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--- visual3d:documentation:pipeline:force_commands:fp_zero [2026/06/05 19:57] – Cleaned up formatting and updated section headers. wikisysop
+++ visual3d:documentation:pipeline:force_commands:fp_zero [2026/06/09 20:38] (current) – wikisysop
@@ Line 9: / Line 9: @@
   * select frames in which the force platform is unloaded.
-In some cases it is not feasible to use the ZERO parameter to define a BASELINE for each signal. All force platform signals have some drift in the amplifiers, so it isn't a good idea to simply set the ZERO parameter to 0,0 so that no baseline is subtracted. The following three examples demonstrate alternatives to using the ZERO parameter to remove a baseline. In each example the ZERO parameter is set to 0,0 so that no inadvertent baseline is removed:
+===== Modify_Force_Platform_Parameters =====
+The FP_ZERO parameter can be updated using the [[visual3d:documentation:pipeline:force_commands:modify_force_platform_parameters|Modify_Force_Platform_Parameters]] pipeline command and specifying the desired /FP_ZERO parameter. It can also be updated interactively using the [[visual3d:documentation:pipeline:force_commands:modify_force_platform_parameters#modify_force_platform_parameters_command_dialog|associated dialog]].
 <code>
@@ Line 19: / Line 21: @@
 </code>
-===== Example 1: Subtract the mean value for several frame ranges =====
+**NOTE**: The value specified for /FP_ZERO can be an expression.
+===== General Examples =====
+The following two examples are general examples for working with the ZERO parameter.
+==== Example 1: Using the last 10 frames for non-treadmill data ====
+For non-treadmill data we recommend that you choose the last 10 frames of the trial as almost every activity ends with the participant off of the force platform.
+<code>
+Modify_Force_Platform_Parameters
+/FP_USED=2
+/FP_ZERO=EOF-10+EOF
+/FP_ZEROS=EOF-10+EOF+EOF-10+EOF
+;
+</code>
+==== Example 2: Using COFP DATA_NOT_FOUND for Treadmill Trials ====
+Working with treadmill data, we suggest finding a period of time for each force platform where the [[visual3d:documentation:visual3d_signal_types:cofp_data_type|COFP]] signal is [[visual3d:documentation:c3d_signal_types:data_not_found|DATA_NOT_FOUND]] since this is a reliable indication that the force platform is unloaded and that these frames can be used as a baseline. This will likely have to be done manually per force platform and per file as your treadmill force platforms will likely have different loading and unloading patterns throughout the trials.
+===== Examples Removing Baselines without the ZERO Parameter =====
+In some cases it is not feasible to use the ZERO parameter to define a BASELINE for each signal. All force platform signals have some drift in the amplifiers, so it isn't a good idea to simply set the ZERO parameter to 0,0 so that no baseline is subtracted. The following three examples demonstrate alternatives to using the ZERO parameter to remove a baseline. In each example the ZERO parameter is set to 0,0 so that no inadvertent baseline is removed:
+==== Example 1: Subtract the mean value for several frame ranges ====
 This example demonstrates how to subtract the mean value from several ranges from each analog signal. Consider a subject running on an instrumented treadmill. The mean value of each ANALOG signal is determined when the subject is airborne (e.g. between LTO and RHS) and a collection of these airborne phases are averaged. This overall mean value is to be subtracted from each ANALOG signal. The option to use Processed Analog signals for the Force Platform calculations should be selected. The FORCE_PLATFORM:ZERO parameter is set to (0,0) because it is to be ignored.
@@ Line 88: / Line 117: @@
 </code>
-===== Example 2: Using Evaluate_Expression to subtract mean values from several frame ranges =====
+==== Example 2: Using Evaluate_Expression to subtract mean values from several frame ranges ====
 Again we will see how to subtract from each analog signal its mean value computed from several frame ranges; this time using Evaluate_Expression. Again we consider a subject running on an instrumented treadmill. The mean value of each ANALOG signal is determined when the subject is airborne (e.g. between LTO and RHS) and a collection of these airborne phases are averaged. This overall mean value is to be subtracted from each ANALOG signal. The option to use Processed Analog signals for the Force Platform calculations should be selected. The FORCE_PLATFORM:ZERO parameter is set to (0,0) because it is to be ignored.
@@ Line 149: / Line 178: @@
 </code>
-===== Example 3: Using mean values from another trial =====
+==== Example 3: Using mean values from another trial ====
 This example demonstrates how to compute mean values for the force platform analog signals in one trial, and then use these values in other trials. For this example assume that: