#include "geometry_msgs/TransformStamped. #include "tf2_ros/transform_broadcaster.h" The program is to subscribe to the turtle posture of turtle SIM, and then publish the TF transformation of turtle coordinate system relative to the world coordinate system according to the turtle posture. The following is the program for TF broadcasting. Take the coordinate transformation of tf2 (originally TF, later officially improved to tf2, and it is recommended to use tf2) in ROS as an example. Therefore, TF has the concept of timestamp. The same is true when coordinate points are represented in different coordinate systems. If you want to know the posture of the forearm to the shoulder at 0.5S time, you need to multiply the data at 0.5S time A and 0.5S time B, instead of multiplying the data at other times, because time alignment is required. Geographic coordinate systems (GCS) typically have units in decimal degrees, measuring degrees of longitude (x-coordinates) and degrees of latitude (y-coordinates). You can determine which type of coordinate system your data uses by examining the layers properties. However, the data of the two Imus are always sent. Horizontal coordinate systems can be of three types: geographic, projected, or local. Through these two data calculations, we can finally get the posture of the forearm relative to the shoulder. For example, A detects the posture of the boom relative to the shoulder, and B detects the posture of the jib relative to the boom. There are two Imus on the boom and jib respectively, which can detect the posture. The big arm rotates around the shoulder joint and the small arm rotates around the elbow joint. This leads to the problem of time alignment: for example, A manipulator has A big arm and A small arm. And this coordinate relationship is man-made or sensor detection data, called TF broadcast in the program. However, there is a problem: the coordinate system established by TF is generally dynamic coordinate system, that is, the transformation relationship between coordinate systems changes with time. Then TF Subscribers get these adjacent coordinate transformation relationships, and TF can calculate the coordinate transformation relationship between any two coordinate systems. Function of timestampįirst clarify what is the coordinate transformation of TF: in fact, it is the pose represented by the child coordinate system in the parent coordinate system, which can also be regarded as the coordinate transformation relationship from the child coordinate system to the parent coordinate system.īy using TF broadcasting, you only need to publish the coordinate relationship between two adjacent coordinate systems at a time. Time stamp of TF coordinate broadcast 1.1.
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