Mobility and Geometrical Analysis of a Two Actuated Spoke Wheel Robot Modeled as a Mechanism With Variable Topology

2008 ◽  
Author(s):  
Ya Wang ◽  
Ping Ren ◽  
Dennis Hong
Keyword(s):  
Degrees Of Freedom ◽  
Contact Point ◽  
Future Research ◽  
Coordinate Systems ◽  
Line Geometry ◽  
Geometrical Analysis ◽  
Constraint Equations ◽  
Contact Points ◽  
Different Types ◽  
Variable Topology

In this paper, the mobility and geometrical analysis of a novel mobile robot that utilizes two actuated spoke wheels is presented. Intelligent Mobility Platform with Active Spoke System (IMPASS) is a wheel-leg hybrid robot that can walk in unstructured environments by stretching in or out three independently actuated spokes of each wheel. First, the unique locomotion scheme of IMPASS is introduced and the definitions of the coordinate systems are developed to describe the kinematic configurations. Since this robot is capable of utilizing its metamorphic configurations to implement different types of motion, its topology structures are classified into different groups based on the cases of ground contact points. For each contact point case, the mobility analysis is performed using the conventional Gru¨bler and Kutzbach criterion. However, as for the cases in which the structure is overconstrained, the Modified Gru¨bler and Kutzbach criterion based on reciprocal screws are implemented to obtain the correct number of degrees of freedom. Line geometry is adopted to assist in the process. Additionally, the geometrical constraint equations of the robot are derived. The results in this work lay the foundation of the future research on inverse and forward kinematics, instantaneous kinematics, dynamics analysis and motion planning of this unique locomotion robot.

Three-Dimensional Kinematic Analysis of a Two Actuated Spoke Wheel Robot Based on Its Equivalency to a Serial Manipulator

2008 ◽  
Author(s):  
Ping Ren ◽  
Ya Wang ◽  
Dennis Hong
Keyword(s):  
Inverse Kinematics ◽  
Degrees Of Freedom ◽  
Three Dimensional ◽  
Forward Kinematics ◽  
Future Research ◽  
Ground Contact ◽  
Contact Points ◽  
Prismatic Joints ◽  
Forward Kinematic ◽  
The Relationship

In this paper, the inverse and forward kinematics of a novel mobile robot that utilizes two actuated spoke wheels is presented. Intelligent Mobility Platform with Active Spoke System (IMPASS) is a wheel-leg hybrid robot that can walk in unstructured environments by stretching in or out three independently actuated spokes of each wheel. First, the unique locomotion scheme of IMPASS is introduced. Then the configuration of the robot when each of its two spoke wheels has one spoke in contact with the ground is modeled as a two-branch parallel mechanism with spherical and prismatic joints. An equivalent serial manipulator of the 2-SP mechanism with the same degrees of freedom is proposed to solve for the inverse and forward kinematic problems. The relationship between the physical limits of the stroke of the spokes (effective spoke length) and the limits of its equivalent degree of freedom is established. This approach can also be expanded to deal with the forward and inverse kinematics of other configurations which has more than two ground contact points. Several examples are used to illustrate the method. The results obtained will be used in the future research on the motion planning of IMPASS walking in unstructured environment.

Tooth Contact and 3-D Stress Analysis of Involute Helical Gears

1992 ◽  
Author(s):  
M. A. Sahir Arikan ◽  
Mustafa Tamar
Keyword(s):  
Stress Analysis ◽  
Gear Tooth ◽  
Contact Point ◽  
Helical Gear ◽  
Contact Analysis ◽  
Contact Lines ◽  
Coordinate Systems ◽  
Tooth Contact Analysis ◽  
Tooth Contact ◽  
Contact Points

Abstract An involute helical gear tooth is modelled by using helical gear geometry and a solid modelling package, and this model is used to determine the load distribution on contact lines of mating teeth, and to make the stress analysis by using three-dimensional tetrahedron finite elements with four nodes. Tooth contact analysis is made by using the theory of gearing. Geometry of the cutting tool is used to determine the surface equations of the pinion and the gear in their own coordinate systems, then these equations are transformed to a fixed coordinate system to make the tooth contact analysis and to find the coordinates of contact points. Found contact point coordinates are then transformed back to the original coordinate systems and contact lines on helical gear teeth are formed. Results of this analysis is used to determine the application points and directions of the forces acting on the tooth. Then the stiffnesses of meshing teeth and the load distributions on contact lines are found, which are then used for stress analysis.

