scholarly journals A 3D-Printable Robotic Gripper Based on Thick Panel Origami

2021 ◽  
Vol 8 ◽  
Author(s):  
Chenying Liu ◽  
Perla Maiolino ◽  
Zhong You
Keyword(s):  
Degrees Of Freedom ◽  
2D Materials ◽  
Thin Sheet ◽  
Finite Thickness ◽  
Plane Symmetric ◽  
Actuation Force ◽  
Grasping Force ◽  
Kinematic Modelling ◽  
Spherical Linkages ◽  
Thickness Sheet

Origami has been a source of inspiration for the design of robots because it can be easily produced using 2D materials and its motions can be well quantified. However, most applications to date have utilised origami patterns for thin sheet materials with a negligible thickness. If the thickness of the material cannot be neglected, commonly known as the thick panel origami, the creases need to be redesigned. One approach is to place creases either on top or bottom surfaces of a sheet of finite thickness. As a result, spherical linkages in the zero-thickness origami are replaced by spatial linkages in the thick panel one, leading to a reduction in the overall degrees of freedom (DOFs). For instance, a waterbomb pattern for a zero-thickness sheet shows multiple DOFs while its thick panel counterpart has only one DOF, which significantly reduces the complexity of motion control. In this article, we present a robotic gripper derived from a unit that is based on the thick panel six-crease waterbomb origami. Four such units complete the gripper. Kinematically, each unit is a plane-symmetric Bricard linkage, and the gripper can be modelled as an assembly of Bricard linkages, giving it single mobility. A gripper prototype was made using 3D printing technology, and its motion was controlled by a set of tendons tied to a single motor. Detailed kinematic modelling was done, and experiments were carried out to characterise the gripper’s behaviours. The positions of the tips on the gripper, the actuation force on tendons, and the grasping force generated on objects were analysed and measured. The experimental results matched well with the analytical ones, and the repeated tests demonstrate that the concept is viable. Furthermore, we observed that the gripper was also capable of grasping non-symmetrical objects, and such performance is discussed in detail in the paper.

scholarly journals Kinematic Modelling of FES Induced Sit-to-stand Movement in Paraplegia

2017 ◽  
Vol 7 (6) ◽  
pp. 3060
Author(s):  
Mohammed Ahmed ◽  
M. S. Huq ◽  
B. S. K. K. Ibrahim
Keyword(s):  
Dynamic Model ◽  
Initial Phase ◽  
Degrees Of Freedom ◽  
Kinematic Model ◽  
Future Research ◽  
Upper Limbs ◽  
Body System ◽  
Segmental Dynamics ◽  
Sit To Stand ◽  
Kinematic Modelling

FES induced movements from indication is promising due to encouraging results being obtained by scholars. The kinematic model usually constitute the initial phase towards achieving the segmental dynamics of any rigid body system. It can be used to ascertain that the model is capable of achieving the desired goal. The dynamic model builds on the kinematic model and is usually mathematically cumbersome depending on the number of degrees-of-freedom. This paper presents a kinematic model applicable for human sit-to-stand movement scenario that will be used to obtain the dynamic model the FES induced movement in a later study. The study shows that the 6 DOF conceptualized sit-to-stand movement can be achieved conveniently using 4 DOF. The 4 DOF has an additional joint compared to similar earlier works which makes more it accurate and flexible. It is more accurate in the sense that it accommodates additional joint i.e. the neck joint whose dynamics could be captured. And more flexible in the sense that if future research uncover more contributions by the segments it can be easily incorporated including that of other segments e.g. the trunk, neck and upper limbs.

scholarly journals A Finger Grip Force Sensor with an Open-Pad Structure for Glove-Type Assistive Devices

Sensors ◽  
2019 ◽  
Vol 20 (1) ◽  
pp. 4 ◽  
Author(s):  
Junghoon Park ◽  
Pilwon Heo ◽  
Jung Kim ◽  
Youngjin Na
Keyword(s):  
Degrees Of Freedom ◽  
Grip Force ◽  
Force Sensor ◽  
Assistive Devices ◽  
Finger Joint ◽  
Assistive Device ◽  
Force Estimation ◽  
Joint Angles ◽  
Fingertip Force ◽  
Grasping Force

