I. Introduction
With the advancement of autonomous navigation technology for car-like robots, some scenes depicted in science fiction movies, such as adaptive and flexible collaborative rescue and transportation in complex environments, have become a realistic possibility [1], [2]. The key to realizing these tasks lies in achieving precise and computing-efficient collaborative planning for the car-like robotic team, which is a high-dimensional, strongly-coupled system with non-holonomic motion constraints. However, achieving both high precision and high efficiency can be a dilemma, remaining challenging to perform online adaptive and precise collaborative trajectory planning in unstructured environments.