Calibrating the MotoTrak Isometric Pull Module

  1. First, if you are using Version 2.0 of the MotoTrak software, the Pull Calibration function is built into the main MotoTrak program, and you can skip to Step 2. Iif you are using Version 1.1 of the MotoTrak software and have not already downloaded the Isometric Pull calibration standalone program, you can download it from the following link:

http://www.vulintus.com/downloads/MotoTrak_Pull_Calibration_Web_Installer.exe

  1. Follow the prompts to install the program.

  1. To begin, after installing the calibration program, remove the pull module from the main cage assembly by using the hand crank or autopositioner to move the module to the end of the positioner rail.

  1. If the pull module is unplugged from the controller, plug it back in with the usual mini-DIN8 cable.

  1. In your MotoTrak program folder, find the program called “MotoTrak_Pull_Calibration.exe” and double-click it to run it (it may take several seconds to start up).

  1. If you have more than one MotoTrak system, select the USB COM port corresponding to the system you want to calibrate.

  1. Hold the isometric pull module so that the handle hangs down vertically. Try to hold the module as level as you can. A helpful trick is to hold the module against the top of the cage to keep it level.

  1. While holding the pull module so that handle hangs down vertically, press the “0 gm (Re-baseline)” button on the pull calibration program.

  1. A prompt will come up to say that a baseline is being established. Try to hold the module steady for several seconds while the baseline is measured. The program will say “thank you” when the measurement is finished.

  1. By default, the program counts down to the measurement to allow you time to move between the computer and the module if the two are far apart. However, you can skip the countdown to make the process quicker by pressing the “Countdown On” button, after which it should read “Countdown Off”.

  1. At this point you might see that there are now 2 lines on the calibration program. The blue line shows the original calibration function, and the black line shows the new calibration function. The calibration of the force sensor is linear, so we only need to determine 2 coefficients. The first coefficient is the baseline (or y-intercept), which is what we just measured. Next we’ll measure the second coefficient, the slope of the calibration function.

  1. Next, find the hanging calibration weights that were provided with your pull module, and create a stack weighing 50 gm, if the system is set up for mice, or 250 gm, if the system is set up for rats.
  1. MICE = 50 gm
  2. RATS = 250 gm

  1. Now hang the specified weight from the handle of the pull module, while keeping the module level and horizontal. Again, it’s helpful to use the top of the cage or some other horizontal surface.

  1. With the specified weight hanging from the pull module handle, click the button corresponding to the specified weight on the calibration program. You should see that the signal from the module is showing an increased weight, although that weight will likely be incorrect since the calibration is not yet set.

  1. After the button is pressed, a prompt will again come up to say that a baseline is being established. Try to hold the module steady for several seconds while the baseline is measured. The program will say “thank you” when the measurement is finished. You may now see that slope of the current calibration function differs from the slope of the original calibration function. If your lines aren’t too far apart, that’s good! That means the calibration wasn’t far off to begin with.

  1. (OPTIONAL) Typically, one baseline measurement and one weighted measurement are all you need to establish a good calibration function. If you want to test the measured function, however, you can add or remove weight from the calibration weight stack and hang it from the handle of the pull module as before.

  1. (OPTIONAL) If you want to measure the calibration function slope coefficient at multiple weights, you can click the corresponding weight buttons on the programs as many times as you like. After each measurement, it will add a datapoint to the calibration function plot, and will compute the slope coefficient from an average of the values. You should see that all the new points more or less fall along the same line.

  1. Now that the calibration function slope coefficient has been measured, we actually need to re-measure the baseline (or y-intercept) coefficient with the pull module placed back on the cage in the upright position. This is because the handle itself applies a weight to the force sensor when it’s held in the horizontal positioner. Re-measuring the baseline in the upright position will ensure that the force sensor is only measuring force applied to it. First, we’ll put the pull module back on the main cage. It’s okay if you need to unplug the mini-DIN cable from the module to do this, but plug it back in before continuing.

  1. With the module returned to the main cage, and with nothing leaning or pressing against it, press the “0 gm (Re-baseline)” button on the calibration program.

  1. One last time a prompt will come up to say that a baseline is being established. Try not to bump the cage as the baseline is re-measured. When the program says “thank you”, the measurement is finished. The calibration function is now set, but it hasn’t been saved. To save the calibration function to the controller, press the “SAVE CALIBRATION” button on the calibration program.

  1. When you save the new calibration function, you’ll see the previous calibration function disappear. Good job! Your pull module is calibrated and you’re ready to go. Close the pull calibration and start up MotoTrak to run the behavior.