(1)-_SOW_FINAL_10_July_2015.docx

STATEMENT OF WORK

FOR

MULTI-SHAKER

VIBRATION CONTROL SYSTEM

Naval Surface Warfare Center IHEODTD DET Picatinny, Code G12

February 2015

TABLE OF CONTENTS

Page No.

1. Introduction

The Naval Surface Warfare Center, Indian Head Explosive Ordnance Disposal Technology Division Detachment Picatinny (NSWC IHEODTD DET PICA) has a requirement for a multi-axis, multi-shaker vibration control system. This Statement of Work (SOW) specifies the equipment and performance specifications.

2. Reference Documents

MIL-STD-810G Method 527, Multiple Exciter Testing

3. General Description

3.1. This SOW uses the term control system for the multiple-axis, multiple-shaker shock and vibration control system to be purchased. The control system will operate both electro-dynamic and servo-hydraulic shakers at the Naval Packaging Handling Shipping and Transportation Center located in Building 458, Picatinny Arsenal, NJ. The control system consists of hardware and software to generate control signals and acquire response signals that will input a specified mechanical shock or vibration profile to an item under test.

3.2. The control system shall be capable of controlling the following configurations as outlined in MIL-STD-810G Method 527: single input single output (SISO), multiple input single output (MISO), or multiple input multiple output (MIMO). These tests may use either electro-dynamic shaker(s) or a servo-hydraulic shaker(s).

3.3. The Government intends to procure a shock and vibration control system that is a commercial off-the-shelf product. To this end, only currently fielded and proven systems (hardware and software) that meet at least 100% of the control and performance requirements of this document will be considered.

3.4. Control systems submitted for consideration will be evaluated in the following areas: demonstrated performance at NSWC IHEODTD DET PICA facilities, technical specifications, and cost.

4. Vibration Control Installation/Operation requirements

4.1. Documentation. The system shall be delivered with at least two complete sets of comprehensive documentation on all major hardware and software components.

a. Operation manuals for each control system software.

b. Maintenance manuals for all delivered hardware, including sections on planned preventative maintenance if applicable.

c. Installation instructions for all delivered hardware and software.

4.2. Checkout and acceptance.

a. Delivery shall be within 60 days from contract acceptance.

b. The contractor will perform the installation at Building 458, NSWC IHEODTD – DET PICATINNY, Naval PHST Center, Picatinny Arsenal NJ. All personnel providing the installation and acceptance tests at Picatinny Arsenal must be U.S. citizens or hold permanent residence status.

4.3. Training requirements. A 3-day on-site training on the system will be provided by the contractor within a month following the system’s delivery.

4.4. Warranty. A 1-year warranty on all parts, software, and labor shall be provided by the manufacturer following delivery of the full system.

4.5. Calibration. 1st year of calibration included

5. Basic Requirements

5.1. This VCS shall be capable of running multiple input, multiple output (MIMO) and multiple input, single output (MISO) digital shock and vibration tests. The VCS will be used at the NSWC IHEODTD DET PICA Naval PHST Center test facility in Picatinny Arsenal, New Jersey.

5.2. For MIMO control, the VCS must be able to control from two to 12 vibration shakers, moving in the same axis, and provide phase, coherence, and amplitude control for closed loop random and closed loop sine.

5.3. For MIMO control, the VCS shall be capable of controlling two independent 6 DOF vibration machines and provide phase, coherence, and amplitude control for closed loop random and closed loop sine.

5.4. For MIMO control, the VCS shall be capable of future expansion by software only to run closed loop random on random, closed loop sine on random, and closed loop waveform replication.

5.5. For MISO control, the VCS shall be capable of running closed loop random, and closed loop sine.

5.6. For MISO control, the VCS shall be capable of future expansion by software only to run closed loop random on random, closed loop sine on random, and closed loop waveform replication shaker transient waveform (including shock response spectrum (SRS) and classical shock pulse testing) for single shaker testing.

5.7. The VCS must have the ability of updating the system response matrix every loop to assure true control of non-linear responses that occur during a test to account for dynamic changes in a unit under test (UUT).

5.8. The VCS must be able to display all control channels, measurement channels, impedance matrix or H(f) matrix, drive spectra, etc.; simultaneously during the test. In addition, data stored in the system throughput drive shall be available to analyze posttest.

5.9. For MIMO testing the VCS must provide a method to provide for control of singularities, or control zeros that may exist at particular frequencies while running a test. A control parameter that is adjustable shall be provided to address this.

5.10. For MIMO applications, the control system shall account for and properly control the complete impedance matrix of all possible input/output combinations. For example, a four-shaker test with four control transducers will require a impedance matrix of 4 X 4 terms that result in a 16-output/input matrix pair of terms. On the other hand, a four-shaker test with seven transducers will require a matrix of 4 X 7 terms that result in 28-output/input impedance matrix pair terms.

