scholarly journals Analysis and research of quadruped robot’s legs: A comprehensive review

2019 ◽  
Vol 16 (3) ◽  
pp. 172988141984414 ◽  
Author(s):  
Yuhai Zhong ◽  
Runxiao Wang ◽  
Huashan Feng ◽  
Yasheng Chen
Keyword(s):  
Degrees Of Freedom ◽  
Walking Speed ◽  
Load Capacity ◽  
Basic Component ◽  
Application Performance ◽  
Comprehensive Review ◽  
Research Results ◽  
The Core ◽  
Quadruped Robots ◽  
Job Adaptability

As an important basic component of quadruped robots, mechanical legs provide the robots with excellent maneuverability and versatility, which determine the core application performance such as job adaptability, walking speed, and load capacity. A large number of robotics institutes for the last few decades have studied mechanical legs used by quadruped robots and published many research results. In this article, we collect these research results and classify them into three categories (prismatic legs, articulated legs, and redundant articulated legs) according to the degrees of freedom and then introduce and analyze them. On this basis, we summarize and study the design methods of the actuators and mechanical leg structures. Finally, we make some suggestions for the development of quadruped robot’s legs in the future. The motivation of this review is to summarize and analyze previous research efforts and provide useful guidance for future robotic designers to develop more efficient mechanical legs of quadruped robots.

scholarly journals THE ENGINEERING DESIGN COMPETENCY

2011 ◽  
Author(s):  
Jorge Angeles ◽  
Ron Britton ◽  
Liuchen Chang ◽  
Franҫois Charron ◽  
Peter Gregson ◽  
...  
Keyword(s):  
Engineering Education ◽  
Engineering Design ◽  
Value Added ◽  
Global Competition ◽  
Education Programs ◽  
Environmental Challenges ◽  
Research Results ◽  
The Core ◽  
Product And Process ◽  
Value Added Products

There is increasing global competition for better product and process functionality, higher quality, lower costs, and other considerations including energy and environmental challenges. This trend requires that Canadian industry be more innovative and responsive in order to stay competitive internationally. The Canadian capability in Engineering Design is at the core of our ability to achieve this goal. At both the undergraduate and graduate levels, we must improve the capability and capacity of engineering graduates so that they are capable of leading innovation, and converting research results into value-added products and services. This paper addresses the engineering design competency, identifies needs in engineering design training, and describes directions for the design content in engineering education programs.

Elements of Cognitive Robotics (Elemente kognitiver Robotik)

2007 ◽  
Vol 49 (4) ◽  
Author(s):  
Christian Goerick ◽  
Edgar Körner
Keyword(s):  
Motion Control ◽  
Cognitive Robotics ◽  
Research Results ◽  
The Core ◽  
Core Elements ◽  
Processing Architecture

SummaryIn this paper we present our research aiming at creating a cognitive humanoid. We describe our understanding of the core elements of a processing architecture for such kind of an artifact. After these conceptual considerations we present our research results in the areas of task and body oriented motion control as well as visually and behaviorally oriented learning.

scholarly journals Degrees of Freedom at the Start of the Second 100 Years: A Pedagogical Treatise

2019 ◽  
Vol 2 (4) ◽  
pp. 396-405
Author(s):  
Joseph Lee Rodgers
Keyword(s):  
Statistical Models ◽  
Degrees Of Freedom ◽  
Introductory Statistics ◽  
Core Concept ◽  
Traditional Treatment ◽  
The Core ◽  
History Of ◽  
Data Points

