The context in which the following thesis work has been carried out is the development of control strategies for a trailer steerable axle. In particular, this research focuses on methods aimed at easing the driver's effort during reversing manoeuvres of articulated vehicles. The problem is further subdivided into two main situations: reversing along a curved path and reversing along a straight track. As far as the first situation is concerned, two solutions are proposed. The first one is based on physical observations and leads to a feedforward controller. The second one is an evolution of the previous control law and introduces a feedback loop. Both proved to be able to reduce the space, the time and the driver's effort during various reversing tasks. Moreover, they are also effective in reducing the trailer rear end off-tracking when driving forward at low-speed. To address the second situation and solve the inherent instability of the system, two feedback controllers are proposed. Within the discussed boundaries, both of them are able to automatically align the trailer to the tractor direction of motion. When straight reversing, this action frees the driver from the task of manually compensate the unstable dynamics of the trailer. In support to the above-described control laws, observers and switching strategies are developed. Observers are needed to obtain all the necessary information from the measurements available on the trailer; switching strategies enable a trailer automatic controller to adapt to the driver's intentions.
Il seguente lavoro di Tesi è rivolto alla definizione di leggi di controllo per assali sterzanti di rimorchi commerciali. In particolare, la ricerca riguarda metodi per semplificare il compito del guidatore durante le manovre di retromarcia di veicoli articolati. Il problema è stato suddiviso in due situazioni principali: retromarcia lungo tragitti curvilinei e retromarcia lungo tratti rettilinei. Due soluzioni vengono proposte per quanto riguarda il primo sottoproblema. La prima si basa su principi fisici e permette di ottenere un controllore in feedforward. La seconda, invece, è un'evoluzione della precedente ed include un'azione in feedback. Entrambe risultano efficaci nel ridurre lo spazio, il tempo ed il compito del guidatore lungo diversi percorsi affrontati in retromarcia. Sono inoltre capaci di ridurre l'off-tracking della parte posteriore del rimorchio durante manovre di marcia in avanti a bassa velocità. Due controllori in feedback sono introdotti per affrontare il secondo problema e risolvere l'instabilità del sistema considerato. Rispettando i limiti discussi per tali soluzioni, entrambe sono in grado di ri-allineare automaticamente il rimorchio alla direzione di marcia della motrice. Cosicché, quando il guidatore vuole retrocedere in linea retta, è sollevato dal compito di compensare manualmente la dinamica instabile del rimorchio. A supporto delle tecniche di controllo introdotte, sono presentati osservatori dello stato e strategie di commutazione. I primi sono richiesti per ricostruire tutte le grandezze necessarie a partire dalle misure disponibili sul rimorchio; le seconde, invece, permettono ad un sistema di controllo montato sul rimorchio di adattarsi alle intenzioni del guidatore.
Semi-trailer steering strategies. Model based vehicle dynamics controllers for reversing manoeuvres
VIVALDELLI, MICHELE
2011/2012
Abstract
The context in which the following thesis work has been carried out is the development of control strategies for a trailer steerable axle. In particular, this research focuses on methods aimed at easing the driver's effort during reversing manoeuvres of articulated vehicles. The problem is further subdivided into two main situations: reversing along a curved path and reversing along a straight track. As far as the first situation is concerned, two solutions are proposed. The first one is based on physical observations and leads to a feedforward controller. The second one is an evolution of the previous control law and introduces a feedback loop. Both proved to be able to reduce the space, the time and the driver's effort during various reversing tasks. Moreover, they are also effective in reducing the trailer rear end off-tracking when driving forward at low-speed. To address the second situation and solve the inherent instability of the system, two feedback controllers are proposed. Within the discussed boundaries, both of them are able to automatically align the trailer to the tractor direction of motion. When straight reversing, this action frees the driver from the task of manually compensate the unstable dynamics of the trailer. In support to the above-described control laws, observers and switching strategies are developed. Observers are needed to obtain all the necessary information from the measurements available on the trailer; switching strategies enable a trailer automatic controller to adapt to the driver's intentions.| File | Dimensione | Formato | |
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2012_12_Vivaldelli.pdf
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Descrizione: Testo della Tesi
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https://hdl.handle.net/10589/72584