5.11. For MIMO application the VCS shall solve the control equation for PSD, phase and coherence simultaneously during each control loop during the test.

5.12. For MIMO multiple degree of freedom application (e.g., 3 DOF or 6 DOF), the VCS shall provide a software coordinate transformation technique and a method for controlled torsional reduction.

a. The system must allow transformation from linear accelerometers to rigid body translations (X, Y, and Z) and rotations (Rx, Ry, ad Rz).

b. The system shall calculate the transformation channels in realtime and these channels may be used as control, measurement, or limit channels.

5.13. The controller must have output anti-imaging filters on all drive channels to prevent signals from being sent to the shakers that are outside of the vibration test profiles.

5.14. The controller must have the capability to use active auxiliary channels that are not assigned as control channels as limit channels. (All available auxiliary channels shall be capable of this.) The limit channels shall allow a profile definition to control a limit situation. This profile could be different than the test input profile. This will allow a response on a test item to not exceed a predefined limit.

5.15. For all MIMO operations, it is required that the VCS be capable of square and rectangular control strategies. Square control is defined as having the same number of input channels as output channels. (One control transducer for every drive channel.) Rectangular control is defined as having more control channels then output channels. (More control transducers then drive channels.)

5.16. All power for the VCS should be 110 volts. Surge protector and noise suppression power strips shall be supplied with the VCS.

6. Optional Requirements

6.1. For MIMO control, the VCS must be able to control from two to 12 vibration shakers, moving in the same axis, and provide phase, coherence, and amplitude control for closed loop random on random, closed loop sine on random, and closed loop waveform replication.

6.2. For MIMO control, the VCS shall be capable of controlling two independent 6 DOF vibration machines and provide phase, coherence, and amplitude control for closed loop random on random, closed loop sine on random and closed loop waveform replication.

6.3. For MISO control, the VCS shall be capable of running closed loop random on random, closed loop sine on random, closed loop waveform replication shaker transient waveform (including shock response spectrum (SRS) and classical shock pulse testing) for single shaker testing.

6.4. In addition to the MIMO and MISO random on random and sine on random capabilities, a feature to combine these into a true mixed mode test shall be provided (e.g., sweeping narrow band random tones on broadband random with sweeping sine tones running simultaneously).

6.5. Sixteen (16) additional analog digital converter (ADC) input channels

6.6. A 250 Gigabyte or greater throughput disk drive shall be supplied to record the time histories for post-test processing and storage.

7. Host Computer/Vibration Control Subsystem Requirements.

7.1. Workstation computer (host). The host shall be an industry standard workstation computer. The host shall function as the operator interface to the vibration control subsystem via a high-speed digital link. The host shall incorporate at a minimum:

a. A 500 Gigabyte or larger and 7200 RPM or faster hard drive (2 smaller capacity disk drives may be substituted as long as the capacity is 500 Gigabyte or larger)

b. A 27-inch or larger liquid crystal display (LCD) displays

c. A DVD/CD-rom drive with read/writer capability

d. At least 4 USB ports

e. Support at least 48 input channels and 12 output channels for MIMO applications. Must be capable of support up to 96 input channels for future expansion. The input channel count requirement may be modified based on vendor’s cost quotes and available funding.

f. The host shall have full windowing capability.

7.2. DSP/matrix compute capability. The VCS shall incorporate sufficient floating point computational capability to optimally perform the necessary Digital Signal Processor (DSP) and matrix processing required for full closed loop real time control of two 6 DOF vibration test systems (12 drive channels and at least 24 control channels).

7.3. Terminal location. The system terminal shall be housed on an existing computer desk located in the Naval PHST Center.

7.4. Grounding: The VCS shall have all signal grounds connected at the ADC for input channels and at the Digital to Analog Converter (DAC) for output channels that are isolated from the cabinets and isolated from the input power safety ground.

7.5. Environmental Conditions: The control system shall operate in a moderately controlled environment with temperature maintained in the 50-100 degree Fahrenheit range, and relative humidity in the 20 - 80 percent range non-condensing.

7.6. Vibration control subsystem hardware.

7.6.1 The vibration control subsystem hardware shall be set up, initialized, and operated from a host computer via a high-speed data link. The host computer provides the operator interface and may or may not participate directly in the control loop.

