Difference between revisions of "Creating PID Tuning Graphs"
From wikidb
(→Message Additions to the Motor Controller) |
(→Plot termination Criteria) |
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= Plot termination Criteria = | = Plot termination Criteria = | ||
| − | There are two termination criteria | + | There are two termination criteria 1) cnt-c and 2) time. After one of the criteria is |
met, the graph is drawn. | met, the graph is drawn. | ||
* [https://stackoverflow.com/questions/1112343/how-do-i-capture-sigint-in-python Capture Ctl-C in Python] | * [https://stackoverflow.com/questions/1112343/how-do-i-capture-sigint-in-python Capture Ctl-C in Python] | ||
* [https://stackoverflow.com/questions/474528/what-is-the-best-way-to-repeatedly-execute-a-function-every-x-seconds-in-python capture timer event] | * [https://stackoverflow.com/questions/474528/what-is-the-best-way-to-repeatedly-execute-a-function-every-x-seconds-in-python capture timer event] | ||
Revision as of 13:17, 22 September 2017
Overview
This page documents a Python program designed to graph the first few seconds of power applied to the motors and robot speed. It is used to help calibrate PID parameters. I didn't know how to configure rqt_plot to display snapshots.
Message Additions to the Motor Controller
A "wheels" message of type Float64MultiArray is published in the setMotorPower function. It has five elements.
- data[0]: time is seconds since the motor controller was started.
- data[1]: wheel 0 speed in m/sec
- data[2]: percent of full power applied to wheel 0
- data[3]: wheel 1 speed
- data[4]: wheel 1 power
Wheel published global declaration
ros::Publisher wheel_pub_; ros::Time beginning_time_;
Publisher initialization in the main.
wheel_pub_ = n.advertise<std_msgs::Float64MultiArray>("wheels", 100);
Initializing beginning time in InitMotorPower
beginning_time_ = ros::Time::now();
Publishing a wheel status message in setMotorPower
std_msgs::Float64MultiArray wheel_data;
wheel_data.data.clear();
ros::Time odom_time(odom_.header.stamp.sec, odom_.header.stamp.nsec);
ros::Duration elapsed_time = odom_time - beginning_time_;
wheel_data.data.push_back(elapsed_time.toSec());
wheel_data.data.push_back(wheel0_speed);
wheel_data.data.push_back(power_wheel0_);
wheel_data.data.push_back(wheel1_speed);
wheel_data.data.push_back(power_wheel1_);
wheel_pub_.publish(wheel_data);
Plot termination Criteria
There are two termination criteria 1) cnt-c and 2) time. After one of the criteria is met, the graph is drawn.
