In industrial facilities, regardless of the product being produced, machines are often installed to perform specific tasks. To confirm that these machines are working properly, sensors and other related monitoring devices are used to gather and present data regarding the operation or condition of the machines.
One type of sensor is an accelerometer, which measures acceleration of a machine's vibration. Industrial accelerometers have traditionally been mechanical (i.e. using a piezoelectric element and a proof mass assembled within a sensor body wherein when the mass is accelerated, it impacts a force on the crystal that is proportional to the mass and the acceleration, resulting in the crystal outputting an electrical signal). MEMS accelerometers have been available in recent years and are used in various applications. In a MEMS accelerometer, the sensing mechanical assembly is micro machined within a microchip that also contains electronic components. These accelerometers have rarely been used for machine monitoring due to their limited frequency range. However, recently MEMS accelerometers have been manufactured that are capable of high-frequency measurements suitable for industrial applications.
FIG. 1 shows an example of a traditional mechanical accelerometer device 2 having a mounting stud 4 installed in a device threaded hole 6. The device 2 is then mounted to the side of the machine 8 by having the stud 4 engage a machine threaded hole 9. However, by mounting externally on the side of the machine 8, the device 2 relies on a precisely machined surface to maintain an adequately rigid position or connection to the machine. Further, in these systems, the device 2 is relatively bulky and often located relatively far from the vibration transmitting components. For these reasons, the device 2 often provides unreliable measurements.
MEMS accelerometers are typically manufactured in a microchip format and therefore require being installed on a printed circuit board. In machines that have printed circuit boards, such as a motor controller built into a motor, the location of the printed circuit board is typically unrelated to an optimal position of the sensor. Further, many industrial machines have no electronic components at all, and therefore lack a convenient and appropriate location for the accelerometer. As such, in these traditional systems, it is difficult to mount a MEMS accelerometer and obtain reliable measurements.