Integrated vibration measurement and analysis system

Abstract

A vibration data collection system performs an integration or differentiation process on incoming digitized vibration data in real time. The system uses a digital Infinite Impulse Response (IIR) filter running at the input data rate to provide the integration or differentiation function. With this approach, the system reduces hardware complexity and data storage requirements. Also, the system provides the ability to directly integrate or differentiate stored time waveforms without resorting to FFT processing methods.

What is claimed is: 
     
         1 . A real-time signal conversion apparatus for use in measuring vibration levels of a machine that are indicative of a machine fault condition or a machine performance, the signal conversion apparatus comprising:
 a vibration sensor for producing an analog vibration signal comprising a dynamic vibration signal component and a direct current (DC) signal component, wherein at least the analog vibration signal component is indicative of performance of the machine or a fault condition of the machine;   an analog-to-digital conversion (ADC) circuit for sampling the analog vibration signal at an input data rate to convert the analog vibration signal into a first digital vibration signal, the ADC circuit having a dynamic range to enable removal of the DC signal component by real-time digital filtering; and   a digital infinite impulse response filter for receiving the first digital vibration signal at the input data rate and performing a mathematical operation at the input data rate on the first digital vibration signal to generate a second digital vibration signal substantially in real time, wherein the second digital vibration signal is indicative of the vibration level of the machine, and wherein the mathematical operation is selected from the group consisting of an integration operation and a differentiation operation.   
     
     
         2 . The real-time signal conversion apparatus of  claim 1  wherein
 the analog-to-digital conversion circuit converts the analog vibration signal into a plurality of first input data values of the first digital vibration signal during a first period of time defined by a plurality of ADC clock cycles at the input data rate; and 
 the digital infinite impulse response filter generates a plurality of first output data values of the second digital vibration signal during the first period of time. 
 
     
     
         3 . The real-time signal conversion apparatus of  claim 1  wherein:
 the analog-to-digital conversion circuit generates a plurality of input data values of the first digital vibration signal; and 
 the digital infinite impulse response filter performs the mathematical operation on the plurality of input data values of the first digital vibration signal to generate a plurality of output data values of the second digital vibration signal according to:
     y   n   =A·x   n   +B·x   n-2   +C·y   n-1   +D·y   n-2    
 where 
 y n  is an nth output data value of the second digital vibration signal, 
 y n-1  is an output data value of the second digital vibration signal prior to output data value y n , 
 y n-2  is an output data value of the second digital vibration signal prior to y n-1 , 
 x n  is an nth input data value of the first digital vibration signal, 
 x n-1  is an input data value of the first digital vibration signal prior to x n , 
 x n-2  is an input data value of the first digital vibration signal prior to x n-1 , and A, B, C and D are constants. 
 
 
     
     
         4 . The real-time signal conversion apparatus of  claim 1  wherein the input data rate at which the analog-to-digital conversion circuit samples the analog vibration signal is at least twice the Nyquist frequency of the analog vibration signal so that the second digital vibration signal generated by the digital infinite impulse response filter is substantially equivalent to an output of a band-limited analog infinite impulse response filter. 
     
     
         5 . The real-time signal conversion apparatus of  claim 1  wherein the digital infinite impulse response filter is implemented in a field programmable gate array (FPGA). 
     
     
         6 . The real-time signal conversion apparatus of  claim 5  wherein the FPGA includes an embedded processor for controlling storage and processing of data associated with at least one of the first digital vibration signal and the second digital vibration signal. 
     
     
         7 . The real-time signal conversion apparatus of  claim 1  wherein the digital infinite impulse response filter is implemented in an application specific integrated circuit (ASIC). 
     
     
         8 . The real-time signal conversion apparatus of  claim 7  wherein the ASIC includes an embedded processor for controlling storage and processing of data associated with at least one of the first digital vibration signal and the second digital vibration signal. 
     
