Automated Synthesis of Passive Dynamic Brachiating Robots Using a Simulation-Driven Graph Grammar Method

2017 ◽  
Vol 139 (9) ◽  
Author(s):  
Fritz Stöckli ◽  
Kristina Shea

Passive dynamic systems have the advantage over conventional robotic systems that they do not require actuators and control. Brachiating, in particular, involves the swinging motion of an animal from one branch to the next. Such systems are usually designed manually by human designers and often are bio-inspired. However, a computational design approach has the capability to search vast design spaces and find solutions that go beyond those possible by manual design. This paper addresses the automated design of passive dynamic systems by introducing a graph grammar-based method that integrates dynamic simulation to evaluate and evolve configurations. In particular, the method is shown to find different, new solutions to the problem of the design of two-dimensional passive, dynamic, continuous contact, brachiating robots. The presented graph grammar rules preserve symmetry among robot topologies. A separation of parametric multi-objective optimization and topologic synthesis is proposed, considering four objectives: number of successful swings, deviation from cyclic motion, required space, and number of bodies. The results show that multiple solutions with varying complexity are found that trade-off cyclic motion and the space required. Compared to research on automated design synthesis of actuated and controlled robotic systems, this paper contributes a new method for passive dynamic systems that integrates dynamic simulation.

Author(s):  
Fritz R. Stöckli ◽  
Kristina Shea

Topologic configurations of passive dynamic locomotion robots are usually designed manually by human designers and often bio-inspired. However, it is possible that, among the large number of possible configurations, some valid solutions to the problem exist that are potentially superior to existing solutions and, at the same time, different from bio-inspired or otherwise intuition-inspired configurations, and thus not likely discovered without an automated design method. This paper addresses the problem of the automated design of passive dynamic systems in general by introducing a graph grammar based method that integrates dynamic simulation to evaluate and evolve configurations. In particular, the method is shown to find different, new solutions to the problem of the design of two-dimensional passive dynamic continuous contact brachiating robots. Brachiating is the swinging locomotion of primates moving from one tree branch to the next. The presented graph grammar rules preserve system properties among robot topologies, which makes it possible to maintain the necessary symmetry of the brachiating configurations. A separation of parametric optimization and topologic synthesis actions is proposed for the synthesis of passive dynamic systems. Compared to research on automated synthesis of robot topologies that use dynamic simulation to evaluate actuated and controlled robotic systems, this paper contributes a method to automatically generate alternative topologies for passive dynamic systems, which do not draw energy from a power source.


Author(s):  
Corinna Königseder ◽  
Kristina Shea

Computational Design Synthesis (CDS) is used to enable the computer to generate valid and even creative solutions for an engineering task. Graph grammars are a CDS approach in which engineering knowledge is formalized using graphs to represent designs and rules that describe possible graph transformations, i.e. changes of designs. For most engineering tasks two different kinds of rules are required: rules that change the topology and rules that change parameters of a design. One of the main challenges in CDS using both topologic and parametric rules is to decide a priori which type of rule to apply in which stage of the synthesis process. The research presented in this paper describes different strategies for the combination of topologic and parametric rules during automated design synthesis. A graph grammar for the design of gearboxes is investigated in which topologic rules change the structure, i.e. the number and connections of gears and shafts, whereas parametric rules change the layout and sizing, i.e. the dimensions and positions of gears and shafts, in the gearbox. For the generation of new designs, two simple multi-objective stochastic search algorithms are used and compared. Four different strategies are presented that determine in different ways which type of rule (topologic or parametric) to apply in which stage of the synthesis process. The presented strategies are compared considering the quantity of the generated designs, i.e. the number of topologically different designs, and their quality, i.e. their objective function values. Results show a significant influence of the chosen strategy only in an early stage of the synthesis process. The discussion examines the adaptability of the proposed strategies to other engineering tasks.


