EFFECT OF HUMAN RESPONSE-TIME ON ROCKING INSTABILITY OF A 2-WHEELED SUITCASE

A two-wheeled suitcase being pulled in a straight line on a horizontal ground is considered. Rocking motion of the suitcase from one wheel t o the other is analyzed. The action of the puller to resist the rockin g of the suitcase involves a time delay, due to the human response tim e. This time delay may increase the likelihood that the suitcase will become unstable and fall onto one of its sides. The effects of the fol lowing quantities are investigated: the magnitude of the time delay, t he coefficient of the puller's restoring moment, and the amplitude and frequency of the excitation moment applied by the puller during walki ng. The results exhibit a fractal behavior in certain cases due to the sensitivity of the response to variations in the excitation. (C) 1997 Academic Press Limited.