In this paper we present a dynamic model formulation for thermal-fluid systems that enables direct minimization of dissipative and frictional losses, otherwise known as entropy generation. While analysis based upon the second law of thermodynamics has long been used for optimizing steady-state design of thermodynamic systems, transient performance and efficiency have largely been overlooked. Across a range of sectors, from power generation to microelectronics, answering the question of how to control a system to minimize these transient losses is becoming increasingly important. Unfortunately, thermodynamic expressions for entropy generation are typically highly nonlinear and not easily amenable to control synthesis and design. Here we derive a control-oriented dynamic model of a notional thermal-fluid system with entropy generation rate as part of the dynamic state vector. The proposed model formulation technique is generalizable to a wide range of energy conversion systems and, importantly, enables the synthesis of model-based state feedback controllers which can in turn optimize transient system performance to minimize irreversibilities due to energy conversion and transport in real-time. To illustrate the utility of the formulation, we design a state feedback H ∞ controller to minimize the total entropy generation rate of the notional system in the presence of pulsed, episodic load disturbances.

Due to the potential of achieving high speed and high precision, linear motor driven gantry systems are widely used in industrial applications such as machine tools, semiconductor manufacturing equipments and microelectronics manufacturing equipments. To have large enough driving force, a H-type structure with dual parallel driving motors is usually adopted. Though dual-motor driven structure can deliver higher driving power, the “pull and drag” problem between two motors exists when they are controlled separately. In this paper, a synchronous control scheme is proposed which has an effective thrust allocation to deal with the chattering of the “pull and drag” effect, and uses adaptive robust control (ARC) technique to obtain a guaranteed performance with the presence of both parametric uncertainties and uncertain nonlinearities. Comparative experiments have been done on a dual-linear-motor-driven industrial gantry. The results show that the control input chattering is significantly reduced without sacrificing the good tracking performance of ARC controllers.