  
Three Dimensional ◽  
Contact Spot ◽  
Design Criterion ◽  
Contact Model ◽  
Basic Design ◽  
Shaft Angle ◽  
Gear Mechanism ◽  
Gear Contact

In this paper, a novel line gear mechanism is proposed; it is called the variable shaft angle line gear mechanism (VSALGM). VSALGM has two rotational degrees of freedom, one is the rotation of the two gears with a constant transmission ratio, and the other is the relative swing of the two gears shafts. First, a novel contact model of VSALGM composed of one driven contact curve and one driving line teeth working surface (DLTWS) was proposed. With the concept, the basic design equations for VSALGM were derived on the basis of the space curve meshing theory of line gear. Moreover, the design criterion of pressure angle for VSALGM was analysed and proposed on the basis of the contact model. A basic design method for VSALGM was thus developed. A design example was given, and prototypes were manufactured using three-dimensional (3D) printing. Kinematic experiments and gear contact spot testing were carried out on a self-made kinematic test rig by the prototypes. The results show that the VSALGM designed in this paper can achieve a continuous, smooth and stable meshing transmission while the shaft angle is continuously changed within its setting range.

Jacobian approach to the kinestatic analysis of a full vehicle model with application to cornering motion analysis

2020 ◽  
Vol 234 (18) ◽  
pp. 3543-3559
Author(s):  
Guofeng Zhou ◽  
Junwoo Kim ◽  
Yong Je Choi
Keyword(s):  
Parallel Mechanism ◽  
Degrees Of Freedom ◽  
Kinematic Model ◽  
Three Dimensional ◽  
Kinematic Chain ◽  
Contact Model ◽  
Vehicle Body ◽  
Spatial Parallel Mechanism ◽  
6 Degrees Of Freedom ◽  
Instantaneous Screw

The Jacobian approach to the kinestatic analysis of a planar suspension mechanism has been previously presented. In this paper, the theory is extended to three-dimensional kinestatic analysis by developing a full kinematic model and viewing it as a spatial parallel mechanism. The full kinematic model consists of two pairs of the front (double wishbone) and rear (multi-link) suspension mechanisms together with a newly developed ground-wheel contact model. The motion of each wheel of four suspension mechanisms is represented by the corresponding instantaneous screw at any instant. A vehicle is considered to be a 6-degrees-of-freedom spatial parallel mechanism whose vehicle body is supported by four serial kinematic chains. Each kinematic chain consists of a virtual instantaneous screw joint and a kinematic pair representing ground-wheel contact model. The kinestatic equation of the 6-degrees-of-freedom spatial parallel mechanism is derived in terms of the Jacobian. As an important application, a cornering motion of a vehicle is analysed under the assumption of steady-state cornering. A numerical example is presented to illustrate how to determine the optimal locations of strut springs for the least roll angle in cornering motion using the proposed method.

Research on the centre distance separability of parallel shaft line gear pair

2021 ◽  
pp. 095440622110358
Author(s):  
Chao He ◽  
Yangzhi Chen ◽  
Weijia Lin ◽  
Yueling Lyu
Keyword(s):  
Theoretical Basis ◽  
Design Theory ◽  
Simulation Analysis ◽  
Design Method ◽  
Contact Spot ◽  
Gear Pair ◽  
Shaft Line ◽  
Pure Rolling ◽  
Milling Method ◽  
Gear Contact

For gear pairs with centre-distance separability, transmission ratios are not affected by centre distance error. Based on space curve meshing theory, the centre distance separability of a line gear pair was studied. A novel line gear pair called the separable and pure rolling parallel shaft line gear pair (SPRPSLG) was proposed, which has centre-distance separability characteristics and pure rolling transmission. The basic design theory of the SPRPSLG pair was established. A design method of the SPRPSLG pair with an eccentric arc tooth profile was given. An SPRPSLG pair example was designed and manufactured using the form milling method. Kinematic experiments and meshing efficiency experiments were conducted. Gear contact spot testing and gear contact simulation analysis were carried out. The SPRPSLG pair was shown to have centre distance separability, which provides a further theoretical basis for the popularization and application of line gears.

scholarly journals Control and Evaluation of Slow-Active Suspensions with Preview for a Full Car

2012 ◽  
Vol 2012 ◽  
pp. 1-19 ◽  
Author(s):  
Mohamed M. ElMadany
Keyword(s):  
Optimal Control ◽  
Degrees Of Freedom ◽  
Design Method ◽  
Three Dimensional ◽  
Control Design ◽  
Rear Wheel ◽  
Performance Potential ◽  
Active Suspensions ◽  
Limited Bandwidth ◽  
In Series

