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Console path parser package

Console path parser is a ROS package written in C++ responsible for parsing a mission/path string from an external source to a format that can be interpreted by the path following algorithms of the Medusa Vx stack.

console_path_parser Diagram

Rationale

Mission/path string format

The format of the mission for a single vehicle comes from the console in a string like the following:

#Version
3
#Xrefpoint Yrefpoint UTM Zone
491890.163 4290832.905 29S

# LINE xInit yInit xEnd yEnd velocity <nVehicle> <gamma> <user data>
# ARC xInit yInit xCenter yCenter xEnd yEnd velocity adirection radius <nVehicle> <gamma> <user data>
# POINT xInit yInit radius velocity heading time <nVehicle> <gamma> <user data>
# DEPTH depth time <nVehicle> <gamma> <user data>
# ALT altitude time <nVehicle> <gamma> <user data>

Example of lawn mower maneuver for a single vehicle

# Mission from vehicle -1
LINE -20.26 -20.26 -20.26 10.13 0.30 -1 
ARC -20.26 10.13 -10.13 10.13 0.00 10.13 0.30 -1 10.13 -1 
LINE 0.00 10.13 0.00 -10.13 0.30 -1 
ARC 0.00 -10.13 10.13 -10.13 20.26 -10.13 0.30 1 10.13 -1 
LINE 20.26 -10.13 20.26 20.26 0.30 -1

For case where cooperative path following is desired the mission is adapted as seen in the example bellow:

#Version
3
#Xrefpoint Yrefpoint UTM Zone
491854.338 4290819.848 29S

# FORMATION ID1 x_dist y_dist ID2 x_dist y_dist ID3 x_dist y_dist
FORMATION 1 0 -3 2 0 0 3 0 3

# LINE xInit yInit xEnd yEnd velocity <nVehicle> <gamma> <user data>
# ARC xInit yInit xCenter yCenter xEnd yEnd velocity adirection radius <nVehicle> <gamma> <user data>
# POINT xInit yInit radius velocity heading time <nVehicle> <gamma> <user data>
# DEPTH depth time <nVehicle> <gamma> <user data>
# ALT altitude time <nVehicle> <gamma> <user data>

# Mission from vehicle -1
LINE -24.57 -24.57 -24.57 12.29 0.30 -1 
ARC -24.57 12.29 -12.29 12.29 0.00 12.29 0.30 -1 12.29 -1 
LINE 0.00 12.29 0.00 -12.29 0.30 -1 
ARC 0.00 -12.29 12.29 -12.29 24.57 -12.29 0.30 1 12.29 -1 
LINE 24.57 -12.29 24.57 24.57 0.30 -1

Note that the only difference is the addition of a FORMATION line. Console path parser will read this information and save in a vector of sections (Mission). The section structure can be seen below.

Path following sections format

    SECTION()
    {
        Type = 0; # Line / Arc / Point / Depth / ALT
        xi = 0; # initial x of section
        yi = 0; # initial y of section
        xc = -1; # x of center of arc (-1 if line or point)
        yc = -1; # y of center of arc (-1 if line or point)
        xe = 0; # ending x of section
        ye = 0; # ending y of section
        velocity = 0; # velocity desired of the vehicle
        adirection = 0; # -1 if vehicle is turning clockwise, -1 otherwise (only applied to arcs)
        radius = 0; # radius of the arc
        heading = -1;
        time = -1; 
        nVehicle = -1;
        Gamma_s = 0; # Starting gamma (not normalized)
        Gamma_e = 0, # Ending gamma (not normalized)
        depth = 0.0;
    }

The console path parser will then publish the first section (topic /path_section) of the vector while subscribing to the topic /Gamma which contains a the value of the parameter gamma (see path following theory) not normalized. When the received gamma surpasses the ending gamma (Gamma_e) of the section, it will then update its section and publish it. It will do this process for the amount of sections in Mission.

Note that /Gamma is being published by the path following node, where there is a conversion of the gamma from normalized to not normalized.

Package Content

console_path_parser struct

Code documentation

source

Using console path parser

Examples

Requirements

Yebisu - creates the mission to be parsed

console_server - receives the mission and sends it here

folder to save path - ex: ROS_BAG_FOLDER/paths_from_console

path following algorithms - receive sections of the mission

Last update: May 30, 2022
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