A. Balluchi

Hybrid Control of Networked Embedded Systems

Hybrid systems that involve the interaction of continuous and discrete dynamics have been an active area of research for a number of years. In this paper, we start by briefly surveying the main theoretical control problems that have been treated in the hybrid systems setting and classify them into stabilization, optimal control and language specification problems. We then provide an overview of recent developments in four of the most prominent areas where these hybrid control methods have found application: control of power systems, industrial process control, design of automotive electronics and communication networks.

Hybrid command governors for idle speed control in gasoline direct injection engines

The idle speed control problem for automotive GDI engines is formalized as a constrained optimal control problem for a hybrid model of the GDI engine, where fuel consumption is the cost function to be minimized. A sub-optimal but effective and easily implementable solution is obtained by resorting to the command governor methodology for a discrete-time abstraction of the hybrid model. Simulation results of the hybrid closed-loop system are presented.

Formal verification of an automotive engine controller in cutoff mode

We describe formal verification of convergence and performance properties of an engine control algorithm being developed for Magneti-Marelli. We study the cutoff mode, where the driver releases the accelerator and the controller regulates fuel injection to minimize the oscillations while decelerating. The engine and its controller are modeled with hybrid automata and the sliding action of the hybrid controller is formally verified with the model checker HYTECH.

Engine idle speed control via maximal safe set computation in the crank-angle domain

In this paper, the idle speed control problem is addressed via maximal safe set computation. A hybrid model of the engine in idle mode is used. The solution is based on the transformation of the continuous dynamics from the time-domain to the crank-angle domain and on the linearization and discretization of these dynamics. A flexible and portable algorithm in the discrete-time domain is proposed for the determination of the maximal safe set. Simulation results show the efficiency of the proposed approach.

Hybrid systems and the design of embedded controllers for automotive engine management

The problem of designing an automotive engine control unit for the next-generation automobiles has been formulated as a hybrid control problem. We present first the overall methodology and its basic components. Then we focus on the highest levels of abstraction that involve the formulation of the control problem and its solution. Two particular control sub-problems (cut-off and fast positive force tracking) are formulated as hybrid optimal control problems. A formal analysis as well as experimental results demonstrate the properties and the quality of the control laws.

Complexity reduction for the design of interacting controllers

The complexity of embedded controllers in important industrial domains such as automotive and avionics is growing constantly making error-free system integration almost impossible. We address the complexity issues posed by the analysis and design of interacting controllers introducing approximation techniques that are shown to be effective on a substantial industrial test case: the control system for common-rail fuel-injection developed by Magneti Marelli Powertrain.

Special Issue on Advanced design methodologies in automotive control

This Special Issue addresses the use of hybrid systems in an important industrial domain of embedded systems: automotive control. Hybrid systems are a fascinating topic of research that has captured the attention of the research community in the past few years. Important theory results have been obtained but applying them to industrial strength control problems has been challenging. Automotive control has been the first field where hybrid systems have revealed their potential. The contributions published in the Special Issue span a number of applications in automotive control: from design flows to traffic control, from engine to suspension control. In Hybrid systems in automotive electronics design, A. Balluchi, L. Benvenuti, A. Ferrari and A.L. Sangiovanni-Vincentelli present a broad view of the development process for embedded control systems in the automotive industry with the purpose of identifying challenges and opportunities for hybrid systems. Critical steps in the design flow are identified and a number of open problems where hybrid system technology might play an important role are pointed out. In Verification of cooperating traffic agents, W. Damm, H. Hungar and E.-R. Olderog exploit design patterns used in coordinating autonomous transport vehicles to ease the burden of verifying cooperating hybrid systems. The authors present a verification rule explicating the essence of employed design patterns, guaranteeing global safety properties of the kind ‘‘a collision will never occur’’, and whose premises can either be established by off-line analysis of the worstcase behavior of the involved traffic agents, or by purely local proofs, involving only a single traffic agent. In Hybrid control of homogeneous charge compression ignition (HCCI) engine dynamics, J. Bengtsson, P. Strandh, R. Johansson, P. Tunestal and B. Johansson consider real-time control of a six-cylinder heavy-duty HCCI engine on a cycle-to-cycle basis. The authors compare different combustion controllers obtained by considering possible choices for sensors (ion current and cylinder pressure), actuators (dual-fuel and variable valve actuations) and control structures (MPC, PID and LQG). While satisfying the constraints on cylinder pressure, both control of the combustion phasing and control of load torque were achieved with simultaneous minimization of the fuel consumption and emissions. In Automotive engine hybrid modelling and control for reduction of hydrocarbon emissions, P.R. Sanketi, J.C. Zavala and K. Hedrick develop hybrid models for engine control that incorporate time and events in their formulation. The resulting hybrid controllers have the capability of switching between two alternative control modes. The first mode is designed to reduce the raw HC (hydrocarbon) emissions while the second mode tries to increase the temperature of the catalytic converter as rapidly as possible during the initial transient or ‘‘cold start’’ period. Reachability, as a tool for system analysis, is used to verify the properties of the closed loop system. In Constrained optimal control of an electronic throttle, M. Vašak, M. Baotić, M. Morari, I. Petrović and N. Perić propose a constrained optimal control problem formulation for a discrete-time piecewise affine model of the throttle valve. The optimal control is represented by look-up tables for on-line implementation. The reference tracking controller significantly outperforms a tuned PID controller with feed-forward compensation of non-linearities in terms of the response speed while preserving the response quality regarding the absence of an overshoot and the static accuracy within the measurement resolution. In Modelling and control of auxiliary loads in heavy vehicles, N. Pettersson and K. Johansson evaluate the benefits of driving auxiliary units with electricity instead of mechanically are evaluated in terms of fuel saving. A Modelica library of the energy consumption of the auxiliaries is presented. A case study on optimal control of the cooling system is illustrated. Control actuators are the electrical generator, the cooling fan and the