add GM

selfdrive/car/gm/interface.py

@@ -2,14 +2,18 @@
 from cereal import car
 from selfdrive.config import Conversions as CV
 from selfdrive.car.gm.values import CAR, CruiseButtons, \
-                                    AccState
+                                    AccState, CarControllerParams
 from selfdrive.car import STD_CARGO_KG, scale_rot_inertia, scale_tire_stiffness, gen_empty_fingerprint
 from selfdrive.car.interfaces import CarInterfaceBase
 
 ButtonType = car.CarState.ButtonEvent.Type
 EventName = car.CarEvent.EventName
 
 class CarInterface(CarInterfaceBase):
+  @staticmethod
+  def get_pid_accel_limits(current_speed, cruise_speed):
+    params = CarControllerParams()
+    return params.ACCEL_MIN, params.ACCEL_MAX
 
   @staticmethod
   def get_params(candidate, fingerprint=gen_empty_fingerprint(), car_fw=None):

selfdrive/car/gm/values.py

@@ -25,10 +25,20 @@ def __init__(self):
     MAX_GAS = 3072              # Only a safety limit
     ZERO_GAS = 2048
     MAX_BRAKE = 350             # Should be around 3.5m/s^2, including regen
+
+    self.ACCEL_MAX = 2.0 # m/s^2
+
+    # Allow small margin below -3.5 m/s^2 from ISO 15622:2018 since we
+    # perform the closed loop control, and might need some
+    # to apply some more braking if we're on a downhill slope.
+    # Our controller should still keep the 2 second average above
+    # -3.5 m/s^2 as per planner limits
+    self.ACCEL_MIN = -4.0 # m/s^2
+
     self.MAX_ACC_REGEN = 1404  # ACC Regen braking is slightly less powerful than max regen paddle
     self.GAS_LOOKUP_BP = [-1.0, 0., 2.0]
     self.GAS_LOOKUP_V = [self.MAX_ACC_REGEN, ZERO_GAS, MAX_GAS]
-    self.BRAKE_LOOKUP_BP = [-4., -1.0]
+    self.BRAKE_LOOKUP_BP = [self.ACCEL_MIN, -1.0]
     self.BRAKE_LOOKUP_V = [MAX_BRAKE, 0]
 
 class CAR: