Description

This Navigation module was implemented on a real AGV( Botsync’s Volta) and presented as a demonstration for ”Robot Navigation using Infrastructure Cameras” at the Indian Mobile Congress 2022

Documentation for Navigation Module

Config Params

x_max : 1.6
x_min : -1.1
y_max : 1.08
y_min : -0.99 

x_max_offset : 0.3
x_min_offset : 0.2
y_max_offset : 0.2
y_min_offset : 0.2

corner_factor : 0.5

lidar_safe_dist : 0.20

shift_goal : 0.2

front_angle : 180
clearance : 120

x_max, x_min, y_max ,y_min

• Description : The x and y limits covering the furthermost boundaries of the arena

x_max_offset, x_min_offset ,y_max_offset , y_min_offset

• Description : The offest given along each direction from the max limits

corner_factor

• Description : Determines the size of the corner (for 45 degree orientation). The smaller the factor the smaller the corner area.

lidar_safe_dist

• Description : Distance beyond which the robot will stop.

shift_goal

• Description : Distance by which the goal will be shifted inside along the desired orientation

front_angle

• Description : Laser angle corresponding to the front of the robot

clearance

• Description : Angular clearance on each side of the robot

Class Functions

handle_goal

• Description : Callback to the /goals topic. Starts the sequence.

movebase_client

• Description : Function acting as a layer between movebase action client and input goals

approach_goal

• Description : Forward Translation as long as bot is within safe distance from boundary

retreat

• Description : As long as bot is within safe distance from boundary Backward Translation by 30 cm

approach_yaw

• Description : Rotates robot to desired yaw orientation

get_velocity

• Description : Gives velocity as a function of distance from goal

get_orientation

• Description : Gives orientation of a goal based on where itlies with respect to the arena

• Depends on : All max limits, offsets and corner factor

• For example , Corner limit for xmax is -> corner_xmax = x_max - corner_factor * x_max_offset. Thus lower the corner_factor the smaller the corner area

generate_new_goal

• Description : Converts invalid goal / goal inside arena to a goal on the boundary

• Depends on : Soft limits

generate_intermediate_goal

• Description : Generates a point fixed distance away from the generated goal point along it's orientation

• Depends on : shift_goal

euler_from_quaternion

• Description : Convert a quaternion into euler angles (roll, pitch, yaw). Ouput in radians

isValid

• Description : Checks if goal is within soft limits

get_current_xy

• Description : Returns robot's current Pose

laser_callback

• Description : Sets lidar_safe and lidar_safe_yaw to True/False

• Depends on : lidar_safe_dist

marker_publish

• Description : Publishes rviz marker to visualize recieved goals and converted goal

Flowchart detailing the fallback behaviors