simple_object_merger

This package can merge multiple topics of autoware_auto_perception_msgs/msg/DetectedObject without data association algorithm.

Algorithm

Background

This package can merge multiple DetectedObjects without matching processing. Object_merger solve data association algorithm like Hungarian algorithm for matching problem, but it needs computational cost. In addition, for now, object_merger can handle only 2 DetectedObjects topics and cannot handle more than 2 topics in one node. To merge 6 DetectedObjects topics, 6 object_merger nodes need to stand.

So this package aim to merge DetectedObjects simply. This package do not use data association algorithm to reduce the computational cost, and it can handle more than 2 topics in one node to prevent launching a large number of nodes.

Limitation

• Sensor data drops and delay

Merged objects will not be published until all topic data is received when initializing. In addition, to care sensor data drops and delayed, this package has a parameter to judge timeout. When the latest time of the data of a topic is older than the timeout parameter, it is not merged for output objects. For now specification of this package, if all topic data is received at first and after that the data drops, and the merged objects are published without objects which is judged as timeout. The timeout parameter should be determined by sensor cycle time.

• Post-processing

Because this package does not have matching processing, so it can be used only when post-processing is used. For now, clustering processing can be used as post-processing.

Use case

Use case is as below.

• Multiple radar detection

This package can be used for multiple radar detection. Since clustering processing will be included later process in radar faraway detection, this package can be used.

Input

Name	Type	Description
	std::vector	3D detected objects. Topic names are set by parameters

Output

Name	Type	Description
~/output/objects	autoware_auto_perception_msgs/msg/DetectedObjects.msg	Merged objects

Parameters

Name	Type	Description	Default value
update_rate_hz	double	Update rate. [hz]	20.0
new_frame_id	string	The header frame_id of output topic.	"base_link"
timeout_threshold	double	Threshold for timeout judgement [s].	1.0
input_topics	List[string]	Input topics name.	"[]"