7.6.2 The vibration control subsystem shall consist of instrument quality hardware designed to provide adequate cooling for all internal components operating at 100% duty cycle, provide adequate power for maximum component configuration specified herein. It shall incorporate sufficient noise isolation/suppression to permit the Analog to Digital Converters (ADC's) and Digital to Analog Converters (DAC's) to operate with an internal (grounded inputs and outputs) noise floor of 90 dB below full scale. Hardware shall include power supply for integral electronic sensors for a minimum of 48 measurement channels, operating simultaneously. The input channels shall also be capable of taking conditioned voltage signals that are not integral electronic type sensors. The system shall be upgradable to 96 input channels for future expansion.

7.6.3 Vibration control subsystem hardware and software shall be designed/selected to minimize latency in the control loop. Latency in this context is the time it takes to acquire enough data to process an update to the control outputs, perform the necessary processing, and output the resultant drive signals. In order to achieve minimum latency the system shall provide the fastest possible movement of the data from the ADC's to the vibration control subsystem's processors, very fast processing, and very fast output through the DAC's. This must be accomplished via Real Time Adaptive Control (RTAC), which is defined as a closed loop control that updates its system response model estimate at every control loop iteration to minimize errors arising from the use of an improper frequency response.

7.6.4 The vibration control subsystem hardware shall be fully developed and supported

7.7 Analog input and output.

7.7.1 The vibration control subsystem shall include hardware modules for anti-alias filtering of the data, digitizing analog signals, spectral computations for control loop processing, and generation of a compensated shaker drive signal.

7.7.2 The input channel hardware shall be capable of sampling up to 48 (and expandable to 96) channels of data simultaneously. The input channel hardware shall meet or exceed the following requirements:

7.7.2.1 A separate ADC for each input channel capable of acquiring data at a maximum frequency of 40 kHz. For the 40 kHz frequency (which will be required for shock testing) the sampling rate shall exceed the nyquist criteria and be in excess of 100,000 samples per sec.

7.7.2.2 Each ADC shall provide at least 24 bits of resolution.

7.7.2.3 Zero-to-peak full-scale voltage ranges shall be selectable by the control software from 1 V to 10 V with at least 4 selectable ranges.

7.7.2.4 Measurement dynamic range of at least 120 dB on each channel.

7.7.2.5 For shaker control applications, anti-aliasing filters shall be programmable in at least 9 frequency ranges from 50 to 20 kHz.

7.7.2.6 The anti-aliasing filters shall have at least 90 dB of stop-band attenuation and, above 1.56 times the cutoff frequency, a guard-band roll-off of at least 120 dB/octave.

7.7.2.7 The ripple in the pass band of the anti-aliasing filters shall be a maximum of + 0.15 dB from DC to 90% of the cutoff frequency.

7.7.2.8 The amplitude match between channels shall be within + 0.25 dB while the phase difference between channels shall not exceed ±1 degree from 0 Hz to 20 kHz and ±2 degrees above 20 to 40 kHz.

7.7.2.9 Cross talk between channels shall not exceed 90 dB below full scale.

7.7.2.10 Channel calibration procedures shall be available for automatic calibration without the need for potentiometer adjustments.

7.7.2.11 Selection of AC or DC signal coupling shall be available.

7.7.2.12 Power for low impedance piezoelectric (IEPE type) accelerometers shall be supplied.

7.7.3 The output channel hardware shall be capable of generating 12 high fidelity, low distortion, and analog voltage signals capable of driving electro-dynamic or hydraulic shakers. The output channel hardware shall meet the following requirements:

7.7.3.1 Each DAC shall provide at least 24 bits of resolution.

7.7.3.2 Cross talk between channels shall not exceed 90 dB below full scale.

7.7.3.3 Each output channel shall be capable of an output rate as high as 50,000 samples per second.

7.7.3.4 The output frequency bandwidths for vibration control shall be selectable from 50 to 20 kHz with at least 9 frequency ranges.

7.7.3.5 Each output signal shall be capable of driving at least 140 feet of shielded coaxial 50-ohm cable without the need for external amplification.

7.7.3.6 Digital Anti-imaging filters combined with analog smoothing filters after the D/A conversion must be included in each output channel.

7.7.4 The system shall include a 1 V peak Constant Output Level Amplitude (COLA) output signal.

7.8 VCS operating system/utility software.

7.8.1 General requirements. The host vibration workstation shall operate with a stable and reliable operating system. The operating system used shall be designed for 64 bit high performance computing.

7.8.2 Calibration requirements. The system shall include software calibration routines that shall provide calibration capability with the calibration traceable to National Institute of Standards and Technology (NIST) standards. At a minimum, these routines shall provide calibration of the DAC's, ADC's, filters, and other applicable components in the system. This routine shall provide a interactive mode of operation that leads the operator through a step by step calibration routine by providing operator oriented prompts, accepting credible inputs, and reporting system actions. Calibration, not simply verification of calibration, must be accomplished.

