Design of a Contact-Aided Compliant Notched-Tube Joint for Surgical Manipulation in Confined Workspaces

2017 ◽  
Vol 10 (1) ◽  
Author(s):  
Kyle W. Eastwood ◽  
Peter Francis ◽  
Hamidreza Azimian ◽  
Arushri Swarup ◽  
Thomas Looi ◽  
...  
Keyword(s):  
Sensitivity Analysis ◽  
Compliant Mechanism ◽  
Surgical Instruments ◽  
Minimally Invasive Neurosurgery ◽  
Fem Simulations ◽  
Trade Off ◽  
Compliant Joints ◽  
Compliant Joint ◽  
Joint Mechanism ◽  
Surgical Manipulation

This work presents a novel miniature contact-aided compliant joint mechanism that can be integrated into millimeter-sized manual or robotic surgical instruments. The design aims to address the trade-off between notched-tube compliant joints' range of motion and stiffness, while also ensuring a compact form factor. The mechanism is constructed from a nitinol tube with asymmetric cutouts and is actuated in bending by a cable. The innovative feature of this design is the incorporation of a contact aid into the notched-tube topology, which acts to both increase the stiffness of the joint and change the shape that it undertakes during bending. Using finite element modeling (FEM) techniques, we present a sensitivity analysis investigating how the performance of this contact-aided compliant mechanism (CCM) is affected by its geometry, and derive a kinematics and statics model for the joint. The FEM simulations and the kinematic and static models are compared to experimental results. The design and modeling presented in this study can be used to develop new miniature dexterous instruments, with a particular emphasis on applications in minimally invasive neurosurgery.

Design and Optimization of a Contact-Aided Compliant Mechanism for Passive Bending

2014 ◽  
Vol 6 (3) ◽  
Author(s):  
Yashwanth Tummala ◽  
Aimy Wissa ◽  
Mary Frecker ◽  
James E. Hubbard
Keyword(s):  
Design Optimization ◽  
Compliant Mechanism ◽  
Leading Edge ◽  
Optimization Procedure ◽  
Peak Stress ◽  
Nonlinear Bending ◽  
Design And Optimization ◽  
Compliant Joints ◽  
Compliant Joint

A contact-aided compliant mechanism (CCM) called a compliant spine (CS) is presented in this paper. It is flexible when bending in one direction and stiff when bending in the opposite direction, giving it a nonlinear bending stiffness. The fundamental element of this mechanism is a compliant joint (CJ), which consists of a compliant hinge (CH) and contact surfaces. The design of the compliant joint and the number of compliant joints in a compliant spine determine its stiffness. This paper presents the design and optimization of such a compliant spine. A multi-objective optimization problem with three objectives is formulated in order to perform the design optimization of the compliant spine. The goal of the optimization is to minimize the peak stress and mass while maximizing the deflection, subject to geometric and other constraints. Flapping wing unmanned air vehicles, also known as ornithopters, are used as a case study in this paper to test the accuracy of the design optimization procedure and to prove the efficacy of the compliant spine design. The optimal compliant spine designs obtained from the optimization procedure are fabricated, integrated into the ornithopter's wing leading edge spar, and flight tested. Results from the flight tests prove the ability of the compliant spine to produce an asymmetry in the ornithopter's wing kinematics during the up and down strokes.

Design of a Generic Zero Stiffness Compliant Joint

2010 ◽  
Author(s):  
Femke M. Morsch ◽  
Just L. Herder
Keyword(s):  
Compliant Mechanisms ◽  
Compliant Mechanism ◽  
Great Promise ◽  
Optimized Design ◽  
Analytic Model ◽  
Total Potential ◽  
Fea Model ◽  
Compliant Joint ◽  
Joint Element ◽  
Cross Axis

The objective of this paper is to design a generic zero stiffness compliant joint. This compliant joint could be used as a generic construction element in a compliant mechanism. To avoid the spring-back behavior of conventional compliant joints, the principle of static balancing is applied, implying that for each position of the joint the total potential energy should be constant. To this end, a conventional balanced mechanism, consisting of two pivoted bodies which are balanced with two zero-free-length springs, is taken as an initial concept. The joint is replaced by a compliant cross-axis flexural pivot and each spring is replaced by a pair of compliant leaf springs. For both parts an analytic model was implemented and a configuration with the lowest energy fluctuation was found through optimization. A FEA model was used to verify the analytic model of the optimized design. A prototype was manufactured and tested. Both the FEA model and the experiment confirm the reduction of the needed moment to rotate the compliant joint. The experiment shows the balanced compliant joint is not completely balanced but the moment required to rotate the joint is reduced by 70%. Thus, a statically balanced compliant generic joint element was designed which bears great promise in designing statically balanced compliant mechanisms and making this accessible to any designer.

