how to plot theta with a peak value

[isso]

hi

i'm new to LabView and i'm building a system using 2 force (load cell) sensors to measure a peak value that happens at a certain Theta (which is measured by an incremental encoder maunted on a rotating shaft )

my problem is how to measure this peak value with it's certain Theta...

another question....

i'm controlling the speed of the rotating shaft but i dont really have an idea how to do such thing using the LabView,i simulated the system with MathLab and i found it's best using a PI controller.

i got the speed of the rotating shaft measured also it's position(theta)

i'm using LabView 8.5&Sound And Vibration ToolKit using a M series Daq USB 6210 and an incremental encoder with 1000 pulse resolution per cycle.

thanks in advance

[Nathan_R]

Hi isso,

It sounds like you may want to synchronize the encoder measurements with your load cell measurements. This will let you have a theta value for each load cell value. This can be accomplished by buffering the angular position measurements using the same sample clock as the load cell measurements. The example VI Meas Angular Position-Buffered-Cont-Ext Clk.vi shows how to setup a buffered continuous angular measurement. This example can be found in the NI Example Finder. In LabVIEW go to Help >> Find Examples… >> Hardware Input and Output >> DAQmx >> Counter Measurements >> Position >> Meas Angular Position-Buffered-Cont-Ext Clk.vi. Once you integrate this example code with your load cell measurement code the external sample clock will be specified as the AI Sample clock such as “/Dev1/ai/SampleClock”.  Then to make sure they are synchronized start the encoder task before the load cell task. Please let me know if you have any questions and take care.

Thanks,