Conceptual Design Synthesis Research Articles

Empirical studies on conceptual design synthesis of multiple-state mechanical devices

Empirical studies on conceptual design synthesis of multiple-state mechanical devices

DEVELOPMENT OF A DESIGN SUPPORT TOOL FOR SYNTHESISING MULTI-STATE MECHANICAL DEVICE CONCEPTS

AbstractConceptual design synthesis, which focuses on generating solution alternatives, has a significant impact on the cost and quality of the final product. The development of radically new and significantly better solutions requires the generation and exploration of a large solution space. This work deals with the conceptual design synthesis of multi-state mechanical devices (MSMD). A scheme for representing a MSMD design task is described. Empirical studies have been carried out to develop a common understanding of the MSMD design synthesis process and use this knowledge for developing a prescriptive model. In order to support the effective and efficient use of the proposed prescriptive model, a web-based computational tool is developed.

Integration of the athena vortex lattice aerodynamic analysis software into the multivariate design synthesis of a blended wing body aircraft

This paper describes the process of integrating the Athena Vortex Lattice aerodynamics solver into a conceptual design environment for the multivariate design synthesis and optimisation of a Blended Wing Body (BWB) Aircraft. The work is derived from a PhD study, by one of the authors, which developed a design methodology for the conceptual design synthesis, analysis and optimisation of a BWB aircraft. This research was driven by the desire to utilise proven aerodynamic solvers, written in legacy codes, in modern computational design environments in order to improve the accuracy and fidelity in the design of novel aircraft configurations. The Athena Vortex Lattice code is a legacy code written in the FORTRAN programming language and developed at the Massachusetts Institute of Technology by Mark Drela while the multivariate conceptual design synthesis and optimisation was implemented in JAVA object oriented programming tool. The result from this study is the successful integration of the AVL software into the JAVA programming environment for the multivariate design synthesis optimisation of the BWB without loss of accuracy. The successful integration of these codes permit a more accurate design synthesis, analysis and optimisation of the novel aircraft configuration in the absence of a tailor-made and realistic empirical aerodynamic analysis model for the BWB Aircraft. Additionally, this research enables the automation of the design process and the accomplishment of the multivariate optimisation.

A Tool for Supporting Conceptual Design of Multiple State Mechanical Devices

Research into conceptual design of mechanical systems has evolved as an area of interest since last few decades. Conceptual design plays a significant role as an early stage of design to produce designs with higher quality by economically exploring a larger solution space. Several attempts have been made by researchers to automate the conceptual design synthesis process using computer support. However, most of that work has been focused on single state design problems. This paper deals with multiple state mechanical design problems and proposes a systematic method for synthesizing a larger solution space. A web-based tool is developed to guide designers through the step-by-step synthesis process by providing automated retrieval of initial solution proposals and modification rules.

A graph-based computerized optimal conceptual design synthesis within the distributed multi-disciplinary resource environment

The trend of inter-disciplinary conceptual design synthesis requires designers to involve more and more distributed multi-disciplinary design resources. Therefore, this paper proposes a graph-based computerized optimal conceptual design synthesis to help designers explore novel design schemes within the distributed multi-disciplinary resource environment. The design resources tightly related to the design goal can be extracted from the huge resource environment by a proposed searching engine. The optimal design scheme can be generated from these related design resources by a proposed graph-based algorithm. A set of computer applications called Automatic Conceptual Design System (ACDS) is established to verify the feasibility of this proposed conceptual design synthesis, and a garbage power system’s conceptual design is completed by this software prototype.

Design-airworthiness integration method for general aviation aircraft during early development stage

