ROS assignment

This is the second assignment of the Research Track 1 course. It's a C++ code to move a robot in the environment (a reproduction of the Monza's circuit) and allows the user to increase or decrease the velocity of the robot, according to the given input, or even reset its position by calling a built in service 'reset_position'.

Installing and running

First of all is necessary to execute the roscore & command in one shell.

You have to download the repository from http://CarmineD8/second_assignment (github.com) and created your environment.

To run the simulation use:

$ rosrun stage_ros stageros $(rospack find second_assignment)/world/my_world.world

To run the controller node (in a second terminal) use:

$  rosrun assignment_2 controller_node

To run the client node (in a third terminal) use:

$  rosrun my_srv client

Now you can see the robot starts to move in the cicuit.

Code

In this code there are three nodes communicating between them: the controller_node contained in ' controller.cpp ', the stage_ros node contained in 'my_world.world' and the client node contained in the 'client.cpp'.

Controller

The controller node is the the most important part of the code. It allows to increase or decrease the velocity of the robot thank's to this function:

bool drive (my_srv::Velocity::Request &req, my_srv::Velocity::Response &res)

This function contains the input:

if (req.v == "i" ){
		// increase the speed
		res.x = vel + 0.1*vel;		
	}
	else if (req.v == "d" ){
		// decrease the speed
		res.x = vel - 0.1*vel;
	}
	if (res.x > 1.4 || res.x < 0.3){
		// set speed limits 
		res.x = 1.0;
	}
	vel=res.x;
	return res.x;

Where the last condition sets the speed limit to the robot to prevent that, the high speed value, get him into the wall.

Then there is a function which check the obstacles and let the robot move within the circuit:

void laserCallback(const sensor_msgs::LaserScan::ConstPtr& msg)