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Refactor default Civic params (#720)

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* move civic params out

* fix variable name

* simplify ford scaling

* cleanup

* remove import dependency

* requested changes

* keep hyundai

old-commit-hash: 4a48ef8dbc
commatwo_master
dekerr 6 years ago committed by rbiasini
parent 08d6a11d21
commit ae1fbf70fa
8 changed files with 65 additions and 157 deletions
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  1. 28
      selfdrive/car/__init__.py
  2. 23
      selfdrive/car/chrysler/interface.py
  3. 31
      selfdrive/car/ford/interface.py
  4. 25
      selfdrive/car/gm/interface.py
  5. 30
      selfdrive/car/honda/interface.py
  6. 27
      selfdrive/car/hyundai/interface.py
  7. 24
      selfdrive/car/subaru/interface.py
  8. 32
      selfdrive/car/toyota/interface.py

28
selfdrive/car/__init__.py
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@ -4,6 +4,34 @@ from common.numpy_fast import clip
# kg of standard extra cargo to count for drive, gas, etc...
STD_CARGO_KG = 136.
# FIXME: hardcoding honda civic 2016 touring params so they can be used to
# scale unknown params for other cars
class CivicParams:
MASS = 1326. + STD_CARGO_KG
WHEELBASE = 2.70
CENTER_TO_FRONT = WHEELBASE * 0.4
CENTER_TO_REAR = WHEELBASE - CENTER_TO_FRONT
ROTATIONAL_INERTIA = 2500
TIRE_STIFFNESS_FRONT = 192150
TIRE_STIFFNESS_REAR = 202500
# TODO: get actual value, for now starting with reasonable value for
# civic and scaling by mass and wheelbase
def scale_rot_inertia(mass, wheelbase):
return CivicParams.ROTATIONAL_INERTIA * mass * wheelbase ** 2 / (CivicParams.MASS * CivicParams.WHEELBASE ** 2)
# TODO: start from empirically derived lateral slip stiffness for the civic and scale by
# mass and CG position, so all cars will have approximately similar dyn behaviors
def scale_tire_stiffness(mass, wheelbase, center_to_front, tire_stiffness_factor=1.0):
center_to_rear = wheelbase - center_to_front
tire_stiffness_front = (CivicParams.TIRE_STIFFNESS_FRONT * tire_stiffness_factor) * mass / CivicParams.MASS * \
(center_to_rear / wheelbase) / (CivicParams.CENTER_TO_REAR / CivicParams.WHEELBASE)
tire_stiffness_rear = (CivicParams.TIRE_STIFFNESS_REAR * tire_stiffness_factor) * mass / CivicParams.MASS * \
(center_to_front / wheelbase) / (CivicParams.CENTER_TO_FRONT / CivicParams.WHEELBASE)
return tire_stiffness_front, tire_stiffness_rear
def dbc_dict(pt_dbc, radar_dbc, chassis_dbc=None):
return {'pt': pt_dbc, 'radar': radar_dbc, 'chassis': chassis_dbc}