Experimental Validation of the Kinematics of a 3PRS Compliant Mechanism for Micromilling

2015 ◽  
Author(s):  
Antonio Ruiz ◽  
Francisco Campa Gomez ◽  
Constantino Roldan-Paraponiaris ◽  
Oscar Altuzarra
Keyword(s):  
Parallel Mechanism ◽  
Degrees Of Freedom ◽  
Experimental Validation ◽  
Compliant Mechanism ◽  
Motion Controller ◽  
End Effector ◽  
Compliant Joints ◽  
Hybrid Manipulator ◽  
Compliant Parallel Mechanism ◽  
Actuated Joints

The present work deals with the development of a hybrid manipulator of 5 degrees of freedom for milling moulds for microlenses. The manipulator is based on a XY stage under a 3PRS compliant parallel mechanism. The mechanism takes advantage of the compliant joints to achieve higher repetitiveness, smoother motion and a higher bandwidth, due to the high precision demanded from the process, under 0.1 micrometers. This work is focused on the kinematics of the compliant stage of the hybrid manipulator. First, an analysis of the workspace required for the milling of a single mould has been performed, calculating the displacements required in X, Y, Z axis as well as two relative rotations between the tool and the workpiece from a programmed toolpath. Then, the 3PRS compliant parallel mechanism has been designed using FEM with the objective of being stiff enough to support the cutting forces from the micromilling, but flexible enough in the revolution and spherical compliant joints to provide the displacements needed. Finally, a prototype of the 3PRS compliant mechanism has been built, implementing a motion controller to perform translations in Z direction and two rotations. The resulting displacements in the end effector and the actuated joints have been measured and compared with the FEM calculations and with the rigid body kinematics of the 3PRS.

scholarly journals Design of Compliant Joints for Large Scale Structures

2020 ◽  
Author(s):  
Angela Nastevska ◽  
Jovana Jovanova ◽  
Mary Frecker
Keyword(s):  
Large Scale ◽  
Compliant Mechanisms ◽  
Compliant Mechanism ◽  
Small Scale ◽  
Nonlinear Bending ◽  
Large Scale Structures ◽  
Compliant Joints ◽  
Scale Structures ◽  
High Level ◽  
Novel Design

Abstract Large scale structures can benefit from the design of compliant joints that can provide flexibility and adaptability. A high level of deformation is achieved locally with the design of flexures in compliant mechanisms. Additionally, by introducing contact-aided compliant mechanisms, nonlinear bending stiffness is achieved to make the joints flexible in one direction and stiff in the opposite one. All these concepts have been explored in small scale engineering design, but they have not been applied to large scale structures. In this paper the design of a large scale compliant mechanism is proposed for novel design of a foldable shipping container. The superelasticity of nickel titanium is shown to be beneficial in designing the joints of the compliant mechanism.

Incentive genetic algorithm based time–cost trade-off analysis across a build–operate–transfer project concession period

2011 ◽  
Vol 38 (2) ◽  
pp. 166-174 ◽  
Author(s):  
Hongxian Li ◽  
Mohamed Al-Hussein ◽  
Zhen Lei
Keyword(s):  
Genetic Algorithm ◽  
Sensitivity Analysis ◽  
Genetic Algorithms ◽  
Construction Cost ◽  
Methodological Framework ◽  
Time Cost ◽  
Trade Off ◽  
Operation Period ◽  
Concession Period ◽  
New Infrastructure

The build–operate–transfer (BOT) scheme is widely applied to finance new infrastructure projects with private sector (concessionaire) participation. For a predetermined concession period (CP), assuming that CP consists of the construction duration (CD) and the concession operation period (OP), different construction durations result in different profits for the concessionaire. Meanwhile, according to the time–cost trade-off (TCT) principle, shortening the CD increases the construction cost; shortening the CD also prolongs the OP, which could increase the total benefit of BOT projects. Hence, how to arrange construction reasonably to maximize the whole profit is a key issue for a concessionary. This paper proposes a methodological framework including optimization, sensitivity analysis, and improved (incentive) genetic algorithms (GA) for BOT projects. Through the proposed methodological framework, the reasonable construction duration of a BOT project can be obtained. A numerical example is used to verify the proposed methodology.

