longitudinal comments (#21898)

* cmt

* Update longcontrol.py

selfdrive/controls/lib/longcontrol.py

@@ -72,7 +72,7 @@ class LongControl():
   def update(self, active, CS, CP, long_plan):
     """Update longitudinal control. This updates the state machine and runs a PID loop"""
     # Interp control trajectory
-    # TODO estimate car specific lag, use .5s for now
+    # TODO estimate car specific lag, use .15s for now
     if len(long_plan.speeds) == CONTROL_N:
       v_target = interp(DEFAULT_LONG_LAG, T_IDXS[:CONTROL_N], long_plan.speeds)
       v_target_future = long_plan.speeds[-1]

selfdrive/controls/lib/longitudinal_planner.py

@@ -105,7 +105,7 @@ class Planner():
     for key in self.mpcs:
       self.mpcs[key].set_cur_state(self.v_desired, self.a_desired)
       self.mpcs[key].update(sm['carState'], sm['radarState'], v_cruise)
-      if self.mpcs[key].status and self.mpcs[key].a_solution[5] < next_a:
+      if self.mpcs[key].status and self.mpcs[key].a_solution[5] < next_a:  # picks slowest solution from accel in ~0.2 seconds
         self.longitudinalPlanSource = key
         self.v_desired_trajectory = self.mpcs[key].v_solution[:CONTROL_N]
         self.a_desired_trajectory = self.mpcs[key].a_solution[:CONTROL_N]