A large number of road accidents worldwide involve heavy commercial vehicles. Due to their large mass they are more inclined to cause severe damages than light vehicles, such as serious injuries and fatalities. One of the most common causes of these crashes involving commercial trucks is the rollover of tractor semitrailer combinations. This particular type of accident is governed by a lack of lateral stability. Several researches have been carried out in the past on the topic of rollover prevention, and active roll control turned out to be one of the most effective solutions. The aim of this study is to design and validate an active roll control system that takes advantage of the built-in pneumatic suspensions installed on the large majority of the tractor semitrailer combinations commercialized nowadays. The goal is to increase the lateral stability of the vehicle by reducing the lateral load transfer on the axles during corner-ing maneuvers. The decrease in lateral load transfer is achieved using the air springs to counter the natural tendency of the vehicle to tilt towards the outside of the turn while cornering. The proposed solution is compared to the state-of-the-art active roll control system based on active anti-roll bars. A complete model of the tractor semitrailer combination is developed using a multi-body software, and it is used to simulate the response of the vehicle during several maneuvers, in order to evaluate both steady-state and transient conditions. Two additional linear vehicle models are designed for control purposes, and they are then validated against the multibody model. Three different control logics are designed and then compared, in order to find the best trade-off between performance and cost. A sensitivity analysis is performed to evaluate their robustness against different payload positions. A large number of road accidents worldwide involve heavy commercial vehicles. Due to their large mass they are more inclined to cause severe damages than light vehicles, such as serious injuries and fatalities. One of the most common causes of these crashes involving commercial trucks is the rollover of tractor semitrailer combinations. This particular type of accident is governed by a lack of lateral stability. Several researches have been carried out in the past on the topic of rollover prevention, and active roll control turned out to be one of the most effective solutions. The aim of this study is to design and validate an active roll control system that takes advantage of the built-in pneumatic suspensions installed on the large majority of the tractor semitrailer combinations commercialized nowadays. The goal is to increase the lateral stability of the vehicle by reducing the lateral load transfer on the axles during cornering maneuvers. The decrease in lateral load transfer is achieved using the air springs to counter the natural tendency of the vehicle to tilt towards the outside of the turn while cornering. The proposed solution is compared to the state of the art active roll control system based on active anti-roll bars. A complete model of the tractor semitrailer combination is developed using a multibody software, and it is used to simulate the response of the vehicle during several maneuvers, in order to evaluate both steady-state and transient conditions. Two additional linear vehicle models are designed for control purposes, and they are then validated against the multibody model. Three different control logics are designed and then compared, in order to find the best trade-off between performance and cost. A sensitivity analysis is performed to evaluate their robustness against different payload positions. The simulations results show that active air springs are able to increase the maximum lateral acceleration bearable by the vehicle during steady-state cornering by 15%. Significant reductions in lateral load transfer are achieved both during steady-state and transient maneuvers. Compared to active anti roll-bars, active air springs lead to a lower power consumption and lower installation costs.
Gran parte degli incidenti stradali a livello mondiale vede coinvolti veicoli commerciali pesanti. A causa della loro massa elevata sono maggiormente inclini a provocare danni considerevoli a cose e persone rispetto ai veicoli leggeri. Una delle cause più frequenti dei sinistri che coinvolgono i veicoli commerciali è il ribaltamento degli autoarticolati. Questo particolare tipo di incidente è provocato da una scarsa stabilità laterale del veicolo stesso. In passato sono stati condotti diversi studi riguardanti sistemi anti-ribaltamento ed il controllo attivo del rollio è risultato essere la soluzione più efficace. L’obiettivo principale di questo studio è quello di progettare e validare un sistema di controllo attivo del rollio che sfrutti le sospensioni pneumatiche installate di serie sulla maggior parte degli autoarticolati in commercio oggigiorno. La finalità è quella di aumentare la stabilità laterale del veicolo riducendo il trasferimento di carico agli assi. Il decremento nel trasferimento di carico è ottenuto utilizzando le molle ad aria per contrastare la naturale tendenza del veicolo ad inclinarsi verso l’esterno della curva. L’efficacia della soluzione proposta è valutata tramite un confronto con lo stato dell’arte, costituito da un sistema di controllo attivo del rollio basato su barre anti-rollio attive. Grazie all’utilizzo di un software multibody è stato possibile sviluppare un modello completo di un autoarticolato; quest’ultimo è stato utilizzato per simulare la risposta del veicolo durante differenti tipi di manovra. Sono stati sviluppati anche due modelli lineari del veicolo necessari per la definizione delle logiche di controllo. La loro validità è stata poi valutata tramite un confronto con la risposta del modello multibody. Al fine di trovare il miglior compromesso tra efficacia, efficienza e costi, sono state sviluppate, e successivamente confrontate tra di loro, tre differenti logiche di controllo. È stata poi effettuata un’analisi di sensitività alla posizione del baricentro del semirimorchio per ognuno dei controllori proposti, con lo scopo di verificarne la robustezza. I risultati delle simulazioni mostrano che le molle ad aria attive sono in grado di incrementare del 15% l’accelerazione laterale che il veicolo può sopportare. L’efficacia del sistema proposto, in termini di riduzione del trasferimento di carico, si mantiene elevata anche nel caso di manovre severe, come ad esempio il doppio cambio di corsia. L’utilizzo delle molle ad aria porta ad un consumo di energia nettamente inferiore rispetto alle barre anti-rollio attive ed a costi di installazione quasi nulli.
