Reliability analysis of a tendon-driven actuation for soft robots

2020 ◽  
pp. 027836492090715
Author(s):  
Useok Jeong ◽  
Keunsu Kim ◽  
Sang-Hun Kim ◽  
Hyunhee Choi ◽  
Byeng Dong Youn ◽  
...  
Keyword(s):  
Reliability Analysis ◽  
Domain Knowledge ◽  
Design Stage ◽  
Concept Design ◽  
Force Transmission ◽  
Soft Robots ◽  
Nonlinear Properties ◽  
Highly Nonlinear ◽  
Life Model ◽  
Robotic Devices

The reliability of soft robotic devices will be the bottleneck that slows their commercialization. In particular, fatigue failure issues are a major concern. Thus, reliability should be taken into account from the earliest stages of development. However, to date, there have been no attempts to analyze the reliability of soft robotic devices in a systematic manner. When soft robots are employed to force transmission applications, reliability is typically a dominant issue, since soft robotic structures are constructed with soft material components; these materials have highly nonlinear properties that arise due to the large distribution in the material properties. Furthermore, reliability should be analyzed from the robot’s system down to the components using domain knowledge about the system; this requires a systematic approach. This study presents a framework for reliability analysis of soft robotic devices taking into account a probability distribution that has not been considered before and examines a case study of a tendon-driven soft robot. This study focuses specifically on the (a) concept design process, (b) lifetime analysis process, and (c) design and optimization process. A life model that considers distribution is proposed using accelerated life testing based on analysis of the failure mechanism of the tendon-driven system. The tensile stress of the wire was varied during the experiment with different bend angles and output tension. The result was validated with different stress levels using a testbed to simulate an actual application. The proposed reliability analysis methodology could be applied to other soft robotic systems, such as pneumatic actuators, to improve the reliability-related properties during the robot design stage, and the life model can be used to estimate the device lifetime under various stress conditions.

Model-Based Optimal Control for Underwater Robotics

2010 ◽  
Author(s):  
Yingfeng Ji ◽  
Ryoichi S. Amano ◽  
Ronald A. Perez
Keyword(s):  
High Speed ◽  
Linear Control ◽  
Design Stage ◽  
Underwater Robotics ◽  
Fluid Forces ◽  
Nonlinear Properties ◽  
Highly Nonlinear ◽  
Control Technologies ◽  
The One ◽  
External Forces

It is always one of the most challenging problems to control an underwater robotics due to the complex external forces in an underwater environment. It is difficult to obtain an ideal control performance using linear control technologies due to highly nonlinear properties of system. A valid method of linearization for nonlinear system is provided in this study. Based on this linearized system, the linear control theories were therefore employed for the tracking control of underwater robotics. The panning and tilting motions of this underwater robotics can basically track two given sinusoidal references based on the simulation results. In order to achieve a high-speed manipulation of this underwater robotics, fluid forces have to be considered and modeled. A computational fluid dynamics (CFD) technology is adopted in order to obtain more precise hydrodynamic models for simulation at the design stage. Two torque models that represent the degree of freedoms (DOFs) of panning and tilting respectively have been developed using the CFD software. The dynamic model of this robotics used in this paper is the one by Ji, et al [1].

scholarly journals Time-Dependent Reliability Analysis of Reinforced Concrete Beams Subjected to Uniform and Pitting Corrosion and Brittle Fracture

Materials ◽  
2021 ◽  
Vol 14 (8) ◽  
pp. 1820
Author(s):  
Mohamed El Amine Ben Seghier ◽  
Behrooz Keshtegar ◽  
Hussam Mahmoud
Keyword(s):  
Reinforced Concrete ◽  
Brittle Fracture ◽  
Reliability Analysis ◽  
Pitting Corrosion ◽  
Structural Reliability ◽  
Time Dependent ◽  
State Function ◽  
Rc Beams ◽  
Highly Nonlinear ◽  
Reliability Method

Reinforced concrete (RC) beams are basic elements used in the construction of various structures and infrastructural systems. When exposed to harsh environmental conditions, the integrity of RC beams could be compromised as a result of various deterioration mechanisms. One of the most common deterioration mechanisms is the formation of different types of corrosion in the steel reinforcements of the beams, which could impact the overall reliability of the beam. Existing classical reliability analysis methods have shown unstable results when used for the assessment of highly nonlinear problems, such as corroded RC beams. To that end, the main purpose of this paper is to explore the use of a structural reliability method for the multi-state assessment of corroded RC beams. To do so, an improved reliability method, namely the three-term conjugate map (TCM) based on the first order reliability method (FORM), is used. The application of the TCM method to identify the multi-state failure of RC beams is validated against various well-known structural reliability-based FORM formulations. The limit state function (LSF) for corroded RC beams is formulated in accordance with two corrosion types, namely uniform and pitting corrosion, and with consideration of brittle fracture due to the pit-to-crack transition probability. The time-dependent reliability analyses conducted in this study are also used to assess the influence of various parameters on the resulting failure probability of the corroded beams. The results show that the nominal bar diameter, corrosion initiation rate, and the external loads have an important influence on the safety of these structures. In addition, the proposed method is shown to outperform other reliability-based FORM formulations in predicting the level of reliability in RC beams.

