acquire data from an accelerometer -凯发k8网页登录

this example shows how to acquire and display data from an accelerometer attached to a vehicle driven under uneven road conditions.

discover devices that support accelerometers

to discover a device that supports accelerometers, access the device in the table returned by the daqlist command. this example uses national instruments® compactdaq chassis ni cdaq-9178 and module ni 9234 with id cdaq1mod3.

d = daqlist("ni")

d =
  12×4 table
     deviceid                 description                    model             deviceinfo     
    ___________    __________________________________    _____________    ____________________
    "cdaq1mod1"    "national instruments ni 9205"        "ni 9205"        [1×1 daq.deviceinfo]
    "cdaq1mod2"    "national instruments ni 9263"        "ni 9263"        [1×1 daq.deviceinfo]
    "cdaq1mod3"    "national instruments ni 9234"        "ni 9234"        [1×1 daq.deviceinfo]
    "cdaq1mod4"    "national instruments ni 9201"        "ni 9201"        [1×1 daq.deviceinfo]
    "cdaq1mod5"    "national instruments ni 9402"        "ni 9402"        [1×1 daq.deviceinfo]
    "cdaq1mod6"    "national instruments ni 9213"        "ni 9213"        [1×1 daq.deviceinfo]
    "cdaq1mod7"    "national instruments ni 9219"        "ni 9219"        [1×1 daq.deviceinfo]
    "cdaq1mod8"    "national instruments ni 9265"        "ni 9265"        [1×1 daq.deviceinfo]
    "dev1"         "national instruments pcie-6363"      "pcie-6363"      [1×1 daq.deviceinfo]
    "dev2"         "national instruments ni elvis ii"    "ni elvis ii"    [1×1 daq.deviceinfo]
    "dev3"         "national instruments pcie-6363"      "pcie-6363"      [1×1 daq.deviceinfo]
    "dev4"         "national instruments pcie-6363"      "pcie-6363"      [1×1 daq.deviceinfo]

deviceinfo = d{3, "deviceinfo"}

deviceinfo = 
ni: national instruments ni 9234 (device id: 'cdaq1mod3')
   analog input supports:
      -5.0 to  5.0 volts range
      rates from 1000.0 to 51200.0 scans/sec
      4 channels ('ai0','ai1','ai2','ai3')
      'voltage','accelerometer','microphone','iepe' measurement types
   
this module is in slot 3 of the 'cdaq-9178' chassis with the name 'cdaq1'.

add an accelerometer channel

create a dataacquisition, and add an analog input channel with accelerometer measurement type.

dq = daq("ni");
ch = addinput(dq, "cdaq1mod3", "ai0", "accelerometer");

set the scan rate

change the acquisition scan rate to 4000 scans per second.

dq.rate = 4000;

set the sensitivity

you must set the sensitivity value to the value specified in the accelerometer's data sheet. this example uses a ceramic shear accelerometer model 352c22 from pcb piezotronics with 9.22 mv per gravity.

ch.sensitivity = 0.00922;
ch

ch = 
    index    type      device       channel       measurement type              range                 name      
    _____    ____    ___________    _______    ______________________    ____________________    _______________
      1      "ai"    "cdaq1mod3"     "ai0"     "accelerometer (diff)"    "-5.0 to  5.0 volts"    "cdaq1mod3_ai0"

acquire and plot data

use the read command to acquire data for 30 seconds.

data = read(dq, seconds(30));
plot(data.time, data.cdaq1mod3_ai0);
ylabel("acceleration (gravities)");