Practical implementation of non linear control system the magnetic levitation system
Magnetic levitation has evolved into an important consideration in designing systems requiring low losses due to friction and low energy consumption. Applications range from high-speed rail transportation systems to various industrial applications (e.g. magnetic bearings). Magnetism and closed-loop
2025-06-28 16:34:34 - Adil Khan
Practical implementation of non linear control system the magnetic levitation system
Project Area of Specialization RoboticsProject SummaryMagnetic levitation has evolved into an important consideration in designing systems requiring low losses due to friction and low energy consumption. Applications range from high-speed rail transportation systems to various industrial applications (e.g. magnetic bearings). Magnetism and closed-loop control system are the secrets to making an object float in mid-air. Maglev is the means of floating one magnet over another. This maglev system is divided into two types attractive systems and repulsive systems, which are referred to as electromagnetic suspension and electrodynamics suspension. Thus many countries spend billions of dollars to use this maglev system.
Project ObjectivesThe given problem is to design, build, and test a magnetic Levitation of system which will levitate a metallic object below the electromagnet.
The objective of this thesis was to design and build the magnetic levitation system. The magnetic Levitation systems has been analyzed mathematically and design a control system which levitates a metallic object below the electromagnet, for an indefinite period of time at approximately 15 millimeters from the base of the electromagnet. The specific objective of this thesis work is to analyze the magnetic levitation system analysis and develop a hardware implementation to analyze the behavior of magnetic levitation system. In order to achieve this goal, the following sub-objectives need to be accomplished.
- Design and fabrication of a sensor to sense the ball's vertical displacement (height).
- Design and implementation of a HD controller.
- Design and fabrication of an electromagnet that provides sufficient magnetic attraction to suspend the metallic ball.
- Designing and fabricating the actuator (a voltage controlled current source) to regulate current flowing into the electromagnet's coil.
- Design and fabrication of an interlacing mechanism between the hardware project and Matlab
If you hold two permanent magnets close together, you see that one of them will jump
strongly toward (or away) from the other.The general principle is straight forward: An electromagnet pulls a ball upward while
a light beam measures the exact position of the ball's top edge. The magnet's lifting force is
adjusted according to position of the steel ball.
As less light is detected, the circuit reduces the electromagnet's current. With less current, the lifting effect is weaker and the ball can move downward until the light beam is less
blocked. The ball stays centered on the detector, it is a small distance across the photo-detector,
and perhaps a one millimeter or two, but this is sufficient to measure small changes in position.
Of course, if the ball is removed the coil runs at full power. And conversely, if the light beam
is blocked the coil is turned completely off.
This device uses photo-detectors, the "signal" detector looks for an interruption in the
light beam, and the "reference" detector measures the background light. The circuit subtracts
one signal from the other to determine the ball's position. This design automatically compensates for changes in ambient light, and eliminates a manually adjusted potentiometer.
The system was designed taking into account the object to be levitated which was a
metallic object of 30-40 grams in mass. This metallic object was chosen since it was relatively
light and therefore would not require an unreasonably powerful electromagnet. The practical
approach of magnetic levitation system is using optical sensors, the optical sensor configuration was chosen since it would not obstruct the view of the object while it was being levitated.
There was also a concern in that the field exerted by the electromagnet would be picked
up by the photo sensors. Since the sensors would operate by sensing the field exerted by the
levitating steel ball, the clearly dominant field of the electromagnet would drown out any recognizable signal.
Magnetic Bearings
A magnetic bearing is a metal shaft surrounded by a casing that contains magnets.
The shaft is suspended and rotated within the casing by magnetic forces. Because of the magnetic forces, the shaft has no contact with other parts of the equipment and very little friction
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or vibration (which wears out parts) occurs. In addition, no lubrication is required and the
bearings can withstand very high temperatures. Magnetic bearings have an unlimited life.
These benefits save money in equipment replacement.
Environmental Magnets
Responding to the interest in using recycled materials, Master Magnets, a British company, has developed a magnetic separator to be used in recycling plants. It has many advantages
over electromagnetic separators. Because the Mastermag Type K Permanent Magnetic Separator is a strong permanent magnet, no electrical power is needed to generate a magnetic field
and the resulting attraction.
Superconducting Magnets
Air Force scientists and private industry researchers have developed small powerful
magnets that weigh much less than traditional magnets. These magnets are oval-shaped magnetic coils, made by winding lengths of superconducting wire. Because superconducting wire
conducts electricity with very little resistance, the coils produce stronger magnetic fields. The
superconducting coil is relatively light in weight and can be used in many applications, including maglev train systems, compact generators, motors and satellite
Maglev Trains
Maglev (magnetically levitated ground transportation) is likely to become an important
mode of future transportation. Magnets located in a monorail-like train and in the walls of the
train track suspend, propel, and control the cars above the track. The train-like cars literally
float above the track, and there is no friction. Maglev trains can travel 300 miles per hour and
offer the speed of airline travel with the convenience of numerous stops provided by rail systems.
Microrobotics
Besides many industrial applications of magnetic levitation systems, remote actuation
of objects can lead into promising results in the field of microrobotics. One of the more complex issues related to the design of microrobotic systems is the design of the propulsion system.
As objects scale down in size, viscous forces start to become dominant, and the amount of
power required to propel the system per unit mass will increase.
This project is purely an example of analogue feedback control system and can be to
used teach analogous feedback to the undergraduate students.
The system was initially unstable and it was difficult to model such a non-linear system.
Also it was difficult to implement the sensing mechanism, because of the external disturbance
to the infra-red sensors. Due to these disturbances the operating range of the device was limited
to 0- 15 mm from the electromagnet pole.
Though the objectives of this thesis were successfully achieved using Hardware design
and a lot of controller design and implementation skills were gained. The difficulties involved
in developing the sensing mechanism proved to be the most difficult and time-consuming part
to this project. A better understanding of sensing techniques and technologies would have improved the chances of developing a reasonably stable Maglev system.
This project generates a lot of interest. Levitators are fun and are seen very rarely. This
project would make a highly unusual science fair display, and illustrates the potential for maglev devices.
Using a lighter object would reduce average and maximum coil current requirements
which would greatly reduce the heat dissipation. A, PWM stage can be used to control the coil
current PWM can be changed to desired level to achieve a good result using a PWM generator IC or a microcontroller.
| Item Name | Type | No. of Units | Per Unit Cost (in Rs) | Total (in Rs) |
|---|---|---|---|---|
| Total in (Rs) | 8000 | |||
| Inductor | Equipment | 1 | 4000 | 4000 |
| Frame | Equipment | 1 | 2000 | 2000 |
| components | Miscellaneous | 2 | 1000 | 2000 |