Introduction to PID Controller

PID Controller

What is PID?

PID stands for Proportional Integral Derivative controller. It is one of the modern controller technique that use negative feedback in order to have proper required output. To make it understand let me use some analogy of riding a bike.

Let say we are riding a bike on a highway with some normal traffic. To accelerate, we will rotate the knob on the right handle, so the vehicle will accelerate in proportional to how much the knob is rotated at that time. This is known as Proportional controller. We increase and decrease the acceleration according to our need and proportionally with the help of knob. In this, we are maintaining our speed to move constantly on the path.

Now, there is a hill the bike need to climb. In order to maintain the same speed, we quickly apply more acceleration to gain same speed on the hill so that the vehicle do not slow down. This is called as Derivative control. Whenever there is a large error in speed achievement, it can be achieved by the proportional controller, and if there is change in environment due to which proportional controller is unable to tackle then, the proportional must be changed and for that derivative is needed. 

But the problem is that there is always some error in the targeted speed and actual speed due to Proportional, and Derivative controller as they compliment each other. When error is large, proportional controller handle it and when the error is low, derivative controller handles it which makes speed-graph slope decreasing w.r.t. time in order to have low error which only tends to 0 theoretically at ∞.

To make that error deflate, Integral Controller is used in parallel to the above controller. This integral controller helps in reducing the error as it add up the error, and tune the input to the system. I have designed a PID controller in MATLAB 2017a Simulink already.

Why PID?

As we have already seen what is PID controller and it's analogy with the bike example the question arises as why PID is used. In the era of industrial automation PID controller stands firm in the way to develop intelligent automation machines. The PID controllers are very much reliable in the industry and provide a smooth functioning of many electrical devices like motors, actuators, hydraulics operations etc. It's immunity to noise in the system is also plausible and controllable with fine tuning.

Major Applications

• Industrial automation
• Temperature control
• Furnace control
• Automated motor control
• Machining operations

Minor Application 

I have seen and also used this PID controller in many college level projects in programming and hardware form. Some of the applications are:

• Line follower robots
• Self balancing robots
• Quad copters and drones
• Intelligent coolers and air conditioners.

Summary

In conclusion, we have seen what is PID controller and what does it mean for the automation in Industries with it's major and minor applications. In the next blog I will come-up with some MATLAB Simulink diagrams in order to explain it in more detail.

 

Please comment below what else I missed and how better I can do to explain in my next blog.