Showing papers by "Nicholas Kottenstette published in 2009"

Digital passive attitude and altitude control schemes for quadrotor aircraft

Abstract: This paper presents a formal method to design a digital inertial control system for quad-rotor aircraft. In particular, it formalizes how to use approximate passive models in order to justify the initial design of passive controllers. Fundamental limits are discussed with this approach — in particular, how it relates to the control of systems consisting of cascades of three or more integrators in which input actuator saturation is present. Ultimately, two linear proportional derivative (PD) passive controllers are proposed to be combined with a nonlinear saturation element. It is also shown that yaw control can be performed independently of the inertial controller, providing a great deal of maneuverability for quad-rotor aircraft. A corollary, based on the sector stability theorem provided by Zames and later generalized for the multiple-input-output case by Willems, provides the allowable range of k for the linear negative feedback controller KI in which the dynamic system H 1 : x 1 → y 1 is inside the sector [a 1 , b 1 ], in which −∞ 1 , 0 1 ≤ ∞, and b 1 > a 1 . This corollary provides a formal method to verify stability, both in simulation and in operation for a given family of inertial set-points given to the quad-rotor inertial controller. The controller is shown to perform exceptionally well when simulated with a detailed model of the STARMAC, which includes blade flapping dynamics.

An Experimental Model-Based Rapid Prototyping Environment for High-Confidence Embedded Software

Abstract: The development of embedded software for high confidencesystems is a challenging task that must be supportedby a deep integration of control theoretical and computational aspects. Model-based development of embeddedsoftware has been practiced for more than a decade now,but very few integrated approaches have emerged to provideend-to-end support for the process, and integrate platformaspects as well as verification. The paper describes anearly version of a model-based prototyping toolchain thatprovides such support and covers most engineering steps.The toolchain is coupled with a hardware-in-the-loop simulation system, allowing quick experimental evaluation ofdesigns.

A passivity-based framework for resilient cyber physical systems

Abstract: Resilient control systems play a special role in the area of cyber-physical systems, where the design must address the question how complex dynamic plants are to be controlled safely and reliably when a control system is under a cyber attack. In this paper we describe a control theoretical framework based on the concept of passivity for designing a control network which can tolerate, for instance, denial-of-service attacks on networks used in the closed loop. In particular, we demonstrate how the resilient power junction structure could be applied, and provide simulated results.

Wireless digital control of continuous passive plants over token ring networks

Abstract: In a recent paper we have shown how wave variables can be used to interconnect passive plants with passive controllers such that the system remains l2-stable in spite of time-varying delays and data dropouts. The present paper further enhances these results by providing a detailed model that captures time-varying delays, data dropouts and network capacity for wireless ring token networks. It also provides a new theorem showing how an asynchronous controller can be implemented, which maintains an l2-stable system. Simulations show that the asynchronous control of a passive motor reduces the overall distortion when compared with a synchronous controller which relies on lossy data reduction techniques. These two distinct results pave the way to study high-performance rate-adaptive control schemes that minimize their control rate in order to match the network capacity. Copyright © 2008 John Wiley & Sons, Ltd.

Communication in Automation, Including Networking and Wireless

Abstract: An introduction to the fundamental issues and limitations of communication and networking in automation is given. Digital communication fundamentals are reviewed and networked control systems together with teleoperation are discussed. Issues in both wired and wireless networks are presented.

Communicatio 13. Communication in Automation, Including Networking and Wireless

Abstract: An introduction to the fundamental issues and limitations of communication and networking in automation is given. Digital communication fundamentals are reviewed and networked control systems together with teleoperation are discussed. Issues in both wired and wireless networks are presented.