7.8.3 Data conversion. All vibration and shock data shall be able to be converted from the contractors' proprietary format to industry formats including American Standard Code for Information Interchange (ASCII) and universal file format (UFF) format using simple pull-down menus.

8 Vibration Control and Data Analysis Software:

8.1 Shaker Configurations

The system shall support the following shaker configuration.

8.1.1 Single shaker (SISO), multiple shaker single axis (MISO), and multiple shaker multiple axis (MIMO) testing shall be supported. Shaker configurations with up to twelve exciters shall be supported.

8.1.2 The control system shall use closed loop control for SISO, MISO, and MIMO shaker configuration.

8.1.3 Control of any multi-shaker configuration shall provide synchronization, phase control, and suppression of interactions between shakers (cross talk). Suppressing interactions between shakers shall include removing energy at frequencies where the interactions cause excitation levels above the test levels specified in the current test setup.

8.2 Software Backup Copies and Licensing

8.2.1 The system shall include backup copies of all system software on CD Rom or DVD.

8.2.2 The software licensing shall not be performed via a license server or other method that requires network connectivity.

8.3 Vibration Control Setup and Methodology

8.3.1 Control Bandwidth: The control bandwidths shall be selectable up to 10,000 Hz minimum for shock and 5,000 Hz minimum for all other test types.

8.3.2 Limit Channels: All ADC Input channels shall be available for limit channels. Each limit channel shall have a not-to-exceed profile associated with it independent of the control channels. Data acquired by these channels shall be analyzed in the same manner as control channels. If the limit profile is exceeded or an ADC overload is detected on a limit channel, the test shall be aborted.

8.3.3 Measurement Channels: All ADC Input channels shall be available for measurement channels. Data acquired by these channels shall be analyzed in the same manner as control and limit channels. They shall be monitored for ADC overload only. If an ADC overload is detected on a measurement channel, the test shall be aborted.

8.3.4 Adaptive Control: For all closed loop testing, the system shall incorporate adaptive control. Adaptive control in this context means closed loop control where the drive outputs for random, sine, and waveform replication are continually updated while the waveform is being output, with the updates being based on response measurements from the portion of the waveform already output. Adaptive control shall incorporate both feed-back and feed-forward control to improve the control speed and stability of the control loop. For transient (shock) events, adaptive control shall be used to update the drive following each event.

8.3.5 Control Methods: The system shall control single shaker, multi-shaker single axis, and multi-shaker multi-axis configurations.

8.3.5.1 Control of any multi-shaker and/or multi-axis configuration shall permit the operator to specify a test profile for each axis (X, Y, Z).

8.3.5.2 It shall be possible to associate a unique reference profile to each controlled degree of freedom (axis).

8.3.5.3 It shall be possible to associate a unique reference profile with several (or all) control axes.

8.3.5.4 Averaging

9.3.5.4.1 For Single Shaker Control: The system shall average the selected control signals for each amplitude profile. Averaging in this context means arithmetic averaging of the responses of all control channels in a given axis

9.3.5.4.2 For Multiple Shaker Control: The system shall allow for non-square matrix control configurations where the number of control response channels exceeds the number of exciters (DAC outputs).

9.3.5.4.3 Extremal: For Single Shaker Control: Control based on the maximum values at each line of all specified control channels. Not applicable to multi-shaker control.

8.3.6 Protection

8.3.6.1 Automatic Abort: The VCS shall automatically shut down the shaker system being controlled to protect it and the test item from damage or out-of-tolerance conditions. It shall do this by quickly decreasing all output levels to zero in a smooth manner. The error source and cause of the shutdown shall be prominently displayed on the terminal screen and entered into the Run Log. The following is a minimum list of conditions to be monitored. The system shall abort if any of these conditions are detected:

8.3.6.1.1 Loss of Control Signal (ADC Channel Open): The system shall automatically detect a loss of signal on any control or limit channel.

8.3.6.1.2 Limit +: Any control or limit channel acceleration response exceeding upper limits specified in the test setup. Active at user specified levels. At lower levels, the system shall warn the operator if an out of tolerance condition relative to that level occurs.

8.3.6.1.3 Limit -: All control channel acceleration responses in a given axis are below the lower limits specified in the test setup. Active at user specified levels. At lower levels, the system shall warn the operator if an out of tolerance condition occurs.

8.3.6.1.4 DAC Output Overload: At all output levels below full level, the system shall compute the peak output voltages required for control at full test level. If any output voltage level exceeds the maximum output voltage available from the DAC, the system shall abort the test. If a synthesized drive signal exceeds the maximum DAC output level, the system shall abort the test.

