Longitudinal Controller#
Overview#
For following target trajectory, control stack needs to output lateral control commands (steering angle, steering angle velocity), and longitudinal control commands (acceleration, velocity). Longitudinal controller module is responsible for calculation of longitudinal control commands.
Role#
Longitudinal controller module calculates velocity and acceleration for following target velocity profile. This module velocity error from target trajectory.
Input#
The input to Longitudinal Controller module:
| Input | Data Type | Explanation |
|---|---|---|
| Trajectory | autoware_planning_msgs::Trajectory |
Target trajectory to follow (target position, twist, acceleration) |
| Pose | /tf ( tf2_msgs::TFMessage) |
Current pose of the vehicle |
| Twist | geometry_msgs::TwistStamped |
Current twist of the vehicle |
Output#
The output type from Longitudinal Controller module is autoware_control_msgs/ControlCommandStamped.
The main outputs included in autoware_control_msgs/ControlCommandStamped are as follows:
| Output | Data Type |
|---|---|
| Velocity | std_msgs/Float64 |
| Acceleration | std_msgs/Float64 |
| Steering angle | std_msgs/Float64 |
| Steering angle velocity | std_msgs/Float64 |
Note that steering angle and steering angle velocity are always output as 0 from Longitudinal Controller module.