Markus Reichhartinger

Application of Higher Order Sliding-Mode Concepts to a Throttle Actuator for Gasoline Engines

In this paper, the control of an electronic throttle valve based on second-order sliding-mode concepts is presented. The so-called twisting algorithm is chosen as the control law. It is shown that the tracking performance for discontinuous reference signals is significantly improved by introducing nonlinear damping by appropriately specifying the sliding surface. The control concept requires the measured plate angle as well as its time derivative, which is computed with the help of a robust exact differentiator. The effectiveness of the proposed concept, consisting of a twisting algorithm for control and supertwisting algorithm for differentiation, is demonstrated by experimental results.

Second-order sliding mode control of electronic throttle valves

Higher-order sliding mode concepts eliminate undesired chattering arising in classical variable structure systems. In this paper the control of electronic throttle valves based on second-order sliding mode control is outlined from a practical point of view. First two control strategies, namely the twisting algorithm and the super-twisting algorithm, are tuned by numerical simulations. Then the realtime implementation of the control laws using Matlab is demonstrated. Finally experimental results are presented.

Control of an electronic throttle valve based on concepts of sliding-mode control

This paper deals with the design of controllers for electronic throttle valves, which are used in combustion engines for adjusting the air-fuel-ratio. First a simplified model of the throttle valve is presented. Nonlinear phenomena like stick-slip-friction and gear-backlash are neglected. In order to cope with these uncertainties as well with the modelpsilas discontinuous right hand side, concepts of sliding-mode control are applied. A standard integrating sliding-mode controller is opposed to a higher order concept, namely the super-twisting algorithm. Finally experimental results are presented and discussed.

Cascaded sliding-mode control of permanent magnet synchronous motors

In this paper, a cascaded sliding-mode controller for permanent magnet synchronous motors is presented. As it is usual in electrical drive engineering the proposed feedback loop consists of an inner current control loop and an outer velocity control loop. In contrast to conventional realizations with e.g. PI-controllers the current controller is a classical 1-sliding controller, whereas the velocity controller is based on a 2-sliding technique. The resulting control concept is implemented in an industrial power converter. The effectiveness of the approach is demonstrated with the help of real world experiments.

Elimination of limit cycles in HVAC systems using the describing function method

In heating, ventilating and air conditioning systems, the presence of undesirable limit cycles is a common problem. This paper outlines the application of the well known describing function method to the analysis and synthesis of a temperature control system used for air-conditioning an office room. PI-controllers are most commonly used in this field of application. In the present case, an existing standard controller leads to limit cycles around the desired room temperature. The so-called inward approach in combination with the describing function method proves to be an innovative tool for eliminating oscillations while preserving desired performance specifications.

Performance improvement of servo drives with mechanical elasticity via Extended Acceleration Feedback

In this paper, the application of acceleration feedback technique for improving the performance of an industrial servo drive whose velocity loop bandwidth is limited by torsional oscillations, caused by mechanical resonance, is considered. Acceleration feedback works by effectively increasing the moment of inertia of the motor, thereby reducing the drives sensitivity to mechanical resonance. The performance improvement achievable with this technique is limited due to the presence of dead time in the system. An extended version of this technique, using loop shaping techniques is proposed. It is shown experimentally that the extended version is superior to the original version in terms of achievable performance.

Finite-time stabilization by robust backstepping for a class of mechanical systems

In this paper, a control law based on the ideas of backstepping is presented. A plant model, motivated by mechanical systems, serves as controller design model. In order to ensure robustness and an improved convergence time of the closed loop system, techniques of sliding mode control are introduced. The convergence time of the closed loop system is estimated with the help of Lyapunovs direct method. A real world system is considered in order to discuss the performance of the proposed strategy. The controller parameters are tuned based on stability conditions and numerical simulations. Finally the performance of the method is compared to two alternative control strategies.

Model-free control of a thermal plant

This paper deals with the model-free control of a thermal plant with nonlinear and time-varying dynamics. It is shown that so-called intelligent PI controllers are well suited to cope with the uncertain plant behaviour. By exploiting the basic ideas of intelligent PI control a sliding-mode controller is derived. Experimental results demonstrate that the ”intelligent” concepts are superior to a standard PI controller with a setting found by classic tuning rules.

Certainty equivalence adaptation combined with super-twisting sliding-mode control

ABSTRACT In this paper, a Lyapunov-based control concept is presented that combines variable structure and adaptive control. The considered system class consists of nonlinear single input systems which are affected by matched structured and unstructured uncertainties. Resorting to the certainty equivalence principle, the controller exploits advantages of both the sliding-mode and the adaptive control methodology. It is demonstrated that the gains of the discontinuous control action may be reduced remarkably when compared with pure sliding-mode-based approaches. The efficiency of the presented concept is demonstrated in detail, using results of numerical simulations.

Design of an unknown input observer to enhance driver experience of electric power steering systems

Electric power steering (EPS) systems assist the driver during manoeuvres by applying an additional steering torque generated by an electric motor. Although there are many advantages for electric actuated steering systems including fuel efficiency, they are known to deteriorate the feel of the steering as experienced by the driver. This paper presents a sliding mode observer based estimation concept which provides signals to evaluate and improve perception and feel of the steering as experienced by the driver. The proposed strategy is based on a physically motivated dynamic model of a power steering system and the measurements considered are typically available in any modern vehicle. The performance of the estimator is investigated using numerical simulation as well as experimental results obtained using a laboratory steering testbed.