The Application of ANSYS Multipoint Constraint on the Combination Modeling of SOLID-SHELL

2012 ◽  
Vol 588-589 ◽  
pp. 226-229
Author(s):  
Bao Qin Zhang ◽  
Jian Xia He ◽  
Yun Fang Qiao
Keyword(s):  
Degrees Of Freedom ◽  
Three Dimensional ◽  
Shell Element ◽  
Engineering Practice ◽  
Solid Shell ◽  
Element Modeling ◽  
Constraint Equations ◽  
Solid Element ◽  
Different Types

The problem of the modeling connection of different units is encountered in engineering practice. Its reasonable proposals are that the modeling is discrete into the respective discrete three-dimensional solid elements for calculation. But different types of units’ degrees of freedom are not discontinuity，it will lead to significant deviation of calculated results and the actual. In the paper, the methods and characteristics of SOLID-SHELL unit with the application of ANSYS constraint equations method and the MPC law are discussed, and compared the shell - solid element with the whole solid element modeling combined the results, it draw a conclusion that MPC law is advantage in modeling of three-dimensional solid element and shell element.

Passive and Active Closures by Constraining Mechanisms

1999 ◽  
Vol 121 (3) ◽  
pp. 418-424 ◽  
Author(s):  
Tsuneo Yoshikawa
Keyword(s):  
Degrees Of Freedom ◽  
Contact Point ◽  
Three Dimensional ◽  
Internal Force ◽  
Existence Condition ◽  
Passive Force ◽  
Contact Points ◽  
Force Closure ◽  
Grasping And Manipulation ◽  
Form Closure

This paper provides a unified theoretical framework for analytical characterization of grasping and manipulation capability of robotic grippers and hands as well as fixing capability of fixtures and vises. The concept of passive closure and active closure for general constraining mechanisms consisting of fixed and/or articulated constraining limbs is introduced. These concepts are useful for explicitly distinguishing the two kinds of capabilities of the constraining mechanism: Passive closure represents the ability of fixing devices and active closure represents the ability of manipulating devices. Passive closure is further classified into passive form closure and passive force closure. Passive form closure is essentially the same as Reuleaux’s classical form closure and passive force closure is a substantial generalization of classical force closure to the case where articulated constraining limbs exist. Conditions for these closures to hold are studied. After a brief review of conditions for passive form closure, several conditions for passive force closure are given. One outcome is that, under the assumption that the contact points are frictionless and the active contact points are independent, for the existence of passive force closure there must be at least six (three) fixed contact points and one active contact point in the case of three-dimensional (two-dimensional, respectively) space. Finally, a necessary and sufficient condition for active closure is given for the case of frictional point contacts by constraining limbs with enough degrees-of-freedom. This condition consists of a general positioning condition of contact points and the existence condition of nonzero internal force. This condition has a quite natural physical interpretation.

Overview of Subsynchronous Oscillation in Grid-connected Wind Farm

2020 ◽  
Vol 13 (7) ◽  
pp. 969-979
Author(s):  
Xu Pei-Zhen ◽  
Lu Yong-Geng ◽  
Cao Xi-Min
Keyword(s):  
Power Systems ◽  
Wind Turbine ◽  
Large Scale ◽  
Wind Farm ◽  
Wind Farms ◽  
Induction Generator ◽  
Future Research ◽  
Stable Operation ◽  
Subsynchronous Oscillation ◽  
Different Types

