A novel variable stiffness mechanism with linear spring characteristic for machining operations

Robotica ◽  
2016 ◽  
Vol 35 (7) ◽  
pp. 1627-1637 ◽  
Author(s):  
Ngoc-Dung Vuong ◽  
Renjun Li ◽  
Chee-Meng Chew ◽  
Amir Jafari ◽  
Joseph Polden
Keyword(s):  
Energy Efficient ◽  
Mechanical Design ◽  
Variable Stiffness ◽  
Stiffness Properties ◽  
Pros And Cons ◽  
Linear Spring ◽  
Working Principle ◽  
Machining Operations ◽  
Novel Design

SUMMARYVariable stiffness mechanisms are able to mechanically reconfigure themselves in order to adjust their system stiffness. It is generally accepted that only antagonistic designs, featuring quadratic springs, can produce linear spring-like behaviour (i.e., a linear relationship between the displacement and its resultant force). However, these antagonistic designs typically are not as energy efficient as series-based designs. In this work, we propose a novel variable stiffness mechanism that can achieve both linear-spring behaviour whilst maintaining an energy efficient characteristic. This paper will present the working principle, mechanical design and characterization of the joints stiffness properties (verified via experimental procedure). The pros and cons of this novel design with reference to the other Variable Stiffness Actuator (VSA) designs will be discussed based on experimental results and in the context of general machining tasks.

Design of a parallel compliance device with variable stiffness

2020 ◽  
pp. 095440622093259
Author(s):  
Yong Zhao ◽  
Kunyong Chen ◽  
Jue Yu ◽  
Shunzhou Huang
Keyword(s):  
Mechanical Characteristics ◽  
Variable Stiffness ◽  
Spring Stiffness ◽  
Synthesis Algorithm ◽  
Stiffness Properties ◽  
Linear Spring ◽  
Endpoint Stiffness ◽  
Stiffness Adjustment ◽  
Translational Stiffness

This paper presents a parallel compliance device with variable translational stiffness properties. The variation of endpoint stiffness depends on the change of the spring stiffness in each limb. A synthesis algorithm for realizing the desired force compliance performance is built. Based on the proposed algorithm, a group of optimal spring stiffness can be derived. For the implementation of this device, an electromagnetic linear spring with current-controlled stiffness is developed. After testing the mechanical characteristics of the electromagnetic spring, a prototype of the parallel compliance device is built. The endpoint stiffness under different combinations of spring stiffness values is exhibited in the form of stiffness ellipsoids. A case is studied and verifies the ability of the presented compliance device to realize the desired endpoint stiffness. As the stiffness adjustment range of electromagnetic spring is limited, the bound of physically realizable stiffness of the presented compliance device is also discussed.

253. Characterization of Beryllium Aerosols Associated with Machining Operations

1999 ◽  
Author(s):  
J.W. Martyny ◽  
M. Hoover ◽  
K. Ellis ◽  
M. Mroz ◽  
L. Newman ◽  
...  
Keyword(s):  
Machining Operations

Simplified Approach to Calculating Geometric Stiffness Properties of Tread Pattern Elements

2003 ◽  
Vol 31 (3) ◽  
pp. 132-158 ◽  
Author(s):  
R. E. Okonieski ◽  
D. J. Moseley ◽  
K. Y. Cai
Keyword(s):  
Development Process ◽  
Functional Design ◽  
Simplified Approach ◽  
Tire Industry ◽  
Geometric Stiffness ◽  
Stiffness Properties ◽  
Engineering Parameters ◽  
Net To Gross ◽  
Significant Effort

Abstract The influence of tread designs on tire performance is well known. The tire industry spends significant effort in the development process to create and refine tread patterns. Creating an aesthetic yet functional design requires characterization of the tread design using many engineering parameters such as stiffness, moments of inertia, principal angles, etc. The tread element stiffness is of particular interest because of its use to objectively determine differences between tread patterns as the designer refines the design to provide optimum levels of performance. The tread designer monitors the change in stiffness as the design evolves. Changes to the geometry involve many attributes including the number of sipes, sipe depth, sipe location, block element edge taper, nonskid depth, area net-to-gross, and so forth. In this paper, two different formulations for calculating tread element or block stiffness are reviewed and are compared to finite element results in a few cases. A few simple examples are shown demonstrating the basic functionality that is possible with a numerical method.

scholarly journals Implantable Optrode Array for Optogenetic Modulation and Electrical Neural Recording

Micromachines ◽  
2021 ◽  
Vol 12 (6) ◽  
pp. 725
Author(s):  
Saeyeong Jeon ◽  
Youjin Lee ◽  
Daeho Ryu ◽  
Yoon Kyung Cho ◽  
Yena Lee ◽  
...  
Keyword(s):  
Light Emitting Diode ◽  
Neural Recording ◽  
Electrophysiological Recording ◽  
Light Emitting ◽  
Technological Advances ◽  
Neuroscience Research ◽  
Cell Type Specific ◽  
Novel Design

During the last decade, optogenetics has become an essential tool for neuroscience research due to its unrivaled feature of cell-type-specific neuromodulation. There have been several technological advances in light delivery devices. Among them, the combination of optogenetics and electrophysiology provides an opportunity for facilitating optogenetic approaches. In this study, a novel design of an optrode array was proposed for realizing optical modulation and electrophysiological recording. A 4 × 4 optrode array and five-channel recording electrodes were assembled as a disposable part, while a reusable part comprised an LED (light-emitting diode) source and a power line. After the characterization of the intensity of the light delivered at the fiber tips, in vivo animal experiment was performed with transgenic mice expressing channelrhodopsin, showing the effectiveness of optical activation and neural recording.

