longitudinal: use VehicleModel in limit_accel_in_turns#37540
Open
Dragoadri wants to merge 1 commit intocommaai:masterfrom
Open
longitudinal: use VehicleModel in limit_accel_in_turns#37540Dragoadri wants to merge 1 commit intocommaai:masterfrom
Dragoadri wants to merge 1 commit intocommaai:masterfrom
Conversation
This file contains hidden or bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
Sign up for free
to join this conversation on GitHub.
Already have an account?
Sign in to comment
1 participant
Add this suggestion to a batch that can be applied as a single commit.This suggestion is invalid because no changes were made to the code.Suggestions cannot be applied while the pull request is closed.Suggestions cannot be applied while viewing a subset of changes.Only one suggestion per line can be applied in a batch.Add this suggestion to a batch that can be applied as a single commit.Applying suggestions on deleted lines is not supported.You must change the existing code in this line in order to create a valid suggestion.Outdated suggestions cannot be applied.This suggestion has been applied or marked resolved.Suggestions cannot be applied from pending reviews.Suggestions cannot be applied on multi-line comments.Suggestions cannot be applied while the pull request is queued to merge.Suggestion cannot be applied right now. Please check back later.
Description
limit_accel_in_turns was using a simplified kinematic formula to calculate lateral acceleration:
a_y = v² × angle × DEG_TO_RAD / (steerRatio × wheelbase)
This ignores tire slip (understeer gradient) and road roll, overestimating lateral accel by up to 48% at highway speeds, causing unnecessary longitudinal acceleration limiting in moderate turns.
Fix: use VM.calc_curvature(math.radians(angle), v_ego, roll) * v_ego², consistent with the pattern already used in controlsd.py:79 and latcontrol_torque.py:62.
Resolves the FIXME comment on line 39.
Verification
The process replay shows intentional diffs in plannerd (longitudinalPlan.accels, jerks, speeds). This is expected: limit_accel_in_turns now uses VehicleModel.calc_curvature() instead of the simplified kinematic formula, producing slightly different a_y values in real driving segments.
The new values are more physically accurate as they account for tire slip (understeer gradient) and road roll — consistent with how controlsd.py:79 and latcontrol_torque.py:62 already calculate lateral acceleration.
All other modules (controlsd, card, calibrationd, etc.) show no diffs.