Public Member Functions
JOINT_TRAJECTORY_CONTROLLER_PUBLIC	Trajectory (std::shared_ptr< trajectory_msgs::msg::JointTrajectory > joint_trajectory)

JOINT_TRAJECTORY_CONTROLLER_PUBLIC	Trajectory (const rclcpp::Time &current_time, const trajectory_msgs::msg::JointTrajectoryPoint &current_point, std::shared_ptr< trajectory_msgs::msg::JointTrajectory > joint_trajectory)

JOINT_TRAJECTORY_CONTROLLER_PUBLIC void	set_point_before_trajectory_msg (const rclcpp::Time &current_time, const trajectory_msgs::msg::JointTrajectoryPoint &current_point, const std::vector< bool > &joints_angle_wraparound=std::vector< bool >())

JOINT_TRAJECTORY_CONTROLLER_PUBLIC void	update (std::shared_ptr< trajectory_msgs::msg::JointTrajectory > joint_trajectory)

JOINT_TRAJECTORY_CONTROLLER_PUBLIC bool	sample (const rclcpp::Time &sample_time, const interpolation_methods::InterpolationMethod interpolation_method, trajectory_msgs::msg::JointTrajectoryPoint &output_state, TrajectoryPointConstIter &start_segment_itr, TrajectoryPointConstIter &end_segment_itr, const bool search_monotonically_increasing=true)

JOINT_TRAJECTORY_CONTROLLER_PUBLIC void	interpolate_between_points (const rclcpp::Time &time_a, const trajectory_msgs::msg::JointTrajectoryPoint &state_a, const rclcpp::Time &time_b, const trajectory_msgs::msg::JointTrajectoryPoint &state_b, const rclcpp::Time &sample_time, trajectory_msgs::msg::JointTrajectoryPoint &output)

JOINT_TRAJECTORY_CONTROLLER_PUBLIC TrajectoryPointConstIter	begin () const

JOINT_TRAJECTORY_CONTROLLER_PUBLIC TrajectoryPointConstIter	end () const

JOINT_TRAJECTORY_CONTROLLER_PUBLIC rclcpp::Time	time_from_start () const

JOINT_TRAJECTORY_CONTROLLER_PUBLIC bool	has_trajectory_msg () const

JOINT_TRAJECTORY_CONTROLLER_PUBLIC bool	has_nontrivial_msg () const

JOINT_TRAJECTORY_CONTROLLER_PUBLIC std::shared_ptr< trajectory_msgs::msg::JointTrajectory >	get_trajectory_msg () const

JOINT_TRAJECTORY_CONTROLLER_PUBLIC bool	is_sampled_already () const

JOINT_TRAJECTORY_CONTROLLER_PUBLIC size_t	last_sample_index () const
	Get the index of the segment start returned by the last `sample()` operation. More...

Member Function Documentation

◆ interpolate_between_points()

void joint_trajectory_controller::Trajectory::interpolate_between_points	(	const rclcpp::Time &	time_a,
		const trajectory_msgs::msg::JointTrajectoryPoint &	state_a,
		const rclcpp::Time &	time_b,
		const trajectory_msgs::msg::JointTrajectoryPoint &	state_b,
		const rclcpp::Time &	sample_time,
		trajectory_msgs::msg::JointTrajectoryPoint &	output
	)

Do interpolation between 2 states given a time in between their respective timestamps

The start and end states need not necessarily be specified all the way to the acceleration level:

If only positions are specified, linear interpolation will be used.
If positions and velocities are specified, a cubic spline will be used.
If positions, velocities and accelerations are specified, a quintic spline will be used.

If start and end states have different specifications (eg. start is position-only, end is position-velocity), the lowest common specification will be used (position-only in the example).

Parameters

[in]	time_a	Time at which the segment state equals `state_a`.
[in]	state_a	State at `time_a`.
[in]	time_b	Time at which the segment state equals `state_b`.
[in]	state_b	State at time `time_b`.
[in]	sample_time	The time to sample, between time_a and time_b.
[out]	output	The state at `sample_time`.

◆ last_sample_index()

JOINT_TRAJECTORY_CONTROLLER_PUBLIC size_t joint_trajectory_controller::Trajectory::last_sample_index ( ) const

inline

Get the index of the segment start returned by the last sample() operation.

As the trajectory is only accessed at monotonically increasing sampling times, this index is used to speed up the selection of relevant trajectory points.

◆ sample()

bool joint_trajectory_controller::Trajectory::sample	(	const rclcpp::Time &	sample_time,
		const interpolation_methods::InterpolationMethod	interpolation_method,
		trajectory_msgs::msg::JointTrajectoryPoint &	output_state,
		TrajectoryPointConstIter &	start_segment_itr,
		TrajectoryPointConstIter &	end_segment_itr,
		const bool	search_monotonically_increasing = `true`
	)

Find the segment (made up of 2 points) and its expected state from the containing trajectory. Sampling trajectory at given sample_time. If position in the end_segment_itr is missing it will be deduced from provided velocity, or acceleration respectively. Deduction assumes that the provided velocity or acceleration have to be reached at the time defined in the segment.

This function by default assumes that sampling is only done at monotonically increasing sample_time for any trajectory. That means, it will only search for a point matching the sample time after the point it has been called before. If this isn't desired, set search_monotonically_increasing to false.

Specific case returns for start_segment_itr and end_segment_itr:

Sampling before the trajectory start: start_segment_itr = begin(), end_segment_itr = begin()
Sampling exactly on a point of the trajectory: start_segment_itr = iterator where point is, end_segment_itr = iterator after start_segment_itr
Sampling between points: start_segment_itr = iterator before the sampled point, end_segment_itr = iterator after start_segment_itr
Sampling after entire trajectory: start_segment_itr = –end(), end_segment_itr = end()
Sampling empty msg or before the time given in set_point_before_trajectory_msg() return false

Parameters

[in]	sample_time	Time at which trajectory will be sampled.
[in]	interpolation_method	Specify whether splines, another method, or no interpolation at all.
[out]	output_state	Calculated new at `sample_time`.
[out]	start_segment_itr	Iterator to the start segment for given `sample_time`. See description above.
[out]	end_segment_itr	Iterator to the end segment for given `sample_time`. See description above.
[in]	search_monotonically_increasing	If set to true, the next sample call will start searching in the trajectory at the index of this call's result.

◆ set_point_before_trajectory_msg()

void joint_trajectory_controller::Trajectory::set_point_before_trajectory_msg	(	const rclcpp::Time &	current_time,
		const trajectory_msgs::msg::JointTrajectoryPoint &	current_point,
		const std::vector< bool > &	joints_angle_wraparound = `std::vector<bool>()`
	)

Set the point before the trajectory message is replaced/appended Example: if we receive a new trajectory message and it's first point is 0.5 seconds from the current one, we call this function to log the current state, then append/replace the current trajectory

Parameters

joints_angle_wraparound Vector of boolean where true value corresponds to a joint that wrap around (ie. is continuous).

The documentation for this class was generated from the following files:

ros2_controllers/joint_trajectory_controller/include/joint_trajectory_controller/trajectory.hpp
ros2_controllers/joint_trajectory_controller/src/trajectory.cpp

Public Member Functions

Member Function Documentation

◆ interpolate_between_points()

◆ last_sample_index()

◆ sample()

◆ set_point_before_trajectory_msg()