dragonpilot/selfdrive/controls/lib/longcontrol.py

from common.numpy_fast import clip, interp
from selfdrive.controls.lib.pid import PIController

STOPPING_EGO_SPEED = 0.5
MIN_CAN_SPEED = 0.3  #TODO: parametrize this in car interface
STOPPING_TARGET_SPEED = MIN_CAN_SPEED + 0.01
STARTING_TARGET_SPEED = 0.5
BRAKE_THRESHOLD_TO_PID = 0.2


class LongCtrlState:
  #*** this function handles the long control state transitions
  # long_control_state labels (see capnp enum):
  off = 'off'  # Off
  pid = 'pid'  # moving and tracking targets, with PID control running
  stopping = 'stopping'  # stopping and changing controls to almost open loop as PID does not fit well at such a low speed
  starting = 'starting'  # starting and releasing brakes in open loop before giving back to PID



def long_control_state_trans(active, long_control_state, v_ego, v_target, v_pid,
                             output_gb, brake_pressed, cruise_standstill):

  stopping_condition = (v_ego < 2.0 and cruise_standstill) or \
                       (v_ego < STOPPING_EGO_SPEED and \
                        ((v_pid < STOPPING_TARGET_SPEED and v_target < STOPPING_TARGET_SPEED) or
                        brake_pressed))

  starting_condition = v_target > STARTING_TARGET_SPEED and not cruise_standstill

  if not active:
    long_control_state = LongCtrlState.off

  else:
    if long_control_state == LongCtrlState.off:
      if active:
        long_control_state = LongCtrlState.pid

    elif long_control_state == LongCtrlState.pid:
      if stopping_condition:
        long_control_state = LongCtrlState.stopping

    elif long_control_state == LongCtrlState.stopping:
      if starting_condition:
        long_control_state = LongCtrlState.starting

    elif long_control_state == LongCtrlState.starting:
      if stopping_condition:
        long_control_state = LongCtrlState.stopping
      elif output_gb >= -BRAKE_THRESHOLD_TO_PID:
        long_control_state = LongCtrlState.pid

  return long_control_state


stopping_brake_rate = 0.2  # brake_travel/s while trying to stop
starting_brake_rate = 0.8  # brake_travel/s while releasing on restart
brake_stopping_target = 0.5  # apply at least this amount of brake to maintain the vehicle stationary

_MAX_SPEED_ERROR_BP = [0., 30.]  # speed breakpoints
_MAX_SPEED_ERROR_V = [1.5, .8]  # max positive v_pid error VS actual speed; this avoids controls windup due to slow pedal resp


class LongControl(object):
  def __init__(self, CP, compute_gb):
    self.long_control_state = LongCtrlState.off  # initialized to off
    self.pid = PIController((CP.longitudinalKpBP, CP.longitudinalKpV),
                            (CP.longitudinalKiBP, CP.longitudinalKiV),
                            rate=100.0,
                            sat_limit=0.8,
                            convert=compute_gb)
    self.v_pid = 0.0
    self.last_output_gb = 0.0

  def reset(self, v_pid):
    self.pid.reset()
    self.v_pid = v_pid

  def update(self, active, v_ego, brake_pressed, standstill, cruise_standstill, v_cruise, v_target, v_target_future, a_target, CP, lead_1):
    # actuation limits
    gas_max = interp(v_ego, CP.gasMaxBP, CP.gasMaxV)
    brake_max = interp(v_ego, CP.brakeMaxBP, CP.brakeMaxV)

    output_gb = self.last_output_gb
    rate = 100.0
    self.long_control_state = long_control_state_trans(active, self.long_control_state, v_ego,
                                                       v_target_future, self.v_pid, output_gb,
                                                       brake_pressed, cruise_standstill)

    v_ego_pid = max(v_ego, MIN_CAN_SPEED)  # Without this we get jumps, CAN bus reports 0 when speed < 0.3

    # *** long control behavior based on state
    if self.long_control_state == LongCtrlState.off:
      self.v_pid = v_ego_pid  # do nothing
      output_gb = 0.
      self.pid.reset()

    # tracking objects and driving
    elif self.long_control_state == LongCtrlState.pid:
      prevent_overshoot = not CP.stoppingControl and v_ego < 1.5 and v_target_future < 0.7

      self.v_pid = v_target
      self.pid.pos_limit = gas_max
      self.pid.neg_limit = - brake_max
      deadzone = interp(v_ego_pid, CP.longPidDeadzoneBP, CP.longPidDeadzoneV)
      output_gb = self.pid.update(self.v_pid, v_ego_pid, speed=v_ego_pid, deadzone=deadzone, feedforward=a_target, freeze_integrator=prevent_overshoot)
      if prevent_overshoot:
        output_gb = min(output_gb, 0.0)

    # intention is to stop, switch to a different brake control until we stop
    elif self.long_control_state == LongCtrlState.stopping:
      # TODO: use the standstill bit from CAN to detect movements, usually more accurate than looking at v_ego
      if not standstill or output_gb > -brake_stopping_target:
        output_gb -= stopping_brake_rate / rate
      output_gb = clip(output_gb, -brake_max, gas_max)

      self.v_pid = v_ego
      self.pid.reset()

    # intention is to move again, release brake fast before handling control to PID
    elif self.long_control_state == LongCtrlState.starting:
      if output_gb < -0.2:
        output_gb += starting_brake_rate / rate
      self.v_pid = v_ego
      self.pid.reset()

    self.last_output_gb = output_gb
    final_gas = clip(output_gb, 0., gas_max)
    final_brake = -clip(output_gb, -brake_max, 0.)

    return final_gas, final_brake