Team #11Embodiment Design Report
MECH 4010 & 4015
Design Project I
EMBODIMENT DESIGN REPORT
Magnetic Levitation Demonstration Apparatus
Team #11
Ajay Puppala
Fuyuan Lin
Marlon McCombie
Xiaodong Wang
Submitted: November 22, 2013
Table of Contents
List of Figures
List of Tables
1.Project Information
1.1.Project Title
1.2.Project Customer
1.3.Group Members
1.4.Useful Definitions and Acronyms
2.Background and Context
2.1.Background and Overall Objective
2.2.Requirements
3.System Architecture
3.1.Selected Design
3.2.Subsystems / Components
4.Levitation: Electromagnet
4.1.Component Description
4.2.Component Design
4.3.Stand Design
5.System Feedback: Sensor
5.1.Component Description
6.Microcontroller Unit
6.1.Component Description
7.Signal Conditioning : Control Circuit
7.1.Component Description
7.2.Component Design
8.User Interface
8.1.Component Description
8.2.Component Design
9.Testing and Verification Plan
10.Feasibility and Risk Assessment
11.Cost Estimates & Budget
12.Progress Report
13.Future Considerations
14.Project Management Plan
14.1.Organizational Responsibilities
14.2.Work Breakdown Structure
14.3.Schedule
14.4.Specialized Facilities and Resources
14.4.1.Facilities
14.4.2.Additional Advisors
15.References
Appendix AStand Design Draft Files
Appendix BSimulink block diagram for electromagnetic levitation
Appendix CMATLAB LED and LM35 Temperature Sensor Test Code
Appendix DExcel Calculations for Electromagnet Design
Appendix ENovember to December Schedule
List of Figures
Figure 1 Single electromagnet design with Hall Effect sensor
Figure 2 General Schematic of demonstration device
Figure 3 Functional block diagram for the magnetic levitation apparatus
Figure 4 Magnetic field generated by the current carrying coil (courtesy of superconductors.solidchem.net)
Figure 5 Assembled view of the stand (left) and exploded view (right).
Figure 6 Picture of Hall Effect Sensor
Figure 7 Picture of Arduino UNO.
Figure 8 Electromagnetic coil driving circuit (Mekonikuv)
Figure 9 Sensor with amplifier circuit (Mekonikuv).
Figure 10 Arduino Simulink block diagram example
Figure 11 Materials used for building the prototype (left) and first build and testing (right).
Figure 12 General work breakdown structure
Figure 13 Research work breakdown structure
Figure 14 Product design work breakdown structure
Figure 15 Concept evaluation breakdown
Figure 16 Process flow diagram
List of Tables
Table 1 Arduino UNO specification summary
Table 2 Component and materials cost breakdown
Table 3 Required engineering expertise
Table 4 Allocation of team responsibilities
Table 5 Summary of project tasks for fall 2013 term
Table 6 Breakdown of remaining hours of work for the fall 2013 term
Table 7 Summary of project tasks for winter 2013 term
1. Project Information
1.1. Project Title
Magnetic Levitation Demonstration Apparatus
1.2. Project Customer
Dr Robert Bauer
Professor
Mechanical Engineering Department
Dalhousie University
1.3. Group Members
Ajay Puppala email:
Fuyuan Lin email:
Marlon McCombie email:
Xiaodong Wang email:
1.4. Useful Definitions and Acronyms
PID-Proportional Integral Derivative Control
P-Proportional Control
PI-Proportional Integra Control
GUI-Graphical User Interface
PC-Personal Computer
PPE-Personal Protective Equipment
PCB- Printed Circuit Board
MagLev-Magnetic Levitation
EM - Electromagnet
MCU - Microcontroller Unit
PWM- pulse width modulation
I/O -Input/output
EOPD-Electro-Optical Proximity Detector
RISC-Reduced instruction set computing
CMOS-Complementary metal-oxide semiconductor
AVR - no meaning
ISCP - In-circuit serial programming
EEPROM-Electrically Erasable Programmable Read-Only Memory
SRAM -Static random-access memory
DC-Direct current
AC-Alternating current
WBS - Work Breakdown Structure
2. Background and Context
2.1. Background and Overall Objective
Demonstrations provide the opportunity for students to predict theoretical outcomes of real life applications of course material which in turn allow them to confirm their initial understanding of those same concepts. By making a prediction, students develop an expectation based on their initial understanding of the concept. As they observe the demonstration they find out whether their prediction is accurate. If not, the instructor can discuss any differences between their initial understanding and what the demonstration actually shows.
Visual demonstrations help to bridge the gap between visual and verbal communication of course material. Although diagrams may be a step further to having a better visual understanding of a concept, a demonstration that produces live feedback vastly improves the delivery of course material. This concept is similar to a salesman increasing the appeal of a product by showing its many uses through infomercials; i.e. demonstrations of the basic use of a known concept (e.g. blending with the Magic Bullet). The only difference for course material from this analogy is that the concepts being taught are new to students and may not be initially understood from course lectures. Consequently, demonstrations allow students an extra chance to try out their own theories on a subject to confirm their understanding.
