Bolt EUV: Non-linear torque function (#27696)

* add erf based ff

* silly bug; diff of nonlinear != nonlinear of diff

* add sigmoid based ff, ensure slope at 0 > 1

* reduce steer down limit and increase driver allowance

* rebase panda

* atry without friction, and with tanh nonlinear

* finalize the nonlinear function

* do not disable friction compensation in the ff

* bump panda

* bump panda

* update refs

* update refs

* resolve comments

* Add type hints

---------

Co-authored-by: Adeeb Shihadeh <adeebshihadeh@gmail.com>
old-commit-hash: 15b880c0ea

panda

@@ -1 +1 @@
-Subproject commit db6c50cd09f773c231f962fc0e31b4612c572b08
+Subproject commit a1e1451d1c2f23b953d82eea7691a657c9a8a75a

selfdrive/car/gm/interface.py

@@ -1,13 +1,14 @@
 #!/usr/bin/env python3
 from cereal import car
-from math import fabs
+from math import fabs, exp
 from panda import Panda
 
 from common.conversions import Conversions as CV
 from selfdrive.car import STD_CARGO_KG, create_button_event, scale_tire_stiffness, get_safety_config
 from selfdrive.car.gm.radar_interface import RADAR_HEADER_MSG
 from selfdrive.car.gm.values import CAR, CruiseButtons, CarControllerParams, EV_CAR, CAMERA_ACC_CAR, CanBus
-from selfdrive.car.interfaces import CarInterfaceBase
+from selfdrive.car.interfaces import CarInterfaceBase, TorqueFromLateralAccelCallbackType, FRICTION_THRESHOLD
+from selfdrive.controls.lib.drive_helpers import get_friction
 
 ButtonType = car.CarState.ButtonEvent.Type
 EventName = car.CarEvent.EventName
@@ -44,6 +45,29 @@ class CarInterface(CarInterfaceBase):
     else:
       return CarInterfaceBase.get_steer_feedforward_default
 
+  @staticmethod
+  def torque_from_lateral_accel_bolt(lateral_accel_value: float, torque_params: car.CarParams.LateralTorqueTuning,
+                                     lateral_accel_error: float, lateral_accel_deadzone: float, friction_compensation: bool) -> float:
+    friction = get_friction(lateral_accel_error, lateral_accel_deadzone, FRICTION_THRESHOLD, torque_params, friction_compensation)
+
+    def sig(val):
+      return 1 / (1 + exp(-val)) - 0.5
+
+    # The "lat_accel vs torque" relationship is assumed to be the sum of "sigmoid + linear" curves
+    # An important thing to consider is that the slope at 0 should be > 0 (ideally >1)
+    # This has big effect on the stability about 0 (noise when going straight)
+    # ToDo: To generalize to other GMs, explore tanh function as the nonlinear
+    a, b, c, _ = [2.6531724862969748, 1.0, 0.1919764879840985, 0.009054123646805178]  # weights computed offline
+
+    steer_torque = (sig(lateral_accel_value * a) * b) + (lateral_accel_value * c)
+    return float(steer_torque) + friction
+
+  def torque_from_lateral_accel(self) -> TorqueFromLateralAccelCallbackType:
+    if self.CP.carFingerprint == CAR.BOLT_EUV:
+      return self.torque_from_lateral_accel_bolt
+    else:
+      return self.torque_from_lateral_accel_linear
+
   @staticmethod
   def _get_params(ret, candidate, fingerprint, car_fw, experimental_long):
     ret.carName = "gm"

selfdrive/car/gm/values.py

@@ -14,8 +14,8 @@ class CarControllerParams:
   STEER_STEP = 3  # Active control frames per command (~33hz)
   INACTIVE_STEER_STEP = 10  # Inactive control frames per command (10hz)
   STEER_DELTA_UP = 10  # Delta rates require review due to observed EPS weakness
-  STEER_DELTA_DOWN = 25
-  STEER_DRIVER_ALLOWANCE = 50
+  STEER_DELTA_DOWN = 15
+  STEER_DRIVER_ALLOWANCE = 65
   STEER_DRIVER_MULTIPLIER = 4
   STEER_DRIVER_FACTOR = 100
   NEAR_STOP_BRAKE_PHASE = 0.5  # m/s

selfdrive/car/interfaces.py

@@ -8,10 +8,10 @@ from cereal import car
 from common.basedir import BASEDIR
 from common.conversions import Conversions as CV
 from common.kalman.simple_kalman import KF1D
-from common.numpy_fast import clip, interp
+from common.numpy_fast import clip
 from common.realtime import DT_CTRL
 from selfdrive.car import apply_hysteresis, gen_empty_fingerprint, scale_rot_inertia, scale_tire_stiffness
-from selfdrive.controls.lib.drive_helpers import V_CRUISE_MAX, apply_center_deadzone
+from selfdrive.controls.lib.drive_helpers import V_CRUISE_MAX, get_friction
 from selfdrive.controls.lib.events import Events
 from selfdrive.controls.lib.vehicle_model import VehicleModel
 
