Nick Weinhold

Feedback Control Structures, Embedded Residual Signals, and Feedback Control Schemes With an Integrated Residual Access

Driven by the increasing needs for the integration of model-based fault diagnosis into the electronic control units (ECUs) with limited computation capacity and motivated by the recent study on the fault tolerant controller architecture, we investigate feedback controller structures aiming at accessing the residuals embedded in the control loops. For this purpose, we first develop an observer-based realization of the Youla parameterization. This result reveals a new interpretation of control signals as a composite of the residual and reference signals. From this viewpoint, different control schemes are studied and useful relationships between the controller structures and embedded residual signals are established. It leads to the development of two kinds of schemes: 1) extracting residual signals from an existing control loop and 2) configuring control loops with an integrated residual access. The achieved results are demonstrated by two examples of the feedback control loops in engine management systems.

Parity space based FDI-scheme for vehicle lateral dynamics

In this paper, a model-based FDI-scheme for the detection and isolation of sensor faults in the vehicle lateral dynamics control system ESP is presented. The main objective is to handle the model uncertainties and to isolate faults. In order to reduce false alarm rate on the one hand and to ensure fault detectability on the other hand, a parity space based solution is presented. To achieve a numerical stable online realization on an electronic control unit (ECU), the FDI system is realized in an observer structure. The FDI-scheme has been tested using real driving data

Embedded model-based fault diagnosis for on-board diagnosis of engine control systems

In this paper, a model-based fault diagnosis scheme for on-board diagnosis in spark ignition (SI) engine control systems is presented. The developed fault diagnosis system fully makes use of the available control structure and is embedded into the control loops. As a result, the implementation of the diagnosis system is realized with low demands on engineering costs, computational power and memory. The developed diagnosis scheme has been successfully applied to the air intake system of an SI-engine

Integration of fdi functional units into embedded tracking control loops and its application to FDI in engine control systems

A scheme is presented for the integration of FDI functional units into control loops embedded in mechatronic systems. The core of this FDI scheme is to design the FDI functional units by making use of the available tracking control structure. The developed FDI scheme is applied to the air-intake control system of an SI-engine

Beobachtergestützte Überwachung vernetzter regelungstechnischer Systeme (Observer Schemes for Networked Control Systems)

Abstract Die Überwachung vernetzter regelungstechnischer Systeme gewinnt in der Prozessautomatisierung zunehmend an Bedeutung. Da das Gesamtsystemverhalten verstärkt von technischen Gegebenheiten des eingesetzten Bussystems beeinflusst wird, werden im vorliegenden Beitrag vernetzte Systeme zunächst modelliert, indem die unbekannten und statistisch schwankenden Datenübertragungszeiten als Modellunsicherheit erfasst werden. Basierend darauf werden zwei beobachtergestützte Ansätze erarbeitet, welche die Schätzung der Prozesszustandsgrößen bzw. der Störgrößen ermöglichen. Anhand eines Beispiels wird schließlich die Anwendbarkeit dieser Ansätze demonstriert.

A differential flatness based model predictive control approach

In this contribution a novel extension to model predictive control for a certain class of input affine nonlinear systems is proposed, which satisfy the property of differential flatness and are of minimum phase. By feedforward linearization of the nonlinear system via a flatness based control law, the problem of nonlinear model predictive control is reduced to the well known linear model predictive control. This results in a considerable reduction in computational effort. Input constraints are considered via a nonlinear transformation and the cost functional can be minimized by usage of a standard quadratic programming algorithm. A simulation example is given to demonstrate the usefulness of this new strategy.

Control performance index minimal tuning of set-point weighted PID-controllers for LTI plants based on convex optimisation

This paper addresses the problem of control performance index (CPI) minimal tuning of proportional integral differential (PID) feed-back-controllers with set-point weighting. Common CPIs, such as the integrated absolute error (IAE), are considered as objective functions to be minimised by parameter tuning. Many CPIs are convex functions, if their domain is convex and thus their only minimum is the global minimum. In order to exploit this for optimal tuning, we formulate parameter tuning as an optimisation problem with controller parameters as variables. Convexity of the IAE as CPI is shown exemplarily, since it can be used for PIDparameter and set-point weight tuning. Furthermore, we show the necessary convexity of the CPIs domain for the fixed structure set-point weight and PID-parameter tuning. For setpoint weight tuning, convexity of the domain is shown straight forward from the standard definition of a convex set. For PID parameter tuning, a convex representation of the domain is found that can be used equivalently to the original domain. To this end, we utilise the fact that CPIs merely quantify input-output behaviour which allows to relax structural constraints. Furthermore, it is shown how readily available iterative algorithms can be used to automate tuning and find the global optimal controller parameters. In a simulation example, the proposed techniques are applied to tune a set-point weighted PI-controller for a first order lag plus delay plant.

Data-driven self-tuning control by iterative learning control with application to optimize the control parameter of turbocharged engines

The applications of iterative learning control (ILC) in control of modern process and mechatronic system have received more attentions in recent years. This is due the fact that ILC does not depend on physical model of the system. In the application of ILC in automotive industry, the restriction is that these methods calculate the input value and the tuning of an available controller with fixed structure is not possible. To solve this problem a method is proposed in this paper which consists of two main steps: the first step is the calculation of an input variable, based on an ILC algorithm, and the second step is the optimization of the given parameters of the feedforward controller. The performance and effectiveness of the proposed method are shown with experiments on a test vehicle with an one stage turbocharged gasoline motor with wastegate.

Exact air charge feed forward control of a turbocharged SI engine

In this work, a MIMO feed forward control for the air charge, i.e. the mass of air in the cylinders of a turbo charged spark ignition (SI) engine is presented. The control inputs are the angle of the throttle plate and the opening of the wastegate. There are many publications in this field of application. Often the control task is separated into an air charge control with the throttle plate as control input and a boost pressure control with the wastegate opening as control input. These approaches often lack the ability to precisely track reference trajectories in the transition between suction mode operation and turbocharged operation. The approach presented here is based on exact input-output linearization and enables a perfect tracking of air charge reference trajectories in both modes of operation and the transition between them.

A novel mid-ranging approach for idle speed control of a hybrid electric powertrain

In this paper the problem of idle speed control for the powertrain of a hybrid electric vehicle is investigated. On the one hand, the proposed control structure ensures control of the powertrains idle speed, by using the electric motor as a secondary actuator besides the combustion engine. On the other hand, it enables the use of the electric motor as a generator by appropriate load level shifting. The coordination of the two actuators is provided by a novel control structure, which is based on the idea of mid-ranging control. Based on a nonlinear system description, a suitable design model is derived, capturing the fundamental properties of the powertrain. The nonlinear dynamic behavior of the intake manifold pressure is handled via an inversion-based linearization. The controller design itself is based upon a frequency shaped LQG design, which allows for explicit consideration of the powertrains oscillatory behavior, which is due to a dual mass flywheel. Time delays, which occur in both the plant input and output channels, are encountered by extending the LQG Kalman filter with a predictor. Finally, measurements from a passenger car are presented to validate the performance of the new controller structure.