A PROFILE MEASURING, RECORDING AND PROCESSING SYSTEM

A DESCRIPTION OF THE SURFACE DYNAMICS PROFILOMETER MEASURING SYSTEM IS INCLUDED IN THIS REPORT. THE OBJECTIVE OF THIS SYSTEM IS TO PROVIDE THE TEXAS HIGHWAY DEPARTMENT WITH THE CAPABILITY TO MEASURE AND EVALUATE HIGHWAY PROFILES. THE PROFILOMETER MEASURING SYSTEM IS COMPOSED OF TWO ROAD-FOLLOWING WHEELS MOUNTED ON TRAILING ARMS BENEATH A VEHICLE, ONE IN EACH WHEEL PATH. THE WHEELS ARE HELD IN CONTACT WITH THE ROAD BY A 300-LB SPRING FORCE. THE RELATIVE MOTION BETWEEN THE VEHICLE AND THE ROAD-FOLLOWING WHEEL IS MEASURED BY A POTENTIOMETER WHILE THE ACCELEROMETER MEASURES THE ACCELERATION OF THE VEHICLE BODY. THESE SIGNALS ARE INPUT INTO A SPECIAL PURPOSE ANALOG COMPUTER CARRIED IN THE MEASURING VEHICLE. THE COMPUTER INTEGRATES THE ACCELERATION SIGNAL TWICE AND ADDS TO IT THE POTENTIOMETER SIGNAL. THIS SIGNAL IS CONDITIONED, DEPENDING ON THE FILTER SELECTION; TO MAKE THE RIGHT AND LEFT PROFILES. SINCE THESE DATA ARE IN ANALOG FORM, AND DIGITAL PROCESSING WAS CONSIDERED DESIRABLE, AN ANALOG-TO-DIGITAL PROGRAM WAS DEVELOPED. IT IS DESCRIBED IN DETAIL. AN OPERATING PROCEDURE FOR USE WITH THE PROFILOMETER IS PRESENTED ALONG WITH DETAILED CALIBRATION PROCEDURES FOR BOTH THE PROFILE-COMPUTER AND THE SENSING DEVICES. AN ANALYSIS OF THE SYSTEM INCLUDES AN EXPERIMENT WHICH WAS CONDUCTED TO CHECK THE AUTHENTICITY OF THE CALIBRATION SIGNALS, THE ERRORS IN THE DIGITIZATION PROCESS, AND VERIFICATION OF THE OVERALL FREQUENCY-RESPONSE OF THE SYSTEM. /AUTHOR/