Degrees of freedom is a critical core concept within the field of statistics. Virtually every introductory statistics class treats the topic, though textbooks and the statistical literature show mostly superficial treatment, weak pedagogy, and substantial confusion. Fisher first defined degrees of freedom in 1915, and Walker provided technical treatment of the concept in 1940. In this article, the history of degrees of freedom is reviewed, and the pedagogical challenges are discussed. The core of the article is a simple reconceptualization of the degrees-of-freedom concept that is easier to teach and to learn than the traditional treatment. This reconceptualization defines a statistical bank, into which are deposited data points. These data points are used to estimate statistical models; some data are used up in estimating a model, and some data remain in the bank. The several types of degrees of freedom define an accounting process that simply counts the flow of data from the statistical bank into the model. The overall reconceptualization is based on basic economic principles, including treating data as statistical capital and data exchangeability (fungibility). The goal is to stimulate discussion of degrees of freedom that will improve its use and understanding in pedagogical and applied settings.

scholarly journals Kinematic Strategies in Newly Walking Toddlers Stepping Over Different Support Surfaces

2010 ◽  
Vol 103 (3) ◽  
pp. 1673-1684 ◽  
Author(s):  
Nadia Dominici ◽  
Yuri P. Ivanenko ◽  
Germana Cappellini ◽  
Maria Luisa Zampagni ◽  
Francesco Lacquaniti
Keyword(s):  
Degrees Of Freedom ◽  
Walking Speed ◽  
Search Space ◽  
Systematic Change ◽  
Support Surface ◽  
Coordination Pattern ◽  
Surface Conditions ◽  
Surface Inclination ◽  
Support Surfaces ◽  
Inclined Surface

In adults, locomotor movements are accommodated to various support surface conditions by means of specific anticipatory locomotor adjustments and changes in the intersegmental coordination. Here we studied the kinematic strategies of toddlers at the onset of independent walking when negotiating various support surface conditions: stepping over an obstacle, walking on an inclined surface, and on a staircase. Generally, toddlers could perform these tasks only when supported by the arm. They exhibited strategies very different from those of the adults. Although adults maintained walking speed roughly constant, toddlers markedly accelerated when walking downhill or downstairs and decelerated when walking uphill or upstairs. Their coordination pattern of thigh–shank–foot elevation angles exhibited greater inter-trial variability than that in adults, but it did not undergo the systematic change as a function of task that was present in adults. Thus the intersegmental covariance plane rotated across tasks in adults, whereas its orientation remained roughly constant in toddlers. In contrast with the adults, the toddlers often tended to place the foot onto the obstacle or across the edges of the stairs. We interpret such foot placements as part of a haptic exploratory repertoire and we argue that the maintenance of a roughly constant planar covariance—irrespective of the surface inclination and height—may be functional to the exploratory behavior. The latter notion is consistent with the hypothesis proposed decades ago by Bernstein that, when humans start to learn a skill, they may restrict the number of degrees of freedom to reduce the size of the search space and simplify the coordination.

Kinematics Research for a High-Precise Multi-Gratings Mosaic Mechanism

2012 ◽  
Vol 452-453 ◽  
pp. 1496-1500
Author(s):  
Li Hua Lu ◽  
Ying Chun Liang ◽  
Fu Li Yu ◽  
Bao Ku Su
Keyword(s):  
Degrees Of Freedom ◽  
Design Principle ◽  
Load Capacity ◽  
Dual Mode ◽  
Micro Actuator ◽  
Feed Drives ◽  
Parallel Kinematic ◽  
High Load Capacity ◽  
Novel Design ◽  
Kinematic Properties

A novel design of high load capacity multiaxis positioning stages with accuracy in the range of nanometers is presented. For strokes of 2mm with no play and high stiffness a general design principle supporting five Cartesian degrees of freedom has been developed using a new parallel kinematic topology based on Parallelogram arrangements. The five uniform feed drives are improved dual mode mechanism with servomotor and ballscrew as macro-actuator and piezoelectric transducer (PZT) with resolution of 1.2nm as micro-actuator. The performance of the setup and its kinematic properties are described as well as resolution of the five motions and their crosstalk. The setup has been implemented with outstanding characteristics and excellent reliability for alignment of a multigrating mosaic compressor in a PW-class CPA-laser.

