PPOD User Guide - Revision history

Philip Dames at 20:05, 14 September 2009

2009-09-14T20:05:42Z

Philip Dames at 19:49, 14 September 2009

2009-09-14T19:49:45Z

Philip Dames at 17:28, 14 September 2009

2009-09-14T17:28:19Z

Philip Dames at 17:13, 14 September 2009

2009-09-14T17:13:07Z

Show changes

Philip Dames at 21:30, 11 September 2009

2009-09-11T21:30:23Z

Philip Dames at 21:23, 11 September 2009

2009-09-11T21:23:38Z

Philip Dames at 17:30, 11 September 2009

2009-09-11T17:30:04Z

Philip Dames at 16:45, 11 September 2009

2009-09-11T16:45:33Z

Philip Dames at 15:50, 11 September 2009

2009-09-11T15:50:02Z

Philip Dames at 15:41, 11 September 2009

2009-09-11T15:41:03Z

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 * If one or more signals are zero, or the signals do not match the plate motions then there may be a problem with the speaker/accelerometer connections.  Check the connections on the back on the amplifiers.  CH 1 input corresponds to Channel A output, and CH 2 with Channel B.  Ex. Channel 1 leading out from the DAQ board should connect to CH 1 of the bottom amplifier and the leading out of Channel A should connect to the screw terminal labeled Speaker 1 on the accelerometer board.  Accelerometer 1 should be found above Speaker 1, Accelerometer 2 should be found above Speaker 2, etc on the PPOD.  The pins on the accelerometers plug into the holes on the ribbon cable sockets that are closest to the end of the cable.  As a last resort, check the MATLAB function L2Wconverter.m to ensure that the accelerometer locations in the function correspond to the actual locations on the plate.
-= Source Code =
+= Code =
 [[Media:PPOD_6D.zip]]

