Stabilnost sklopljenega sistema vlečno vozilo-prikolica

Kotar, Andrej (author), Šmit, Žiga (mentor)

Študirali smo dinamično stabilnost sklopljenega sistema vlečno vozilo – enoosna prikolica pri velikih hitrostih. Preučevali smo različne parametre prikolice in vlečnega vozila ter njihov vpliv na stabilnost sistema pri različnih hitrostih. Opazovali smo gibanje fizičnega modela sklopljenega sistema na tekočem traku in gibanje realnega avtomobila s prikolico. Pri meritvah smo uporabljali senzor kotne hitrosti, vgrajen v pametni telefon, ki se je izkazal kot učinkovita in natančna merilna naprava. Rezultate meritev smo primerjali z numeričnimi izračuni, ki smo jih naredili v programskem orodju MATLAB na osnovi poenostavljenega enoslednega analitičnega modela. Gibanje sistema vlečno vozilo – prikolica smo tudi računalniško simulirali v kompleksnem programskem orodju Simscape Vehicle Templates. Ključne ugotovitve iz eksperimentov in računalniških simulacij so: • Pri nizkih hitrostih je nihanje sistema, ki ga sproži motnja, dušeno in se hitro izniha. • S povečevanjem hitrosti je nihanje sistema postajalo manj dušeno, dokler ni prišlo do prehoda v vsiljeno nihanje v resonanci, kar je sistem naredilo nestabilen. Parametri, ki prispevajo k dinamični stabilnosti, so: • Prikolica: pravilna lega težišča, manjši vztrajnostni moment, večja masa, večja dolžina, ustrezne pnevmatike in primerno podvozje. • Vlečno vozilo: večja masa, ustrezne pnevmatike in primerno podvozje. Nekateri parametri, ki prispevajo k dinamični stabilnosti, hkrati povečujejo tako imenovano divergentno nestabilnost sistema (velika masa in naprej pomaknjena lega težišča prikolice) ali povečujejo nevarnost prevrnitve prikolice (visoka lega težišča prikolice). Poskus stabilizacije sistema z zaviranjem prikolice ali vlečnega vozila je bil v določeni meri uspešen. Vendar pa je pri velikih hitrostih premočno zaviranje vlečnega vozila lahko povečalo nihanje, pri zelo velikih hitrostih pa je postala stabilizacija sistema s tem načinom praktično nemogoča. Razporeditev pogona ni bistveno vplivala na dinamično stabilnost sistema, tudi med zaviranjem ne. Ugotovimo lahko, da bi sistem polnjenja električnega vozila s prikolico, ki deluje kot pogonsko vozilo, lahko bil stabilen, če bi pri njegovi zasnovi upoštevali naše ugotovitve.

• Language: Slovenian
• Keywords: dinamična nestabilnost, vlečno vozilo, prikolica, sklopljen sistem, hitrost, fizični model, računalniške simulacije, dušeno nihanje, vsiljeno nihanje, resonanca
• Work type: Final paper
• Typology: 2.11 - Undergraduate Thesis
• Organization: FMF - Faculty of Mathematics and Physics
• Year: 2023
• PID: 20.500.12556/RUL-152841
• COBISS.SI-ID: 167223299
• Publication date in RUL: 08.12.2023

Secondary language

• Language: English
• Title: Stability of the towing vehicle-trailer coupled system

Abstract

We studied the dynamic stability of a coupled system consisting of a towing vehicle and a single-axle trailer at high speeds. We examined various parameters of the trailer and towing vehicle and their impact on the system's stability at different speeds. We observed the motion of a physical model of the coupled system on a moving conveyor belt and the motion of a real car with a trailer. For measurements, we used an angular velocity sensor built into a smartphone, which proved to be an efficient and accurate measuring device. We compared the measurement results with numerical calculations we performed in the MATLAB software based on a simplified single-track analytical model. We also computer-simulated the motion of the towing vehicle-trailer system using the complex software tool Simscape Vehicle Templates. Key findings from experiments and computer simulations are as follows: • At low speeds, disturbances induced oscillations in the system that were quickly damped and faded out. • As speed increased, the oscillations became less damped until the system transitioned into forced oscillations in resonance, making the system unstable. Parameters contributing to dynamic stability are as follows: • Trailer: Proper centre of gravity positioning, smaller moment of inertia, greater mass, increased length, suitable tires, and appropriate chassis. • Towing vehicle: Greater mass, suitable tires, and suitable chassis. However, some parameters that contribute to dynamic stability also increase what is known as divergent instability (e.g., high trailer mass and forward-shifted centre of gravity) or raise the risk of trailer overturning (elevated trailer centre of gravity). Attempts for stabilisation of the system by braking the trailer or towing vehicle were partially successful. However, at high speeds, excessive towing vehicle braking could increase oscillations, and at very high speeds, stabilizing the system using this method became practically impossible. The distribution of drive did not significantly affect the dynamic stability of the system, even during braking. We can determine that a system for charging an electric vehicle with a trailer functioning as a propulsion vehicle could be stable if our findings were considered in its design.

• Keywords: Dynamic instability, towing vehicle, trailer, coupled system, speed, physical model, computer simulations, damped oscillation, forced oscillation, resonance