@@ -131,15 +131,11 @@ class CarInterfaceBase(ABC):
     return self.get_steer_feedforward_default
 
   @staticmethod
-  def torque_from_lateral_accel_linear(lateral_accel_value, torque_params, lateral_accel_error, lateral_accel_deadzone, friction_compensation):
+  def torque_from_lateral_accel_linear(lateral_accel_value: float, torque_params: car.CarParams.LateralTorqueTuning,
+                                       lateral_accel_error: float, lateral_accel_deadzone: float, friction_compensation: bool) -> float:
     # The default is a linear relationship between torque and lateral acceleration (accounting for road roll and steering friction)
-    friction_interp = interp(
-      apply_center_deadzone(lateral_accel_error, lateral_accel_deadzone),
-      [-FRICTION_THRESHOLD, FRICTION_THRESHOLD],
-      [-torque_params.friction, torque_params.friction]
-    )
-    friction = friction_interp if friction_compensation else 0.0
-    return (lateral_accel_value / torque_params.latAccelFactor) + friction
+    friction = get_friction(lateral_accel_error, lateral_accel_deadzone, FRICTION_THRESHOLD, torque_params, friction_compensation)
+    return (lateral_accel_value / float(torque_params.latAccelFactor)) + friction
 
   def torque_from_lateral_accel(self) -> TorqueFromLateralAccelCallbackType:
     return self.torque_from_lateral_accel_linear

selfdrive/controls/lib/drive_helpers.py

@@ -190,3 +190,13 @@ def get_lag_adjusted_curvature(CP, v_ego, psis, curvatures, curvature_rates):
                                 current_curvature_desired + max_curvature_rate * DT_MDL)
 
   return safe_desired_curvature, safe_desired_curvature_rate
+
+
+def get_friction(lateral_accel_error: float, lateral_accel_deadzone: float, friction_threshold: float, torque_params: car.CarParams.LateralTorqueTuning, friction_compensation: bool) -> float:
+  friction_interp = interp(
+    apply_center_deadzone(lateral_accel_error, lateral_accel_deadzone),
+    [-friction_threshold, friction_threshold],
+    [-torque_params.friction, torque_params.friction]
+  )
+  friction = float(friction_interp) if friction_compensation else 0.0
+  return friction

selfdrive/controls/lib/latcontrol_torque.py

@@ -61,10 +61,12 @@ class LatControlTorque(LatControl):
       low_speed_factor = interp(CS.vEgo, LOW_SPEED_X, LOW_SPEED_Y)**2
       setpoint = desired_lateral_accel + low_speed_factor * desired_curvature
       measurement = actual_lateral_accel + low_speed_factor * actual_curvature
-      error = setpoint - measurement
       gravity_adjusted_lateral_accel = desired_lateral_accel - params.roll * ACCELERATION_DUE_TO_GRAVITY
-      pid_log.error = self.torque_from_lateral_accel(error, self.torque_params, error,
+      torque_from_setpoint = self.torque_from_lateral_accel(setpoint, self.torque_params, setpoint,
                                                      lateral_accel_deadzone, friction_compensation=False)
+      torque_from_measurement = self.torque_from_lateral_accel(measurement, self.torque_params, measurement,
+                                                     lateral_accel_deadzone, friction_compensation=False)
+      pid_log.error = torque_from_setpoint - torque_from_measurement
       ff = self.torque_from_lateral_accel(gravity_adjusted_lateral_accel, self.torque_params,
                                           desired_lateral_accel - actual_lateral_accel,
                                           lateral_accel_deadzone, friction_compensation=True)

selfdrive/test/process_replay/ref_commit

@@ -1 +1 @@
-50f1e873095fe2462d2aadb9c401bda76759c01c
+1da098f096cee9f2871dafd2788dc9ddac85eeab