Development of a Multi-Cable-Driven Continuum Robot Controlled by Parallel Platforms

2020 ◽  
pp. 1-11 ◽  
Author(s):  
Xinbo Chen ◽  
Jiantao Yao ◽  
Tong Li ◽  
Haili Li ◽  
Pan Zhou ◽  
...  
Keyword(s):  
Degrees Of Freedom ◽  
Load Capacity ◽  
Continuum Robots ◽  
Position Accuracy ◽  
Continuum Robot ◽  
In Series ◽  
Kinematic Models ◽  
Parallel Platform ◽  
Tube Structure ◽  
The Continuum

Abstract Cable-driven continuum robots exhibit excellent capabilities in the unstructured environment due to their inherent compliance and dexterity. To improve the reliability and load capacity of continuum robots, increasing the number of cables is often used in the control of continuum robots. However, the number of actuators will increase with the cables. To tackle this challenge, this work proposes a method for increasing the number of cables without increasing actuators in a continuum robot through parallel platforms. The parallel platforms are used to control all the cables in the continuum robot, and can be separated from the continuum robot to enable the remote drive of a manipulation arm by using the cable-tube structure. The manipulation arm is composed of several independent bending modules in series, which can be configured freely according to the demand of degrees of freedom. Further, each bending module is controlled independently by a parallel platform, which can avoid the mutual interference between the cables of one bending module and another one, improve the position accuracy and simplify the control difficulty of the manipulation arm. To evaluate the proposed method, this work develops a prototype of six-cable-driven continuum robot controlled by 3RPS parallel platforms, and presents some basic kinematic models to describe its function, and then an experimental work characterizing its performance. Experimental results illustrated the importance of increasing the number of cables, the rationality of kinematic models of the continuum robot, and the feasibility of controlling multiple cables by a parallel platform.

Investigation of Structural Conformity in a Three-Pad Adaptive Air Foil Bearing With Regard to Active Control of Radial Clearance

2019 ◽  
Vol 141 (8) ◽  
Author(s):  
Hossein Sadri ◽  
Henning Schlums ◽  
Michael Sinapius
Keyword(s):  
Shape Control ◽  
Degrees Of Freedom ◽  
Load Capacity ◽  
Radial Clearance ◽  
Foil Bearings ◽  
Compliant Structure ◽  
Foil Bearing ◽  
Points Of View ◽  
Lift Off ◽  
Structural Conformity

Abstract Various solutions for the design of oil-free bearings are discussed in the literature. Adding hydrodynamic preload to the foil bearings by profiling the inner bore of the bearing is one of the most frequently investigated methods for improving the bearing stability and damping character of the entire system. However, this approach leads to a reduced load capacity and thus to an increased lift-off speed of the foil bearings. Observations of this kind lead to the presentation of various solutions for active bearing contour adjustment, which benefits from different profiles of the lubricant film. Most of these concepts use piezoelectric stack actuators to generate the required alternating force, although the influence of the stiffness of adaptive elements on bearing performance is not fully discussed in the literature. The focus of this study is on the investigation of structural conformity, i.e., the harmonization of stiffness with respect to the requirements for shape control and load capacity of an adaptive air foil bearing (AAFB). The result may be a basis for the consideration of additional degrees of freedom in any concept with shape control as the main design framework in interaction between the lubricant and compliant structure in an air foil bearing from both static and dynamic points of view.