PurposeMajor changes of an aircraft configuration are conducted during the early design stage. It is important to include the airworthiness regulations at this stage while there is extensive freedom for designing. The purpose of this paper is to introduce an efficient design framework that integrates airworthiness guidelines and documentation at the early design stage.Design/methodology/approachA new design and optimization process is proposed that logically includes the airworthiness regulations as design parameters and constraints by constructing a certification database. The design framework comprises requirements analysis, preliminary sizing, conceptual design synthesis and loads analysis. A design certification relation table (DCRT) describes the legal regulations in terms of parameters and values suitable for use in design optimization.FindingsThe developed framework has been validated and demonstrated for the design of a Federal Aviation Regulations (FAR) 23 four-seater small aircraft. The validation results show an acceptable level of accuracy to be applied during the early design stage. The total mass minimization problem has been successfully solved while satisfying all the design requirements and certification constraints specified in the DCRT. Moreover, successful compliance with FAR 23 subpart C is demonstrated. The proposed method is a useful tool for design optimization and compliance verifications during the early stages of aircraft development.Practical implicationsThe new certification database proposed in this research makes it simpler for engineers to access a large amount of legal documentation related to airworthiness regulations and provides a link between the regulation text and actual design parameters and their bounds.Originality/valueThe proposed design optimization framework integrates the certification database that is built of several types of legal documents such as regulations, advisory circulars and standards. The Engineering Requirements and Guide summarizes all the documents and design requirements into a single document. The DCRT is created as a summary table that indicates the design parameters affected by a given regulation(s), the design stage at which the parameter can be evaluated and its value bounds. The introduction of the certification database into the design optimization framework significantly reduces the engineer’s load related for airworthiness regulations.

Conceptual design and dimensional synthesis of a novel parallel mechanism for lower-limb rehabilitation

SUMMARYThis paper introduces a novel 2R1T parallel manipulator redundantly actuated by pneumatic muscles for lower-limb rehabilitation. First, the conceptual design of the proposed 3-DOF parallel mechanism is presented. Then, the inverse kinematics and the generalized Jacobian analysis are carried out. Based on the generalized Jacobian and the constraint characteristics of the mechanism, the force/motion transmissibility of the redundantly actuated parallel mechanism is investigatedviafour individual cases without actuation redundancy, leading to a suitable local transmission index for the evaluation of kinematic performance of the proposed mechanism. Finally, the design variables are optimized by maximizing the mean value of the local transmission index with the aid of genetic algorithm. The numerical result shows that the proposed parallel mechanism can achieve a good kinematic performance in its task workspace.

Conceptual design synthesis based on series-parallel functional unit structure

ABSTRACTConceptual design synthesis is the core and starting phase of the design process. During this phase, the designers should deal with a large number of design resources to construct conceptual systems which meet the functional requirement. Therefore, a conceptual design synthesis approach based on series-parallel function unit structure is proposed as an assistant tool for the designers. This approach can help the designers completing the conceptual design synthesis of simple design missions or elementary functional modules of complex design missions with series-parallel-structured synthesis results. A corresponding computer programme is established as an implementation, and the conceptual design synthesis of the mechanical part of a friction-abrasion testing machine is completed with this programme to prove the practicability of this proposed approach.

A computational approach for the optimal conceptual design synthesis based on the distributed resource environment

Optimal conceptual design synthesis is the very starting and key phase in the product design. Its result is the optimal alternative in the solution space, and will be further completed and improved into the final product design scheme in the next detailed design works. With the progress of the Internet technology, a large number of design resources actually construct an increasingly growing distributed resource environment. If these rich resources can be fully introduced into the optimal conceptual design synthesis, the design efficiency and product innovation will be promoted largely. Therefore, a computational approach was proposed for the optimal conceptual design synthesis based on the distributed resource environment. In this approach, the distributed resource environment is modelled as a set of numerous functional units (FUs), and the optimal conceptual design synthesis is concluded into a process of generating the optimal objective FU chain. Here, the main workload is completed by a proposed computer algorithm. To prove the feasibility of this approach, a computer programme called Optimal Conceptual Design Synthesis System (OCDSS) was established. A garbage-powered lighting system was designed with OCDSS as an illustration.

A function unit integrating approach for the conceptual design synthesis in the distributed resource environment

With the help of the well-developed Internet technologies, designers can obtain numerous resources distributed all over the world. These resources actually construct the distributed resource environment. If this environment can be fully considered and applied during the key and starting phase of the product design, the conceptual design synthesis, the design efficiency will be largely promoted and the design product will have better quality, innovation, and competition. Therefore, a function unit integrating approach was proposed for the conceptual design synthesis in the distributed resource environment. This approach is based on the integration of function units which represent the resources in the distributed resource environment. With the proposed computer algorithm, these function units can be firstly connected up into appropriate function unit chains and, then, improved into the final function unit set as the result of the conceptual design synthesis. Based on this approach, a computer program called function unit integrating system was established. And finally, the design process of a friction testing machine was completed by function unit integrating system as an illustrative case.

