Difference between revisions of "Move With PID"
From wikidb
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== Modifications == | == Modifications == | ||
The move_it program introduced in [[Create and Build Follow]] is modified to use PID. | The move_it program introduced in [[Create and Build Follow]] is modified to use PID. | ||
− | + | See the [http://http://mediabox.grasp.upenn.edu/roswiki/doc/electric/api/control_toolbox/html/classcontrol__toolbox_1_1Pid.html link control_toolbox:Pid] package. | |
== Source == | == Source == |
Revision as of 15:42, 26 August 2012
Modifications
The move_it program introduced in Create and Build Follow is modified to use PID. See the link control_toolbox:Pid package.
Source
Addition to main
plot = nh.advertise<geometry_msgs::Point> ("/pid_values", 1000);
New trackCallback
void trackCallback (const geometry_msgs::Point::ConstPtr & track_msg) { ros::NodeHandle nh; geometry_msgs::Twist move_msg; geometry_msgs::Point plot_msg; ros::Time time = ros::Time::now(); double effort = 0; // Set the turn - turn on the z axis move_msg.linear.x = 0; move_msg.linear.y = 0; move_msg.linear.z = 0; move_msg.angular.x = 0; move_msg.angular.y = 0; // PID update effort = pid.updatePid(track_msg->x - MID_X, time - last_time); move_msg.angular.z = -effort / SCALE * MAX_POWER; if (move_msg.angular.z > MAX_POWER) move_msg.angular.z = MAX_POWER; if (move_msg.angular.z < -MAX_POWER) move_msg.angular.z = -MAX_POWER; // Execute turn mover.publish(move_msg); // debug output plot_msg.x = track_msg->x - MID_X; plot_msg.y = - effort; plot_msg.z = move_msg.angular.z; plot.publish(plot_msg); }
Plot PID
This command:
rxplot /pid_values/x,/pid_values/y /pid_values/z
Results in the following plot