This paper presents a fingertip grip force sensor based on custom capacitive sensors for glove-type assistive devices with an open-pad structure. The design of the sensor allows using human tactile sensations during grasping and manipulating an object. The proposed sensor can be attached on both sides of the fingertip and measure the force caused by the expansion of the fingertip tissue when a grasping force is applied to the fingertip. The number of measurable degrees of freedom (DoFs) are the two DoFs (flexion and adduction) for the thumb and one DoF (flexion) for the index and middle fingers. The proposed sensor allows the combination with a glove-type assistive device to measure the fingertip force. Calibration was performed for each finger joint angle because the variations in the expansion of the fingertip tissue depend on the joint angles. The root mean square error (RMSE) for fingertip force estimation ranged from 3.75% to 9.71% after calibration, regardless of the finger joint angles or finger posture.

Design and locomotion analysis of a novel deformable mobile robot with two spatial reconfigurable platforms and three kinematic chains

2016 ◽  
Vol 231 (8) ◽  
pp. 1481-1499 ◽  
Author(s):  
Wan Ding ◽  
Qiang Ruan ◽  
Yan-an Yao
Keyword(s):  
Mobile Robot ◽  
Degrees Of Freedom ◽  
Three Dimensional ◽  
Three Dimensional Model ◽  
Dynamic Simulations ◽  
Gait Planning ◽  
Plane Symmetric ◽  
Kinematic Chains ◽  
Reconfigurable Platforms ◽  
Actuation Systems

A novel five degrees of freedom deformable mobile robot composed of two spatial reconfigurable platforms and three revolute–prismatic–spherical kinematic chains acting in parallel to link the two platforms is proposed to realize large deformation capabilities and multiple locomotion modes. Each platform is an improved deployable single degrees of freedom three-plane-symmetric Bricard linkage. By taking advantage of locomotion collaborating among platforms and kinematic chains, the mobile robot can fold into stick-like shape and possess omnidirectional rolling and worm-like motions. The mechanism design, kinematics, and locomotion feasibility are the main focus. Through kinematics and gait planning, the robot is analyzed to have the capabilities of rolling and turning. Based on its deformation, the worm-like motion performs the ability to overcome narrow passages (such as pipes, holes, gaps, etc.) with large range of variable size. Dynamic simulations with detailed three-dimensional model are carried out to verify the gait planning and provide the variations of essential motion and dynamic parameters in each mode. An experimental robotic system with servo and pneumatic actuation systems is built, experiments are carried out to verify the validity of the theoretical analysis and the feasibility of the different locomotion functions, and its motion performances are compared and analyzed with collected data.

General Beam Cross-Section Analysis Using a 3D Finite Element Slice

2014 ◽  
Author(s):  
Philippe Couturier ◽  
Steen Krenk
Keyword(s):  
Finite Element ◽  
Cross Section ◽  
Cross Sections ◽  
Degrees Of Freedom ◽  
Finite Thickness ◽  
Single Layer ◽  
Element Discretization ◽  
Cubic Polynomial ◽  
Hermitian Interpolation ◽  
Section Analysis

A formulation for analysis of general cross-section properties has been developed. This formulation is based on the stress-strain states in the classic six equilibrium modes of a beam by considering a finite thickness slice modelled by a single layer of 3D finite elements. The displacement variation in the lengthwise direction is in the form of a cubic polynomial, which is here represented by Hermitian interpolation, whereby the degrees of freedom are concentrated on the front and back faces of the slice. The theory is illustrated by application to a simple cross-section for which an analytical solution is available. The paper also shows an application to wind turbine blade cross-sections and discusses the effect of the finite element discretization on the cross-section properties such as stiffness parameters and the location of the elastic and shear centers.

scholarly journals A 4-DOF SCARA Robotic Arm for Various Farm Applications: Designing, Kinematic Modelling, and Parameterization

2021 ◽  
Vol 24 (2) ◽  
pp. 61-66
Author(s):  
Ali Roshanianfard ◽  
Du Mengmeng ◽  
Samira Nematzadeh
Keyword(s):  
Degrees Of Freedom ◽  
Surface Coverage ◽  
Kinematic Model ◽  
Robotic Arm ◽  
Agricultural Field ◽  
Farm Work ◽  
Working Space ◽  
Agriculture Industry ◽  
Smooth Motion ◽  
Kinematic Modelling