A complex-number-domain-based conceptual design synthesis for multidisciplinary products

With the increase of the customer demands for the products, multidisciplinary products are gradually becoming more competitive than the traditional products. Considering conceptual design synthesis is the core phase of the product design and its result is the starting point of the next detail design works, if the rich resources in multiple disciplinary domains can be fully used during this phase, the efficiency of multidisciplinary product design will be largely promoted. Therefore, we proposed a novel conceptual design synthesis system for multidisciplinary products, which consists of three parts, i.e. basic framework, complex-number-domain-based mathematical model, and achieving approach. In the framework, three groups of concepts were defined and the conceptual design synthesis was concluded into three steps. The model can completely describe and modularize the function units which are the basic components of a design scheme. Based on the model, the achieving approach can automatically generate stable objective function unit chains which can directly construct the design scheme. Finally, the design of a multifunctional agricultural hydroelectric power system was taken as an illustration to prove the practicability of this proposed system.

Conceptual design and dimensional synthesis of cam-linkage mechanisms for gait rehabilitation

In order to overcome the drawbacks of traditional gait training methods, gait rehabilitation robotized systems have been developed to provide a consistent, labor-saving and efficient treatment. However, the high cost of these systems makes them impracticable for home healthcare. This paper deals with the conceptual design and dimensional synthesis of cam-linkage mechanisms for gait rehabilitation. First, a two degrees of freedom seven-bar crank-slider mechanism is selected as the original mechanism, of which the displacement of the slider is formulated as a function of the crank angle to achieve the target trajectory by using the inverse kinematics. A cam is then designed to reduce the mobility of the mechanism to one. Moreover, a constant speed motor is sufficient for the control of the mechanism. For the dimensional synthesis, a goal function is proposed based on the kinematic performance criteria and constraints, and the genetic algorithm is employed for global searching. Two target trajectories are used for the dimensional synthesis of the mechanism. The results show the generated trajectories match well with the desired ones, which illustrates the feasibility of the methodology.

Formal Verification of Complex Systems based on SysML Functional Requirements


 
 
 As modern systems continue to increase in size and complexity, they pose increasingly significant safety and risk management challenges. A model-based safety approach is an efficient way of coping with the increasing system complexity. It helps better manage the complexity by utilizing reasoning tools that require abstract models to detect failures as early as possible during the design process. This paper develops a methodology for the verification of safety requirements for design of complex engineered systems. The proposed approach combines a SysML modeling approach to document and structure safety requirements, and an assume-guarantee technique for the formal verification purpose. The assume- guarantee approach, which is based on a compositional and hierarchical reasoning combined with a learning algorithm, is able to simplify complex design verification problems. The objective of the proposed methodology is to integrate safety into early design stages and help the system designers to consider safety implications during conceptual design synthesis, reducing design iterations and cost. The proposed approach is validated on the quad-redundant Electro-Mechanical Actuator (EMA) of a Flight Control Surface (FCS) of an aircraft.
 
 

An improved algorithm for the construction of generalized kinematic chains

Generating generalized kinematic chains is one of the most important steps in the conceptual design or structural synthesis of mechanisms. An improved method for the systematic construction of generalized kinematic chains (including both kinematic chains and rigid chains) is presented based on two algorithms, namely the cut-links checking algorithm and Kuratowski (nonplanar) graph checking algorithm. Examples are provided to illustrate the algorithms. The atlases of generalized kinematic chains comprising up to sixteen links are listed.

A multi-agent-based approach for conceptual design synthesis of multi-disciplinary systems

It is encouraged that designers should explore in wide multi-disciplinary solution spaces for finding novel and promising principle solutions to desired functions during conceptual design. However, due to lack of sufficient multi-disciplinary knowledge, it is often difficult for human designers to explore in wide multi-disciplinary solution spaces. Therefore, this paper proposes a multi-agent-based approach for assisting designers in achieving multi-disciplinary conceptual design synthesis. The roles of different kinds of designing agents are identified, and the collaborative mechanisms among these agents are also elaborated. The conceptual design test case of a solar toy demonstrates that the proposed multi-agent-based design synthesis approach, compared with our previous approach, can achieve higher efficiency and better robustness through collaborative conceptual design synthesis.