Background: Over the past few years, the subsynchronous oscillation (SSO) caused by the grid-connected wind farm had a bad influence on the stable operation of the system and has now become a bottleneck factor restricting the efficient utilization of wind power. How to mitigate and suppress the phenomenon of SSO of wind farms has become the focus of power system research. Methods: This paper first analyzes the SSO of different types of wind turbines, including squirrelcage induction generator based wind turbine (SCIG-WT), permanent magnet synchronous generator- based wind turbine (PMSG-WT), and doubly-fed induction generator based wind turbine (DFIG-WT). Then, the mechanisms of different types of SSO are proposed with the aim to better understand SSO in large-scale wind integrated power systems, and the main analytical methods suitable for studying the SSO of wind farms are summarized. Results: On the basis of results, using additional damping control suppression methods to solve SSO caused by the flexible power transmission devices and the wind turbine converter is recommended. Conclusion: The current development direction of the SSO of large-scale wind farm grid-connected systems is summarized and the current challenges and recommendations for future research and development are discussed.

Antecedents and Consequences of Gossip in Work Groups

2019 ◽  
pp. 416-434
Author(s):  
Bianca Beersma ◽  
Gerben A. van Kleef ◽  
Maria T. M. Dijkstra
Keyword(s):  
Social Order ◽  
Information Exchange ◽  
Work Groups ◽  
Psychological Theory ◽  
Future Research ◽  
Group Norms ◽  
Group Effectiveness ◽  
Interpersonal Aggression ◽  
Different Types ◽  
Antecedents And Consequences

This chapter provides an overview of the antecedents and consequences of gossip in work groups. First, the chapter reviews the different motives for gossip in work groups (i.e., bonding, entertainment, emotional venting, information exchange, maintenance of group norms/social order, and interpersonal aggression) and links each motive to psychological theory. Second, the chapter reviews the different types of influence that gossip can have on various indicators of group effectiveness. Reflecting on the motives underlying gossip in work groups, as well as on its outcomes, it argues that future research should start integrating the diverse insights provided by earlier research on both gossip motives and outcomes, and it provides a number of suggestions for doing so.

scholarly journals Advantages and potential challenges of data management in e-maintenance

2019 ◽  
Vol 25 (3) ◽  
pp. 378-396 ◽  
Author(s):  
Arian Razmi-Farooji ◽  
Hanna Kropsu-Vehkaperä ◽  
Janne Härkönen ◽  
Harri Haapasalo
Keyword(s):  
Data Management ◽  
Design Methodology ◽  
Management Practices ◽  
Future Research ◽  
Conceptual Approach ◽  
Content Type ◽  
Different Types ◽  
Maintenance Systems ◽  
Industry Leader ◽  
Practical Implications

Purpose The purpose of this paper is twofold: first, to understand data management challenges in e-maintenance systems from a holistically viewpoint through summarizing the earlier scattered research in the field, and second, to present a conceptual approach for addressing these challenges in practice. Design/methodology/approach The study is realized as a combination of a literature review and by the means of analyzing the practices on an industry leader in manufacturing and maintenance services. Findings This research provides a general understanding over data management challenges in e-maintenance and summarizes their associated proposed solutions. In addition, this paper lists and exemplifies different types and sources of data which can be collected in e-maintenance, across different organizational levels. Analyzing the data management practices of an e-maintenance industry leader provides a conceptual approach to address identified challenges in practice. Research limitations/implications Since this paper is based on studying the practices of a single company, it might be limited to generalize the results. Future research topics can focus on each of mentioned data management challenges and also validate the applicability of presented model in other companies and industries. Practical implications Understanding the e-maintenance-related challenges helps maintenance managers and other involved stakeholders in e-maintenance systems to better solve the challenges. Originality/value The so-far literature on e-maintenance has been studied with narrow focus to data and data management in e-maintenance appears as one of the less studied topics in the literature. This research paper contributes to e-maintenance by highlighting the deficiencies of the discussion surrounding the perspectives of data management in e-maintenance by studying all common data management challenges and listing different types of data which need to be acquired in e-maintenance systems.

scholarly journals Advances in Forest Robotics: A State-of-the-Art Survey

Robotics ◽  
2021 ◽  
Vol 10 (2) ◽  
pp. 53
Author(s):  
Luiz F. P. Oliveira ◽  
António P. Moreira ◽  
Manuel F. Silva
Keyword(s):  
Future Research ◽  
Navigation Systems ◽  
Public And Private ◽  
Environmental Preservation ◽  
The Public ◽  
Forest Exploitation ◽  
Different Types ◽  
Scientific Papers ◽  
Great Relevance ◽  
Robotic Applications

