def update_state_init(self, state, imu_msg):
# average state with new imu_information
# Renamed state vars
# (time - time) => duration
dt = (imu_msg.header.stamp - state.timestamp()).to_sec()
final_orientation = self.quat_to_euler(imu_msg.orientation)
# jerk
twerk = self.twerk(state.theta(), final_orientation, state.omega(), state.alpha(), dt)
# intermediate vars
avg_heading = self.theta_avg(twerk, state.theta(), state.omega(), state.alpha(), dt)
ang_acc = self.ang_acc(twerk, state.alpha(), dt)
# lin_vel((a_measured, v0, dt))
lin_vel = self.lin_vel(imu_msg.linear_acceleration.x, state.v(), dt)
# average final state
# so the values collected during the init are a moving average
# this all should be pretty stable around 0, because the robot should be stopped
# also, all state models should use this to zero-out their models
state.point = Vector.average(state.point, self.linear_shift(state.x(), state.y(), avg_heading, state.v(), imu_msg.linear_acceleration.x, dt)) # includes x, y
state.heading = state.heading/2 + final_orientation/2 # includes heading
state.ang_acc = Vector.average(state.ang_acc, ang_acc) # includes alpha
state.ang_vel = Vector.average(state.ang_vel, Vector.from_Vector3(imu_msg.angular_velocity)) # includes omega
state.lin_vel = Vector.average(state.lin_vel, lin_vel) # includes v
state.lin_acc = Vector.average(state.lin_acc, Vector.from_Vector3(imu_msg.linear_acceleration)) # includes a
return state
