AIRCRAFT WHEEL USAGE INDICATOR SYSTEMS

PROPOSAL FOR UTILIZING SOLID STATE PIEZO-RESISTIVE SENSORS TO MEASURE AND RECORD CUMULATIVE WHEEL ROTATIONS. WHEEL ROTATION IS SENSED BY EXPLOITING THE FORCE DUE TO NORMAL (CENTRIPETAL) ACCELERATION, WHICH IS A FUNCTION OF THE ROTATIONAL SPEED SQUARED. THE ELECTRONIC PACKAGE IS SMALL (INCORPORATING SMT) AND CONSISTS MAINLY OF THE SENSOR AND A MOTOROLA F68HC11 MICROPROCESSOR. THE MICROPROCESSOR IS PACKAGED AS A COMPLETE COMPUTER ON A CHIP AND OPERATES UNDER THE HIGH LEVEL LANGUAGE OF FORTH. THE COMPUTER IS PROGRAMMED USING ANY IBM PC VIA THE RS232 PORT AND BITCOM COMMUNICATIONS SOFTWARE. THE SOFTWARE PROGRAMMING EFFORT IS REDUCED BY A FACTOR OF 10 WITH THIS LANGUAGE PRESENT. THE UNIT CAN BE ADAPTED TO ANY WHEEL SIZE BY CHANGING A "LOOKUP" TABLE THAT RESIDES IN THE EEPROM. MULTIPLE SENSORS CAN BE INCORPORATED TO MEASURE THE "TAXI" MILES AND THE "LANDING MILES". TOTAL REVOLUTIONS OR MILES CAN BE RECORDED AND RESET USING A TEST INSTRUMENT THE SIZE OF A TIRE GAGE OR BY USING AN IBM PC. THE COMPLETE UNIT IS SMALL, LIGHTWEIGHT, AND CAN BE RIVETED TO THE WHEEL. THE ELECTRONICS ARE SEALED AND PROTECTED TO SURVIVE ALL LANDING ENVIRONMENTS. THE SIMPLE DESIGN FEATURES A LOW COST, DISPOSABLE UNIT.