Thus, the scope of our project is to design and build a portable and compact device that magnetically levitates an object to demonstrate different control design theories presented in MECH4900 Systems II.
2.2. Requirements
- Purpose
- Build portable demonstration device
- Levitate object magnetically
- Educational tool
- Demonstrate theories presented in MECH4900(4905) Control Systems II
- Visual Requirements
- Shall be viewable from a back of the classroom and/or using cameras
- Levitate object for range of 5 cm
- User Convenience & Safety
- Easy to carry; i.e. lightweight
- Levitating object will be approximately 30mm in diameter and weigh 10 g
- Apparatus shall be no more than 1.5 kg (or about the weight of a standard laptop)
- Easy to store
- No potential electrical risk to user
- No PPE required for operation
- Power Requirements
- Conventional 120 VAC input
- User Interactive Requirements
- Simulate a wide variety of control methods available in MATLAB/Simulink
- User shall interact with the device using a graphical user interface (GUI)
- Device shall be ready to operate once plugged into PC
- No additional programming shall be required
- Demonstrative Requirements
- Comparison of desired, simulated, manipulated, and measured controller variables
- Nyquist plots
- Bode diagrams
- Lag, lead, lag-lead compensation techniques
- P, PI, PID control
- Miscellaneous
- Shall be an active controller
- Budget $1,500
3. System Architecture
3.1. Selected Design
It was decided to move forward with a single coil electromagnetic source, a Hall Effect sensor, and an Arduino UNO for the project. This decision was made based on the basic requirements of the project. The Arduino UNO is one of the more basic MCU models and was chosen since the project does not require a large amount of computing power or I/O signals. A single cool electromagnet was chosen for the design since it is more simplistic to build and test and has been used for electromagnetic levitation before (Mekonikuv Blog, Lieberman). The Hall Effect sensor was chosen because it is one of the more simple magnetic sensors on the market and has also been used for magnetic levitation in the past. Additionally, all the above components were chosen because of their low cost.
Figure 1 Single electromagnet design with Hall Effect sensor
3.2. Subsystems / Components
Figure 2 shows a general schematic of the system components needed to build a functional magnetic levitation demonstration apparatus based on the specified requirements.
Figure 2 General Schematic of demonstration device
For magnetic levitation to be achieved for the purpose of demonstrating various design techniques presented in Control Systems II, a user would need to vary a magnetic field which in theory should vary the position of a levitating object. A varying magnetic field is most commonly achieved by a non-permanent magnet or more specifically by using an electromagnet. Electromagnets allows for a varying input current to be applied to them for the purpose of manipulating a magnetic field and hence the position of a magnetically levitating object. In Figure 2, the electromagnet is represented by the magnetic source.
It is required to use MATLAB/Simulink to design controllers for demonstration of the different control theories presented in Systems II. The designed controllers must then be able to control the apparatus to achieve the desired control being demonstrated; this is achieved through the microcontroller unit. Using MATLAB/Simulink a user will be able to communicate with the microcontroller which would then execute the desired I/O signals to perform the desired control of the electromagnetic field. Once this communication is achieved, some form of feedback becomes necessary to inform the designed controller of the output result of its input to the electromagnet. A sensor will be responsible for providing this feedback. Generally, the microcontroller would be instructed, by the user/designed controller through MATLAB/Simulink, to retrieve necessary data from the sensor during the implementation of the control demonstration. The microcontroller then sends this information back to MATLAB/Simulink where it is presented to the user in graphical form.
The amount of current and voltage required to power an electromagnet (usually 12V) to levitate a reasonably visible object is more than the amount that can be supplied by a microcontroller unit which usually gives a maximum output voltage of 5V. Consequently, an external power supply is required. Therefore, before any input is given to the electromagnet or any data is retrieved from the sensor, some form of signal conditioning is required to:
- Maintain a relatively steady magnetic field
- Sensitize system feedback
- Protect the system and the user from electrical harm
Signal conditioning is handled by the circuitry. In order to maintain a steady magnetic field, a steady input current must be supplied to the electromagnet. In addition, a more sensitive sensor would produce a more sensitive feedback on the position of the levitating object. Finally, it is required to design and build a safe-to-use apparatus; thus, it is required to have protective measures designed into the systems signal transmission so that users are protected from electrical injury and the apparatus is protected from electrical damage. The next figure summarizes the required functionality of the operating device. The final design shall meet these major functionality requirements.
Figure 3 Functional block diagram for the magnetic levitation apparatus
4. Levitation: Electromagnet
4.1. Component Description
Electromagnets is a type of magnet that can generate magnetic field when current is allowed to pass through it (please see figure 4 below). The field induces flux on ferromagnetic material that is introduced in the field. It is important to design an electromagnet that would meet the requirements of the project in terms of range of levitation of the object, required flux to hold the object in place, duration of levitation, and power supply limitations. Off the shelf electromagnets are available; however, they are designed and used for different purposes. Finding the right one and testing it would be cumbersome. Instead, designing an electromagnet based on the required strength of the magnetic field is suitable and most appropriate for this project.
