Bond Graph Representations of Hybrid System Models

2014 ◽  
pp. 21-50
Author(s):  
Wolfgang Borutzky
Keyword(s):  
Hybrid System ◽  
Bond Graph ◽  
Graph Representations ◽  
System Models

Multicontact Locomotion on Transfemoral Prostheses via Hybrid System Models and Optimization-Based Control

2016 ◽  
Vol 13 (2) ◽  
pp. 502-513 ◽  
Author(s):  
Huihua Zhao ◽  
Jonathan Horn ◽  
Jacob Reher ◽  
Victor Paredes ◽  
Aaron D. Ames
Keyword(s):  
Hybrid System ◽  
System Models

Comparative Study of Bond Graph Models for Hydraulic Transmission Lines With Transient Flow Dynamics

2012 ◽  
Vol 134 (3) ◽  
Author(s):  
Limin Yang ◽  
Jørgen Hals ◽  
Torgeir Moan
Keyword(s):  
Flow Rate ◽  
Transmission Lines ◽  
Transient Flow ◽  
Transfer Functions ◽  
Separation Of Variables ◽  
Bond Graph ◽  
Input Output ◽  
Bond Graphs ◽  
Graph Representations ◽  
Linear Resistance

The partial differential equation describing one-dimensional flow in a hydraulic pipeline with linear resistance can be approximated and solved numerically using different modal approaches. Modal models can be obtained either by using rational transfer functions (RTF) in the Laplace domain solution or by using separation of variables (SOV) techniques. The pipeline models have four possible input–output configurations: pressure inputs at both ends, flow rate inputs at both ends, and the two cases of mixed inputs. In this paper, modal bond graph representations for pipeline sections are reviewed, and new bond graphs are proposed for combinations of solution method and input–output configurations not yet presented in the literature. This includes bond graph representations for the two mixed input cases developed using the SOV technique, and bond graphs for the other two cases, pressure inputs or flow rate inputs, constructed on the basis of RTF solutions. Through numerical simulations of hydraulic single lines, the obtained models are compared to alternative models already established in the literature. It is shown that the modal models developed by the RTF and SOV methods have the same accuracy when the same number of modes is used. For both of these approaches, correction methods to maintain a high accuracy when truncating high-order modes are described, and also adapted to the bond graph form. Finally, simulation results for various line configurations are illustrated.

Structural Simplification of Modular Bond-Graph Models Based on Junction Inactivity

2006 ◽  
Author(s):  
Tulga Ersal ◽  
Hosam K. Fathy ◽  
Jeffrey L. Stein
Keyword(s):  
Graph Model ◽  
Bond Graph ◽  
General Purpose ◽  
Graph Models ◽  
Modular Modeling ◽  
System Models ◽  
Modeling Paradigm ◽  
Component Models ◽  
Domain Independent ◽  
Structural Simplification

The modular modeling paradigm facilitates the efficient building, verification and handling of complex system models by assembling them from general-purpose component models. A drawback of this paradigm, however, is that the assembled system models may have excessively complex structures for certain purposes due to the amount of detail of the component models, which is introduced to promote modularity. This work presents a domain-independent structural simplification technique that can detect such unnecessary complexities in a modular bond-graph model and eliminate them from the model without compromising accuracy. To this end, the activity concept in the literature is extended to define "inactivity" for junction elements, and simplification is obtained by detecting and eliminating inactive junction elements and by propagating the implications. It is shown that this simple idea can result in models that are conceptually and computationally more efficient. Some subtleties associated with this approach are highlighted.

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