Vehicles operating in an autonomous mode (e.g., driverless) can relieve occupants, especially the driver, from some driving-related responsibilities. When operating in an autonomous mode, the vehicle can navigate to various locations using onboard sensors, allowing the vehicle to travel with minimal human interaction or in some cases without any passengers.
Motion planning and control are critical operations in autonomous driving. When planning operations of an autonomous driving vehicle (ADV), the goal is to plan a route or trajectory and to control the ADV to follow the planed route or trajectory as close as possible. However, due to a variety of factors of driving circumstances, sometimes the ADV may not be able to follow the planned route or trajectory as close as expected. In such situation, a replanning of the route or trajectory may be needed. It is difficult to determine whether the replanning or regular planning should be performed under the driving environment at the point in time.