Author(s):  
Shraddha Sangelkar ◽  
Daniel A. McAdams

Graph grammars, a technique for formulating new graphs based on a set of rules, is a very powerful tool for computational design synthesis. It is particularly suitable for discrete categorical data where principal component analysis is generally not applicable. Furthermore, this technique utilizes three different programs in conjunction with a design repository, which is opposed to traditional methods that require experts to empirically derive graph grammars. This technique can be separated into three steps. These steps are the creation of the input, graph data mining, and interpretation of the output with the intention of these steps being to automate or assist an expert with the process of extracting engineering graph grammars. Graph grammars that can then serve as guidelines during concept generation. The results of this paper show that this technique is very applicable to computational design synthesis by testing only a small number of products and still producing tangible results that coincide with empirically derived graphs. Fifty electromechanical products from the design repository are used in this study. When comparing, the machine generated grammar rules with expert derived grammar rules, it can be seen that only 14% cannot be developed, 58% cannot be mined with the current setup and 28% were mined with the current set up. However, it is important to keep in mind a few considerations. Specifically, the technique does not replace the expert. Instead, the technique acts as more of an aid than a replacement. Also, while this technique has great potential in regards to computational design synthesis, it is limited to the products in the design repository and the current implementation of the aforementioned programs. Despite these minor considerations, this work proposes application of graph data mining to derive engineering grammars.


Author(s):  
ADITYA SOMAN ◽  
SWAPNIL PADHYE ◽  
MATTHEW I. CAMPBELL

The design of sheet metal components is perhaps one of the more challenging concurrent activities for design and manufacturing engineers. To aid this design process, a method is developed to encapsulate the constraints of sheet metal that make designing such components a tedious and iterative procedure. This project involves the implementation and testing of a geometric representation scheme for building feasible sheet metal components through the use of 17 grammar rules that capture manufacturing operations like cutting and bending. The implemented system has benefits both as a user interaction tool and as the basis for a computational design synthesis approach for designing sheet metal components. An example of a constructed sheet metal component is shown along with the method for invoking the sheet metal grammar to create this component.


Author(s):  
Bergen Helms ◽  
Hansjo¨rg Schultheiß ◽  
Kristina Shea

Innovation processes are highly susceptible to cyclic influences, such as evolving knowledge due to new technologies. In order to cope with these challenge, computational support is required. Paper-based design methods have vast amounts of knowledge at their disposal in the form of design catalogues. However, lacking a computational implementation, these knowledge sources provide no support for considering dynamic influences in the innovation process. The presented method is targeted at making the physical effects contained in design catalogues available for computational design synthesis approaches. For this purpose, this paper introduces the notion of abstraction ports that is used to represent the valid mapping between functional operators and physical effects. For the automated assignment of abstraction ports, a method has been developed that analyzes the equation structure of physical effects. This approach is derived from the modeling technique of bond graphs and is independent of any selection process proposed by design catalogues. Moreover, it allows for the formalization of evolving knowledge in new physical effects that are not yet contained in design catalogues. The assignment of abstraction ports has been successfully validated through the formalization of the physical effects of two design catalogues. Future work comprises the integration of quantitative characteristics of physical effects and the realization within the object-oriented graph grammar system booggie.


Author(s):  
Corinna Königseder ◽  
Kristina Shea

AbstractThe use of generative design grammars for computational design synthesis has been shown to be successful in many application areas. The development of advanced search and optimization strategies to guide the computational synthesis process is an active research area with great improvements in the last decades. The development of the grammar rules, however, often resembles an art rather than a science. Poor grammars drive the need for problem specific and sophisticated search and optimization algorithms that guide the synthesis process toward valid and optimized designs in a reasonable amount of time. Instead of tuning search algorithms for inferior grammars, this research focuses on designing better grammars to not unnecessarily burden the search process. It presents a grammar rule analysis method to provide a more systematic development process for grammar rules. The goal of the grammar rule analysis method is to improve the quality of the rules and in turn have a major impact on the quality of the designs generated. Four different grammars for automated gearbox synthesis are used as a case study to validate the developed method and show its potential.