     
         9 . A method for measuring vibration levels of a machine that are indicative of a machine fault condition or a machine performance, the method comprising:
 (a) sensing vibration of the machine and generating an analog vibration signal based on the sensed vibration;   (b) sampling the analog vibration signal at a fixed sampling rate to generate a first digital vibration signal;   (c) synthesizing other sampling rates based on the fixed sampling rate of the first digital vibration signal, thereby eliminating any need for an anti-aliasing filter;   (d) high-pass filtering the first digital vibration signal to remove direct current (DC) components; and   (e) performing a first mathematical operation on the first digital vibration signal to generate a second digital vibration signal that is indicative of the vibration level of the machine,.   
     
     
         10 . The method of  claim 9  further comprising performing a second mathematical operation on the second digital vibration signal to generate a third digital vibration signal that is indicative of the vibration level of the machine, wherein the second mathematical operation is selected from the group consisting of an integration operation and a differentiation operation. 
     
     
         11 . The method of  claim 9  wherein at least steps (d) and (e) are performed in a field programmable gate array (FPGA). 
     
     
         12 . The method of  claim 9  wherein at least steps (d) and (e) are performed in an application specific integrated circuit (ASIC). 
     
     
         13 . The method of  claim 9  wherein no signal conditioning step is performed between steps (a) and (b), wherein the signal conditioning step is selected from the group consisting of gain amplification, DC removal, anti-aliasing filtration, and high-pass filtration. 
     
     
         14 . A real-time signal conversion apparatus for use in measuring vibration levels of a machine that are indicative of a machine fault condition or a machine performance, the signal conversion apparatus comprising:
 a vibration sensor for sensing vibration of the machine and generating an analog vibration signal based on the sensed vibration, wherein the analog vibration signal is indicative of performance of the machine or a fault condition of the machine;   an analog-to-digital conversion (ADC) circuit for sampling the analog vibration signal to generate a first digital vibration signal;   a digital high-pass filter for filtering the first digital vibration signal to remove direct current (DC) components; and   a digital infinite impulse response filter for performing a mathematical operation on the first digital vibration signal to generate a second digital vibration signal that is indicative of the vibration level of the machine,   wherein the analog vibration signal is provided to the analog-to-digital conversion circuit without gain amplification and without anti-aliasing filtration.   
     
     
         15 . The real-time signal conversion apparatus of  claim 14  wherein the digital high-pass filter and the digital infinite impulse response filter are implemented in a field programmable gate array (FPGA). 
     
     
         16 . The real-time signal conversion apparatus of  claim 15  wherein the FPGA includes an embedded processor for controlling storage and processing of data associated with at least one of the first digital vibration signal and the second digital vibration signal. 
     
     
         17 . The real-time signal conversion apparatus of  claim 14  wherein
 the analog-to-digital conversion circuit samples the analog vibration signal at an input data rate converts the analog vibration signal into a plurality of first input data values of the first digital vibration signal during a first period of time defined by a plurality of ADC clock cycles at the input data rate; and 
 the digital infinite impulse response filter generates a plurality of first output data values of the second digital vibration signal during the first period of time. 
 
     
     
         18 . The real-time signal conversion apparatus of  claim 17  wherein the input data rate at which the analog-to-digital conversion circuit samples the analog vibration signal is at least twice the Nyquist frequency of the analog vibration signal so that the second digital vibration signal generated by the digital infinite impulse response filter is substantially equivalent to an output of a band-limited analog infinite impulse response filter. 
     
     
         19 . A real-time signal conversion apparatus for use in measuring vibration levels of a machine that are indicative of a machine fault condition or a machine performance, the signal conversion apparatus comprising:
 a vibration sensor for sensing vibration of the machine and generating an analog vibration signal based on the sensed vibration, wherein the analog vibration signal is indicative of performance of the machine or a fault condition of the machine;   an analog-to-digital conversion (ADC) circuit for sampling the analog vibration signal to generate a first digital vibration signal;   a digital infinite impulse response filter for performing a mathematical operation on the first digital vibration signal to generate a second digital vibration signal that is indicative of the vibration level of the machine;   a non-rechargeable battery for providing power at a first power level to the apparatus;   an energy harvester for providing power at a second power level to the apparatus, wherein the second power level is substantially less than the first power level; and   switch control circuitry for switching between the non-rechargeable battery and the energy harvester based at least in part on power demands of the apparatus, wherein the switch control circuitry provides power from the energy harvester to the apparatus when the second power level is sufficient to power the apparatus, and for providing power from the non-rechargeable battery to the apparatus when the second power level is not sufficient to power the apparatus.   
     
