Browse Publications Technical Papers 2008-01-2951

State Transition Diagrams of Transient Roll and Pitch 2008-01-2951

In racing, understanding how the setup and setup changes affect the racecar's ability to produce optimum longitudinal and lateral acceleration is vital to producing a winning team. To better understand and characterize how setup and setup changes affect the racecar, the use of state transition diagrams to model the vehicle's transient roll and pitch while negotiating the track is being investigated. State transition diagrams are made up of statistically significant patterns or events, and show the interconnection or transition from one state to another.1 The basic application of a state transition diagram to the phenomena of a racecar's roll and pitch is to identify the locations on the race course of the major events that make up the vehicle braking into, maneuvering through, and accelerating out of a corner. Major events that are examined include the maximum roll and pitch displacements, velocities, and accelerations. These maxima are directly affected by the racecar's roll and pitch stiffness, damping, and polar moments of inertia respectively. Using the Pi Research software, Pi Toolbox, math channels were created to calculate the displacements, velocities, and accelerations from the information collected by the on board data logger. The locations of the maxima were plotted for multiple distinct corners, allowing for visual identification of how a vehicle pitches and rolls while at qualifying and race pace. The results demonstrated clear identifiable locations of roll and pitch maxima for displacement, velocity, and acceleration that were repeated from lap to lap depending on driver input. By comparing the change of the magnitudes and locations of these maxima on a state transition diagram, due to a change in the setup of the racecar, an engineer would have further insight into how actual changes affect the cars roll and pitch characteristics, as well as possible characterization of how the driver prefers the vehicle to maneuver.


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