Tom O'Mahony

System identification of a domestic residence using Wireless sensor node data

This paper focuses on the system identification of the thermal dynamics of a domestic dwelling and the aim of the modelling process is to design an efficient control scheme that minimises energy usage and, consequently, fuel bills. Existing software packages for thermal modelling of structures are based on physical models or finite element analysis and use real data for comparative purposes only. In contrast, in this study a wireless sensor network was used to measure actual temperature variations and this data was used to identify a process model. By successfully twinning wireless technology and system identification techniques, an overall model structure of the heat characteristics of a domestic residence is presented in this paper.

Design considerations for piecewise affine system identification of nonlinear systems

A PieceWise AutoRegressive eXogenous (PWARX) model for the AMIRA DR300 DC motor is identified using clustering techniques available in the Hybrid Identification Toolbox (HIT). The choice of design parameters like magnitude of the noise variance and size of the local dataset are discussed. These parameters influence the quality and performance of the PWARX model. The performance of the PWARX model is compared with that of a linear model. The results show superior performance of the PWARX model especially in the nonlinear regions.

Optimising dynamic behaviour of electrostatically actuated MEMS contact switch

The reliability of the electrostatically actuated MEMS contact switches is known to be significantly undermined by the unstable dynamic behaviour of devices. High impact forces, bouncing at the contact and oscillations upon release result in substantial mechanical damage to the contacts and the switch compromising the functionality of the switch and reducing its lifetime. Certain effects become more pronounced, such as stiction causing ‘fail-to-open’ malfunctions, resistance increases leading to degraded performance, as well as fracture. To address the issue of the dynamic instability of the switch behaviour this work employs Finite Element Analysis (FEA), linear and nonlinear system identification techniques and optimal control theory to study the dynamic performance of the switch and optimise (soften) its dynamic behaviour by establishing an actuation input voltage that substantially reduces or eliminates the instabilities.

Assessing engineering learning: Formative, summative and dialogical

In this paper an assessment strategy based on the idea that students submit a draft assignment, receive audio feedback (as an .MP3 file) on the assignment and subsequently submit a revised, final version is proposed. The strategy is shown to align with current recommendations for best practice. The proposal is extensively used by the author in his teaching and two engineering courses are presented as case-studies to illustrate how the approach works. These courses were evaluated using an established student questionnaire. 91% of respondents stated that they were either satisfied or very satisfied with assessment and feedback as it applied to these courses. Grades awarded to final version of the assignment were, on average, 11% higher than those awarded to the draft. Clearly, students are reading, engaging with and learning from the audio feedback.

A virtual control engineering laboratory based on an industrial pasteurisation process

Abstract Virtual laboratories are becoming increasingly popular for educational purposes. This paper reports on the development of a virtual lab that is based on an industrial pasteurisation plant. An accurate first-principles non-linear single-input single-output physical model represents the pasteurisation process. A comprehensive range of experiments was designed to explore issues in, and support an introductory-level course in process control. The experiments focus on process modelling and PID control technology.