Devlog – Pure Pursuit Controller Improvements

One of the biggest improvements I made during this stage of the project was upgrading the Pure Pursuit controller. While the original implementation could follow the racing line, it wasn’t reliable enough once the car started driving faster. It would oversteer in corners, make unnecessary steering corrections, and sometimes struggle to recover after obstacle avoidance or localization drift.

The first thing I focused on was waypoint tracking. The previous controller would occasionally target waypoints that were too close or even behind the vehicle, causing unstable steering behavior. I improved the waypoint selection logic so the controller consistently looks farther ahead on the racing line, resulting in much smoother and more predictable steering.

I also refined how the controller handles corners. Instead of making aggressive steering inputs when approaching a turn, the updated controller transitions into corners much more naturally. This allows the car to maintain higher speeds while staying much closer to the ideal racing line.

Recovery was another major area of improvement. Previously, if the car drifted off the planned path because of localization error or obstacle avoidance, it could take several seconds to find the racing line again. I redesigned the path reacquisition logic so the controller intelligently finds the best point to merge back onto the path instead of simply driving toward the nearest waypoint. This made recovery significantly faster and reduced unnecessary crashes.

I spent a considerable amount of time tuning controller parameters, including lookahead behavior, steering gain, waypoint progression, and cornering performance. Most of this work involved iterative testing, making small adjustments, and analyzing the car’s behavior until it drove consistently across the entire track.

Results

After these improvements, the difference was immediately noticeable:

• Much smoother steering with fewer oscillations
• Cleaner cornering at higher speeds
• More accurate tracking of the racing line
• Faster recovery after localization drift or obstacle avoidance
• More stable autonomous driving overall
• Better foundation for future high-speed racing improvements

These Pure Pursuit upgrades made the car feel significantly more polished and reliable. With a much stronger path-following system in place, the project is now ready for future improvements such as adaptive lookahead, curvature-based speed control, and more advanced racing algorithms.