Active roll control for rollover prevention of heavy commercial vehicles
ZUCCHI, JACOPO
2015/2016
Abstract
A large number of road accidents worldwide involve heavy commercial vehicles. Due to their large mass they are more inclined to cause severe damages than light vehicles, such as serious injuries and fatalities. One of the most common causes of these crashes involving commercial trucks is the rollover of tractor semitrailer combinations. This particular type of accident is governed by a lack of lateral stability. Several researches have been carried out in the past on the topic of rollover prevention, and active roll control turned out to be one of the most effective solutions. The aim of this study is to design and validate an active roll control system that takes advantage of the built-in pneumatic suspensions installed on the large majority of the tractor semitrailer combinations commercialized nowadays. The goal is to increase the lateral stability of the vehicle by reducing the lateral load transfer on the axles during corner-ing maneuvers. The decrease in lateral load transfer is achieved using the air springs to counter the natural tendency of the vehicle to tilt towards the outside of the turn while cornering. The proposed solution is compared to the state-of-the-art active roll control system based on active anti-roll bars. A complete model of the tractor semitrailer combination is developed using a multi-body software, and it is used to simulate the response of the vehicle during several maneuvers, in order to evaluate both steady-state and transient conditions. Two additional linear vehicle models are designed for control purposes, and they are then validated against the multibody model. Three different control logics are designed and then compared, in order to find the best trade-off between performance and cost. A sensitivity analysis is performed to evaluate their robustness against different payload positions. A large number of road accidents worldwide involve heavy commercial vehicles. Due to their large mass they are more inclined to cause severe damages than light vehicles, such as serious injuries and fatalities. One of the most common causes of these crashes involving commercial trucks is the rollover of tractor semitrailer combinations. This particular type of accident is governed by a lack of lateral stability. Several researches have been carried out in the past on the topic of rollover prevention, and active roll control turned out to be one of the most effective solutions. The aim of this study is to design and validate an active roll control system that takes advantage of the built-in pneumatic suspensions installed on the large majority of the tractor semitrailer combinations commercialized nowadays. The goal is to increase the lateral stability of the vehicle by reducing the lateral load transfer on the axles during cornering maneuvers. The decrease in lateral load transfer is achieved using the air springs to counter the natural tendency of the vehicle to tilt towards the outside of the turn while cornering. The proposed solution is compared to the state of the art active roll control system based on active anti-roll bars. A complete model of the tractor semitrailer combination is developed using a multibody software, and it is used to simulate the response of the vehicle during several maneuvers, in order to evaluate both steady-state and transient conditions. Two additional linear vehicle models are designed for control purposes, and they are then validated against the multibody model. Three different control logics are designed and then compared, in order to find the best trade-off between performance and cost. A sensitivity analysis is performed to evaluate their robustness against different payload positions. The simulations results show that active air springs are able to increase the maximum lateral acceleration bearable by the vehicle during steady-state cornering by 15%. Significant reductions in lateral load transfer are achieved both during steady-state and transient maneuvers. Compared to active anti roll-bars, active air springs lead to a lower power consumption and lower installation costs.| File | Dimensione | Formato | |
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https://hdl.handle.net/10589/133859