scholarly journals SIMULTANEOUS DEFINITION OF KEY CHARACTERISTICS IN ORDER TO FACILITATE ROBUST DESIGN IN EARLY PRODUCT DEVELOPMENT STAGES

2021 ◽  
Vol 1 ◽  
pp. 2691-2700
Author(s):  
Stefan Goetz ◽  
Dennis Horber ◽  
Benjamin Schleich ◽  
Sandro Wartzack
Keyword(s):  
Product Development ◽  
Robust Design ◽  
Language Processing ◽  
Design Stage ◽  
Concept Design ◽  
Clear Definition ◽  
Implicit Information ◽  
Key Characteristics ◽  
Associated Functions ◽  
Definition Of

AbstractThe success of complex product development projects strongly depends on the clear definition of target factors that allow a reliable statement about the fulfilment of the product requirements. In the context of tolerancing and robust design, Key Characteristics (KCs) have been established for this purpose and form the basis for all downstream activities. In order to integrate the activities related to the KC definition into product development as early as possible, the often vaguely formulated requirements must be translated into quantifiable KCs. However, this is primarily a manual process, so the results strongly depend on the experience of the design engineer.In order to overcome this problem, a novel computer-aided approach is presented, which automatically derives associated functions and KCs already during the definition of product requirements. The approach uses natural language processing and formalized design knowledge to extract and provide implicit information from the requirements. This leads to a clear definition of the requirements and KCs and thus creates a founded basis for robustness evaluation at the beginning of the concept design stage. The approach is exemplarily applied to a window lifter.

scholarly journals TOWARDS A VERIFICATION AND VALIDATING TESTING FRAMEWORK TO DEVELOP BESPOKE MEDICAL PRODUCTS IN RESEARCH-FUNDED PROJECTS

2021 ◽  
Vol 1 ◽  
pp. 3199-3208
Author(s):  
Emanuel Balzan ◽  
Pierre Vella ◽  
Philip Farrugia ◽  
Edward Abela ◽  
Glenn Cassar ◽  
...  
Keyword(s):  
Medical Devices ◽  
Early Stage ◽  
Design Stage ◽  
Concept Design ◽  
Proof Of Concept ◽  
Detailed Design ◽  
Testing Framework ◽  
Medical Products ◽  
Manufacturing Technologies ◽  
Validation Testing

AbstractResearch funded projects are often concerned with the development of proof-of-concept products. Consequently, activities related to verification and validation testing (VVT) are often not considered in depth, even though various design iterations are carried out to refine an idea. Furthermore, the introduction of additive manufacturing (AM) has facilitated, in particular, the development of bespoke medical products. End bespoke products, which will be used by relevant stakeholders (e.g. patients and clinicians) are fabricated with the same manufacturing technologies used during prototyping. As a result, the detailed design stage of products fabricated by AM is much shorter. Therefore, to improve the market-readiness of bespoke medical devices, testing must be integrated within the development from an early stage, allowing better planning of resources. To address these issues, in this paper, a comprehensive VVT framework is proposed for research projects, which lack a VVT infrastructure. The framework builds up on previous studies and methods utilised in industry to enable project key experts to capture risks as early as the concept design stage.

Response surface method strategies coupled with NLFEA for structural reliability analysis of prestressed bridges

2021 ◽  
Author(s):  
Silvia J. Sarmiento Nova ◽  
Jaime Gonzalez-Libreros ◽  
Gabriel Sas ◽  
Rafael A. Sanabria Díaz ◽  
Maria C. A. Texeira da Silva ◽  
...  
Keyword(s):  
Reliability Analysis ◽  
Response Surface ◽  
Response Surface Method ◽  
Structural Reliability ◽  
Limit State ◽  
Material Behavior ◽  
Nonlinear Material ◽  
State Function ◽  
Surface Method ◽  
Highly Nonlinear

<p>The Response Surface Method (RSM) has become an essential tool to solve structural reliability problems due to its accuracy, efficacy, and facility for coupling with Nonlinear Finite Element Analysis (NLFEA). In this paper, some strategies to improve the RSM efficacy without compromising its accuracy are tested. Initially, each strategy is implemented to assess the safety level of a highly nonlinear explicit limit state function. The strategy with the best results is then identified and used to carry out a reliability analysis of a prestressed concrete bridge, considering the nonlinear material behavior through NLFEA simulation. The calculated value of &#120573; is compared with the target value established in Eurocode for ULS. The results showed how RSM can be a practical methodology and how the improvements presented can reduce the computational cost of a traditional RSM giving a good alternative to simulation methods such as Monte Carlo.</p>