Author(s):  
Corinna Königseder ◽  
Kristina Shea

Design grammars have been successfully applied in numerous engineering disciplines, e.g. in electrical engineering, architecture and mechanical engineering. A successful application of design grammars in Computational Design Synthesis (CDS) requires a) a meaningful representation of designs and the design task at hand, b) a careful formulation of grammar rules to synthesize new designs, c) problem specific design evaluations, and d) the selection of an appropriate algorithm to guide the synthesis process. Managing these different aspects of CDS requires not only a detailed understanding of each individual part, but also of the interdependencies between them. In this paper, a new method is presented to analyze the exploration of design spaces in CDS. The method analyzes the designs generated during the synthesis process and visualizes how the design space is explored with respect to a) design characteristics, and b) objectives. The selected algorithm as well as the grammar rules can be analyzed with this approach to support the human designer in successfully understanding and applying a CDS method. The case study demonstrates how the method is used to analyze the synthesis of bicycle frames. Two algorithms are compared for this task. Results demonstrate how the method increases the understanding of the different components in CDS. The presented research can be useful for both novices to CDS to help them gain a deeper understanding of the interplay between grammar rules and guidance of the synthesis process, as well as for experts aiming to further improve their CDS application by improving parameter settings of their search algorithms, or by further refining their design grammar. Additionally, the presented method constitutes a novel approach to interactively visualize design space exploration considering not only designs objectives, but also the characteristics and interdependencies of different designs.


2021 ◽  
pp. 1-57
Author(s):  
Luca Zimmermann ◽  
Kristina Shea ◽  
Tino Stankovic

Abstract Today most origami crease patterns employed in technical applications are selected from a handful of well-known origami principles. Computational algorithms capable of generating novel crease patterns either target artistic origami, focus on quadrilateral creased paper, or do not incorporate direct knowledge for the purposeful design of crease patterns tailored to engineering applications. The lack of computational methods for the generative design of crease patterns for engineering applications arises from a multitude of geometric complexities intrinsic to origami, such as rigid foldability and rigid body modes, many of which have been addressed by recent work of the authors. Based on these findings, in this paper we introduce a Computational Design Synthesis method for the generative design of novel crease patterns to develop origami concepts for engineering applications. The proposed method first generates crease pattern graphs through a graph grammar that automatically builds the kinematic model of the underlying origami and introduces constraints for rigid foldability. Then, the method enumerates all design alternatives that arise from the assignment of different rigid body modes to the internal vertices. These design alternatives are then automatically optimized and checked for intersection to satisfy the given design task. The proposed method is generic and applied here to two design tasks that are a rigidly foldable gripper and a rigidly foldable robotic arm.


Author(s):  
Clemens Münzer ◽  
Kristina Shea ◽  
Bergen Helms

Computational design synthesis aims to support human designers throughout the design process. However, most approaches to date are limited to narrow parts of this process. The approach presented in this paper aims to respond to the need for a method that covers not only single aspects of the design process, but the whole design process from requirements to a dimensioned product concept, i.e. product architecture and related parameters. A generic approach is presented that covers requirements engineering, graph grammar-based concept architecture synthesis and automated parameterization of components based on constraint solving. Requirements are elaborated and divided into different categories. Procedures to treat each category of requirement are introduced to provide the initial state for the graph grammar-based concept synthesis. After finishing the automated synthesis based on generic and problem-specific rules, valid solutions for the resulting product concept parameterization are automatically created by setting up and solving a constraint satisfaction problem. Finally, the method is validated through the synthesis of automotive powertrains. This research goes beyond prior work in the field as it provides a continuous and generic approach starting with product requirements and ending with a valid, parameterized product concept.


2013 ◽  
Vol 135 (5) ◽  
Author(s):  
Bergen Helms ◽  
Hansjoerg Schultheiss ◽  
Kristina Shea

Innovation processes are highly susceptible to cyclic influences, such as evolving knowledge due to new technologies. In order to better meet these challenges, improved computational design support is required. Paper-based design methods have vast amounts of knowledge at their disposal in the form of their design catalogs. However, they lack a corresponding computational implementation that could lead to increased use in design. The method presented is targeted at making the physical effects contained in design catalogs available for use within computational design synthesis approaches. This paper introduces the notion of abstraction ports that are used to represent the valid mapping between functional operators and physical effects. For the automated assignment of abstraction ports, a method is presented that analyzes the equation structure of physical effects. This approach is derived from the modeling technique of bond graphs and is independent of any selection process proposed by design catalogs. Moreover, it allows for the uniform formalization of evolving knowledge in new physical effects that are not yet contained in design catalogs. The assignment of abstraction ports is successfully validated through the formalization of the physical effects of two design catalogs. Furthermore, a software prototype is developed that implements a search process for suitable physical effects for a given function. Future work includes the integration of quantitative characteristics of physical effects and the integration of the approach within the object-oriented graph grammar implementation booggie (project web site: http://booggie.org) for computational design synthesis.


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