Optical and mechanical design and characterization of the new baffle for the 2.4-m Thai National Telescope

2015 ◽  
Author(s):  
Christophe Buisset ◽  
Apirat Prasit ◽  
Thierry Lépine ◽  
Saran Poshyajinda
Keyword(s):  
Mechanical Design

A Novel Design of the Device for Measuring Draw and Plug Forces

2012 ◽  
Vol 542-543 ◽  
pp. 1029-1032
Author(s):  
Ye Hu ◽  
Zhao Jun Yang ◽  
Ming Jun Xiang ◽  
Zi Chen Qiu ◽  
Chuan Gui Yang ◽  
...  
Keyword(s):  
Data Conversion ◽  
Memory Module ◽  
Novel Device ◽  
Working Principle ◽  
Tool Shank ◽  
Novel Design

The purpose of this paper is to present a novel device for measuring draw and plug forces, which is composed chiefly of a pull stud, a top modified tool shank, a middle modified tool shank, a down modified tool shank, and an end cover. The modified tool shank structure is proposed, and the working principle of the device for measuring draw and plug forces is demonstrated. Also, the data conversion and memory module and the circuit principle are investigated.

scholarly journals An Experimental Characterization of TORVEastro, Cable-Driven Astronaut Robot

Robotics ◽  
2021 ◽  
Vol 10 (1) ◽  
pp. 21
Author(s):  
Francesco Samani ◽  
Marco Ceccarelli
Keyword(s):  
Mechanical Design ◽  
Vision System ◽  
Service Robot ◽  
Test Results ◽  
Operation Performance ◽  
Space Applications ◽  
Outdoor Space ◽  
Motion Characteristics ◽  
Three Degree Of Freedom

TORVEastro robot design is presented with a built prototype in LARM2 (Laboratory of Robot Mechatronics) for testing and characterizing its functionality for service in space stations. Several robot astronauts are designed with bulky human-like structures that cannot be convenient for outdoor space service in monitoring and maintenance of the external structures of orbital stations. The design features of TORVEastro robot are discussed with its peculiar mechanical design with 3 arm-legs as agile service robot astronaut. A lab prototype is used to test the operation performance and the feasibility of its peculiar design. The robot weighs 1 kg, and consists of a central torso, three identical three-degree of freedom (DoF) arm–legs and one vision system. Test results are reported to discuss the operation efficiency in terms of motion characteristics and power consumption during lab experiments that nevertheless show the feasibility of the robot for outdoor space applications.

Analysis and Design of a Shape Memory Alloy Actuated Arm to Replicate Human Biomechanics

2016 ◽  
Author(s):  
Cody Wright ◽  
Onur Bilgen
Keyword(s):  
Shape Memory Alloy ◽  
Shape Memory ◽  
Biceps Brachii ◽  
Characteristic Curve ◽  
Stress Strain ◽  
Analysis And Design ◽  
Human Arm ◽  
Linear Spring ◽  
Mechanism Kinematic

Shape memory alloy actuators paired in an antagonistic arrangement can be used to produce mechanisms that replicate human biomechanics. To investigate this proposal, the biomechanical articulation of the elbow by means of the biceps brachii muscle are compared with that of a shape memory alloy actuated arm. Initially, the movement of the human arm is modeled as a single degree of freedom rocker-slider mechanism. Using this model, a purely kinematical analysis is performed on the rigid body rocker-slider. Force analysis follows by modeling the muscle as a simple linear spring. Torque, rocking angle, and energy are calculated for a range of rocker-slider geometries. Actuator characterization of the SMA wire is conducted by experimentally determining the stress-strain curves for the martensite detwinned and full austenite states. Using the experimentally obtained stress-strain curves, nonlinear and linear theoretical actuator characteristic curves are produced for the isolated SMA wire. Using the theoretical actuator characteristic curve on the rocker-slider mechanism, kinematic and force analyses are performed for both the nonlinear and linear actuated mechanisms. To compare to biomechanics, a literature survey is performed on human musculotendon and skeletal lengths and introduced to the kinematic analysis. Examination of biological and mechanical results are then discussed.

scholarly journals Equivalent Electronic Circuit of a System of Oscillators Connected With Periodically Variable Stiffness

2022 ◽  
Author(s):  
Soumyajit Seth ◽  
Grzegorz Kudra ◽  
Krzysztof Witkowski ◽  
Jan Awrejcewicz
Keyword(s):  
Mechanical System ◽  
Electronic Circuit ◽  
Mechanical Design ◽  
Variable Stiffness ◽  
State Variables ◽  
Fixed Point Attractor ◽  
Point Attractor ◽  
Magnetic Resistance ◽  
Nonlinear Behaviors ◽  
Resistance Forces

In this paper, we have shown the electronic circuit equivalence of a mechanical system consists of two oscillators coupled with each other. The mechanical design has the effects of the magnetic, resistance forces and the spring constant of the system is periodically varying. We have shown that the system’s state variables, such as the displacements and the velocities, under the effects of different forces, lead to some nonlinear behaviors, like a transition from the fixed point attractor to the chaotic attractor through the periodic and quasi-periodic attractors. We have constructed the equivalent electronic circuit of this mechanical system and have verified the numerically obtained behaviors using the electronic circuit.

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