A novel semi-heuristic planning approach for automated conceptual design synthesis

Automated conceptual design often shows significant promise for generating conceptual solutions automatically through searching and synthesizing known principle solutions for a desired function. However, existing automated conceptual design systems lack an efficient heuristic search strategy and a knowledge-based planning mechanism, which lead to less chance of finding promising principle solutions within a limited time. This article proposes a novel semi-heuristic planning approach for automated conceptual design which comprises two successive steps, i.e. DESIGN PLAN and DESIGN COMBINATION. During the stage of DESIGN PLAN, the planning-graph technique is employed to extract a design plan from a planning graph, which is composed of various principle solution clusters. Under the guidance of the design plan, in the second stage, DESIGN COMBINATION combines compatible principle solutions from the principle solution clusters in the design plan until finding promising conceptual solutions. A prototype system and design case illustrate that the proposed semi-heuristic planning approach can successfully achieve an automated conceptual design synthesis.

A knowledge-based system for multi-disciplinary conceptual design synthesis

Exploring wide multi-disciplinary solution spaces to create conceptual design solutions is a difficult task for human designers due to lack of sufficient multi-disciplinary knowledge. A viable approach would be to develop a computer-aided system to synthesize the wide variety of knowledge for a given design task. However, the existing design synthesis systems are mainly domain-specific, focusing on conceptual design synthesis in a single or few limited disciplines. Therefore, this article introduces the development of a knowledge-based system for multi-disciplinary conceptual design synthesis, including the establishment of a knowledge base for organizing multi-disciplinary principle solutions and a design synthesis algorithm. The implementation of a prototype software is also reported, with the conceptual design of a solar fountain as a demonstrative case. The results of the case study show that the system can automatically and conveniently generate multi-disciplinary conceptual solutions.

Comparison of CAD and manual sketching tools for teaching architectural design

Communications for information synchronisation during the conceptual design phase usually require designers to employ more flexible and intuitive digital design tools. In developing such support tools, a case study research was initiated to first understand the current state of communication among novice design team members. The main purpose of the study is to understand the novice designers' collaboration culture when working on conceptual architectural design projects. The overall case study research involves 1) ethnography for data collection and 2) artefact and protocol analyses for data analysis. This paper presents the latter data analyses based on the earlier ethnography results about novice designers' conceptual design and technology design synthesis strategies. Data analyses on the characteristics of utilised external representation tools indicate that although conventional manual sketching is beneficial for providing rich intuitive design concepts, they have limitations when novice designers need to oversee complicated design problems. The study also found that although current conventional CAD tools are advantageous for detailed engineering design articulation, they do hinder novice designers' creativity due to their intuitive ideation limitation. Based on these results, this paper discusses the identified advantages and challenges of current design media and then proposes an alternative VR-based design interface for enhancing cognition and communication among designers during the conceptual design phase.

Function to structure/material mappings for conceptual design synthesis and their supportive strategies

Conceptual design aims at developing design concepts that can satisfy the specified design requirements, where the design concepts are normally in the form of a physical structure. There has been quite a lot of work done in this area of design research, from which it is now generally agreed that functional decomposition and function to structure mapping are two fundamental steps of design task in synthesis for design solution. However, there have not been many strategies to support these design tasks, especially for the function to structure mapping. In addition, design solutions may not just consist of physical structure. Sometimes only materials can provide a feasible design solution; sometimes a materials solution might be more effective and/or more economic than a structural solution. Again, there have not been many strategies that explicitly considered materials solution at the early design stage. To address these problems, this paper proposes three mappings from function to both structure and material. Several embodiment strategies supporting these mappings are also proposed, including four functional matches used for identifying functional design solutions, and a performance match used for ensuring that the identified solution can satisfy the performance requirements or constraints. A design case is also studied to illustrate as well as to test the effectiveness of these strategies.

Conceptual design and dimensional synthesis of “MicroHand”

Abstract A master–slave surgical robotic system can make the best use of both a doctor’s experience and the characteristics of precise positioning, stable performance and dexterous manipulability of a robot. A new surgical robotic system “MicroHand” is presented in this paper with a master–slave isomerous mechanism to provide more design freedoms. The master of “MicroHand” is a Phantom Desktop device and the slave manipulator is a system designed using a position mechanism and an orientation mechanism. The position mechanism implements the kinematic characteristics of a double parallelogram mechanism driven by a cable, which can decouple the position and posture of the slave manipulator. The orientation mechanism applies three rotating axes intersecting at one point to ensure that the surgical tools have enough dexterity at any position in the workspace. The position mechanism and its parameters are designed based on kinematic analysis of two cable-driven linkage structures and kinematic conditioning index. The suitable positions are analyzed in the workspace of a single arm and also in the coworkspace of the two arms. The optimal results show that the “MicroHand” system can enhance the ability of the surgeon in a blood vessel (1 mm in diameter) suturing and knotting experiment.