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A* ALGORITHM BASICS FOR PATH FINDING & HEURISTICS METHODS : ARTIFICIAL INTELLIGENCE

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 A* ALGORITHM BASICS FOR PATH FINDING A* , widely used  known form of best-first search & path planning algorithm nowadays in mobile robots,games. this is the function for A*,                                     f(n) = g(n) + h(n) g ( n ) is the cost of the path from the start node to n , and h ( n ) is a heuristic function that estimates the cost of the cheapest path from n to the goal This will find cheapest f(n) value in neighbor nodes to archive goal node. check below image  A to B path finding with g(n),h(n),f(n) value In the final level check below image Now we will check the Algorithm // A* Search Algorithm 1. Initialize the open list 2. Initialize the closed list put the starting node on the open list (you can leave its f at zero) 3. while the open list is not empty a) find the node with the least f on the open list, call it "q" b) pop q off the open list c) generate q's 8 successors
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Understanding ROS Nodes

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Its a basic thing & main part in ROS.
Nodes are executables that can communicate with other processes using topics,
services, or the Parameter Server.
Node can be create in python , c++ , Lisp
Two nodes can communicate each other using topics (interchange meassage/data  )
Every nodes have to named by programmer.that name used to communicate or identified by other node.
roscpp is lib to create ros node in c++ & rospy for python language

In ROS have some  commands to retrieve the running nodes information

  • rosnode info node : This prints information about the node
  • rosnode kill node : This kills a running node or sends a given signal
  • rosnode list : This lists the active nodes
  • rosnode machine hostname : This lists the nodes running on a particular machine or lists the machines
  • rosnode ping node : This tests the connectivity to the node
  • rosnode cleanup : This purges registration information from unreachable nodes  
  • rqt_graph :  Provides a GUI plugin for visualizing the ROS computation graph.

roscore  is a collection of nodes and programs that are pre-requisites of a ROS-based system.roscore running is important to ros nodes communication

check it out how to use commands

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A* ALGORITHM BASICS FOR PATH FINDING & HEURISTICS METHODS : ARTIFICIAL INTELLIGENCE

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 A* ALGORITHM BASICS FOR PATH FINDING A* , widely used  known form of best-first search & path planning algorithm nowadays in mobile robots,games. this is the function for A*,                                     f(n) = g(n) + h(n) g ( n ) is the cost of the path from the start node to n , and h ( n ) is a heuristic function that estimates the cost of the cheapest path from n to the goal This will find cheapest f(n) value in neighbor nodes to archive goal node. check below image  A to B path finding with g(n),h(n),f(n) value In the final level check below image Now we will check the Algorithm // A* Search Algorithm 1. Initialize the open list 2. Initialize the closed list put the starting node on the open list (you can leave its f at zero) 3. while the open list is not empty a) find the node with the least f on the open list, call it "q" b) pop q off the open list c) generate q's 8 successors
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