@@ Line 129: / Line 129: @@
 = Troubleshooting =
-If the PPOD is not performing properly, the following steps should followed to ensure everything is set up correctly.  There are a number of simple steps outlined below that fix most of the problems encountered during use of the PPOD.  If problems persist, a more in-depth examination of the code and/or physical setup is needed and is out of the scope of this tutorial.
+If the PPOD is not performing properly, the following steps should followed to ensure everything is set up correctly.  There are a number of simple steps outlined below that fix most of the problems encountered during use of the PPOD.  If problems persist, a more in-depth examination of the code and/or physical setup is needed and is beyond the scope of this tutorial.
+* Check if any of the tensioning springs are loose.  Check the flexures to ensure that they are screwed in properly, that the glue holding the flexures in place has not broken, and that there are no signs of buckling, fatigue, or other failure visually apparent in any flexures (this is likely an issue if one control signal is significantly larger than the others).  Replace flexures as necessary (best to replace all at once).  When changing flexures, sometimes it is necessary to rotate an actuator slightly to keep the flexure aligned.  To do this, loosen the bolts found on the underside of the base below the desired actuator.  Most of these mechanical problems will show up as rattling noises and difficulty controlling.  These are the first things to check and are the most likely sources of problems.
-== Power ==
+* Visually inspect the system to ensure that everything is connected properly and powered.  Take care to look at the actuator/accelerometer board as the wires can break off in the screw terminals.  If you forget to turn the amplifiers on before starting the PPOD, make sure to stop the PPOD before turning them on.  DO NOT USE THE PREVIOUS SIGNALS as they may have grown greatly to try to achieve the desired plate motion.  If the signals are not reset and are used to run the PPOD it may damage the system.
-If the control/accleration signals are zero or the plate is having difficulty controlling then there may be a problem with the power.  Ensure all of the amplifiers and the DAQ board are turned on and have power.  Check to see if all the amplifiers are set to the same gain (+8 dB has been found to work well, though any value that will not overload the actuators should work).
+* Check the amplifiers to make sure they are at the correct gain.  The lower two amplifiers should be set to +8 and the top amplifier set to +11 for channel 1 and +13 for channel 2 for the output voltages to be the same.  These numbers can be easily checked/calibrated with the User Specified Control Signals and an oscilloscope.  This can lead to difficulty controlling the system.
-== Mechanical Connections ==
+* If the PPOD fails to start and there is a MATLAB error about the DAQ boards, there may be a problem with the DAQ initialization in MATLAB.  This can be a problem if there have been any hardware changes recently.  To fix this use the daqhwinfo('nidaq') command from above and check that the BoardNames and InstalledBoardIds in the output structure against those specified in the file Initializedaqinfo.m.  These are found in the handles.daqinfo.ai and handles.daqinfo.ao objects, set in lines 25-26.  Output channels should be 0:6 (0 is the clock pulse, 1:6 are speaker channels) set in line 36.  Input channels should be 0:11 (for the 12 accelerometer signals) set in line 39.
-If one or two control signals are saturating, or the PPOD is rattling then there may be a problem with the mechanical connections.  Manually inspect the flexures for signs of buckling, kinking, or misalignment.  If necessary, replace damaged felxures using Tygon tubing and metal bonding epoxy.  When changing flexures, sometimes it is necessary to rotate an actuator slightly to keep the flexure aligned.  To do this, loosen the bolts found on the underside of the base below the desired actuator.  Check the set screws on the plate and actuators that hold the flexures in place.  Check the springs to make sure they are tensioned approximately evenly.
+* If one or more signals are zero, or the signals do not match the plate motions then there may be a problem with the speaker/accelerometer connections.  Check the connections on the back on the amplifiers.  CH 1 input corresponds to Channel A output, and CH 2 with Channel B.  Ex. Channel 1 leading out from the DAQ board should connect to CH 1 of the bottom amplifier and the leading out of Channel A should connect to the screw terminal labeled Speaker 1 on the accelerometer board.  Accelerometer 1 should be found above Speaker 1, Accelerometer 2 should be found above Speaker 2, etc on the PPOD.  The pins on the accelerometers plug into the holes on the ribbon cable sockets that are closest to the end of the cable.  As a last resort, check the MATLAB function L2Wconverter.m to ensure that the accelerometer locations in the function correspond to the actual locations on the plate.
-== DAQ Initialization ==
-If the PPOD will not function at all or the signals do not match the plate motions then there may be a problem with the DAQ initialization/setup in MATLAB.  The BoardNames match up with the respective InstalledBoardIds in the output structure.  If the PPOD does not work, ensure that the DAQ objects were initialized properly by comparing the 'DevX'  from above with the handles.daqinfo.ai and handles.daqinfo.ao object in the Initializedaqinfo.m file, set in lines 25-26.  Output channels should be 0:6 (0 is the clock pulse, 1:6 are speaker channels) set in line 36.  Input channels should be 0:11 (for the 12 accelerometer signals) set in line 39.
-== Speaker/Accelerometer Connections ==
-If one or more signals are zero, or the signals do not match the plate motions then there may be a problem with the speaker/accelerometer connections.  Check the connections on the back on the amplifiers.  CH 1 input corresponds to Channel A output, and CH 2 with Channel B.  Ex. Channel 1 leading out from the DAQ board should connect to CH 1 of the bottom amplifier and the leading out of Channel A should connect to the screw terminal labeled Speaker 1 on the accelerometer board.  Accelerometer 1 should be found above Speaker 1, Accelerometer 2 should be found above Speaker 2, etc on the PPOD.  The pins on the accelerometers plug into the holes on the ribbon cable sockets that are closest to the end of the cable.  Check the MATLAB function L2Wconverter.m to ensure that the accelerometer locations in the function correspond to the actual locations on the plate.
-== Other ==
-These steps should solve most problems encountered during normal use of the PPOD.
 = Source Code =

