Ambulance Vibration Suppression via Force Field Domain Control

Cotnoir, Paul D

Etd

Ambulance Vibration Suppression via Force Field Domain Control

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This PhD dissertation experimentally characterized the vibration amplitude, frequency, and energy associated with ambulance travel and defined the relationship of the vibration to safety, comfort and care of ambulance patients. Average vertical vibration amplitudes of .46 to 2.55 m/sec2 were recorded in the patient compartment of four ambulances over four road surfaces at three speed settings. Power spectrum analysis of the data revealed that the vibration energy and resulting vertical acceleration forces were concentrated in the .1 to 6 Hz range. Relationships between the measured ambulance vibration and the impact of whole body vibration on human physiology and performance were quantified. It was found that the accelerations measured in the ambulances were in excess of what is considered to be a normal human comfort level. Furthermore, the vibration measured was in a spectrum which could present physical impediments to optimum task performance for the on-board medical team. Phase portrait analysis combined with the power spectrum data revealed the presence of nonlinearities, stochastic fluctuations and time delays inherent in the data. The ambulance vibration data was then used to create a unique analytical model and library of forcing functions corresponding to the vehicles, road surfaces and vehicle speeds that were tested. Using the example of a vibration absorbing force plate fit over an existing ambulance floor, it was demonstrated how the model and forcing functions could be used to develop a control law equation to select parameters for active control of vibration to produce sustainable regions of patient safety, comfort and care.

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