Nullsteering

Nullsteering is a technique used in autonomous driving systems, specifically for controlling the lateral movement of a vehicle. It's a method for calculating the steering angle required to follow a desired path. Unlike traditional control methods that might directly command a steering angle based on a vehicle's current position and orientation, nullsteering focuses on achieving a state where the vehicle's heading is aligned with the direction of the path ahead, while also minimizing lateral deviation.

The core idea behind nullsteering is to determine a steering command that will bring the vehicle towards a "null" state of lateral error and angular error relative to the path. This is often achieved by considering the curvature of the path and the vehicle's kinematics. The algorithm typically aims to find a steering angle that, if applied for a short duration, would result in the vehicle being perfectly on the path and aligned with it. It often involves predicting the vehicle's future position and orientation based on a given steering input and then optimizing that input to satisfy the desired path following objectives.

Nullsteering is known for its ability to provide smooth and stable steering commands, which can be beneficial for passenger comfort and vehicle dynamics. It can be particularly effective in situations where the path has significant curvature. The technique is often implemented as part of a broader path following controller, working in conjunction with other control elements to ensure robust and accurate navigation. It provides a way to decouple the steering control from direct trajectory tracking, focusing instead on the immediate alignment with the path.