Abstract The agriculture industry has faced various challenges nowadays. This research is the first part of a project that presents the designing process, kinematic modelling, and parameterization of a 4-DOF SCARA-type robotic arm specifically designed for work in an agricultural field in terms of seeding, watering, fertilizing, weeding, harvesting, and transporting. The designing of parameters, such as optimum degrees of freedom and component configuration, was done. The kinematic model was calculated using the Denavit-Hartenberg method. The structure of robot was developed for inertia reduction, smooth motion, and torque minimization. The results show that the working space, maximum front access, and side access of developed robotic arm were 11.4 m2, 2.9 m, and 2.4 m, respectively. The results indicate that the robot has sufficient surface coverage for defined farm work.

Stability of gravitating fluid layer of infinite extent but finite thickness including Hall effect

1968 ◽  
Vol 46 (19) ◽  
pp. 2201-2205 ◽  
Author(s):  
K. P. Das
Keyword(s):  
Hall Effect ◽  
Hall Current ◽  
Fluid Layer ◽  
Finite Thickness ◽  
Perturbation Parameter ◽  
Displacement Current ◽  
Plane Symmetric ◽  
Infinite Extent ◽  
Mode Method ◽  
The Stability

The stability of a gravitating, homogeneous, incompressible fluid layer of infinite extent but finite thickness is considered, including Hall effect, by the use of the normal mode method. A uniform magnetic field is assumed to be present throughout parallel to its boundary. The displacement current is neglected. An asymptotic analysis for small nonzero Hall current shows a destabilizing effect of order ε where ε is the perturbation parameter. The stability analysis is restricted to plane-symmetric modes.

Design Considerations for Continuum Robot Actuation Units Enabling Dexterous Transurethral Bladder Cancer Resection

2016 ◽  
Author(s):  
Giuseppe Del Giudice ◽  
Nima Sarli ◽  
Stanley D. Herrell ◽  
Nabil Simaan
Keyword(s):  
Design Process ◽  
Degrees Of Freedom ◽  
Modular Architecture ◽  
Continuum Robots ◽  
Position Sensing ◽  
Actuation Force ◽  
Design Considerations ◽  
Continuum Robot ◽  
Modular Format

The last decade has seen rapid growth in exploring the potential of continuum robots for a variety of surgical applications. The design of these robots requires unique electro-mechanical architectures of actuation units that satisfy operational requirements of precision, workspace, and payload capabilities. This paper presents the task-based design process of a compact nine degrees of freedom actuation unit for transurethral resection of bladder tumor (TURBT). This actuation unit has a unique modular architecture allowing partial decoupling of actuation, force and position sensing in a compact modular format. The derivation of task specifications based on kinematic simulations takes into account workspace, accuracy and force application capabilities for TURBT. Design considerations for supporting modularity, serviceability, sterilization, and compactness are presented. The detailed exposition of the design process serves as a case study that will be helpful for other groups interested in the development and integration of surgical continuum robots.

scholarly journals Branch Reconfiguration of Bricard Linkages Based on Toroids Intersections: Plane-Symmetric Case

2018 ◽  
Vol 10 (3) ◽  
Author(s):  
P. C. López-Custodio ◽  
J. S. Dai ◽  
J. M. Rico
Keyword(s):  
Degrees Of Freedom ◽  
Symmetric Case ◽  
Complete Theory ◽  
Plane Symmetry ◽  
Special Configuration ◽  
Conical Singularities ◽  
Plane Symmetric ◽  
Isolated Points ◽  
First Time ◽  
Special Plane

This paper for the first time reveals a set of special plane-symmetric Bricard linkages with various branches of reconfiguration by means of intersection of two generating toroids, and presents a complete theory of the branch reconfiguration of the Bricard plane-symmetric linkages. An analysis of the intersection of these two toroids reveals the presence of coincident conical singularities, which lead to design of the plane-symmetric linkages that evolve to spherical 4R linkages. By examining the tangents to the curves of intersection at the conical singularities, it is found that the linkage can be reconfigured between the two possible branches of spherical 4R motion without disassembling it and without requiring the usual special configuration connecting the branches. The study of tangent intersections between concentric singular toroids also reveals the presence of isolated points in the intersection, which suggests that some linkages satisfying the Bricard plane-symmetry conditions are actually structures with zero finite degrees-of-freedom (DOF) but with higher instantaneous mobility. This paper is the second part of a paper published in parallel by the authors in which the method is applied to the line-symmetric case.

