Abstract
Vehicles travel at different speeds and, as a consequence, experience a broad spectrum of vibrations. One of the most important source of vehicle vibration is the road profile. Hence the knowledge of the characteristics of a road profile enables engineers to predict the dynamic behavior of a vehicle and to test its components in laboratory.
In this framework a mechanism to measure road profiles is designed and presented. Such a mechanism is composed of two rolling wheels and two long beams attached to the vehicles by means of four Kardan joints. The wheels are kept in contact to the ground profile by means of gravitational and spring forces. Accelerometers are attached above the rolling wheels and the wheels follow the profiles of a rough ground. After integrating the acceleration signal twice and measuring the vehicle displacement the road profiles can be achieved. It is important to highlight that the aim of this device is to independently measure two road profiles, without the influence of the vehicle dynamics where the mechanism is attached.
Before the mechatronic mechanism is attached to a real vehicle, its dynamic behavior must be known. A theoretical analysis of the mechanism dynamics is led with help of a set of non-linear equations of motion obtained using Newton-Euler-Jourdain´s Method. Such a set of equation is numerically solved and the theoretical results are compared with experimental carried out with a laboratory prototype. Comparisons show that the theoretical model predicts well the mechanism movements. However it was also experimentally observed that the contact between the wheels and the road profile is not permanent. To analyze the non-contact between the wheels and the road, the Newton-Euler´s Method is used to calculate forces and moments of reactions between the mechanism components. By modeling impacts between a wheel and the road by Newton´s Law, the complete dynamics of the system can be predicted, and the operational range (velocity limits) of the mechanism can be defined based on the mathematical model.
Key words: multibody dynamics, impact dynamics and road profile.
Original language | English |
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Title of host publication | Society of Automotive Engineers |
Volume | Paper 2002-01-3474 (in Portuguese) |
Publisher | Society of Automotive Engineers |
Publication date | 2002 |
Pages | 1-8 |
Publication status | Published - 2002 |
Event | Society of Automotive Engineers - São Paulo, Brazil Duration: 24 Nov 2002 → 26 Nov 2002 |
Conference
Conference | Society of Automotive Engineers |
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Country/Territory | Brazil |
City | São Paulo |
Period | 24/11/2002 → 26/11/2002 |