MONITORING THE DYNAMICS OF SCALED VEHICLES USING A SONIC DIGITIZER

Certain dynamic stability characteristics of an alternate method of mo unting a front-end loader to a farm tractor were compared to those of a conventionally mounted front-end loader operating on a specified ter rain. One objective of the study was to determine if the alternate met hod of mounting a front-end loader resulted in better stability charac teristics and, in turn, safer operation than a conventional front-end loader. Another objective was to determine ifa three-dimensional sonic digitizer could monitor the motion of the scale model tractor-loader systems accurately enough to perform comparison between the systems. T his article describes the second objective of the study. A battery-pow ered, 114 scale model tractor-loader was used to perform experimental tests. Both tractor-loader systems were operated on two slopes and on random combinations of two sinusoidal bump heights, two load weights, two loader heights, and two velocities. Three replications were perfor med of each test condition. A three-dimensional sonic digitizer was ut ilized to monitor the motion of the scale model tractor-loader systems . The sonic digitizing system made it possible to record position of t he tractor-loader systems versus time at levels of frequency and accur acy faster than any previous methods of obtaining this type of data. T his greater number of observations allowed systems to be statistically compared, which was not possible with previous data collection system s. The digitizing system was able to locate each sound emitter accurat ely. Elapsed time between emitter firing sequences may have resulted i n the measured roll and front axle rotation angles to be less than act ual peaks.