An optimal control design method based on the use of the correlation between the front and rear wheel inputs (wheelbase preview) is introduced and then applied to the optimum design of a slow-active suspension system. The suspension consists of a limited bandwidth actuator in series with a passive spring, the combination being in parallel with a passive damper. A three-dimensional seven degrees of freedom car riding model subjected to four correlated random road inputs is considered. The performance potential of the limited bandwidth system with wheelbase preview in comparison with the nonpreview (uncorrelated inputs) case is investigated.

scholarly journals Design, Fabrication, and Testing of a Novel 3D 3-Fingered Electrothermal Microgripper with Multiple Degrees of Freedom

Micromachines ◽  
2021 ◽  
Vol 12 (4) ◽  
pp. 444
Author(s):  
Guoning Si ◽  
Liangying Sun ◽  
Zhuo Zhang ◽  
Xuping Zhang
Keyword(s):  
Degrees Of Freedom ◽  
Dynamic Properties ◽  
Three Dimensional ◽  
Polyimide Film ◽  
Zebrafish Embryos ◽  
Multiple Degrees Of Freedom ◽  
Electrothermal Actuator ◽  
3D Space ◽  
Pick And Place

This paper presents the design, fabrication, and testing of a novel three-dimensional (3D) three-fingered electrothermal microgripper with multiple degrees of freedom (multi DOFs). Each finger of the microgripper is composed of a V-shaped electrothermal actuator providing one DOF, and a 3D U-shaped electrothermal actuator offering two DOFs in the plane perpendicular to the movement of the V-shaped actuator. As a result, each finger possesses 3D mobilities with three DOFs. Each beam of the actuators is heated externally with the polyimide film. The durability of the polyimide film is tested under different voltages. The static and dynamic properties of the finger are also tested. Experiments show that not only can the microgripper pick and place microobjects, such as micro balls and even highly deformable zebrafish embryos, but can also rotate them in 3D space.

scholarly journals Asymmetry in Three-Dimensional Sprinting with and without Running-Specific Prostheses

Symmetry ◽  
2021 ◽  
Vol 13 (4) ◽  
pp. 580
Author(s):  
Anna Lena Emonds ◽  
Katja Mombaur
Keyword(s):  
Degrees Of Freedom ◽  
Body Position ◽  
Three Dimensional ◽  
Problem Formulation ◽  
Contact Phase ◽  
Individual Level ◽  
Lower Trunk ◽  
Floating Base ◽  
The Asymmetry ◽  
Limb Asymmetry

As a whole, human sprinting seems to be a completely periodic and symmetrical motion. This view is changed when a person runs with a running-specific prosthesis after a unilateral amputation. The aim of our study is to investigate differences and similarities between unilateral below-knee amputee and non-amputee sprinters—especially with regard to whether asymmetry is a distracting factor for sprint performance. We established three-dimensional rigid multibody models of one unilateral transtibial amputee athlete and for reference purposes of three non-amputee athletes. They consist of 16 bodies (head, ipper, middle and lower trunk, upper and lower arms, hands, thighs, shanks and feet/running specific prosthesis) with 30 or 31 degrees of freedom (DOFs) for the amputee and the non-amputee athletes, respectively. Six DOFs are associated with the floating base, the remaining ones are rotational DOFs. The internal joints are equipped with torque actuators except for the prosthetic ankle joint. To model the spring-like properties of the prosthesis, the actuator is replaced by a linear spring-damper system. We consider a pair of steps which is modeled as a multiphase problem with each step consisting of a flight, touchdown and single-leg contact phase. Each phase is described by its own set of differential equations. By combining motion capture recordings with a least squares optimal control problem formulation including constraints, we reconstructed the dynamics of one sprinting trial for each athlete. The results show that even the non-amputee athletes showed less symmetrical sprinting than expected when examined on an individual level. Nevertheless, the asymmetry is much more pronounced in the amputee athlete. The amputee athlete applies larger torques in the arm and trunk joints to compensate the asymmetry and experiences a destabilizing influence of the trunk movement. Hence, the inter-limb asymmetry of the amputee has a significant effect on the control of the sprint movement and the maintenance of an upright body position.

Practitioner-friendly design method to improve the seismic performance of RC frame buildings

2021 ◽  
pp. 875529302098801
Author(s):  
Orlando Arroyo ◽  
Abbie Liel ◽  
Sergio Gutiérrez
Keyword(s):  
Seismic Performance ◽  
Design Method ◽  
Three Dimensional ◽  
Rc Frame ◽  
Structural System ◽  
Standard Code ◽  
Frame Buildings ◽  
Rc Frame Buildings ◽  
Mathematical Justification ◽  
Story Building

Reinforced concrete (RC) frame buildings are a widely used structural system around the world. These buildings are customarily designed through standard code-based procedures, which are well-suited to the workflow of design offices. However, these procedures typically do not aim for or achieve seismic performance higher than code minimum objectives. This article proposes a practical design method that improves the seismic performance of bare RC frame buildings, using only information available from elastic structural analysis conducted in standard code-based design. Four buildings were designed using the proposed method and the prescriptive approach of design codes, and their seismic performance is evaluated using three-dimensional nonlinear (fiber) models. The findings show that the seismic performance is improved with the proposed method, with reductions in the collapse fragility, higher deformation capacity, and greater overstrength. Furthermore, an economic analysis for a six-story building shows that these improvements come with only a 2% increase in the material bill, suggesting that the proposed method is compatible with current project budgets as well as design workflow. The authors also provide mathematical justification of the method.

