PID Controller C++

A PID Controller is a mechanism of control loop feedback which is widely used in engineering applications to maintain the system's behavior. The controller takes the input signal, compares it to the desired setpoint, and generates an output signal to drive the system closer to the setpoint. In this article, we will be discussing the PID Controller in C++ programming language.

What is a PID Controller?

A PID Controller is a kind of feedback system that handles a system's behavior based on the difference between the desired setpoint and the actual value of the system. The controller uses three components - the proportional, integral, and derivative - to generate an output signal that drives the system towards the setpoint.

1. The Proportional Component:

The Proportional Component is proportional to the difference between the setpoint and the actual value of the system. It generates an output signal that is directly proportional to the error. The Proportional Component provides an immediate response to changes in the error signal, and its gain determines the strength of this response.

2. The Integral Component:

The Integral Component sums up the error signal over time and generates an output signal proportional to the accumulated error. The Integral Component considers the past errors and provides a response that is equivalent to the integral of the error over time. The Integral Component eliminates the steady-state error by continually adjusting the controller output signal.

3. The Derivative Component:

The Derivative Component generates an output signal that is proportional to the rate of change of the error signal. The derivative component takes into account the future error and provides a response that is proportional to the derivative of the error over time. The Derivative Component reduces the overshoot and improves the stability of the system.

PID Algorithm:

The PID Algorithm is an algorithm made up of the components like Proportional, Integral, and Derivative components. The output signal of the controller is the sum of the three components multiplied by their respective gains. The gains are set by the user to tune the controller for the particular system. The PID Algorithm is given by the following equation:

Output = K_p * Error + K_i * Integral + K_d * Derivative

Where K_p, K_i, and K_d are the Proportional, Integral, and Derivative gains, respectively, and Error, Integral, and Derivative are the error, Integral, and Derivative terms, respectively.

Implementing a PID Controller in C++:

To implement a PID Controller in C++, we first need to define the data types and variables used in the controller. We need to define the setpoint, process variable, error, and output, as well as the gains for the proportional, integral, and derivative parts.

We can define these variables as follows:

C++ Code:

Once we have defined the variables, we can write a function to calculate the output of the controller. This function takes the setpoint and process variable as input and returns the output.

C++ Code:

In this function, we first calculate the error between the setpoint and process variable. We then calculate the Integral of the error and the Derivative of the error using the previous error value. Finally, we will get the output of the controller using all three gains.

Tuning the PID Controller:

Tuning the PID controller is an iterative process that involves adjusting the gains until the desired response is achieved. There are various methods present for tuning the controller which we will discuss below:

• Manual Tuning Method:

In this method we adjust the gains manually until we get the output we are expecting.Since there are manual adjustments of gain, this process becomes time consuming and it requires knowledge and expertise.

• Ziegler-Nichols Method:

The Ziegler-Nichols Method is generally used for tuning the PID controller. It involves measuring the response of the system and using a set of equations to calculate the gains.

• Cohen-Coon Method:

The Cohen-Coon Method is another popular method for tuning the controller. It involves measuring the response of the system and using a set of equations to calculate the gains.

Conclusion:

In this article, we have discussed the basics of the PID Controller and how to implement it in C++. We have also discussed the tuning process and the different methods for tuning the controller.

The PID Controller is a powerful tool for maintaining a desired output in control systems. There are various applications of PID Controller like controlling the temperature or in robotics or in process control etc.