A New Bump-Type Foil Bearing Structure Analytical Model

2007 ◽  
Vol 129 (4) ◽  
pp. 1047-1057 ◽  
Author(s):  
Sébastien Le Lez ◽  
Mihaï Arghir ◽  
Jean Frene
Keyword(s):  
Analytical Model ◽  
Degrees Of Freedom ◽  
Load Capacity ◽  
Reaction Force ◽  
Analytical Models ◽  
Experimental Investigations ◽  
Underlying Structure ◽  
Static System ◽  
Theoretical Approaches ◽  
Foil Bearing

A gas bearing of bump foil type comprises an underlying structure made of one or several strips of corrugated sheet metal covered by a top foil surface. The fluid film pressure needs to be coupled with the behavior of the structure for obtaining the whole bearing characteristics. Unlike in classical elasto-aerodynamic models, a foil bearing (FB) structure has a very particular behavior due to friction interfaces, bump interactions, and nonisotropic stiffness. Some authors have studied this complex behavior with the help of three-dimensional finite element simulations. These simulations evidenced a lack of reliable analytical models that can be easily implemented in a FB prediction code. The models found in the literature tend to overestimate the foil flexibility because most of them do not consider the interactions between bumps that are highly important. The present work then develops a model that describes the FB structure as a multidegree of freedom system of interacting bumps. Each bump includes three degrees of freedom linked with elementary springs. The stiffnesses of these springs are analytically expressed so that the model can be adjusted for any dimensions and material properties. Once the stiffness matrix of the whole FB structure is obtained, the entire static system is solved taking friction into account. Despite its relative simplicity, comparisons with finite elements simulations for various static load distributions and friction coefficients show a good correlation. This analytical model has been integrated into a foil bearing prediction code. The load capacity of a first generation foil bearing was then calculated using this structure model as well as other simplified theoretical approaches. Significant differences were observed, revealing the paramount influence of the structure on the static and dynamic characteristics of the foil bearing. Some experimental investigations of the static stiffness of the structure were also realized for complete foil bearings. The structure reaction force was calculated for a shaft displacement with zero rotation speed, using either the multidegree of freedom model or the usual stiffness formulas. The comparisons between theoretical and experimental results also tend to confirm the importance of taking into account the bump interactions in determining the response of the structure.

STRUCTURE OF COMPACT STARS WITH DENSE HADRONIC MATTER AT THE CORE

2012 ◽  
Vol 12 ◽  
pp. 350-357
Author(s):  
HYUN KYU LEE
Keyword(s):  
Symmetry Energy ◽  
Degrees Of Freedom ◽  
Chemical Potential ◽  
Compact Stars ◽  
Hadronic Matter ◽  
Stellar Matter ◽  
Kaon Condensation ◽  
The Core ◽  
Weak Equilibrium

For a dense stellar matter, it is generally expected that as density increases, new degrees of freedom will emerge as the electron chemical potential becomes comparable to their energy scales. We discuss the nature of symmetry energy, which measures the energy relevant to the neutron-proton asymmetry and more importantly determines the electron chemical potential in weak equilibrium. The possible structure of compact stars with strangeness is briefly discussed for the case of kaon condensation.

Research on Influence of Fabric Texture and Stretch on Absorption and Quick-Drying of Seamless Underwear

2012 ◽  
Vol 627 ◽  
pp. 622-626
Author(s):  
Li Hua Chen
Keyword(s):  
Spreading Speed ◽  
Transport Capacity ◽  
Research Results ◽  
The Core

In this paper,the 5 types of fabrics were knitted by plain-plated,1+1 and 1+3 float-plated,1+1 and 2+2 tuck-plate stitch and density P6,which are made of cooldry absorption and quick-drying polyester yarns as the facing yarn and the core-spun spandex yarn of nylon as the ground yarns. The absorption and quick-drying were tested and analyzed. The significance of influence of fabric textures and stretch on ab-sorption and quick-drying was analyzed by means of two variance analysis.Results show that the influence of texture and stretch on absorption and quick-drying are significant.The absorption and spreading speed and the accumulative one-way transport capacity of 1+3 and 1+1 float-plated and 2+2 tuck-plated fabric are bigger.As the fabric texture is the same, the absorption and spreading speed are smaller and the accumulative one-way transport capacity are worse with the increase of fabrics stretch.The research results can provide a certain reference for the design & development and choice of seamless underwear.

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