These and other features, aspects, and advantages will become better understood with regard to the following description, appended claims, and accompanying drawings where:
Like reference numbers and designations in the various drawings indicate like elements.
The following detailed description discusses at least one embodiment of an accelerometer-based electronic sensor coupled to a mechanical assembly. The electronic sensor will detect at least one condition where maintenance is required or detect a failure of one or more mechanical devices so that corrective maintenance action is taken. The electronic sensor comprises one or more vibration sensors and is programmable for one or more specific applications. Advantageously, the sensor outputs diagnostic data to indicate one or more fault conditions (for example, to illuminate a light on an instrument panel or be sent and stored by an onboard flight computer). This accelerometer-based electronic sensor is installed primarily where a failure mode frequency of oscillation is in the less than 1 MHz frequency range.
Proposed applications for the electronic sensor include mechanical devices such as jack screws, flap motors, landing gear components, spoiler extenders, control servos, APU, control surface actuators, and the like. In a motorized vehicle, vibration monitoring performed by the electronic sensor will detect worn tappets, periodic thumping of one or more flat tires, bearing failures in water pumps, worn brake pads, wheel bearing failures, and the like. Around a home, monitoring by the electronic sensor is further extended to include pool pumps, air handler motors, air conditioning compressors, lawn watering pumps, and the like. Further applications include monitoring of power generating equipment, motors, valves, and other related electromechanical equipment.
Component monitor 108 is in communication with vibration sensor 104 via sensor communication interface 106. In one implementation, sensor communication interface 106 is a wireless communication link between component monitor 108 and vibration sensor 104. In other implementations, sensor communication interface 106 is a serial wired communication interface between component monitor 108 and vibration sensor 104. Sensor communication interface 106 is further capable of supplying operating power to vibration sensor 104. Other means for providing operating power to vibration sensor 104 are possible (for example, solar, dry cells, and the like).
In operation, vibration sensor 104 senses a plurality of vibration readings from component 102. Vibration sensor 104 processes the plurality of vibration readings and indicates to component monitor 108 a current operating condition of component 102. In one implementation, component 102 is a flap motor on a left wing of an aircraft. Vibration sensor 104 is programmed to compare the plurality of vibration readings from component 102 (that is, vibrations of the flap motor) with one or more sets of expected vibration readings. Each set of expected vibration readings correspond with at least one vibration sample for component 102.
The at least one vibration sample for component 102 exhibits characteristics during operation that indicates when there is an operational problem or the potential for a future operational problem with at least a portion of component 102. In one implementation, component 102 emits one or more mechanical vibrations during start up sequences and/or during operation. A change in frequency of these vibrations provides information as to what portion of component 102 is, or is not, operating properly. A lack of vibration also provides information as to which portion of component 102 is not operating properly. In alternate implementations, component 102 does not vibrate when properly operating. In this case, one or more mechanical vibration emissions from component 102 are an indication that at least a portion of component 102 is not operating properly.
Vibration sensor 104 compares the plurality of vibration readings with the at least one corresponding vibration sample of component 102. Vibration sensor 104 updates component monitor 108 with at least one indication of normal operating activity (that is, acceptable levels of mechanical vibration indicating component 102 is operating as expected). When vibration sensor 104 detects that one of the plurality of vibration readings from component 102 does not match the at least one corresponding vibration sample of component 102, vibration sensor 104 immediately informs component monitor 108 that one or more failure conditions have occurred with component 102. In this example embodiment, component monitor 108 comprises an on-board flight management system that indicates to an operator that the flap motor on the left wing of the aircraft has failed and corrective action is to be taken immediately. Moreover, component monitor 108 is not responsible for detecting the failure. Vibration sensor 104, coupled directly to component 102, is intelligent enough to determine whether component 102 has failed.
Processor 204, I/O block 206, and accelerometers 208 are in communication with one another over sensor interconnect bus 414. In one implementation, sensor bus 414 is a bi-directional communication bus linking processor 204, I/O block 206, and accelerometers 208. I/O block 206 sends and receives one or more data signals from data signal line 210 and at least one power signal from power signal line 212. It is noted that for simplicity in description, a single data signal line 210 and a single power signal line 212 are shown in
In operation, vibration sensor 104 is configured for a particular application. Accelerometers 208 and processor 204 are specifically programmed to detect one or more vibration samples of a particular component 102 being monitored. For instance, one or more sensors 104 are programmed to detect a particular mechanical vibration sample for a landing gear motor, an elevator jack screw, and the like. In one implementation, vibration sensor 104 is programmed for monitoring at least one jack screw found in a typical aircraft tail. When the at least one jack screw is functioning, accelerometers 208 detect a plurality of vibration characteristics of metal to metal contact. Processor 202 compares at least one corresponding vibration sample supplied by memory 202 to determine if a particular “Maintenance Required” message must be sent to component monitor 108 (for example, a flight computer). The at least one corresponding vibration sample consists of one or more vibration waveform samples previously recorded from a jack screw operating without lubrication and from a jack screw that experiences a total failure. Processor 204 makes the comparison and issues at least one alert if at least one vibration waveform sample substantially matches at least one failure pattern.
For example, while an elevator trim is being set by the jack screw, if accelerometers 208 detect a plurality of mechanical vibration characteristics substantially similar to a vibration waveform sample of the jack screw stripping, an “Unsafe For Flight” signal is sent to component monitor 108 from vibration sensor 104. The above examples are representative of a particular application for vibration sensor 104. Programmable vibration samples allow vibration sensor 104 to be applied to a variety of mechanical and electromechanical assembly monitoring applications.
At block 308, the plurality of vibration characteristics are compared with the one or more vibration samples previously programmed into vibration sensor 104. If one or more of the plurality of vibration characteristics (for example, one or more vibration waveform samples) substantially match at least one failure pattern at block 310, vibration sensor 104 notifies component monitor 108 at block 312. In this example embodiment, the one or more vibration waveform samples measured by one or more accelerometers 208 are characterized as oscillating below 1 MHz. If a match is not detected, component monitor 108 is refreshed to indicate normal operation of component 102 at block 311 before method 300 returns to block 306 to continue monitoring.
This application is related to commonly assigned and co-pending U.S. patent application Ser. No. 11/095,152, filed on Mar. 31, 2005 and entitled “ACOUSTIC SIGNATURE TESTING FOR ELECTRONIC, ELECTROMECHANICAL, AND MECHANICAL EQUIPMENT” (the '152 application). The '152 application is incorporated herein by reference.