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. ...
Topics , Its look like pipe line connection between two or more nodes,This is the way to transfer data continuously within two nodes.
Each message in ROS is transported using named buses called topics. When a node sends a message through a topic, then we can say the node is publishing a topic. When a node receives a message through a topic, then we can say that the node is subscribing to a topic. The publishing node and subscribing node are not aware of each other's existence. We can even subscribe a topic that might not have any publisher. In short, the production of information and consumption of it are decoupled. Each topic has a unique name, and any node can access this topic and send data through it as long as they have the right message type
Ros topic have two types of method
1. topic publisher
2. topic subscriber
ROS has a tool to work with topics called rostopic . It is a command-line tool that gives us information about the topic or publishes data directly on the network.
rostopic echo /topic : This prints messages to the screen
rostopic hz /topic : This displays the publishing rate of the topic.
rostopic info /topic : This prints information about the active topic, the topics published, the ones it is subscribed to, and services.rostopic pub /topic type args : This publishes data to the topic.It allows us to create and publish data in whatever topic we want,directly from the command line.
check this video for above terminal commands demo
lets learn in each section ( topic publisher , topic subscriber ) in next post with sample codes & videos
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