8.3.6.2 Manual Abort: The operator shall be able to initiate a smooth shutdown of any test via a single key input from the system terminal or from an external switch. If a test is aborted for any reason, the operator shall have the option of continuing at the point of abort, restarting the test, or terminating the test. In the case of a mission simulation with multiple events, the operator shall also have the option of proceeding to the next event.

8.3.6.3 Zeroing DAC Outputs: The system shall automatically ground or hold the DAC outputs to zero volts at all times when a signal is not being output and remove offsets (zero Hz components) during test.

8.3.6.4 ADC Overloads: At completion of a setup and equalization, the system shall compute the maximum drive voltages required to achieve the maximum acceleration levels specified in the setup.

8.3.6.5 Invalid Output: The system shall protect against invalid output. Whenever a change is made to the test profile that would invalidate the reference, transfer function, or drive data, that data shall not be usable for test execution. If the operator attempts to plot invalid data the system shall display a warning of the invalid condition, e.g., changing number of lines in a random test setup, changing frequency band, etc.

8.4 Random Vibration Control

This section presents the specifications for Random Vibration Control.

8.4.1 Test Setup Inputs: This section details test setup inputs required for setting up a random test. These inputs are in addition to the standard inputs detailed in the previous sections.

8.4.2 Reference Spectrum Shaping: The reference PSD spectrums shall be specified in terms of slope (dB/octave) and the breakpoint frequencies and/or in PSD levels (g2/Hz) and the breakpoint frequencies. Spectrum breakpoint inputs shall include the upper and lower tolerances in dB. The system shall allow for at least 40 breakpoints per reference profile. The PSD energy may start and/or terminate at any frequency from 1 to 5,000 Hz.

8.4.3 Clipping: The operator shall be able to specify a sigma clipping level for the drive outputs. Values in the drive signal greater than the sigma level shall be set to the sigma value if clipping is selected. Sigma is the ratio of the peak value to the Root Mean Square (RMS) value of the shaker drive signal.

8.4.4 Test Schedule: The system shall permit the operator to specify a test schedule consisting of amplitude steps vs. time. The system shall automatically execute this schedule. Random software offers level scheduling as a means to accomplish this, including:

8.4.5 Step levels shall be specified in dB relative to full level (0 dB = 10 Log (full level)). Full level test duration shall be selectable from 3 seconds to at least 24 hours.

8.4.6 The operator shall be able to select whether or not the system will abort at each test level. If the system is not able to control any of the control accelerometer responses to within the specified tolerances within the scheduled time at any test level, the operator shall be warned and the programmed step changes shall be executed.

8.4.7 Manual Mode: Manual mode shall permit the operator to override the test schedule. The system shall provide command inputs for:

8.4.7.1 Raising the test level to the next higher step in the test schedule

8.4.7.2 Lowering the test level to the next lower step in the test schedule

8.4.7.3 Holding the current level - not allow the next programmed step change

8.4.7.4 Resuming the test schedule after a hold

8.4.8 RMS Abort Limit: The RMS abort limit shall be specified in dB and represents the allowable deviation between the GRMS level of the reference profile and the GRMS level of the control PSD. RMS level shall be computed across the bandwidth specified in the test setup.

8.4.9 Narrow Band Abort Criteria: The system shall permit the operator to allow narrow-band excursions above the line abort limits specified in the profile. The bandwidth for these excursions shall selectable in number of lines (filter bandwidth). The operator shall be able to specify the number of control loops the narrow band abort criteria may be exceeded before the system aborts the test.

8.4.10 Alarm Limits: The alarm limits shall be selectable in dB or as a percentage of the abort limits.

8.4.11 Square or Rectangular Control: The operator shall be able to select between square control (equal number of exciters and control responses) and rectangular control (more responses than exciters).

8.4.12 Limit Channels: The system shall permit the operator to select any of the ADC input channels. A limit channel shall limit the g2/Hz amplitude to a frequency/amplitude profile specified in the test setup by the operator. For multiple shaker operations, the system shall measure the contribution of each shaker to the response at the limit location and adjust the drives to each shaker accordingly.

8.4.13 Abort Criteria: The system shall abort the test if any of the following conditions exist:

8.4.13.1 The GRMS level of an input control exceeds its respective 0 dB reference GRMS by greater than the specified GRMS abort limit.

8.4.13.2 Limit Plus: At any level when a full level (0 dB) line abort criteria specified in the test setup is exceeded for an operator selected number of control loops for all control channels in a given axis on a line by line basis.

8.4.13.3 Limit Minus: At any level when a line abort criteria specified in the test setup is exceeded for an operator selected number of control loops for all control channels in a given axis on a line by line basis.

8.4.14 Frequency Resolution: The system shall permit the operator to specify the number of lines of resolution for a given test profile.