23
selfdrive/car/chrysler/interface.py
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@ -6,7 +6,7 @@ from selfdrive.controls.lib.drive_helpers import EventTypes as ET, create_event
from selfdrive.controls.lib.vehicle_model import VehicleModel
from selfdrive.car.chrysler.carstate import CarState, get_can_parser, get_camera_parser
from selfdrive.car.chrysler.values import ECU, check_ecu_msgs, CAR
from selfdrive.car import STD_CARGO_KG
from selfdrive.car import STD_CARGO_KG, scale_rot_inertia, scale_tire_stiffness
class CarInterface(object):
@ -51,16 +51,6 @@ class CarInterface(object):
# pedal
ret.enableCruise = True
# FIXME: hardcoding honda civic 2016 touring params so they can be used to
# scale unknown params for other cars
mass_civic = 2923. * CV.LB_TO_KG + STD_CARGO_KG
wheelbase_civic = 2.70
centerToFront_civic = wheelbase_civic * 0.4
centerToRear_civic = wheelbase_civic - centerToFront_civic
rotationalInertia_civic = 2500
tireStiffnessFront_civic = 85400 * 2.0
tireStiffnessRear_civic = 90000 * 2.0
# Speed conversion: 20, 45 mph
ret.wheelbase = 3.089 # in meters for Pacifica Hybrid 2017
ret.steerRatio = 16.2 # Pacifica Hybrid 2017
@ -85,20 +75,13 @@ class CarInterface(object):
ret.minSteerSpeed = 17.5 # m/s 17 on the way up, 13 on the way down once engaged.
# TODO allow 2019 cars to steer down to 13 m/s if already engaged.
centerToRear = ret.wheelbase - ret.centerToFront
# TODO: get actual value, for now starting with reasonable value for
# civic and scaling by mass and wheelbase
ret.rotationalInertia = rotationalInertia_civic * \
ret.mass * ret.wheelbase**2 / (mass_civic * wheelbase_civic**2)
ret.rotationalInertia = scale_rot_inertia(ret.mass, ret.wheelbase)
# TODO: start from empirically derived lateral slip stiffness for the civic and scale by
# mass and CG position, so all cars will have approximately similar dyn behaviors
ret.tireStiffnessFront = tireStiffnessFront_civic * \
ret.mass / mass_civic * \
(centerToRear / ret.wheelbase) / (centerToRear_civic / wheelbase_civic)
ret.tireStiffnessRear = tireStiffnessRear_civic * \
ret.mass / mass_civic * \
(ret.centerToFront / ret.wheelbase) / (centerToFront_civic / wheelbase_civic)
ret.tireStiffnessFront, ret.tireStiffnessRear = scale_tire_stiffness(ret.mass, ret.wheelbase, ret.centerToFront)
# no rear steering, at least on the listed cars above
ret.steerRatioRear = 0.

31
selfdrive/car/ford/interface.py
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@ -7,7 +7,7 @@ from selfdrive.controls.lib.drive_helpers import EventTypes as ET, create_event
from selfdrive.controls.lib.vehicle_model import VehicleModel
from selfdrive.car.ford.carstate import CarState, get_can_parser
from selfdrive.car.ford.values import MAX_ANGLE
from selfdrive.car import STD_CARGO_KG
from selfdrive.car import STD_CARGO_KG, scale_rot_inertia, scale_tire_stiffness
class CarInterface(object):
@ -51,16 +51,6 @@ class CarInterface(object):
# pedal
ret.enableCruise = True
# FIXME: hardcoding honda civic 2016 touring params so they can be used to
# scale unknown params for other cars
mass_civic = 2923. * CV.LB_TO_KG + STD_CARGO_KG
wheelbase_civic = 2.70
centerToFront_civic = wheelbase_civic * 0.4
centerToRear_civic = wheelbase_civic - centerToFront_civic
rotationalInertia_civic = 2500
tireStiffnessFront_civic = 85400
tireStiffnessRear_civic = 90000
ret.wheelbase = 2.85
ret.steerRatio = 14.8
ret.mass = 3045. * CV.LB_TO_KG + STD_CARGO_KG
@ -69,32 +59,21 @@ class CarInterface(object):
ret.lateralTuning.pid.kf = 1. / MAX_ANGLE # MAX Steer angle to normalize FF
ret.steerActuatorDelay = 0.1 # Default delay, not measured yet
ret.steerRateCost = 1.0
f = 1.2
tireStiffnessFront_civic *= f
tireStiffnessRear_civic *= f
ret.centerToFront = ret.wheelbase * 0.44
tire_stiffness_factor = 0.5328
# min speed to enable ACC. if car can do stop and go, then set enabling speed
# to a negative value, so it won't matter.
ret.minEnableSpeed = -1.
centerToRear = ret.wheelbase - ret.centerToFront
# TODO: get actual value, for now starting with reasonable value for
# civic and scaling by mass and wheelbase
ret.rotationalInertia = rotationalInertia_civic * \
ret.mass * ret.wheelbase**2 / (mass_civic * wheelbase_civic**2)
ret.rotationalInertia = scale_rot_inertia(ret.mass, ret.wheelbase)
# TODO: start from empirically derived lateral slip stiffness for the civic and scale by
# mass and CG position, so all cars will have approximately similar dyn behaviors
ret.tireStiffnessFront = tireStiffnessFront_civic * \
ret.mass / mass_civic * \
(centerToRear / ret.wheelbase) / (centerToRear_civic / wheelbase_civic)
ret.tireStiffnessRear = tireStiffnessRear_civic * \
ret.mass / mass_civic * \
(ret.centerToFront / ret.wheelbase) / (centerToFront_civic / wheelbase_civic)
ret.tireStiffnessFront, ret.tireStiffnessRear = scale_tire_stiffness(ret.mass, ret.wheelbase, ret.centerToFront,
tire_stiffness_factor=tire_stiffness_factor)
# no rear steering, at least on the listed cars above
ret.steerRatioRear = 0.

