One of the fundamental fields in electrical engineering, considered a core branch of the discipline, is control engineering. This field, distinguished by its broad and unrestricted scope compared to other specializations, has today found extensive applications in various scientific domains—even beyond electrical engineering itself. Its wide range of activities is evidence of its growing influence, as its applications span from economic management systems and psychology to environmental, biological, and mechanical engineering.
In this course, linear control systems serve as one of the main foundations of control engineering, playing a crucial role in understanding system behavior for proper analysis and design. Students are introduced to the essential principles of modeling, simulation, and analysis of systems, ultimately enabling them to design controllers and compensators.
Since control theory extensively employs mathematical principles, students are expected to possess sufficient readiness in mathematics and differential equations. Many control problems are formulated through mathematical frameworks. However, achieving mastery in control engineering requires not only mathematical understanding but also a deep engineering insight and analytical perspective. Therefore, the Linear Control Laboratory course has been designed as a complementary and practical part of theoretical control education. By conducting experiments in the Linear Control Laboratory, students gain a conceptual understanding and realistic appreciation of electrical engineering control topics, leading to a more profound intellectual grasp of the discipline.
Controller Design
Having a mathematical model of the process previously obtained through experiments and the method considered in each control experiment, the controller is designed accordingly. The calculations at this stage can be performed using appropriate software (such as MATLAB).
Simulation
The control system with the designed controller is simulated using MATLAB software.
Application to the Plant
The designed controller is applied to the plant. By running the experiment, the behavior of the controlled system and the experimental results are observed as output curves of the system. The controller output will be obtained, and the simulation results and experimental results are compared with each other.
Equipment Available in the Laboratory:
1‑ Levitation Ball:
The present laboratory set is designed for laboratory courses in control engineering (Linear Control, Nonlinear Control, Digital Control, and Industrial Control), corresponding to course syllabi in control system design and analysis. By using this laboratory, the student learns to analyze control systems practically and experimentally and ultimately to design and implement controllers through hands‑on experience.
This set is equipped with a software package that includes PID, FUZZY, LEAD, and LAG controllers. During the session, after obtaining the mathematical model of the process (levitation ball) through experimentation, the student designs the controller in that session. The software allows observation of system behavior, outputs, and implementation of the designed controller. The program also includes the capability to draw output and input curves and step responses. The student is able to compare the simulation results and experimental results by having the graphs.
In the levitation ball experiment, the controller designed through classical control theory will be tested. The aim is to keep the ball levitated at a fixed height or position A.
Due to the use of acoustic sensors inside the levitation tube, avoid inserting hands or objects into the tube, as this may cause detachment or displacement of the transducer inside the device.
2. Furnace
This set is equipped with a software package including controllers ON‑OFF, PID, LEAD, LAG and OPEN Loop. The student in each session of the laboratory class, by having the mathematical model of the process, designs the controller examined in that session. Then, by placing the controller parameters in the software and running the system, observes the system behavior.
Also, the capability to draw output and input diagrams as a graph exists. The student after performing each experiment can view the result in MATLAB software using the M‑File output.
This set has been purchased for the purpose of teaching control of a heating process by module A.
- To power the system, use city electricity equipped with a ground connection or an isolation transformer.
- Avoid sticking objects to the furnace trainer.
- Prevent body contact with the trainer.
- Avoid pouring liquids into the trainer.
- Strictly refrain from pouring liquids onto the trainer’s glass.
- For the protection of the furnace against excessive temperature increase, if the furnace temperature rises above 250 degrees, the internal bimetal of the furnace cuts off the system’s electricity and, after the temperature decreases below 250 degrees, reconnects the trainer’s electricity.
3- Module A
This set is used to run A Model trainers such as the A Model furnace trainer and the A Model levitation ball trainer, which is equipped with a software package including control
controllers On/Off, PID, Scope, System Identification, LEAD/LAG, State Space, and Open-Loop. The student in each session of the laboratory class, by having the mathematical model of the process, designs the controller examined in that session. Then, by placing the controller parameters in the software and running the system, observes the system behavior.
Also, the capability to draw output and input diagrams as a graph exists. The student after performing each experiment can view the result in MATLAB software using the M-File output. On the other hand, due to the modularity of the system, the student can apply any desired signal to the system from the signal section or control the trainer using any existing analog controller or any other desired controller, such as a PLC or microcontroller.
Furthermore, this device has the capability to implement any type of linear (LQR, LQG) and nonlinear (Sliding Mode) controller. This device is used for communication between the furnace and levitation ball devices and the computer. Also, this device has the capability for compensation by the PID section, which is embedded as software hardware on it.
4. Air Pendulum
The air pendulum is one of the educational tools used for familiarization with topics such as control and flight dynamics in aerospace engineering. Among the various experiments that can be performed using this system are:
- Modeling the vertical propulsion system.
- Designing an appropriate apparatus for implementing and testing various linear and nonlinear control algorithms.
- Controlling the pendulum angle using an encoder and a Brushless DC Motor (BLDC) as the system actuator.
- Implementing simple control algorithms using ready-made and powerful blocks in the SIMULINK environment.
The air pendulum device consists of a variable-speed motor along with a propeller attached to its shaft. The motor is connected to the end of a rod that hangs vertically. When the motor is turned on and propulsion force is generated by the propeller, the rod moves from its vertical state and, depending on the speed of the motor, reaches a specific angle relative to the vertical line where the propulsion force creates a torque. The higher the propeller speed, the greater the angle of the rod relative to the vertical line will be.
A Brushless DC (BLDC) Motor is used in this device. The angle of the rod relative to the vertical line is measured by an Optic Encoder. The number of pulses read and processed by an AVR Atmega 328 microcontroller transmits the data via a USB to Serial interface to the MATLAB software on the computer. By calculating the appropriate angle, speed, and command for the motor, the desired angle of the rod relative to the vertical line is achieved and, in fact, the position of the air pendulum is controlled.
Figure 1 shows a schematic image of the air pendulum and its related equipment and parts.
Equipment Specifications:
- Pendulum Length: 13 centimeters
- Pendulum Weight: 250 grams
- Dimensions: 38×32×3638 times 32 times 3638×32×36 centimeters
- Optic Encoder: Used with a resolution of 400 PPR (Pulses Per Revolution)
- Brushless Motor Specifications:
- Voltage: 11.1 V
- Power: 140 W
- Shaft Length: 17 mm
- Body Length: 30 mm
- Shaft Diameter: 3 mm
- Shaft Speed Constant: 1200 RPM/V
- Brushless Motor Driver: A driver is required to operate the brushless motor. The driver used in this system is shown in the figure below. The processor controls the motor speed by creating a pulse with a frequency of 50 Hz and a duty cycle of 1 to 2 milliseconds. The output of this driver connects to the three-phase input of the brushless motor.
- Supply Voltage: 12 Volts