8.4.15 Coherence: The system shall control the level of coherence between each pair of shakers. For the purpose of this document, this means that the control system shall be able to affect increased coupling or decoupling as required to realize the desired level of coherence between each pair of shakers. The system shall force at least 95% coherence between all shaker pairs that are aligned on a common axis for 90% of the frequency band. The system shall enable the operator to specify the desired level of coherence as a function of frequency between each pair of shakers (e.g., in a three shaker system there would be three coherence profiles required). Coherence values shall range from 0.01 to 0.99 in increments of 0.01. Coherence profiles shall be part of each multi-shaker random test setup.

8.4.16 Limit Channels: Each monitor channel can be designated as a limit channel and shall have a frequency/amplitude (PSD) limit profile of up to 40 breakpoints and shall override the control channel profiles (cause a reduction in drive levels on a spectral line by line basis) to protect the test article.

8.5 Sine Vibration Control

This section presents the specifications specific to Sine vibration control.

8.5.1 Control Loop Performance: Up to 120 dB dynamic range.

8.5.2 Setup: The following inputs are peculiar to sine testing and are in addition to the setup inputs detailed previously.

8.5.3 Sweep Mode: The sweep mode input shall allow the operator to select a linear sweep, log sweep, integer sweep, or sine dwell. The range shall be at least 1 Hz to 2000 Hz.

8.5.3.1 If a linear sweep is selected, the system shall prompt the operator to select either the sweep time in minutes or the sweep rate in Hz per minute. If the sweep time is specified, the system shall compute and display the sweep rate. If the sweep rate is specified, the system shall compute and display the sweep time.

8.5.3.2 If a log sweep is selected, the system shall prompt the operator to select either the sweep time or the sweep rate in octaves per minute. If sweep time is selected, the system shall compute and display the sweep rate in octaves per minute. If sweep rate is specified, the system shall compute and display the sweep time.

8.5.3.3 If an integer sweep is selected, the system shall prompt the operator to select the time seconds at each discrete frequency. The system shall compute and displace the sweep time.

8.5.3.4 If a sine dwell is selected, the system shall prompt the operator for the frequency and time duration. The system shall provide the capability to track a dwell based on phase shift of 90 degrees between response and table input.

8.5.4 Reference Spectrums: The system shall permit reference spectra to be input in terms of displacement, velocity, or acceleration. The system shall allow at least 40 frequency-amplitude breakpoints in each reference spectrum. Each breakpoint shall be specified in displacement, velocity, or acceleration vs. frequency. The system shall automatically compute and display the other two values (e.g., if the point is specified in displacement the system shall display the peak velocity and acceleration values). Abort limits in dB shall be selectable at each of the breakpoint frequencies of the reference spectrum. For multi-axis operation, a separate reference spectrum shall be specified for each axis.

8.5.5 Measurement Method: The system shall allow the operator to select the measurement method to be used on control channel data. Options shall be:

8.5.5.1 Peak amplitude based on broadband sampling of the control response signal

8.5.5.2 RMS filter processing with a selection of at least 10 choices for integration time periods proportional to the drive frequency

8.5.5.3 Tracking Filter Processing: Control on fundamental (driven) frequency only

8.5.6 Tracking Filters: Each output channel shall incorporate a bandpass tracking filter.

8.5.7 Limit Channels: The system shall permit the operator to select any of the ADC input channels as limit channels. A limit channel shall limit the amplitude of the sweep to a frequency/amplitude profile specified in the test setup by the operator. For multiple shaker operations, the system shall measure the contribution of each shaker to the response at the limit location and adjust the drives to each shaker accordingly. Limit levels shall be specified in Engineering Units that are consistent with the defined control reference spectrum.

8.5.8 Sweep Direction: This parameter specifies if the initial sweep direction is increasing or decreasing in frequency.

8.5.9 Sweep resolution shall be selectable between at least 400 and 2000 points per sweep.

8.5.10 Number of Single Sweeps: This parameter determines how many times the system shall automatically sweep between the minimum and maximum frequency endpoints specified in the setup. The sweep direction shall reverse each time the low or high frequency is reached. The first sweep is counted in the number of single sweeps even when it does not start at the low or high frequency limits. Data from each sweep shall be automatically saved at the end of the sweep.

8.5.11 Test Duration: The actual test duration shall be computed by multiplying the total number of single sweeps by the sweep time. If the test is not started at the minimum or maximum frequency, the test duration shall be adjusted to account for the partial sweep duration. Test duration shall be displayed on the system terminal at the completion of the setup phase.

8.5.12 Display Format: Sine data shall be displayed in Gpk or GRMS vs. frequency for sine sweeps or Gpk or GRMS vs. time for sine dwells.