25
selfdrive/car/gm/interface.py
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@ -7,7 +7,7 @@ from selfdrive.controls.lib.vehicle_model import VehicleModel
from selfdrive.car.gm.values import DBC, CAR, STOCK_CONTROL_MSGS, AUDIO_HUD, \
SUPERCRUISE_CARS, AccState
from selfdrive.car.gm.carstate import CarState, CruiseButtons, get_powertrain_can_parser
from selfdrive.car import STD_CARGO_KG
from selfdrive.car import STD_CARGO_KG, scale_rot_inertia, scale_tire_stiffness
class CanBus(object):
@ -60,6 +60,7 @@ class CarInterface(object):
# or camera is on powertrain bus (LKA cars without ACC).
ret.enableCamera = not any(x for x in STOCK_CONTROL_MSGS[candidate] if x in fingerprint)
ret.openpilotLongitudinalControl = ret.enableCamera
tire_stiffness_factor = 0.444 # not optimized yet
if candidate == CAR.VOLT:
# supports stop and go, but initial engage must be above 18mph (which include conservatism)
@ -129,30 +130,14 @@ class CarInterface(object):
ret.centerToFront = ret.wheelbase * 0.465
# hardcoding honda civic 2016 touring params so they can be used to
# scale unknown params for other cars
mass_civic = 2923. * CV.LB_TO_KG + STD_CARGO_KG
wheelbase_civic = 2.70
centerToFront_civic = wheelbase_civic * 0.4
centerToRear_civic = wheelbase_civic - centerToFront_civic
rotationalInertia_civic = 2500
tireStiffnessFront_civic = 85400
tireStiffnessRear_civic = 90000
centerToRear = ret.wheelbase - ret.centerToFront
# TODO: get actual value, for now starting with reasonable value for
# civic and scaling by mass and wheelbase
ret.rotationalInertia = rotationalInertia_civic * \
ret.mass * ret.wheelbase**2 / (mass_civic * wheelbase_civic**2)
ret.rotationalInertia = scale_rot_inertia(ret.mass, ret.wheelbase)
# TODO: start from empirically derived lateral slip stiffness for the civic and scale by
# mass and CG position, so all cars will have approximately similar dyn behaviors
ret.tireStiffnessFront = tireStiffnessFront_civic * \
ret.mass / mass_civic * \
(centerToRear / ret.wheelbase) / (centerToRear_civic / wheelbase_civic)
ret.tireStiffnessRear = tireStiffnessRear_civic * \
ret.mass / mass_civic * \
(ret.centerToFront / ret.wheelbase) / (centerToFront_civic / wheelbase_civic)
ret.tireStiffnessFront, ret.tireStiffnessRear = scale_tire_stiffness(ret.mass, ret.wheelbase, ret.centerToFront,
tire_stiffness_factor=tire_stiffness_factor)
# same tuning for Volt and CT6 for now
ret.lateralTuning.pid.kiBP, ret.lateralTuning.pid.kpBP = [[0.], [0.]]

