טכניון מכון טכנולוגי לישראל
הטכניון מכון טכנולוגי לישראל - בית הספר ללימודי מוסמכים  
M.Sc Thesis
M.Sc StudentGal Oren
SubjectTrajectory Planning of Autonomous Vehicle in Dynamic
Environments
DepartmentDepartment of Mechanical Engineering
Supervisors Professor Elon Rimon
Mr. Zvi Shiller
Full Thesis text - in Hebrew Full thesis text - Hebrew Version


Abstract

This research presents a new on-line planner for dynamic environments that is based on the concept of Velocity Obstacles (VO). It addresses the issue of motion safety, i.e. avoiding states of inevitable collision, by selecting a proper time horizon for the velocity obstacle. The time horizon plays an important role in selecting feasible avoidance maneuvers. It allows considering only those maneuvers that would result in a collision within a specified time interval. The smallest safe time horizon is the one that allows sufficient time for the robot to avoid the obstacle either by stopping or by passing. It depends on the size of the obstacle, its velocity, and the robot’s dynamic constraints. The proper choice of the time horizon ensures that the boundary of the velocity obstacle coincides with the boundary of the set of inevitable collision states.

The planner generates a near-time optimal trajectory to the goal by selecting at each time step the velocity that minimizes the time-to-go and is out of the velocity obstacle.

The near time optimal trajectories were compared to the global solutions using off-line planning. Statistical simulations show that the local trajectories were on average 22% longer than the global ones. The planner takes into account the shape, velocity, and path curvature of the obstacle’s trajectory. It is demonstrated for on-line motion planning in very crowded static and dynamic environments. The planner can be used for real-time ground sea and air applications.