Method of Computing Smooth Transitions Between a Sequence of Straight Line Pathsfor an Autonomous Vehicle

摘要

A trajectory generator for an autonomous vehicle is described that calculates therequired platform velocities to achieve a smooth and predictable transition between two straight line paths of motion. The transition motion follows a continuous-curvature path consisting of a clothoid pair or clothoid arc pair of curves. The clothoid curves are a direct result of using a constant angular acceleration during the transition curve. A Taylor series expansion of a Fresnel integral is used to get a closed-form approximation for the clothoid curve. Whenever possible, the linear velocity of the vehicle throughout the transitional curve is the same as what it was during the straight line portion of the specified path. If a transition is not possible at the desired linear velocity then the maximum possible velocity that would allow a smooth transition is computed. Results have been demonstrated by implementing the equations to compute the transition curves on an autonomous vehicle.