@@ Line 120: / Line 120: @@
 <br clear=all>
-# Importing Data - Select the parameters that you would like the program to fit to the data.  If any of the boxes are unchecked then another GUI will appear prompting the user to input the actual values.  Leaving an entry as NaN will fit that parameter, Zeros will set all values to 0, Import allows you to import the values from a previous fit, and Done accepts the values and continues the program.  To begin, press the Import Data button in the bottom center of the screen.
+# Importing Data - Select the parameters (mass, damping, spring constants) that you would like the program to fit to the data.  If any of the boxes are unchecked then another GUI will appear prompting you to input values.  Leaving an entry as NaN will fit that parameter, Zeros will set all values to 0, Import allows you to import the values from a previous saved fit, and Done accepts the values and advances the program.  To begin, press the Import Data button in the bottom center of the screen.
-# Plot Options - On the left side of the GUI, there are several options for the user.  There are two types of plots: FFT and Bode plots.  More details about these can be found below.  The y-scale can either be linear (Force in Newtons) or logarithmic (dB).  The frequency can either be in Hz or rad/s.  The other options are for changing the inputs/outputs being plotted.  The upper box is for a single input to all of the outputs and the lower box is for all of the inputs to a single output.
+# Plot Options - On the left side of the GUI, there are several options for the user.  There are two types of plots: FFT and Bode plots.  More details about these can be found below.  The y-scale can either be linear (Force in Newtons) or logarithmic (dB).  The frequency can either be in Hz or rad/s.  The other options are for changing the inputs/output set to plot.  The upper box is for a single input to all of the outputs and the lower box is for all of the inputs to a single output.
-#* FFT Plots - This option displays the fast Fourier transform of the chosen input/output signals on the upper row of plots, with a legend showing the frequencies in the lower left plot.  The options for the FFT plots are found in the lower left corner.  Users can select the frequencies to plot as well as the number of harmonics of each frequency to plot.  The x-scale can be switched between harmonic and actual frequency.  Ideally all harmonics that are not the first should be zero.
+#* [http://en.wikipedia.org/wiki/Fft FFT Plots] - This option displays the fast Fourier transform of the chosen input/output signals on the upper row of plots, with a legend showing the frequencies in the lower left plot.  The options for the FFT plots are found in the lower left corner.  You can set the frequencies to plot as well as the number of harmonics of base frequency to plot.  The x-scale can be switched between harmonic and absolute frequency.  Ideally all harmonics that are not the first should be zero (all other signals are noise).
-#* Bode Plots - This option displays the Bode plots of the chosen input/output signal.  Each plot shows the data as points and the best fit model as a solid line.
+#* [http://en.wikipedia.org/wiki/Bode_plots Bode Plots] - Th-is option displays the Bode plots of the chosen input/output signal.  Each plot shows the data as points and the best fit model as a solid line.
-# Flexure Parameters - This button opens a new window displaying the fit (or input) mass, damping, and spring coefficients for the flexure being tested.  The button at the bottom of the window saves the three matrices to the base MATLAB workspace.
+# Flexure Parameters - This button opens a new window displaying the fit (or input) mass, damping, and spring coefficients for the flexure being tested.  Save the three matrices to the base MATLAB workspace using the button at the bottom of the window.
-# Export Options - Export Handles will save the handles structure to the base MATLAB workspace.  Save Handles will save the handles structure to a .mat file in the location chosen.
+# Export Options - Export Handles will save the handles structure to the base MATLAB workspace.  Save Handles will save the handles structure to a .mat file in the location chosen for future use.
 = Troubleshooting =
-If the PPOD is not performing properly, the following steps should followed to ensure everything is set up correctly.
+If the PPOD is not performing properly, the following steps should followed to ensure everything is set up correctly.  There are a number of simple steps outlined below that fix most of the problems encountered during use of the PPOD.  If problems persist, a more in-depth examination of the code and/or physical setup is needed and is out of the scope of this tutorial.
 == Power ==
@@ Line 149: / Line 149: @@
 == Other ==
-These steps should solve most problems encountered during normal use of the PPOD.  If problems persist, it may require a more in-depth examination of the code and/or physical setup.
+These steps should solve most problems encountered during normal use of the PPOD.
 = Source Code =

