gamepad_reader.py

import itertools
from absl import app
import inputs
import threading
import time
from MPC_Controller.Parameters import Parameters

from MPC_Controller.utils import GaitType, FSM_StateName


MAX_ABS_VAL = 32768
ALLOWED_MODES = [FSM_StateName.RECOVERY_STAND, FSM_StateName.LOCOMOTION]
ALLOWED_GAITS = [x for x in GaitType]

def _interpolate(raw_reading, max_raw_reading, new_scale):
  return raw_reading / max_raw_reading * new_scale


class Gamepad:
  """Interface for reading commands from xbox Gamepad.

  The control works as following:
  1) Press LB+RB at any time for emergency stop
  2) Use the left joystick for forward/backward/left/right walking.
  3) Use the right joystick for rotation around the z-axis.
  """
  def __init__(self, 
               vel_scale_x: float=.5, 
               vel_scale_y: float=.5, 
               vel_scale_rot: float=1.,
               max_acc: float = .5):
    """Initialize the gamepad controller.
    Args:
      vel_scale_x: maximum absolute x-velocity command.
      vel_scale_y: maximum absolute y-velocity command.
      vel_scale_rot: maximum absolute yaw-dot command.
    """
    if not inputs.devices.gamepads:
      raise inputs.UnpluggedError("No gamepad found.")

    self.gamepad = inputs.devices.gamepads[0]
    self._vel_scale_x = float(vel_scale_x)
    self._vel_scale_y = float(vel_scale_y)
    self._vel_scale_rot = float(vel_scale_rot)
    self._max_acc = max_acc
    self._lb_pressed = False
    self._rb_pressed = False
    self._lj_pressed = False

    self._gait_generator = itertools.cycle(ALLOWED_GAITS)
    self._gait = next(self._gait_generator)
    self._mode_generator = itertools.cycle(ALLOWED_MODES)
    self._mode = next(self._mode_generator)#Parameters.control_mode

    # Controller states
    self.vx, self.vy, self.wz = 0., 0., 0.
    self._FSM_switch = False
    self._estop_flagged = False
    self.is_running = True

    self.read_thread = threading.Thread(target=self.read_loop)
    self.read_thread.start()

  def read_loop(self):
    """The read loop for events.

    This funnction should be executed in a separate thread for continuous
    event recording.
    """
    while self.is_running:# and not self.estop_flagged:
      try:
        events = self.gamepad.read()
        for event in events:
          # print(event.ev_type, event.code, event.state)
          self.update_command(event)
      except Exception as e:
        pass

  def update_command(self, event):
    """Update command based on event readings."""
    if event.ev_type == 'Key' and event.code == 'BTN_TL':
      self._lb_pressed = bool(event.state)
      if not self._estop_flagged and event.state == 0:
        self._gait = next(self._gait_generator)

    elif event.ev_type == 'Key' and event.code == 'BTN_TR':
      self._rb_pressed = bool(event.state)
      if not self._estop_flagged and event.state == 0:
        self._mode = next(self._mode_generator)

    elif event.ev_type == 'Key' and event.code == 'BTN_THUMBL':
      self._lj_pressed = bool(event.state)

    elif event.ev_type == 'Absolute' and event.code == 'ABS_X':
      # Left Joystick L/R axis
      self.wz = _interpolate(-event.state, MAX_ABS_VAL, self._vel_scale_rot)
    elif event.ev_type == 'Absolute' and event.code == 'ABS_Y':
      # Left Joystick F/B axis; need to flip sign for consistency
      self.vx = _interpolate(-event.state, MAX_ABS_VAL, self._vel_scale_x)
    elif event.ev_type == 'Absolute' and event.code == 'ABS_RX':
      self.vy = _interpolate(-event.state, MAX_ABS_VAL, self._vel_scale_y)
    
    if self._estop_flagged and self._lj_pressed:
      print("Estop Released.")
      self._estop_flagged = False
      self._mode_generator = itertools.cycle(ALLOWED_MODES)
      self._mode = next(self._mode_generator)#Parameters.control_mode

    if self._lb_pressed and self._rb_pressed:
      print("EStop Flagged, press LEFT joystick to release.")
      self._estop_flagged = True
      self.vx, self.vy, self.wz = 0., 0., 0.
      self._mode = FSM_StateName.RECOVERY_STAND

  def get_command(self):
    return (self.vx, self.vy, 0), self.wz, self._estop_flagged

  def get_gait(self):
    return self._gait

  def get_mode(self):
    return self._mode

  def fake_event(self, ev_type, code, value):
    eventinfo = {
      "ev_type": ev_type,
      "state": value,
      "timestamp": 0.0,
      "code": code
    }
    event = inputs.InputEvent(self.gamepad, eventinfo)
    self.update_command(event)

  def stop(self):
    self.is_running = False


def main(_):
  gamepad = Gamepad()
  while True:
    print("Vx: {:.3f}, Vy: {:.3f}, Wz: {:.3f}, Estop: {}".format(gamepad.vx, gamepad.vy,
                                                     gamepad.wz,
                                                     gamepad._estop_flagged))
    time.sleep(0.1)


if __name__ == "__main__":
  app.run(main)