Design of a Compact Actuated Compliant Elbow Joint

2014 ◽  
Vol 14 (08) ◽  
pp. 1440030 ◽  
Author(s):  
Johannes Gerard Kleinjan ◽  
Alje Geert Dunning ◽  
Justus Laurens Herder
Keyword(s):  
Smart Materials ◽  
Performance Indicators ◽  
Elbow Joint ◽  
Large Deflection ◽  
Rotational Axis ◽  
Half Cycle ◽  
Compliant Joints ◽  
Compliant Joint ◽  
Cycle Efficiency

Compactness is a valuable property in designs of assistive devices and exoskeletons. Current devices are large and stigmatizing in the eyes of the users. The cosmetic appearance will increase by reducing the size. The users want a device that is small enough to be worn underneath the clothes, so it becomes unnoticeable. The goals of this paper are (1) to provide an overview of the shape-changing-material-actuated large-deflection compliant rotational joints, (2) provide new introduced performance indicators that evaluate the designs on performance with respect to volume or weight and (3) design a compact active assistive elbow device as a case study. In order to reach these goals, two evolving fields of study are brought together that have great potential to reduce the size of exoskeletons: smart materials and compliant rotational joints. Smart materials have the ability to change their shape, which make them suitable as actuators. Compliant joints can be compact, since they are made out of one piece of material. An overview of shape-changing-material-actuated large-deflection compliant rotational joints is presented. Performance indicators are proposed to evaluate the existing designs and the prototype. As a case study a compact actuated rotational elbow joint is presented. An antagonistic actuator made from shape memory alloy wires is able to carry an external load and to actuate to move the arm to different positions. The compliant joint is optimized to balance the weight of the arm and to auto-align with the rotational axis of the human elbow joint. A prototype is able to generate a volume specific stall torque of 5.77 ⋅ 103 Nm/m3, produces a work density of 7.27 ⋅ 103 J/m3 based on volumes including isolation covers and the half-cycle efficiency of the device is 3.6%. The prototype is able to balance and actuate a torque of 1.1 Nm.

The Scope for a Compliant Homokinetic Coupling Based on Review of Compliant Joints and Rigid-Body Constant Velocity Universal Joints

2012 ◽  
Author(s):  
Davood Farhadi Machekposhti ◽  
N. Tolou ◽  
J. L. Herder
Keyword(s):  
Rigid Body ◽  
Constant Velocity ◽  
Compliant Mechanism ◽  
Analytical Data ◽  
Graph Representation ◽  
Universal Joint ◽  
Compliant Joints ◽  
Cylindrical Joint ◽  
Body Joints ◽  
Universal Joints

Many applications require a compliant mechanism to transmit rotation from one direct to another direct with constant velocity. This paper presents a literature survey towards the design of compliant constant velocity universal joints. The traditional constant velocity universal joints available from the literature were studied, classified and their mechanical efficiencies were compared. Also the graph representation of them was studied. In the same manner, literature review for different kind of compliant joints suitable for the Rigid-Body-Replacement of constant velocity universal joints was also performed. For the first time a comparison with analytical data of compliant joints was performed. All of compliant universal joints are non-constant velocity and designed based on rigid Hooke’s universal joint. Also we show there are no equivalent compliant joints for some rigid-body joints such as cylindrical joint, planar joint, spherical fork joint and spherical parallelogram quadrilateral joint. However, we may achieve them by combining numbers of available compliant joints. The universal joints found are non-compliant non-constant velocity universal joint, non-compliant constant velocity universal joint or compliant non-constant velocity universal joint. A compliant constant velocity universal joint has a great horizon for developments, for instance in medical or rehabilitation devices.

Design of a Variable Stiffness Actuator Based on Flexures

2011 ◽  
Vol 3 (3) ◽  
Author(s):  
Gianluca Palli ◽  
Giovanni Berselli ◽  
Claudio Melchiorri ◽  
Gabriele Vassura
Keyword(s):  
Compliant Mechanism ◽  
Variable Stiffness ◽  
Human Robot Interaction ◽  
Experimental Characterization ◽  
Robot Interaction ◽  
Trade Off ◽  
Variable Stiffness Actuator ◽  
Robotic Devices ◽  
Stiffness Profile ◽  
Variable Stiffness Actuators

Variable stiffness actuators can be used in order to achieve a suitable trade-off between performance and safety in robotic devices for physical human–robot interaction. With the aim of improving the compactness and the flexibility of existing mechanical solutions, a variable stiffness actuator based on the use of flexures is investigated. The proposed concept allows the implementation of a desired stiffness profile and range. In particular, this paper reports a procedure for the synthesis of a fully compliant mechanism used as a nonlinear transmission element, together with its experimental characterization. Finally, a preliminary prototype of the overall joint is depicted.

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