Conceptual Design of Kenaf Polymer Composites Automotive Spoiler Using TRIZ and Morphology Chart Methods

2015 ◽  
Vol 761 ◽  
pp. 63-67 ◽  
Author(s):  
Muhd Ridzuan Mansor ◽  
S.M. Sapuan ◽  
A. Hambali ◽  
Edi Syam Zainudin ◽  
A.A. Nuraini
Keyword(s):  
Polymer Composites ◽  
Conceptual Design ◽  
New Product Development ◽  
Design Method ◽  
Idea Generation ◽  
Development Stage ◽  
Concept Development ◽  
Design Stage ◽  
Concept Design ◽  
Solution Strategies

Spoilers are part of an automotive exterior bodywork system that acts to create additional down force for higher traction. In this paper, a new conceptual design of automotive spoiler component using kenaf polymer composites was developed using integrated TRIZ and morphology chart design method. The aim is to enable direct application of kenaf polymer composites to the spoiler design to achieve better environmental performance of the component while maintaining the required structural strength for safe and functional operation. The overall process involved two major stages, which are the idea generation and concept development. TRIZ method was applied in the idea generation stage where specific solution strategies for the design were created. In the concept development stage, the specific TRIZ solution strategies obtained were later refined into relevant alternative system elements using Morphology chart method. Finally, a new conceptual design of an automotive spoiler was developed using the combination of the identified system elements. The integrated TRIZ and morphology chart method were found to be new tools that can be used effectively in the concept design stage, especially in cases where direct material substitution is given the main focus for the new product development.

COVIRDS: Shape Modeling in a Virtual Reality Environment

1997 ◽  
Author(s):  
Tushar H. Dani ◽  
Chi-Cheng P. Chu ◽  
Rajit Gadh
Keyword(s):  
Computer Aided Design ◽  
Visual Display ◽  
Design Stage ◽  
Design System ◽  
Concept Design ◽  
Virtual Design ◽  
Cad Systems ◽  
Product Concept ◽  
Shape Models ◽  
Solid Models

Abstract Rapid shape creation and visualization of solid models remains a tedious task despite advances in the field of Computer Aided Design (CAD)/Solid Modeling. CAD systems require a significant level of detail, such as vertices, edges, and faces to be specified by the user, even before the simplest of shapes can be created and viewed. In addition, most CAD systems have an essentially 2D interface for designing artifacts. This makes artifact visualization, for example by interactive rotation, difficult since all manipulations have be achieved by 2D translation of the mouse or by typing in the required angles of rotation. The limited visualization capability and the requirement to create shapes through the specification of low level entities is especially cumbersome in the concept shape design stage. This paper describes the Conceptual Virtual Design System, COVIRDS, a tool for product concept design. COVIRDS provides an intuitive voice and hand input-based interface for modeling of products using a ‘construction’ approach. Product shape models are created by ‘attaching’ simpler parametrically defined ‘Shape Elements’ to other elements to create more complex models. Voice commands are used to instantiate shape elements and change their parameters, for example, the width, length and height of a block element. 3D hand input is used for positioning shape elements during element attachment. The voice and hand input-based interface together with a stereoscopic visual display facilitates rapid creation and visualization of concept shape models.

scholarly journals Optimisation of passenger ship structures in concept design stage

2019 ◽  
Vol 14 (sup1) ◽  
pp. 320-334 ◽  
Author(s):  
Joni Raikunen ◽  
Eero Avi ◽  
Heikki Remes ◽  
Jani Romanoff ◽  
Ingrit Lillemäe-Avi ◽  
...  
Keyword(s):  
Design Stage ◽  
Concept Design ◽  
Ship Structures ◽  
Passenger Ship

Numerical Co-Simulation of Drag Torque in the Gearbox Combined Multibody Dynamics With Moving Particle Semi-Implicit Method

2019 ◽  
Author(s):  
Lifu Zhang ◽  
Guangqiang Wu ◽  
Lijuan Ju
Keyword(s):  
Power Loss ◽  
Friction Pair ◽  
Helical Gear ◽  
Implicit Method ◽  
Design Stage ◽  
Force Transmission ◽  
Technical Measure ◽  
New Approach ◽  
Simulation Results ◽  
Moving Particle

Abstract In the gearbox, lubrication is an important technical measure to improve the friction state of the friction pair and ensure the smooth operation of the mechanical system, and it also plays an important role in cooling, sealing, rust prevention, shock absorption and force transmission. Common lubrication methods in automobile gearbox include dip lubrication, splash lubrication and forced lubrication, but dip and splash lubrication often result in oil churning power loss of the gearbox, and predicting this loss at design stage can help designers to modify the design and improve efficiency. In this paper, the moving particle semi-implicit method is applied to analyze the churning loss of a single helical gear in the transmission system, and the accuracy of the simulation results is verified by experimental data. This research can provide an effective new approach to study the oil churning power loss of gear in transmission.

Sign in / Sign up

Export Citation Format

Share Document