30
selfdrive/car/honda/interface.py
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@ -10,7 +10,7 @@ from selfdrive.controls.lib.drive_helpers import create_event, EventTypes as ET,
from selfdrive.controls.lib.vehicle_model import VehicleModel
from selfdrive.car.honda.carstate import CarState, get_can_parser, get_cam_can_parser
from selfdrive.car.honda.values import CruiseButtons, CAR, HONDA_BOSCH, AUDIO_HUD, VISUAL_HUD, CAMERA_MSGS
from selfdrive.car import STD_CARGO_KG
from selfdrive.car import STD_CARGO_KG, CivicParams, scale_rot_inertia, scale_tire_stiffness
from selfdrive.controls.lib.planner import _A_CRUISE_MAX_V_FOLLOWING
A_ACC_MAX = max(_A_CRUISE_MAX_V_FOLLOWING)
@ -152,16 +152,6 @@ class CarInterface(object):
ret.enableCruise = not ret.enableGasInterceptor
# FIXME: hardcoding honda civic 2016 touring params so they can be used to
# scale unknown params for other cars
mass_civic = 2923. * CV.LB_TO_KG + STD_CARGO_KG
wheelbase_civic = 2.70
centerToFront_civic = wheelbase_civic * 0.4
centerToRear_civic = wheelbase_civic - centerToFront_civic
rotationalInertia_civic = 2500
tireStiffnessFront_civic = 192150
tireStiffnessRear_civic = 202500
# Optimized car params: tire_stiffness_factor and steerRatio are a result of a vehicle
# model optimization process. Certain Hondas have an extra steering sensor at the bottom
# of the steering rack, which improves controls quality as it removes the steering column
@ -174,9 +164,9 @@ class CarInterface(object):
if candidate in [CAR.CIVIC, CAR.CIVIC_BOSCH]:
stop_and_go = True
ret.mass = mass_civic
ret.wheelbase = wheelbase_civic
ret.centerToFront = centerToFront_civic
ret.mass = CivicParams.MASS
ret.wheelbase = CivicParams.WHEELBASE
ret.centerToFront = CivicParams.CENTER_TO_FRONT
ret.steerRatio = 14.63 # 10.93 is end-to-end spec
tire_stiffness_factor = 1.
# Civic at comma has modified steering FW, so different tuning for the Neo in that car
@ -334,20 +324,14 @@ class CarInterface(object):
# conflict with PCM acc
ret.minEnableSpeed = -1. if (stop_and_go or ret.enableGasInterceptor) else 25.5 * CV.MPH_TO_MS
centerToRear = ret.wheelbase - ret.centerToFront
# TODO: get actual value, for now starting with reasonable value for
# civic and scaling by mass and wheelbase
ret.rotationalInertia = rotationalInertia_civic * \
ret.mass * ret.wheelbase**2 / (mass_civic * wheelbase_civic**2)
ret.rotationalInertia = scale_rot_inertia(ret.mass, ret.wheelbase)
# TODO: start from empirically derived lateral slip stiffness for the civic and scale by
# mass and CG position, so all cars will have approximately similar dyn behaviors
ret.tireStiffnessFront = (tireStiffnessFront_civic * tire_stiffness_factor) * \
ret.mass / mass_civic * \
(centerToRear / ret.wheelbase) / (centerToRear_civic / wheelbase_civic)
ret.tireStiffnessRear = (tireStiffnessRear_civic * tire_stiffness_factor) * \
ret.mass / mass_civic * \
(ret.centerToFront / ret.wheelbase) / (centerToFront_civic / wheelbase_civic)
ret.tireStiffnessFront, ret.tireStiffnessRear = scale_tire_stiffness(ret.mass, ret.wheelbase, ret.centerToFront,
tire_stiffness_factor=tire_stiffness_factor)
# no rear steering, at least on the listed cars above
ret.steerRatioRear = 0.

27
selfdrive/car/hyundai/interface.py
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@ -6,7 +6,7 @@ from selfdrive.controls.lib.drive_helpers import EventTypes as ET, create_event
from selfdrive.controls.lib.vehicle_model import VehicleModel
from selfdrive.car.hyundai.carstate import CarState, get_can_parser, get_camera_parser
from selfdrive.car.hyundai.values import CAMERA_MSGS, CAR, get_hud_alerts, FEATURES
from selfdrive.car import STD_CARGO_KG
from selfdrive.car import STD_CARGO_KG, scale_rot_inertia, scale_tire_stiffness
class CarInterface(object):
@ -51,19 +51,9 @@ class CarInterface(object):
ret.safetyModel = car.CarParams.SafetyModel.hyundai
ret.enableCruise = True # stock acc
# FIXME: hardcoding honda civic 2016 touring params so they can be used to
# scale unknown params for other cars
mass_civic = 2923. * CV.LB_TO_KG + STD_CARGO_KG
wheelbase_civic = 2.70
centerToFront_civic = wheelbase_civic * 0.4
centerToRear_civic = wheelbase_civic - centerToFront_civic
rotationalInertia_civic = 2500
tireStiffnessFront_civic = 192150
tireStiffnessRear_civic = 202500
tire_stiffness_factor = 1.
ret.steerActuatorDelay = 0.1 # Default delay
ret.steerRateCost = 0.5
tire_stiffness_factor = 1.
if candidate == CAR.SANTA_FE:
ret.lateralTuning.pid.kf = 0.00005
@ -129,21 +119,14 @@ class CarInterface(object):
ret.centerToFront = ret.wheelbase * 0.4
centerToRear = ret.wheelbase - ret.centerToFront
# TODO: get actual value, for now starting with reasonable value for
# civic and scaling by mass and wheelbase
ret.rotationalInertia = rotationalInertia_civic * \
ret.mass * ret.wheelbase**2 / (mass_civic * wheelbase_civic**2)
ret.rotationalInertia = scale_rot_inertia(ret.mass, ret.wheelbase)
# TODO: start from empirically derived lateral slip stiffness for the civic and scale by
# mass and CG position, so all cars will have approximately similar dyn behaviors
ret.tireStiffnessFront = (tireStiffnessFront_civic * tire_stiffness_factor) * \
ret.mass / mass_civic * \
(centerToRear / ret.wheelbase) / (centerToRear_civic / wheelbase_civic)
ret.tireStiffnessRear = (tireStiffnessRear_civic * tire_stiffness_factor) * \
ret.mass / mass_civic * \
(ret.centerToFront / ret.wheelbase) / (centerToFront_civic / wheelbase_civic)
ret.tireStiffnessFront, ret.tireStiffnessRear = scale_tire_stiffness(ret.mass, ret.wheelbase, ret.centerToFront,
tire_stiffness_factor=tire_stiffness_factor)
# no rear steering, at least on the listed cars above