     
         20 . A real-time signal conversion apparatus for use in measuring parameters of a machine that are indicative of a machine fault condition or a machine performance, the signal conversion apparatus comprising:
 a first sensor for sensing a first parameter of the machine and generating a first analog signal based on the sensed parameter, wherein the first analog signal is indicative of performance of the machine or a fault condition of the machine;   a second sensor for sensing a second parameter of the machine and generating a second analog signal based on the sensed vibration, wherein the second analog signal is indicative of performance of the machine or a fault condition of the machine;   one or more analog-to-digital conversion (ADC) circuits for sampling the first and second analog signals to generate a first digital signal based on the first analog signal and a second digital signal based on the second analog signal;   a field programmable gate array (FPGA) having multiple channels for processing multiple digital signals in parallel, the multiple channels including:
 a first FPGA channel for processing one or more of the first digital signal and the second digital signal; and 
 a second FPGA channel for processing one or more of the first digital signal and the second digital signal. 
   
     
     
         21 . The real-time signal conversion apparatus of  claim 20  further comprising a switching device operable in a first setting for providing the first digital signal to the first FPGA channel and the second digital signal to the second FPGA channel, and operable in a second setting for providing the first digital signal to the second FPGA channel and the second digital signal to the first FPGA channel. 
     
     
         22 . The real-time signal conversion apparatus of  claim 20  wherein
 the first sensor is a vibration sensor for sensing a vibration level of the machine, the first analog signal is an analog vibration signal, and the first digital signal is a digital vibration signal; 
 the second sensor is a camera for sensing a visual image of the machine, the second analog signal is an analog visual image signal, and the second digital signal is a digital image signal. 
 
     
     
         23 . A real-time signal conversion apparatus for use in measuring parameters of a machine that are indicative of a machine fault condition or a machine performance, the signal conversion apparatus comprising:
 at least one acceleration sensor for sensing an acceleration parameter of the machine and generating an analog acceleration signal based on the sensed acceleration parameter, wherein the analog acceleration signal is indicative of performance of the machine or a fault condition of the machine;   one or more analog-to-digital conversion (ADC) circuits for sampling the analog acceleration signal to generate a digital acceleration signal based on the analog acceleration signal;   a field programmable gate array (FPGA) having multiple channels for processing multiple digital signals in parallel, the multiple channels including:
 a first FPGA channel for performing a first integration process to derive a digital displacement signal from the digital acceleration signal without producing an intermediate velocity signal during the first integration process; and 
 a second FPGA channel for performing a second integration process to derive a digital velocity signal from the digital acceleration signal. 
   
     
     
         24 . The real-time signal conversion apparatus of  claim 23  further comprising a processor for processing one or more of the digital acceleration signal, the digital velocity signal, and the digital displacement signal to analyze a machine fault condition or machine performance. 
     
     
         25 . A real-time signal conversion apparatus for use in measuring parameters of a machine that are indicative of a machine fault condition or a machine performance, the signal conversion apparatus comprising:
 a plurality of sensors for sensing vibration parameters of the machine and generating a plurality of analog vibration signals based on the sensed vibration parameters, wherein the analog vibration signals are indicative of performance of the machine or a fault condition of the machine;   one or more analog-to-digital conversion (ADC) circuits for sampling the plurality of analog vibration signals to generate a plurality of digital vibration signals based on the plurality of analog vibration signals;   a switching device having a plurality of inputs and a plurality of outputs, the plurality of inputs for receiving the plurality of digital vibration signals generated by the one or more ADC circuits, the switching device operable to direct any one of the plurality of digital vibration signals at any one of the plurality of inputs to any one of the plurality of outputs,   a field programmable gate array having a plurality of channels connected to the plurality of outputs of the switching device, the plurality of channels for processing the plurality of digital vibration signals in parallel.