Lane tracking method and lane tracking system for an autonomous vehicle

A lane tracking system for use by an autonomous vehicle, comprising:

• a lane detection module mounted to the autonomous vehicle, and configured to continuously capture, at a detecting frequency, images of a lane on which of the autonomous vehicle is located, and to generate a lane line data piece for each image captured thereby;
• an inertial measurement unit mounted to the autonomous vehicle, and configured to sense inertia of the autonomous vehicle and generate data of an angular speed and an acceleration of the autonomous vehicle;
• a motion sensing unit mounted to the autonomous vehicle, and configured to sense motion of the autonomous vehicle and motions of a steering wheel and wheels of the autonomous vehicle, and to generate vehicle motion information;
• a storage unit storing a reference lane line data piece, a plurality of past location data pieces, and a current location data piece, wherein:
• the reference lane line data piece is generated based on an image of the lane captured at a reference past time point by said lane detection module;
• the past location data pieces include a reference past location data piece that corresponds to a vehicle location, which refers to a location of a reference point of the autonomous vehicle relative to the lane, at the reference past time point;
• the current location data piece corresponds to the vehicle location at a current time point;
• each of the past location data piece(s) other than the reference past location data piece corresponds to the vehicle location at a respective one of one or more past time points that are between the reference past time point and the current time point and that are equidistantly separated by a unit time length;
• and
• each of the past location data pieces and the current location data piece includes a longitudinal location value, a lateral location value, and an azimuth;
• and
• a processing unit electrically coupled to said lane detection module, said inertial measurement unit, said motion sensing unit and said storage unit, and configured to
• calculate an estimated yaw rate and an estimated lateral acceleration that correspond to the current time point based on the angular speed and the acceleration of the autonomous vehicle which are measured by said inertial measurement unit at the current time point,
• calculate a reference yaw rate and a reference lateral acceleration that correspond to the current time point based on the vehicle motion information that is related to the steering wheel and the wheels of the autonomous vehicle and that is sensed by said motion sensing unit at the current time point,
• estimate, upon determining that a similarity between the estimated yaw rate and the reference yaw rate is at least a first predetermined confidence level and that a similarity between the estimated lateral acceleration and the reference lateral acceleration is at least a second predetermined confidence level, a longitudinal displacement, a lateral displacement and an azimuth variation that correspond to a time the unit time length later than the current time point, based on the estimated yaw rate and the estimated lateral acceleration,
• calculate a future location data piece that corresponds to the vehicle location at a future time point based on the current location data piece, the longitudinal displacement, the lateral displacement and the azimuth variation,
• store the future location data piece in said storage unit, wherein the future location data piece includes a longitudinal location value, a lateral location value and an azimuth,
• calculate a total longitudinal displacement, a total lateral displacement and a total azimuth variation of the autonomous vehicle from the reference past time point to the future time point based on the reference past location data piece and the future location data piece,
• calculate a future lane line data piece based on the reference lane line data piece, the total longitudinal displacement, the total lateral displacement and the total azimuth variation,
• store the future lane line data piece in said storage unit, and
• transmit the future lane line data piece to a control system for the control system to control lateral motion of the autonomous vehicle based on the future lane line data piece.