24
selfdrive/car/subaru/interface.py
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@ -6,7 +6,7 @@ from selfdrive.controls.lib.drive_helpers import create_event, EventTypes as ET
from selfdrive.controls.lib.vehicle_model import VehicleModel
from selfdrive.car.subaru.values import CAR
from selfdrive.car.subaru.carstate import CarState, get_powertrain_can_parser, get_camera_can_parser
from selfdrive.car import STD_CARGO_KG
from selfdrive.car import STD_CARGO_KG, scale_rot_inertia, scale_tire_stiffness
class CarInterface(object):
@ -58,7 +58,6 @@ class CarInterface(object):
ret.wheelbase = 2.67
ret.centerToFront = ret.wheelbase * 0.5
ret.steerRatio = 15
tire_stiffness_factor = 1.0
ret.steerActuatorDelay = 0.4 # end-to-end angle controller
ret.lateralTuning.pid.kf = 0.00005
ret.lateralTuning.pid.kiBP, ret.lateralTuning.pid.kpBP = [[0., 20.], [0., 20.]]
@ -84,30 +83,13 @@ class CarInterface(object):
# end from gm
# hardcoding honda civic 2016 touring params so they can be used to
# scale unknown params for other cars
mass_civic = 2923. * CV.LB_TO_KG + STD_CARGO_KG
wheelbase_civic = 2.70
centerToFront_civic = wheelbase_civic * 0.4
centerToRear_civic = wheelbase_civic - centerToFront_civic
rotationalInertia_civic = 2500
tireStiffnessFront_civic = 192150
tireStiffnessRear_civic = 202500
centerToRear = ret.wheelbase - ret.centerToFront
# TODO: get actual value, for now starting with reasonable value for
# civic and scaling by mass and wheelbase
ret.rotationalInertia = rotationalInertia_civic * \
ret.mass * ret.wheelbase**2 / (mass_civic * wheelbase_civic**2)
ret.rotationalInertia = scale_rot_inertia(ret.mass, ret.wheelbase)
# TODO: start from empirically derived lateral slip stiffness for the civic and scale by
# mass and CG position, so all cars will have approximately similar dyn behaviors
ret.tireStiffnessFront = (tireStiffnessFront_civic * tire_stiffness_factor) * \
ret.mass / mass_civic * \
(centerToRear / ret.wheelbase) / (centerToRear_civic / wheelbase_civic)
ret.tireStiffnessRear = (tireStiffnessRear_civic * tire_stiffness_factor) * \
ret.mass / mass_civic * \
(ret.centerToFront / ret.wheelbase) / (centerToFront_civic / wheelbase_civic)
ret.tireStiffnessFront, ret.tireStiffnessRear = scale_tire_stiffness(ret.mass, ret.wheelbase, ret.centerToFront)
return ret

