Trajectory Follower

This is the design document for the trajectory_follower package.

Purpose / Use cases

This package provides the interface of longitudinal and lateral controllers used by the node of the autoware_trajectory_follower_node package. We can implement a detailed controller by deriving the longitudinal and lateral base interfaces.

Design

There are lateral and longitudinal base interface classes and each algorithm inherits from this class to implement. The interface class has the following base functions.

• isReady(): Check if the control is ready to compute.
• run(): Compute control commands and return to Trajectory Follower Nodes. This must be implemented by inherited algorithms.
• sync(): Input the result of running the other controller.
  • steer angle convergence
    • allow keeping stopped until steer is converged.
  • velocity convergence(currently not used)

See the Design of Trajectory Follower Nodes for how these functions work in the node.

Separated lateral (steering) and longitudinal (velocity) controls

This longitudinal controller assumes that the roles of lateral and longitudinal control are separated as follows.

• Lateral control computes a target steering to keep the vehicle on the trajectory, assuming perfect velocity tracking.
• Longitudinal control computes a target velocity/acceleration to keep the vehicle velocity on the trajectory speed, assuming perfect trajectory tracking.

Ideally, dealing with the lateral and longitudinal control as a single mixed problem can achieve high performance. In contrast, there are two reasons to provide velocity controller as a stand-alone function, described below.

Complex requirements for longitudinal motion

The longitudinal vehicle behavior that humans expect is difficult to express in a single logic. For example, the expected behavior just before stopping differs depending on whether the ego-position is ahead/behind of the stop line, or whether the current speed is higher/lower than the target speed to achieve a human-like movement.

In addition, some vehicles have difficulty measuring the ego-speed at extremely low speeds. In such cases, a configuration that can improve the functionality of the longitudinal control without affecting the lateral control is important.

There are many characteristics and needs that are unique to longitudinal control. Designing them separately from the lateral control keeps the modules less coupled and improves maintainability.

Nonlinear coupling of lateral and longitudinal motion

The lat-lon mixed control problem is very complex and uses nonlinear optimization to achieve high performance. Since it is difficult to guarantee the convergence of the nonlinear optimization, a simple control logic is also necessary for development.

Also, the benefits of simultaneous longitudinal and lateral control are small if the vehicle doesn’t move at high speed.

Related issues

Changelog for package autoware_trajectory_follower_base

0.44.0 (2025-04-18)

0.43.0 (2025-03-21)

• Merge remote-tracking branch 'origin/main' into chore/bump-version-0.43
• chore: rename from [autoware.universe]{.title-ref} to [autoware_universe]{.title-ref} (#10306)
• Contributors: Hayato Mizushima, Yutaka Kondo

0.42.0 (2025-03-03)

• Merge remote-tracking branch 'origin/main' into tmp/bot/bump_version_base
• feat(autoware_utils): replace autoware_universe_utils with autoware_utils (#10191)
• Contributors: Fumiya Watanabe, 心刚

0.41.2 (2025-02-19)

• chore: bump version to 0.41.1 (#10088)
• Contributors: Ryohsuke Mitsudome

0.41.1 (2025-02-10)

0.41.0 (2025-01-29)

• Merge remote-tracking branch 'origin/main' into tmp/bot/bump_version_base
• feat: tier4_debug_msgs changed to autoware_internal_msgs in files con… (#9852) feat: tier4_debug_msgs changed to autoware_internal_msgs in files control/autoware_trajectory_follower_base
• Contributors: Fumiya Watanabe, Vishal Chauhan

0.40.0 (2024-12-12)

• Merge branch 'main' into release-0.40.0
• Revert "chore(package.xml): bump version to 0.39.0 (#9587)" This reverts commit c9f0f2688c57b0f657f5c1f28f036a970682e7f5.
• fix: fix ticket links in CHANGELOG.rst (#9588)
• chore(package.xml): bump version to 0.39.0 (#9587)
  • chore(package.xml): bump version to 0.39.0
  • fix: fix ticket links in CHANGELOG.rst

  * fix: remove unnecessary diff ---------Co-authored-by: Yutaka Kondo <<yutaka.kondo@youtalk.jp>>

• fix: fix ticket links in CHANGELOG.rst (#9588)
• 0.39.0
• update changelog
• fix: fix ticket links to point to https://github.com/autowarefoundation/autoware_universe (#9304)
• feat(trajectory_follower): publsih control horzion (#8977)
  • feat(trajectory_follower): publsih control horzion
  • fix typo
  • rename functions and minor refactor
  • add option to enable horizon pub
  • add tests for horizon
  • update docs

  * rename to ~/debug/control_cmd_horizon ---------

• fix: fix ticket links to point to https://github.com/autowarefoundation/autoware_universe (#9304)
• chore(package.xml): bump version to 0.38.0 (#9266) (#9284)
  • unify package.xml version to 0.37.0
  • remove system_monitor/CHANGELOG.rst
  • add changelog

  * 0.38.0

• Contributors: Esteve Fernandez, Fumiya Watanabe, Kosuke Takeuchi, Ryohsuke Mitsudome, Yutaka Kondo

0.39.0 (2024-11-25)

• fix: fix ticket links to point to https://github.com/autowarefoundation/autoware_universe (#9304)
• fix: fix ticket links to point to https://github.com/autowarefoundation/autoware_universe (#9304)
• chore(package.xml): bump version to 0.38.0 (#9266) (#9284)
  • unify package.xml version to 0.37.0
  • remove system_monitor/CHANGELOG.rst
  • add changelog

  * 0.38.0

• Contributors: Esteve Fernandez, Yutaka Kondo

0.38.0 (2024-11-08)

• unify package.xml version to 0.37.0
• refactor(osqp_interface): added autoware prefix to osqp_interface (#8958)
• refactor(autoware_interpolation): prefix package and namespace with autoware (#8088) Co-authored-by: kosuke55 <<kosuke.tnp@gmail.com>>
• refactor(motion_utils)!: add autoware prefix and include dir (#7539) refactor(motion_utils): add autoware prefix and include dir
• feat(autoware_universe_utils)!: rename from tier4_autoware_utils (#7538) Co-authored-by: kosuke55 <<kosuke.tnp@gmail.com>>
• refactor(control)!: refactor directory structures of the trajectory followers (#7521)
  • control_traj
  • add follower_node

  * fix

• refactor(trajectory_follower_node): trajectory follower node add autoware prefix (#7344)
  • rename trajectory follower node package
  • update dependencies, launch files, and README files
  • fix formats

  * remove autoware_ prefix from launch arg option ---------

• refactor(trajectory_follower_base): trajectory follower base add autoware prefix (#7343)
  • rename trajectory follower base package
  • update dependencies and includes

  * fix formats ---------

• Contributors: Esteve Fernandez, Kosuke Takeuchi, Takayuki Murooka, Yuki TAKAGI, Yutaka Kondo, mkquda

0.26.0 (2024-04-03)