POS Library — Coordinate Systems

The POS library [1] is a coordinate system framework based on the POS ontology [2] for representing and transforming generalized coordinates across different coordinate systems and spaces.

See the basic notions for a general description of the fundamental concepts. Below you will find tutorials, with increasingly complex examples, and reference documentation.

Quick Example

Create a child coordinate system, define a point in it, and transform the point to world coordinates.

Coordinate system diagram
quick_example.c++
#include <print>
import ninbot;

int main()
{
   using namespace nin;
   using namespace nin::R2;

   position_coordsys_child CS1 {WCS, translation{3_m, 1_m}};
   point P = {CS1, point_qty{1_m, 2_m}};

   point_qty P_wcs = P.map_to(WCS);

   std::println("Coordinates of point P in WCS are: P={}", P_wcs);
}
Output
Coordinates of point P in WCS are: P=(4, 3) (m)

In the example above,

  • CS1 is a child coordinate system whose origin sits at (3, 1) in the World Coordinate System (WCS).

  • point binds a coordinate quantity to CS1.

  • map_to(WCS) builds a transformation function from CS1 to WCS and invokes it in one step, walking up the tree and composing the rigid transformations along the way.

Tutorials

Basic

Intermediate

Advanced

Expert

Reference

Basic Templates

Template Description

coordsys_traits

Concept for coordinate system spaces

coordsys_bridge_traits

Concept for cross-space bridges

coordsys<CT>

Base class for all coordinate systems

coord_value<CT>

Coordinate quantity bound to a coordinate system

coord_cloud<CT, N>

Batch container of coordinate quantities

mapCS()

Create transformation functions between coordinate systems

coord_tf

Fixed transformation function between coordinate systems

coordsys_backend

Abstract base for backend implementations

coordsys_child

Child node in the kinematic tree

coordsys_generic

Wrapper for arbitrary backends

coordsys_cutoff

Tree traversal cutoff for performance
1. Francisco Jesús Arjonilla García, Yuichi Kobayashi (2023) The POS library: a highly customisable coordinate system library for C++. In RSJ Conference of the Robotics Society of Japan, 1J4-05. Sendai.
2. IEEE Std 1872-2015, "IEEE Standard Ontologies for Robotics and Automation," pp. 1–60, 10 April 2015. doi: 10.1109/IEEESTD.2015.7084073