Conference papers by Gawthrop in 2005

The rapid growth of GNU/Linux in recent years has focused attention on free and open source software. MTT (Model Transformation Tools) is, as far as the authors are aware, the only open source project related to bond graphs. This paper surveys MTT in its present form and invites collaboration from the wider bond graph community.

Bond graph modelling has been applied widely and many ideas have been collected from the user community for improvement, particularly associated with federated systems. A project is underway to address these via a prototype toolset with the working title of Next-Generation Transformation Tools (NTT). This paper will summarise the motivations behind this development and describe notational changes that have been found necessary. This should provide useful insights into the problem of large-scale bond graphs.

The virtual actuator approach is explained and illustrated using three experimental systems. Conclusions are drawn about the importance of transfer system design.

The previously developed Predictive Pole Placement (PPP) controller is modified to give enhanced numerical and stability properties by embedding the method in a linear-quadratic formulation to give a linear-quadratic PPP (LQPPP) controller. Input, output and state constraints are considered using an natural quadratic programming (QP) formulation of LQPPP. Illustrative examples are given.

Although structural constraints such as model order and time delay have been incorporated in the continuous time system identification since its origin, the constraints on the estimated model parameters were rarely enforced. This paper proposes a continuous time system identification approach with constraints. It shows that by incorporating physical parameter information known a priori as hard constraints, the traditional parameter estimation schemes are modified to minimize a quadratic cost function with linear inequality constraints. Using the structure of Frequency Sampling Filters as the vehicle, the paper shows that the constraints can be readily imposed on continuous time frequency response estimation and step response estimation. In particular, a priori knowledge in both time-domain and frequency domain is utilized simultaneously as the constraints for the optimal parameter solution. A Monte-Carlo simulation study with 100 noise realization is used to demonstrate the improvement of the estimation results in terms of continuous time frequency response and continuous time step response.