From 88f5e45844e1a18531e54145ae05d9ccd3669ae5 Mon Sep 17 00:00:00 2001
From: bijoua29 <73511637+bijoua29@users.noreply.github.com>
Date: Thu, 16 Oct 2025 09:54:11 -0700
Subject: [PATCH] Fix calculation of tracking time constant (#511)

(cherry picked from commit 618c96174f544147eefb279e1b1047960fb518cf)
---
 control_toolbox/src/pid.cpp | 8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)

diff --git a/control_toolbox/src/pid.cpp b/control_toolbox/src/pid.cpp
index 306b9991..7db7ecbc 100644
--- a/control_toolbox/src/pid.cpp
+++ b/control_toolbox/src/pid.cpp
@@ -161,12 +161,16 @@ bool Pid::set_gains(const Gains & gains_in)
 
     if (gains.antiwindup_strat_.type == AntiWindupStrategy::BACK_CALCULATION)
     {
-      if (is_zero(gains.antiwindup_strat_.tracking_time_constant) && !is_zero(gains.d_gain_))
+      if (
+        is_zero(gains.antiwindup_strat_.tracking_time_constant) && !is_zero(gains.d_gain_) &&
+        !is_zero(gains.i_gain_))
       {
         // Default value for tracking time constant for back calculation technique
         gains.antiwindup_strat_.tracking_time_constant = std::sqrt(gains.d_gain_ / gains.i_gain_);
       }
-      else if (is_zero(gains.antiwindup_strat_.tracking_time_constant) && is_zero(gains.d_gain_))
+      else if (
+        is_zero(gains.antiwindup_strat_.tracking_time_constant) && is_zero(gains.d_gain_) &&
+        !is_zero(gains.i_gain_))
       {
         // Default value for tracking time constant for back calculation technique
         gains.antiwindup_strat_.tracking_time_constant = gains.p_gain_ / gains.i_gain_;