@@ Line 87: / Line 87: @@
 * Max Number of Updates - The number of controller updates per frequency in the sweep.  Increase from the default if the frequency sweep is coarse (<math>\ge</math>3 Hz between steps).  For each sweep the controller will use a frequency response-based guess for the first frequency then use the previous signal for all subsequent frequencies so small steps are recommended between frequencies to allow the controller to reach steady state.
 * Plate Motion
-** f - A matrix of the frequencies to sweep through.
+** f - A matrix of the frequencies to sweep through when testing the flexure.
 ** A - The upper box is a 1x3 matrix of the magnitude of the linear accelerations and the lower box is a 1x3 matrix of the angular accelerations to use in the frequency sweep.  Decrease these values for stiff materials as the plate motion is more difficult to control and large forces may damage the [[Flexure Characterization and Design#Hardware|force sensor]].
 * Plate Frequency Response - This functions the same as [[#Controller Parameters | above]].  If the run button is pressed and the previous frequency response does not include all the sweep frequencies and their harmonics, it will prompt the user to generate a new plate frequency response.
 * Flexure Frequency Response - This runs the flexure test.  From past experience, a sweep of frequencies from 15 - 60 Hz will capture most of the important flexure response.  Most sweeps do not make it past 40 - 45 Hz.
 * Force Signals - These are plots of the forces being read by the force sensor.  Typically there is a lot of high frequency noise in the signals on the scale of 0.5 V.
+Further information can be found in the article [[Flexure Characterization and Design]].
 = Flexure Analysis =
@@ Line 128: / Line 130: @@
 These steps should solve most problems encountered during normal use of the PPOD.  If problems persist, it may require a more in-depth examination of the code and/or physical setup.
+= Source Code =
+[[Media:PPOD_6D.zip]]
+[[Media:Flexure_Test.zip]]
+[[Media:Flexure_Analysis.zip]]

@@ Line 89: / Line 89: @@
 ** f - A matrix of the frequencies to sweep through.
 ** A - The upper box is a 1x3 matrix of the magnitude of the linear accelerations and the lower box is a 1x3 matrix of the angular accelerations to use in the frequency sweep.  Decrease these values for stiff materials as the plate motion is more difficult to control and large forces may damage the [[Flexure Characterization and Design#Hardware|force sensor]].
+* Plate Frequency Response - This functions the same as [[#Controller Parameters | above]].  If the run button is pressed and the previous frequency response does not include all the sweep frequencies and their harmonics, it will prompt the user to generate a new plate frequency response.
-* Plate Frequency Response -
+* Flexure Frequency Response - This runs the flexure test.  From past experience, a sweep of frequencies from 15 - 60 Hz will capture most of the important flexure response.  Most sweeps do not make it past 40 - 45 Hz.
-* Flexure Frequency Response -
+* Force Signals - These are plots of the forces being read by the force sensor.  Typically there is a lot of high frequency noise in the signals on the scale of 0.5 V.
-* Force Signals -
 = Flexure Analysis =

@@ Line 76: / Line 76: @@
 # Place end of flexure into force sensor mount, tighten with hex key.  Place plate flush with T-bar, if necessary use shims or angle brackets to place flexure in desired orientation.  Attach to T-bar using C-clamps.
-== GUI ==
+== Program ==
+The Flexure_GUI.m program uses the PPOD to generate a response of a flexure at user-specified frequencies.  It actuates along each of the 6 degrees of freedom, sweeping through all frequencies in one direction before moving on to the next, and saves the data to the handles data structure.  Below is a picture of the user interface and an explanation of each component
 [[image:Flexure_GUI.png|thumb|left|800px|Flexure_GUI]]
 <br clear=all>
+* Controller Parameters, Actuator and Plate Signal plots - These are the same as [[#Plate Motion | above]].
 = Flexure Analysis =

@@ Line 68: / Line 68: @@
 == Flexure Setup ==
-[[image:Flexure_setup.jpg|thumb|left|800px|Flexure_GUI]]
+[[image:Flexure_setup.jpg|thumb|left|800px|Flexure Testing Setup]]
 <br clear=all>