Rajarishi Sinha

Composable Models for Simulation-Based Design

This article introduces the concept of combining both form (CAD models) and behavior (simulation models) of mechatronic system components into component objects. By connecting these component objects to each other through their ports, designers can create both a system-level design description and a virtual prototype of the system. This virtual prototype, in turn, can provide immediate feedback about design decisions by evaluating whether the functional requirements are met in simulation. To achieve the composition of behavioral models, we introduce a port-based modeling paradigm. The port-based models are reconfigurable, so that the same physical component can be simulated at multiple levels of detail without having to modify the system-level model description. This allows the virtual prototype to evolve during the design process, and to achieve the accuracy required for the simulation experiments at each design stage. To maintain the consistency between the form and behavior of component objects, we introduce parametric relations between these two descriptions. In addition, we develop algorithms that determine the type and parameter values of the lower pair interaction models; these models depend on the form of both components that are interacting. This article presents the initial results of our approach. The discussion is limited to high-level system models consisting of components and lumped component interactions described by differential algebraic equations. Expanding these concepts to finite element models and distributed interactions is left for future research. Our composable simulation and design environment has been implemented as a distributed system in Java and C11, enabling multiple users to collaborate on the design of a single system. Our current implementation has been applied to a variety of systems ranging from consumer electronics to electrical train systems. We illustrate its functionality and use with a design scenario.

Modeling and simulation methods for design of engineering systems

This article presents an overview of the state-of-the art in modeling and simulation, and studies to which extent current simulation technologies can effectively support the design process. For simulation-based design, modeling languages and simulation environments must take into account the special characteristics of the design process. For instance, languages should allow models to be easily updated and extended to accommodate the various analyses performed throughout the design process. Furthermore, the simulation software should be well integrated with the design tools so that designers and analysts with expertise in different domains can effectively collaborate on the design of complex artifacts. This review focuses in particular on modeling for design of multi-disciplinary engineering systems that combine continuous time and discrete time phenomena.

Intelligent assembly modeling and simulation

Because of the intense competition in the current global economy, a company must conceive, design, and manufacture new products quickly and inexpensively. The design cycle can be shortened through simulation. Rapid technical advances in many different areas of scientific computing provide the enabling technologies for creating a comprehensive simulation and visualization environment for assembly design and planning. An intelligent environment has been built in which simple simulation tools can be composed into complex simulations for detecting potential assembly problems. The goal in this research is to develop high fidelity assembly simulation and visualization tools that can detect assembly related problems without going through physical mock‐ups. In addition, these tools can be used to create easy‐to‐visualize instructions for performing assembly and service operations.

Integration of mechanical CAD and behavioral modeling

This paper introduces the concept of combining both form (CAD models) and behavior (simulation models) of mechatronic system components into component objects. By composing these component objects, designers automatically create a virtual prototype of the system they are designing. This virtual prototype, in turn, can provide immediate feedback about design decisions by evaluating whether the functional requirements are met in simulation. To achieve the composition of behavioral models, we introduce a port-based modeling paradigm where systems consist of component objects and interactions between component objects. To maintain the consistency between the form and behavior of component objects, we introduce parametric relations between these two descriptions. In addition, we develop algorithms that determine the type and parameter values of the interaction models; these models depend on the form of both components that are interacting. The composable simulation environment has been implemented as a distributed system in Java and C++, enabling multiple users to collaborate on the design of a single system.

Behavioral model composition in simulation-based design

We present a simulation and design framework for simultaneously designing and modeling electromechanical systems. By instantiating component objects and connecting them to each other via ports, a designer can configure complex systems. This configuration information is then used to automatically generate a corresponding system-level simulation model. The building block of our framework is the component object. It encapsulates design data and behavioral models and their inter-relationships. Component objects are composed into systems by connecting their ports. However, when converting a system configuration into a corresponding simulation model, the corresponding models for the component objects do not capture the physical phenomena at the component interfaces the interactions. To obtain an accurate composition, the interaction dynamics must also be captured in behavioral models. In this paper, we introduce the concept of an interaction model that captures the dynamics of the interaction. When two ports are connected, there is an intended interaction between the two components. For composition of component objects to work, an interaction model must be introduced between each pair of connected behavioral models. We illustrate these ideas using an example.

Kinematics Support for Design and Simulation of Mechatronic Systems

We present a framework that combines both form (CAD models) and behavior (simulation models) of mechatronic system components into component objects. By composing these component objects, designers automatically create a virtual prototype of the system they are designing. The framework verifies and maintains the consistency between the representations of the form, function, and behavior of the virtual prototype. This virtual prototype, in turn, can provide immediate feedback about design decisions by evaluating whether the functional requirements are met in simulation. When the designer makes a change to one aspect of the representation, our framework automatically updates all other aspects impacted by this change and reports inconsistencies. Inconsistencies occur when the kinematic behavior of the device does not match the form, or the kinematic behavior does not match the currently specified functional description. Continuous feedback of this nature shortens the design-simulate cycle for product design. To achieve composition of behavioral models, we use a port-based modeling paradigm in which component interactions are defined by connections between ports. Component objects and component interactions together form the system model of the device. Simulation models for the components are defined in VHDL-AMS and are solved with a commercial solver.

Extracting Articulation Models from CAD Models of Parts With Curved Surfaces

In an assembly, degrees of freedom are realized by creating mating features that permit relative motion between parts. In complex assemblies, interactions between individual degrees of freedom may result in a behavior different from the intended behavior. In addition, current methods perform assembly reasoning by approximating curved surfaces as piecewise linear surfaces. Therefore, it is important to be able to reason about assemblies using exact representations of curved surfaces; verify global motion behavior of parts in the assembly; and create motion simulations of the assembly by examination of the geometry and material properties. In this paper we present a linear algebraic constraint method to automatically construct the space of allowed instantaneous motions of an assembly from the geometry of its constituent parts. Our work builds on previous work on linear contact mechanics and curved surface contact mechanics. We enumerate the conditions under which general curved surfaces can be represented using a finite number of constraints that are linear in the instantaneous velocities. We compose such constraints to build a space of allowed instantaneous velocities for the assembly, The space is then described as a set-theoretic sum of contact-preserving and contact-breaking subspaces. Analysis of each subspace provides feedback to the designer, which we demonstrate through the use of an example assembly-a 4-part mechanism. Finally, the results of the analysis of a 4-bar linkage are compared to those from mechanism theory.

Supporting Design Refinement in MEMS Design

We present a framework to support design refinement during the virtual prototyping of microelectromechanical systems (MEMS). By instantiating MEMS components and connecting them to each other via ports, the designer can both configure complex systems and simulate them. We examine design refinement in the context of ease of use and representation of the virtual prototype. We propose the use of a common, formal grammar representation for the design entities in the virtual prototype—MEMS components, behavioral models and CAD models. We show that the formal grammar approach leads to easy creation of virtual prototypes. In this paper, we focus on ports—the fundamental building blocks of a virtual prototype. Ports mediate all interactions within and between aspects of the virtual prototype. For even moderately complex designs, there can be many interactions present. The representation and organization of all possible ports is important in the context of design refinement. We provide a set-theoretic formalism that defines the algebra of ports. We present a formal grammar for ports that represents a port as a set of attributes, and provide a design refinement mechanism that involves adding or modifying attributes in the port. We illustrate our framework with a MEMS example. We demonstrate that the MEMS designer can evaluate multiple design alternatives quickly and accurately with our framework.Copyright