@type t() :: %APM.Message.SimState{
  alt: Float32,
  lat: Float32,
  lon: Float32,
  pitch: Float32,
  q1: Float32,
  q2: Float32,
  q3: Float32,
  q4: Float32,
  roll: Float32,
  std_dev_horz: Float32,
  std_dev_vert: Float32,
  vd: Float32,
  ve: Float32,
  vn: Float32,
  xacc: Float32,
  xgyro: Float32,
  yacc: Float32,
  yaw: Float32,
  ygyro: Float32,
  zacc: Float32,
  zgyro: Float32
}