8.5.13 Manual Control: The system shall permit the operator to enable or disable manual control. Manual Control, when enabled, shall provide the operator the following options:

8.5.13.1 Hold: Hold the current frequency and amplitude

8.5.13.2 Resume: Resume the sweep after Hold

8.5.13.3 Reverse: Change sweep direction

8.5.14 Status Indicators: In addition to the items detailed previously, the system shall display the current frequency being output, the elapsed time, and the sweep number during sine test execution.

8.5.15 The system shall output a 1V peak Constant output Level Amplitude (COLA) signal with the same frequency and phase as the first output cannel drive signal.

8.6 Transient Waveform Control

This section details the specifications that are peculiar to transient waveform testing. For the purposes of this document, a transient waveform is any non-stationary time history signal of up to three seconds duration. It includes, but is not limited to, the classical shock pulses, built up (shock spectrum) transients, and field measured transients.

8.6.1 Transient Type: The system shall permit the operator to select either classic shock pulses, shock spectrum synthesis, or user defined time histories. If shock spectrum is selected, the system shall prompt the operator for the required parameters to specify the pulse. If a classic waveform is selected, the system shall prompt the operator to input the peak Gs by axis and the duration in milliseconds.

8.6.1.1 Classical shock waveform synthesis: The system shall synthesize the following waveforms:

8.6.1.1.1 Half sine

8.6.1.1.2 Square Wave

8.6.1.1.3 Terminal peak sawtooth

8.6.1.1.4 Triangular

8.6.1.1.5 Initial peak sawtooth

8.6.1.1.6 Shock spectrum

8.6.1.2 Shock Spectrum: The system shall synthesize a reference waveform for each shaker that conforms to an operator specified shock spectrum. The desired shock spectrum shall be specified in frequency vs. spectral Gs. The system shall synthesize transient waveforms over a frequency range from 2 to 10,000 Hz. Synthesis methods shall include sum of decaying sinusoids and wavelets. Fast Sine Sweep (FSS) is not acceptable.

8.6.2 Abort Limits: Upper and lower abort limits shall be specified in dB or percent.

8.6.3 External Waveform: The operator shall be able to enter an arbitrary transient reference waveform by referencing an external data file. At least one format for external data files shall be an ASCII. The vendor shall provide a detailed specification, with sample files, for the acceptable formats the system will import.

8.6.4 Waveform Conditioning: Pre- and post-waveform conditioning shall be available on all waveforms to optimize the vibrator displacement capability and minimize peak velocity. The system shall display peak velocity and displacement when the waveform specification and synthesis is completed.

8.6.5 Plotting Formats: The system shall plot the reference, drive, and control waveforms for each axis in either time domain or shock spectrum as specified by the operator.

8.6.6 Manual Control: The operator shall be able to execute the following functions during test:

8.6.6.1 Change Test Level: Increase (decrease) output level to the next (previous) programmed step.

8.6.6.2 Stop: Stop the test sequence and wait for operator direction

8.6.6.3 Resume: Proceed with the test from the point where it was stopped.

8.6.6.4 Transfer Function Update: Provide the operator the option of using synthesized pulses to equalize the system. The system shall also update the system transfer functions during test execution after each of the output pulses.

8.7 Random on Random

8.7.1 Broadband Random: The broadband random shall meet the specifications outlined in paragraph 8.4, Random Vibration Control.

8.7.2 Narrow-Band Random Definition: The narrow bands shall be definable either as multiple-line bands or single-line bands. A band as used here refers to a single filter bandwidth of the broadband random signal. Narrow bands shall be defined as constant acceleration in G2/Hz or peak G's and true random or pseudo-random.

8.7.3 Number of Narrow-Band Random Bands: The system shall superimpose up to six narrow-band random signals on a broadband random signal.

8.7.4 Narrow-Band Random Superimposed: The narrow-band random signals shall be superimposed on the broadband random in either a sum of spectra or maximum of spectra combination.

8.7.5 Narrow-Band Random Sweep: The system shall be able to sweep the narrow-band random signals across the frequency band of the broadband random. The sweep rates shall be defined in Hz per second or Octaves per minute. The system shall permit the operator to input the number of sweeps, the initial sweep direction and frequency, and the frequency band(s) to be swept as part of the test setup.

8.7.6 Narrow-Band Random Cycling: The system shall automatically turn the narrow-band random bands on and off. Turn on and turn off shall be in terms of operator specified number of control loops on and number of loops off. This feature shall be operator selectable and shall include an initial start time and a stop time for each band. Start and stop times shall be relative to start of test.

8.8 Sine on Random

8.8.1 Broadband Random: The broadband random shall be as defined in and shall meet the specifications outlined in paragraph 8.4, Random Vibration Control.

