PID Controller by Robotec

PID controller - it's the most powerful and famous type of controllers. It has the ability to correct given data using previous errors (inconsistency between desired and measured values).

Libraries

• The heart of the package is simple-ros-pid package.

ROS Interfaces

This part describes various ROS-related interfaces such as parameters and topics.

Parameters

• ~p: float

  Proportional coefficient of the controller Default: 1.0

• ~i: float

  Integral coefficient of the controller Default: 0.1

• ~d: float

  Derivative coefficient of the controller Default: 0.05

• ~publish_rate: int

  The rate of the main loop of the node. Default: 100

• ~input: string

  Input data topic (data to adjust using the PID controller)

• ~setpoint: string

  Setpoint topic (the desirable value)

• ~adjusted: string

  Data after the correction

Topics Published

• ~adjusted: Float64

  Result of PID correction

Topics Subscribed

• ~input: sensor_msgs/Image

  Input image to be proccessed

Project structure

.
├── cfg
│   └── pid.cfg
├── launch
│   └── pid.launch
├── scripts
│   └── pid.py
├── CMakeLists.txt
├── LICENSE
├── package.xml
├── README.md
└── setup.py

Folders

• ./launch - *.yaml roslaunch files
• ./scripts - main folder of the project (contains executables)
• ./cfg - configuration files for the dynamic_reconfigure package

Files

The project uses following files

Launch

• pid.launch - starting the node (example of use)

Package

• pid.py - the main node (corrects errors of the received data)

ROS

• pid.cfg - a configuration file for the dynamic_reconfigure package

Example of use

To start the controller you should change the parameters in launch/pid.launch and then run :

$ roslaunch robotec_pid pid.launch