Three-dimensional asymmetric maximum weight lifting prediction considering dynamic joint strength

2021 ◽  
pp. 095441192098703
Author(s):  
Rahid Zaman ◽  
Yujiang Xiang ◽  
Jazmin Cruz ◽  
James Yang
Keyword(s):  
Experimental Data ◽  
Degrees Of Freedom ◽  
Inverse Dynamics ◽  
Three Dimensional ◽  
Optimization Method ◽  
Weight Lifting ◽  
Joint Torque ◽  
Maximum Weight ◽  
Angular Velocities ◽  
Asymmetric Lifting

In this study, the three-dimensional (3D) asymmetric maximum weight lifting is predicted using an inverse-dynamics-based optimization method considering dynamic joint torque limits. The dynamic joint torque limits are functions of joint angles and angular velocities, and imposed on the hip, knee, ankle, wrist, elbow, shoulder, and lumbar spine joints. The 3D model has 40 degrees of freedom (DOFs) including 34 physical revolute joints and 6 global joints. A multi-objective optimization (MOO) problem is solved by simultaneously maximizing box weight and minimizing the sum of joint torque squares. A total of 12 male subjects were recruited to conduct maximum weight box lifting using squat-lifting strategy. Finally, the predicted lifting motion, ground reaction forces, and maximum lifting weight are validated with the experimental data. The prediction results agree well with the experimental data and the model’s predictive capability is demonstrated. This is the first study that uses MOO to predict maximum lifting weight and 3D asymmetric lifting motion while considering dynamic joint torque limits. The proposed method has the potential to prevent individuals’ risk of injury for lifting.

A Three-Dimensional Viscous Transonic Inverse Design Method

2000 ◽  
Author(s):  
W. T. Tiow ◽  
M. Zangeneh
Keyword(s):  
Design Method ◽  
Flow Analysis ◽  
Three Dimensional ◽  
Viscous Effects ◽  
Flow Equations ◽  
Flow Solution ◽  
Turbomachinery Blades ◽  
A Cell ◽  
Inverse Design Method ◽  
Euler Solver

The development and application of a three-dimensional inverse methodology is presented for the design of turbomachinery blades. The method is based on the mass-averaged swirl, rV~θ distribution and computes the necessary blade changes directly from the discrepancies between the target and initial distributions. The flow solution and blade modification converge simultaneously giving the final blade geometry and the corresponding steady state flow solution. The flow analysis is performed using a cell-vertex finite volume time-marching algorithm employing the multistage Runge-Kutta integrator in conjunction with accelerating techniques (local time stepping and grid sequencing). To account for viscous effects, dissipative forces are included in the Euler solver using the log-law and mixing length models. The design method can be used with any existing solver solving the same flow equations without any modifications to the blade surface wall boundary condition. Validation of the method has been carried out using a transonic annular turbine nozzle and NASA rotor 67. Finally, the method is demonstrated on the re-design of the blades.

Determination of the Workspace of a Three-Degrees-of-Freedom Parallel Manipulator Using a Three-Dimensional Computer-Aided-Design Software Package and the Concept of Virtual Chains1

2015 ◽  
Vol 8 (2) ◽  
Author(s):  
Andrew Johnson ◽  
Xianwen Kong ◽  
James Ritchie
Keyword(s):  
Computer Aided Design ◽  
Parallel Manipulator ◽  
Degrees Of Freedom ◽  
Graphical Representation ◽  
Three Dimensional ◽  
Parallel Manipulators ◽  
Workspace Analysis ◽  
Computer Aided ◽  
Aided Design

The determination of workspace is an essential step in the development of parallel manipulators. By extending the virtual-chain (VC) approach to the type synthesis of parallel manipulators, this technical brief proposes a VC approach to the workspace analysis of parallel manipulators. This method is first outlined before being illustrated by the production of a three-dimensional (3D) computer-aided-design (CAD) model of a 3-RPS parallel manipulator and evaluating it for the workspace of the manipulator. Here, R, P and S denote revolute, prismatic and spherical joints respectively. The VC represents the motion capability of moving platform of a manipulator and is shown to be very useful in the production of a graphical representation of the workspace. Using this approach, the link interferences and certain transmission indices can be easily taken into consideration in determining the workspace of a parallel manipulator.

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