32
selfdrive/car/toyota/interface.py
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@ -6,7 +6,7 @@ from selfdrive.controls.lib.drive_helpers import EventTypes as ET, create_event
from selfdrive.controls.lib.vehicle_model import VehicleModel
from selfdrive.car.toyota.carstate import CarState, get_can_parser, get_cam_can_parser
from selfdrive.car.toyota.values import ECU, check_ecu_msgs, CAR, NO_STOP_TIMER_CAR
from selfdrive.car import STD_CARGO_KG
from selfdrive.car import STD_CARGO_KG, scale_rot_inertia, scale_tire_stiffness
from selfdrive.swaglog import cloudlog
@ -54,16 +54,6 @@ class CarInterface(object):
# pedal
ret.enableCruise = not ret.enableGasInterceptor
# FIXME: hardcoding honda civic 2016 touring params so they can be used to
# scale unknown params for other cars
mass_civic = 2923. * CV.LB_TO_KG + STD_CARGO_KG
wheelbase_civic = 2.70
centerToFront_civic = wheelbase_civic * 0.4
centerToRear_civic = wheelbase_civic - centerToFront_civic
rotationalInertia_civic = 2500
tireStiffnessFront_civic = 192150
tireStiffnessRear_civic = 202500
ret.steerActuatorDelay = 0.12 # Default delay, Prius has larger delay
if candidate != CAR.PRIUS:
ret.lateralTuning.init('pid')
@ -100,7 +90,7 @@ class CarInterface(object):
ret.safetyParam = 100
ret.wheelbase = 2.70
ret.steerRatio = 17.8
tire_stiffness_factor = 0.444
tire_stiffness_factor = 0.444 # not optimized yet
ret.mass = 2860. * CV.LB_TO_KG + STD_CARGO_KG # mean between normal and hybrid
ret.lateralTuning.pid.kpV, ret.lateralTuning.pid.kiV = [[0.2], [0.05]]
ret.lateralTuning.pid.kf = 0.00003 # full torque for 20 deg at 80mph means 0.00007818594
@ -170,7 +160,7 @@ class CarInterface(object):
ret.safetyParam = 73
ret.wheelbase = 2.63906
ret.steerRatio = 13.9
tire_stiffness_factor = 0.444
tire_stiffness_factor = 0.444 # not optimized yet
ret.mass = 3060. * CV.LB_TO_KG + STD_CARGO_KG
ret.lateralTuning.pid.kpV, ret.lateralTuning.pid.kiV = [[0.6], [0.1]]
ret.lateralTuning.pid.kf = 0.00007818594
@ -179,8 +169,8 @@ class CarInterface(object):
stop_and_go = True
ret.safetyParam = 73
ret.wheelbase = 2.8702
ret.steerRatio = 16.0 #not optimized
tire_stiffness_factor = 0.444
ret.steerRatio = 16.0 # not optimized
tire_stiffness_factor = 0.444 # not optimized yet
ret.mass = 3704. * CV.LB_TO_KG + STD_CARGO_KG
ret.lateralTuning.pid.kpV, ret.lateralTuning.pid.kiV = [[0.6], [0.1]]
ret.lateralTuning.pid.kf = 0.00007818594
@ -195,20 +185,14 @@ class CarInterface(object):
# to a negative value, so it won't matter.
ret.minEnableSpeed = -1. if (stop_and_go or ret.enableGasInterceptor) else 19. * CV.MPH_TO_MS
centerToRear = ret.wheelbase - ret.centerToFront
# TODO: get actual value, for now starting with reasonable value for
# civic and scaling by mass and wheelbase
ret.rotationalInertia = rotationalInertia_civic * \
ret.mass * ret.wheelbase**2 / (mass_civic * wheelbase_civic**2)
ret.rotationalInertia = scale_rot_inertia(ret.mass, ret.wheelbase)
# TODO: start from empirically derived lateral slip stiffness for the civic and scale by
# mass and CG position, so all cars will have approximately similar dyn behaviors
ret.tireStiffnessFront = (tireStiffnessFront_civic * tire_stiffness_factor) * \
ret.mass / mass_civic * \
(centerToRear / ret.wheelbase) / (centerToRear_civic / wheelbase_civic)
ret.tireStiffnessRear = (tireStiffnessRear_civic * tire_stiffness_factor) * \
ret.mass / mass_civic * \
(ret.centerToFront / ret.wheelbase) / (centerToFront_civic / wheelbase_civic)
ret.tireStiffnessFront, ret.tireStiffnessRear = scale_tire_stiffness(ret.mass, ret.wheelbase, ret.centerToFront,
tire_stiffness_factor=tire_stiffness_factor)
# no rear steering, at least on the listed cars above
ret.steerRatioRear = 0.

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