[Lateral PID] Function for steer feedforward (#22638)

* store a function for steer feedforward

* use classmethod

Co-authored-by: Willem Melching <willem.melching@gmail.com>

selfdrive/car/interfaces.py

@@ -57,11 +57,15 @@ class CarInterfaceBase():
     pass
 
   @staticmethod
-  def get_steer_feedforward(desired_angle, v_ego):
+  def get_steer_feedforward_default(desired_angle, v_ego):
     # Proportional to realigning tire momentum: lateral acceleration.
     # TODO: something with lateralPlan.curvatureRates
     return desired_angle * (v_ego**2)
 
+  @classmethod
+  def get_steer_feedforward_function(cls):
+    return cls.get_steer_feedforward_default
+
   # returns a set of default params to avoid repetition in car specific params
   @staticmethod
   def get_std_params(candidate, fingerprint):

selfdrive/controls/lib/latcontrol_pid.py

@@ -11,7 +11,7 @@ class LatControlPID():
                             (CP.lateralTuning.pid.kiBP, CP.lateralTuning.pid.kiV),
                             k_f=CP.lateralTuning.pid.kf, pos_limit=1.0, neg_limit=-1.0,
                             sat_limit=CP.steerLimitTimer)
-    self.get_steer_feedforward = CI.get_steer_feedforward
+    self.get_steer_feedforward = CI.get_steer_feedforward_function()
 
   def reset(self):
     self.pid.reset()