DEVELOPMENT AND APPLICATION OF A COMBINED IMAGING AND MODELING TECHNIQUE FOR DETERMINING BIOMECHANICAL RESPONSE OF ROLLER COASTER PASSENGERS

摘要

Roller Coasters are one of the most popular amusement devices in use throughout the world. In their most basic form, roller coasters consist of a track system in which a car or train rolls under the force of gravity. The major design constraints of roller coasters are determined by the level of force and acceleration that the human body can safely withstand. These forces are commonly measured in multiples of the Earth's gravitational acceleration, and are termed "G" forces. Over the past twenty years, roller coaster designers have developed more and more physically intense rides. Since the modern advent of the steel inverting roller coaster in 1975, roller coaster designers have commonly used an over-the-shoulder restraint, or OTSR, to safely hold the passenger in the roller coaster car. These harnesses are typically U-shaped padded bars that pivot over the passenger's shoulders from overhead, securing the passenger in place by restricting upper and lower torso movement. Despite the success in holding the passenger in the roller coaster car, OTSR restraints may introduce certain injuries. The location and design of the restraint may place it in close proximity to the rider's head. Although the restraint is padded, injury may occur if the rider's head is knocked into the harness due to a quick change in acceleration. There have been reported cases of migraine-like headache symptoms in roller coaster passengers, believed to be caused by short, but powerful head movements experienced during the ride. There are no federal regulations in the United States to govern the design of these shoulder harnesses, in contrast to the detailed regulations of motor vehicle restraints. These cases of injury are somewhat rare, however, with an average of 23.5 total injuries per million park guests in 1999 Steel tracked roller coasters may have a variety of elements which invert the rider into an upside-down position. The most common element is the vertical loop. This element consists of a vertical helix which typically has the shape of an inverted teardrop. Through trial-and-error, this distinctive shape was deemed necessary to minimize the duration and severity of accelerations experienced by the passenger while maintaining train speed through the inversion. In order to develop a theoretical framework for analyzing existing roller coasters and designing new ones, we employed a dynamic model of a roller coaster as it executed a vertical loop element and during the release phase of a lift hill. This model used the Serret-Frenet basis and incorporated experimentally determined accelerations of the roller coaster.