The development of robotic systems to operate in forest environments is of great relevance for the public and private sectors. In this sense, this article reviews several scientific papers, research projects and commercial products related to robotic applications for environmental preservation, monitoring, wildfire firefighting, inventory operations, planting, pruning and harvesting. After conducting critical analysis, the main characteristics observed were: (a) the locomotion system is directly affected by the type of environmental monitoring to be performed; (b) different reasons for pruning result in different locomotion and cutting systems; (c) each type of forest, in each season and each type of soil can directly interfere with the navigation technique used; and (d) the integration of the concept of swarm of robots with robots of different types of locomotion systems (land, air or sea) can compensate for the time of executing tasks in unstructured environments. Two major areas are proposed for future research works: Internet of Things (IoT)-based smart forest and navigation systems. It is expected that, with the various characteristics exposed in this paper, the current robotic forest systems will be improved, so that forest exploitation becomes more efficient and sustainable.

scholarly journals Slipping–rolling transitions of a body with two contact points

2021 ◽  
Author(s):  
Mate Antali ◽  
Gabor Stepan
Keyword(s):  
Rigid Body ◽  
Contact Point ◽  
Static Friction ◽  
Rigid Body Dynamics ◽  
Contact Forces ◽  
Friction Forces ◽  
Contact Points ◽  
Body Dynamics ◽  
Coulomb Model ◽  
Rigid Surfaces

AbstractIn this paper, the general kinematics and dynamics of a rigid body is analysed, which is in contact with two rigid surfaces in the presence of dry friction. Due to the rolling or slipping state at each contact point, four kinematic scenarios occur. In the two-point rolling case, the contact forces are undetermined; consequently, the condition of the static friction forces cannot be checked from the Coulomb model to decide whether two-point rolling is possible. However, this issue can be resolved within the scope of rigid body dynamics by analysing the nonsmooth vector field of the system at the possible transitions between slipping and rolling. Based on the concept of limit directions of codimension-2 discontinuities, a method is presented to determine the conditions when the two-point rolling is realizable without slipping.

scholarly journals Cavitation between cylinder-liner and piston-ring in a new designed optical IC engine

2021 ◽  
pp. 146808742110080
Author(s):  
Jamshid Malekmohammadi Nouri ◽  
Ioannis Vasilakos ◽  
Youyou Yan
Keyword(s):  
High Speed ◽  
Contact Point ◽  
Cylinder Liner ◽  
Optical Methods ◽  
Engine Management System ◽  
Great Success ◽  
Ic Engine ◽  
Contact Points ◽  
Lubricant Flow ◽  
Cavitation Intensity

A new engine block with optical access has been designed and manufactured capable of running up to 3000 r/min with the same specification as the unmodified engine. The optical window allowed access to the full length of the liner over a width of 25 mm to investigate the lubricant flow and cavitation at contact point between the rings and cylinder-liner. In addition, it allowed good access into the combustion chamber to allow charged flow, spray and combustion visualisation and measurements using different optical methods. New custom engine management system with build in LabView allowed for the precise full control of the engine. The design of the new optical engine was a great success in producing high quality images of lubricant flow, cavitation formation and development at contact point at different engine speeds ranging from 208 to 3000 r/min and lubricant temperatures (30°C–70°C) using a high-speed camera. The results under motorised operation confirmed that there was no cavitation at contact points during the intake/exhaust strokes due to low in-cylinder presure, while during compression/expansion strokes, with high in-cylinder pressure, considerable cavities were observed, in particular, during the compression stroke. Lubricant temperatures had the effect of promoting cavities both in their intensity and covered ring area up to 50°C as expected. Beyond that, although the cavitation intensity increases further with temperature, its area reduces due to possible collapse of the cavitating bubbles at higher temperature. The change of engine speed from 208 to 800 r/min increased cavitating area considerably by 52% of the ring area and was further increased by 19% at 1000 r/min. After that, the results showed very small increase in cavitation area (1.3% at 2000 r/min) with similar intensity and distribution across the ring.

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