8.8.2 Number of Sines: The system shall superimpose up to six swept sines on a broadband random signal.

8.8.3 Sine Levels: The sines shall be superimposed on the broadband random as a maximum Gpk level. Frequency band, start frequency, initial sweep direction, sweep rate, and levels of each sine shall be individually defined.

8.8.4 Sine Sweeps: The system shall be able to sweep the sines across the frequency band of the broadband random. Initial frequencies, sweep band(s) frequency limits, and initial sweep direction shall be operator selectable.

8.8.5 Sweep Rates: The sweep rates shall be defined as either Hz per second or Octaves per minute.

8.8.6 Sine Cycling: The system shall automatically turn the sines on and off. Turn on and turn off shall be in terms of operator specified number of cycles on and number of cycles off. This feature shall be operator selectable and shall include a start time and stop time for each band. Start and stop times shall be relative to the start of the test.

8.9 Time Waveform Replication

8.9.1 Waveform Duration: The system shall be capable of replicating user selected time history waveforms of arbitrary length (limited to hard disk storage capacity).

8.10 Waveform Synthesis

8.10.1 The system shall include a waveform synthesis utility that allows the operator to synthesize all common classical waveforms to include but not limited to:

8.10.1.1 MIMO random

8.10.1.2 MIMO sine

8.10.1.3 MIMO shock

8.10.1.4 MIMO random on random (sweeping narrowbands)

8.10.2 It shall allow the user to specify the phase, coherence and spectral shapes

9 Transient Capture

9.1 The Transient Capture program shall have the ability to acquire data from a real-world transient time signal, and to convert the signal to a form that can be used as a reference pulse waveform. This transient signal capture capability should be able to be used for the following events:

9.2 To capture “live” data produced during a test where the data is generated in real time.

9.3 Features

9.3.1 Trigger Source: Shall be selectable as any active channel, or digital trigger, or none (free run, un-triggered data acquisition).

9.3.2 Trigger Level: Shall be selectable from -100% to 100% of the full-scale voltage range.

9.3.3 Trigger Slope: Shall be selectable as positive, negative or either positive or negative.

10 Software Utilities

10.1 Calibration Routines: The system shall include calibration routines that shall provide calibration capability with the calibration traceable to National Institute of Standards and Technology (NIST) standards. At a minimum, these routines shall provide calibration of the DACs, ADCs, analog filters, and other applicable components in the system. This routine shall provide a conversational mode of operation that leads the operator through a step by step calibration routine by providing operator oriented prompts, accepting credible inputs, and reporting system actions.

11 System Safety

11.1 Shaker Test Parameter Limits

11.1.1 It shall be required to define and edit system level shaker limits tables that can be easily accessed and used by any application program test setup. Each application program shall cross check the test reference dynamic limits against the shaker limits and prohibit test execution if any shaker limit parameter is exceeded. This feature shall be capable of being enabled or disabled by the operator. Each table shall allow the user to define:

11.1.1.1 Shaker description text label

11.1.1.2 Positive and negative maximum acceleration values

11.1.1.3 Positive and negative maximum velocity values

11.1.1.4 Positive and negative maximum displacement values

11.1.1.5 Positive and negative maximum voltage values

11.1.1.6 Specification of either Metric or English units

11.2 Pre-Test Validation

11.2.1 Instrumentation: A method for checking out the integrity and operation of each instrumentation channel shall be provided by a “scope-mode” type function, to enable the operator to visually verify the end-to-end condition of the test setup. The system should also automatically check each channel and display the status and/or errors to the operator.

11.3 Test Signal Drive Output and Abort

11.3.1 Drive output signal shall be “clamped” prior to and directly after execution of selecting the test run function to avoid any spurious signals or transient being introduced to the Power Amplifier and in turn to the Shaker and Item under test.

11.3.2. In addition to the normal operator Test Start/Abort features, the system shall provide the electrical input for an emergency stop switch. When the switch is activated, the system shall perform a controlled shutdown of all vibration.

12 Data Storage

12.1 In general, data acquired in its raw form during testing shall be stored in a fashion that makes it available in digital form for use by applications software other than Closed Loop Control software. Independent analysis software shall be able to import or otherwise read the raw data with the intent to perform data reduction and analysis other than what was performed by the originating application software.

12.2 File Conversion and Data Output

12.2.1 Recorded data shall be converted to at least the following:

12.2.1.1 ASCII

12.2.1.2 Universal File Format (UFF)

12.2.1.3 MatLab Binary (preferred but not required)

12.3 Reduced Data Output

12.3.1. Data plots created by the system shall be exportable in the .pdf, .jpg, or Word format at a minimum.