Introduction
Control engineering, also known as control system engineering, involves the design, analysis, and optimization of control systems. These systems are composed of devices that regulate the behavior of other devices or systems, including both mechanical and electronic components. Despite their diversity, all control systems share the common goal of controlling outputs. This map of control theory created by Brian Douglas -which his youtube channel is highly recommended for anyone is interested or studying control engineering- includes all the fields of control engineering.
Brief History of Control Engineering
Before talking about the main concepts of control engineering, let's give a brief history lesson. There might be some control terms that will sound gibberish but that's ok, explanation of the main terms will be given later and references for further reading are attached at the end of the blog.
The history of control engineering goes all the way back to the 18th century. James Watt initially introduced the idea of feedback control in 1788 when he utilized a flyball governor to control the speed of a steam engine. Nicolas Minorsky, the inventor of the closed-loop control system, performed the first mathematical analysis of feedback control in 1922. The telephone system, analogue computers, and ships, as well as airplanes and ships, all utilized feedback control devices in the 1930s. In order to analyze and create non-linear, sampled-data, and stochastic systems, these devices were combined during World War II to construct what are now referred to as the classical frequency response. The post-war period saw the addition of the root locus method and the introduction of the state-space methods of modern control. The beginning of the 20th century is known as the golden age of control engineering, during which classical control methods were developed at the Bell Laboratory by Hendrik Wade Bode and Harry Nyquist
Control Systems
So far we kept talking about control engineering or control systems engineering and we gave a brief history about this field, but what is a control system ? What are we controlling exactly ?
A system that is intended to control or regulate a physical process is known as a control system. It is a system that receives an input, processes it, and then generates an output used to regulate the process. From straightforward thermostats that regulate a room's temperature to sophisticated systems that manage an aircraft's flight, control systems are utilized in a wide range of applications. A system is made up of various parts that cooperate to accomplish a single objective. A system is an actual physical process that is being controlled in the context of control systems. Sensors (for closed loop systems; more on that later) , controllers, and actuators are the parts of a control system. The process is controlled by the actuators using the control signals that the controllers provide after processing the sensor data.
All control systems from the most complex ones to the basic control system of a refrigerator can be categorized into Open loop and Closed loop systems, let's describe them one by one by giving real life examples:
Open-Loop Control Systems
An open-loop control system is a type of control system in which the output is not fed back to the input. In other words, the output of the system is not used to adjust the input. An example of an open-loop control system is the control system of a refrigerator. The refrigerator has a thermostat that is set to a certain temperature. When the temperature inside the refrigerator rises above the set temperature, the thermostat turns on the compressor. The compressor then runs for a certain amount of time, regardless of the temperature inside the refrigerator. Once the time has elapsed, the compressor turns off. This process continues, with the compressor turning on and off at regular intervals, until the temperature inside the refrigerator reaches the set temperature again. The control system of the refrigerator is an open-loop control system because the output (the temperature inside the refrigerator) is not fed back to the input (the thermostat setting).
Closed-Loop Control Systems
A closed-loop control system is a type of control system in which the output is fed back to the input. In other words, the output of the system is used to adjust the input. An example of a closed-loop control system is the control system of a car’s cruise control. The cruise control system maintains a constant speed by adjusting the throttle position. The system uses a speed sensor to measure the speed of the car and a controller to adjust the throttle position. If the speed of the car drops below the set speed, the controller increases the throttle position to increase the speed. If the speed of the car exceeds the set speed, the controller decreases the throttle position to decrease the speed. This process continues, with the controller adjusting the throttle position to maintain a constant speed, until the driver turns off the cruise control system. The control system of the car’s cruise control is a closed-loop control system because the output (the speed of the car) is fed back to the input (the throttle position).
Control Engineering Fields
In the last section we gave practical examples to explain the difference between open loop and closed loop control; Let’s stay in the practical world and see where control engineering students work after their graduation.
Robotics
Control engineers are key players in the robotics sector, designing and developing the control systems for robots used in a variety of industries. In this field, control engineers create sophisticated control algorithms that let robots carry out difficult tasks including object detection, motion planning, and path tracking. They also concentrate on creating feedback control systems that provide robots the stability and accuracy they need to carry out tasks.
Aerospace
Control engineers are in charge of creating the control systems for both aircraft and spacecraft in this field. Engineers that specialize in control work on the navigational and flight control systems as well as other crucial components that keep aircraft and spacecraft safe and reliable. They might also concentrate on creating autonomous flight control systems and using machine learning and artificial intelligence (AI) methods to satellites and unmanned aerial vehicles (UAVs).
Automotive
In the automotive industry, control engineers work on designing and developing control systems for vehicles. They are responsible for developing control algorithms for various systems such as the engine, transmission, and braking systems. Control engineers in this industry work on developing autonomous vehicles and implementing AI and ML algorithms for self-driving cars. They may also work on developing electric and hybrid vehicle systems, which require advanced control systems for the electric motor and battery management.
Control Engineering Techniques
After talking about possible careers for control engineers, we need to mention the most popular control techniques used in these industries. As said before; for further information you can check the resources attached at the end of this blog.
PID Control
One of the most popular if not the most popular control method is PID control, PID stands for Proportional-Integral-Derivative so PID controller is basically the combination of 3 different controllers each with its own advantages and disadvantages. The proportional controller adjusts the output of the system in proportion to the error between the desired output and the actual output. The integral controller adjusts the output of the system based on the accumulated error over time. The derivative controller adjusts the output of the system based on the rate of change of the error.
State-Space Control
State-space control is a type of control system that uses state variables to explain a system's behavior. The internal states of the system that are represented by the state variables include things like a moving object's position, velocity, and acceleration. The state variables are combined to form a state vector that depicts the system's current state. The system's input is altered as a result of computing the system's output using the state vector. State-space control is widely used in industry as a foundation for modeling and managing complex systems because it is robust and flexible.
Optimal Control
The best input to a system that minimizes a cost function is found using an optimal control system, a type of control system. The input that minimizes the cost function is the ideal input, and the cost function serves as a gauge of the system's performance. Several fields, including economics, robotics, and aerospace, use optimal control. State-space control and PID control are two types of control systems that are used in optimal control. State-space control is used to model the behavior of the system, and PID control is used to adjust the input of the system. By combining state-space control and PID control with optimal control, engineers can design control systems that are highly effective and efficient.
Importance of Practical experience for Control engineering Students
If you can notice, most of the topics covered in this blog are theoretical and can be hard to grasp. This emphasizes the importance of hands-on experience for control engineering students because it allows them to apply the theoretical concepts they learn in the classroom to real-world problems. By working with actual control systems, students can gain a deeper understanding of the principles of control engineering and develop the skills they need to design and implement effective control systems.
Acrome’s products offer educational systems like ball balancing table with courseware that can help students gain hands-on experience with control systems. These systems provide students with the opportunity to work with real control systems and learn how to design and implement effective control strategies. By using Acrome’s educational systems, students can gain the practical experience they need to succeed in the field of control engineering.
Conclusion
Control engineering is a fascinating field that has a wide range of applications in industry and academia. It’s a growing on demand field that is evolving rapidly. Understanding the concepts behind it is crucial for a successful career and the best way for this is hands-on experience and completing real life projects.
Resources for further reading:
- Modern Control Engineering by Katsuhiko Ogata
- Automatic Control Systems by Francis H. Raven
- Control Systems by M. Gopal
- https://engineeringmedia.com/
- Brian Douglas youtube channel
- https://www.controleng.com/
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