Transient field solution for a layer of finite thickness on a resistive basement

Geophysics ◽  
2003 ◽  
Vol 68 (4) ◽  
pp. 1232-1240 ◽  
Author(s):  
Bension Sh. Singer ◽  
Andrew Green
Keyword(s):  
Magnetic Field ◽  
Half Space ◽  
Thin Sheet ◽  
Finite Thickness ◽  
Generalized Solution ◽  
Mirror Plane ◽  
Time Range ◽  
Conductive Layer ◽  
Transient Field ◽  
Simple Modification

A closed‐form asymptotic solution is derived for the magnetic field of the currents induced by a transient airborne magnetic source in a conductive layer of finite thickness. The conductive layer rests on top of a resistive half‐space. Like the well‐known solution found by J. C. Maxwell for a thin conductive sheet surrounded by an insulator, the secondary magnetic field is expressed in terms of an image source receding from the layer. However, the new solution also accounts for the layer thickness h and the conductivity of the half‐space. One of the conclusions from the new solution is that the mirror plane that specifies the position of the image is located below the upper interface of the conductive layer at depth h/3. This indicates the correct position at which the equivalent thin sheet should be placed when Maxwell's solution is applied to a layer of finite thickness. If the basement that underlies the layer is highly resistive, Maxwell's solution becomes accurate when induced currents are almost uniformly spread across the layer. It remains accurate as long as currents induced in the basement can be neglected. Eventually, the secondary magnetic field of these currents will prevail over the field of currents in the layer. Maxwell's solution loses its accuracy long before this occurs. Depending on parameters of the model, the validity time range of Maxwell's solution may be narrow or even nonexistent. The generalized image solution is applicable in the time range h/vs < t < (σs/σb)(h/vs), where vs is the image recession speed, and σs and σb are the layer and basement conductivities, respectively. This range is significantly wider than that of Maxwell's solution. At early times, the secondary magnetic field is controlled by the position of the nearest interface of the conductive layer. Accounting for this observation, a simple modification of the new solution may be used to extend the applicability range towards even earlier times. The generalized solution is faster by several orders of magnitude than a numeric solution based on successive wavenumber‐to‐space and frequency‐to‐time domain fast Hankel transforms.

Deployable Prismatic Structures With Rigid Origami Patterns

2016 ◽  
Vol 8 (3) ◽  
Author(s):  
Sicong Liu ◽  
Weilin Lv ◽  
Yan Chen ◽  
Guoxing Lu
Keyword(s):  
Closed Loop ◽  
Design Method ◽  
Kinematic Model ◽  
Deployable Structures ◽  
Engineering Applications ◽  
Single Degree Of Freedom ◽  
General Design ◽  
Plane Symmetric ◽  
Single Degree ◽  
Spherical Linkages

Rigid origami inspires new design technology in deployable structures with large deployable ratio due to the property of flat foldability. In this paper, we present a general kinematic model of rigid origami pattern and obtain a family of deployable prismatic structures. Basically, a four-crease vertex rigid origami pattern can be presented as a spherical 4R linkage, and the multivertex patterns are the assemblies of spherical linkages. Thus, this prismatic origami structure is modeled as a closed loop of spherical 4R linkages, which includes all the possible prismatic deployable structures consisting of quadrilateral facets and four-crease vertices. By solving the compatibility of the kinematic model, a new group of 2n-sided deployable prismatic structures with plane symmetric intersections is derived with multilayer, straight and curvy variations. The general design method for the 2n-sided multilayer deployable prismatic structures is proposed. All the deployable structures constructed with this method have single degree-of-freedom (DOF), can be deployed and folded without stretching or twisting the facets, and have the compactly flat-folded configuration, which makes it to have great potential in engineering applications.

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