ABS design and active suspension control based on HOSM

This paper tackles the control of a brake assisted with an active suspension. The goal of the paper is ensure an effective braking process improving the vehicle safety in adverse driving conditions. To address this, the wheel slip ratio is kept to a desired value reducing the effective braking distance by designing of a robust tracking controller based on high order sliding modes algorithms, imposing the anti-lock brake system feature. On the other hand, the active suspension problem is carried with a nested backward sliding surface design. The purpose of this control is to improve the driving comfort. To this aim, the designed controller compensate the effects of the unmatched perturbation coming from the road. This controller exploits a high order sliding modes observer, which guarantees theoretically exact state and perturbation estimation. In both cases, a continuous control action drives the state trajectories to the designed sliding manifolds and keeps them there in spite of the matched and unmatched perturbations. The feasibility of the proposed scheme has been exposed via simulations.Consejo Nacional de Ciencia y TecnologíaUniversity of Bordeau

Data-Driven Modeling and Regulation of Aircraft Brakes Degradation via Antiskid Controllers

In ground vehicles, braking actuator degradation and tire consumption do not represent a significant maintenance cost as the lifespan of both components, at least in common situations, is rather long. In the aeronautical context, and for aircraft in particular, instead, braking actuator degradation and tire consumption significantly contribute to an aircraft maintenance cost due to the frequency of their replacement. This is mainly due to the fact that aircraft braking maneuvers last significantly longer than those in the automotive context. So that the antilock braking system is always active during the braking maneuver, making its impact on the consumption of the two components significant. This work proposes an innovative data-driven model of brake and tire degradation, showing how they are related to the antiskid controller parameters. The analysis is carried out in a MATLAB/Simulink environment on a single wheel rigid body model, validated experimentally, which includes all the nonlinear effects peculiar of the aeronautic context. The results show that by using an appropriate antiskid control approach, it is possible to directly regulate the consumption of these components while at the same time guaranteeing the required braking performance

Towards the Exhaustive Verification of Real-Time Aspects in Controller Implementation

In industrial applications, the number of final products endowed with real-time automatic control systems that manage critical situations as far as human safety is concerned has dramatically increased. Thus, it is of growing importance that the control system design flow encompasses also its translation into software code and its embedding into a hardware and software network. In this paper, a tool-supported approach to the formal analysis of real-time aspects in controller implementation is proposed. The analysis can ensure that some desired properties of the control loop are preserved in its implementation on a distributed architecture. Moreover, the information extracted automatically from the model can also be used to approach straightforwardly some design problems, such as the hardwar

Limit cycles analysis in hybrid anti-lock braking systems

We investigate the stability and robustness properties of Anti-lock Braking Systems based on actuators with on/off dynamics. Namely, we propose a hybrid ABS controller which gives rise to an asymptotically stable limit cycle on the wheel slip. The proposed approach allows to derive exact information on the maximum allowable uncertainty in the measured variables which guarantee the cycle stability. Moreover, a structural stability analysis is performed with respect to different road conditions and to the actuator rate limit

Limit Cycles Analysis in Hybrid Anti-lock Braking Systems

none5M. Tanelli; G. Osorio; M. Di Bernardo; S. Savaresi; A. AstolfiTanelli, Mara; G., Osorio; M., Di Bernardo; Savaresi, SERGIO MATTEO; A., Astolf

Modellbasierte Anti-Blockier-Regelung für ein Kraftfahrzeug mit konventionellem hydraulischem Bremssystem

Die Anti-Blockier-Regelung eines Kraftfahrzeugs verhindert unerwünschte Radblockierung während eines Bremsvorgangs. Wegen seiner Robustheit wird das Prinzip des schaltenden Anti-Blockier-Reglers, beruhend auf logischen Umschaltungen, in Fahrzeugen mit konventionellem hydraulischem Bremssystem weit verbreitet eingesetzt. Eine Herausforderung stellt die Wahl geeigneter Regler- und Aktuatorparameter zur Gewährleistung der Existenz und Stabilität eines ABS-Grenzzyklus dar. Hierzu werden in dieser Arbeit Bedingungen durch Anwendung der Poincare-Abbildung hergeleitet. Darüber hinaus werden sowohl die Umschaltbedingungen, als auch die Berechnungen der Sollbremsmomente des schaltenden Anti-Blockier-Reglers so ausgelegt, dass der ABS-Grenzzyklus trotz Einschränkungen des realen Bremsaktuators weiterhin annähernd zu erreichen ist. Für eine performante Anti-Blockier-Regelung ist eine genaue und robuste Information über die nicht direkt gemessenen Fahrzustände erforderlich. Hierfür wird ein nichtlinearer Beobachter mit schaltender Struktur entwickelt, dessen Beobachterkoeffizienten je nach Fahrsituation durch die Schaltsignale gewählt werden können. Die Leistungsfähigkeit und die Robustheit des vorgeschlagenen Regelungskonzeptes werden anhand der Messergebnisse an einem Testfahrzeug demonstriert.Anti-lock control of a vehicle prevents wheel lock-up during an emergency braking operation. Because of their robustness, anti-lock control methods based on logical switching are widely used in the conventional hydraulic brake system. The selection of proper controller/actuator parameters is a key challenge in the application of these controllers in order to ensure the existence and stability of an ABS limit cycle. For this purpose, parameter selection conditions are derived in this work by the use of the Poincare map. In addition, both the logical switching conditions and the calculations of the target braking torques of the anti-lock controller are designed in such a way that the ABS limit cycle can still be approximately achieved despite the restrictions of the real brake actuator. Since precise and robust information about the not directly measured vehicle states is required for a high performance anti-lock control design, a switched nonlinear observer is introduced, whose observer coefficients can be selected through the switching signals depending on the driving situation. The performance and robustness of the proposed control concept are demonstrated by means of experimental results on a test vehicle