This thesis work deals with a particular architecture of a suspension spring called multi-chamber air spring, composed of a main chamber with variable volume and two auxiliary chambers with fixed volumes, connected to the main one via two controllable valves. The opening and closing of the valves allow for the modulation of the spring equivalent stiffness. Moreover, it is the only existing technology capable of high-frequency stiffness regulation. This dissertation aims to implement real-time control techniques to improve handling during maneuvers, intended as pitch and roll angle minimization, by properly modulating the valves' position. Three versions of control techniques are proposed, in order of complexity. The V1 version takes as inputs the estimated corner load transfers obtained from longitudinal and lateral acceleration. Pitch and roll values are reduced compared to the full soft configuration by 24% and 20%, respectively, but there is a deterioration in vertical acceleration due to kick force. As a solution, version V2 solves the kick force problem by introducing a switching logic based on the suspension stroke position. Finally, the third version V3 carries all the aforementioned properties and in addition, it introduces smart switching which allows to outperform the previous versions during mixed maneuvers. This is achieved by properly changing the stroke equilibrium positions, and improvements are up to 38% and 26% for pitch and roll angles, respectively. All the controller versions have been tested in simulation, using a multibody full-car model equipped with multi-chamber suspensions, whose parameters have been identified on a real case study by means of a suspension test bench.
Questa tesi tratta di una particolare molla pneumatica per sospensioni basata sull'architettura detta multicamera, che è composta da una camera principale con volume variabile e da due camere ausiliarie a volumi fissi, connesse alla prima tramite valvole regolabili. L'apertura e la chiusura delle valvole permette la modulazione della rigidezza della molla. Oggigiorno è l'unica tecnologia in grado di fare ciò. Lo scopo di questa dissertazione è quello di implementare delle tecniche di controllo in grado di migliorare la stabilità del veicolo durante manovre di sterzo, accelerazione e frenata, inteso come minimizzazione degli angoli di beccheggio e rollio, andando a controllare la posizione delle valvole. Tre versioni del controllore vengono presentate. La prima, V1, usa come solo segnale di ingresso la stima del trasferimento di carico, ottenuta a partire dall'accelerazione longitudinale e laterale. I valori degli angoli di beccheggio e rollio sono ridotti rispettivamente del 24% e del 20% rispetto alla configurazione con minima rigidezza, andando però a peggiorare l'accelerazione verticale a causa del cosiddetto "kick force". La seconda versione, V2, garantisce le stesse performance e risolve il problema dell'accelerazione verticale andando ad implementare una logica di apertura basata sulla posizione della corsa della sospensione. Infine, la terza versione, la V3, che mantiene tutte le proprietà della versione precedente, sfrutta il cambio di equilibrio della sospensione per ottenere maggiori miglioramenti, fino al 38% e al 26% rispettivamente per l'angolo di beccheggio e rollio. Tutte le tecniche di controllo sono state validate tramite simulazioni, usando un modello completo della macchina e i parametri delle sospensioni identificati al banco prova.
Handling-oriented control of a multichamber suspension
Sermisoni, Samuele
2021/2022
Abstract
This thesis work deals with a particular architecture of a suspension spring called multi-chamber air spring, composed of a main chamber with variable volume and two auxiliary chambers with fixed volumes, connected to the main one via two controllable valves. The opening and closing of the valves allow for the modulation of the spring equivalent stiffness. Moreover, it is the only existing technology capable of high-frequency stiffness regulation. This dissertation aims to implement real-time control techniques to improve handling during maneuvers, intended as pitch and roll angle minimization, by properly modulating the valves' position. Three versions of control techniques are proposed, in order of complexity. The V1 version takes as inputs the estimated corner load transfers obtained from longitudinal and lateral acceleration. Pitch and roll values are reduced compared to the full soft configuration by 24% and 20%, respectively, but there is a deterioration in vertical acceleration due to kick force. As a solution, version V2 solves the kick force problem by introducing a switching logic based on the suspension stroke position. Finally, the third version V3 carries all the aforementioned properties and in addition, it introduces smart switching which allows to outperform the previous versions during mixed maneuvers. This is achieved by properly changing the stroke equilibrium positions, and improvements are up to 38% and 26% for pitch and roll angles, respectively. All the controller versions have been tested in simulation, using a multibody full-car model equipped with multi-chamber suspensions, whose parameters have been identified on a real case study by means of a suspension test bench.File | Dimensione | Formato | |
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Sermisoni_thesis.pdf
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Descrizione: Thesis
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Sermisoni_executive_summary.pdf
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https://hdl.handle.net/10589/196989