Figure 4 Magnetic field generated by the current carrying coil (courtesy of superconductors.solidchem.net)
4.2. Component Design
The electromagnet design is based on a few assumptions which are listed as follows:
- The magnetic ball is subjected to gravitational and magnetic forces
- air friction and damping effects are legible
- The air gap range is assumed to be between 30 to 50mm
- The electromagnet core diameter is 30mm and its length is 100mm
- The number of turns in the solenoid is 1000 turns
- The diameter of the levitated object is 25mm
- The length of solenoid is 100mm and
- The stacking factor is 0.9
Based on assumptions made on the diameter of the levitating object as well as the density of steel, it is easy to get the volume as well as the mass of levitating objects. Air gap is an important parameter that will determine the amount of current that goes through the electromagnet and the force required to levitate the magnetic ball. Since the air gap is assumed, the force balance on the object is, where m is the mass of the object, g is gravitational acceleration. Pole area is calculated as A=0.00071m2 with the magnetic force, the magnetic field needed to levitate the object can be calculated by using the following equation:
where F is the magnetic force (N), B is the magnetic field generated by the electromagnet (T), A is the pole area of the electromagnet (m2), and µo is the permeability of free space for air it is always 4π x 10-7 HM-1. The calculation is to estimate the maximum magnetic field needed. Another factor is that the magnetic field B saturated at certain value, which is approximately 1.6T. This will set a limit on the maximum force per unit core area that the electromagnet can exert The strength of magnetic field B can be used to calculate the flux density, Ф in the air gap ,A the surface area of magnetic core using the equation:
The magnetizing force H in the air gap can be calculated using the following equation:
The magneto- motive force (mmf). It primarily depends on magnetizing force, H and air gap l. It is possible to calculate the current value based on the assumption made on the air gap and number of turns that are mounted on the magnetic core. The following is the equation used to calculate the current,
The current value will be used to choose the wire gage. Each gage has the maximum current that can tolerate. It is necessary to compare the calculated current values with those limits on each gage wire. Finally the gage 19 wire is chosen. The wire diameter for gage 19 wire is 0.912mm.The maximum number of turns on the first layer is 109.67 calculated by dividing the length of solenoid by the wire diameter of gage 19. The total number of layers is 10.13 calculated by total number of turns (1000) dividing the total number of turns on the first layer and stack factor 0.9. The total length of wire is calculated as follows: L= the total length of wire for the cylinder is 0.9*1039.26*109.67=102574.68mm =336.53ft. Based on the unit resistor of chosen wire, it is easy to calculate the resistance of wire is 2.71Ω.The associated voltage is 1.27V. The heat generated is 3.45kw (Shuaibu & Adamu).
4.3. Stand Design
A suitable stand is designed to hang the electromagnet in place. The following model (figure 5) is generated using Solid Works. It is decided all of the parts will be made using light weight wood. The cost for purchase of the raw material is considered in the budget analysis section of the document. Workshop facilities in Dalhousie engineering department would be used for the construction of the stand (please see section 11.4.1 for facilities available for the group). Draft files are attached to Appendix A.
Figure 5 Assembled view of the stand (left) and exploded view (right).
5. System Feedback: Sensor
5.1. Component Description
The Hall Effect sensor was chosen for the project as it is a commonly used magnetic sensor found most commonly in motor vehicles to detect the position of rotating parts. Figure 6 shows an example of a Hall Effect sensor.
Figure 6 Picture of Hall Effect Sensor
The Hall Effect sensor is an analog position sensor that operates by generating a steady electrical output, when excited, which can be altered to a higher state when a magnetic field is placed near its body (Honeywell SS49 datasheet). The Hall Effect sensor output voltage intensifies with decreasing distance between its body and a magnetic source. The Hall Effect sensor is an important component of the apparatus as it is responsible for position sensing of the levitating object and thus, for providing position feedback to designed controllers.
6. Microcontroller Unit
6.1. Component Description
The selected Microcontroller for the project is the Arduino UNO (Figure 7). The Arduino UNO is based on the ATmega328 (Arduino UNO webpage), a low-power CMOS 8-bit microcontroller based on AVR enhanced RISC architecture. The ATmega328 is designed to optimize power consumption versus processing speed (ATmega238 datasheet). The Arduino UNO consists of 14 digital I/O pins (including six pins that can be used as PWM outputs), six analog inputs, a 16 MHz ceramic resonator, a USB connection, a power jack, an ICSP header, and a reset button. Additionally, it can be powered through USB or with an AC-to-DC adapter or battery. Unlike preceding boards, the UNO uses Atmega16U2 programmed as a USB-to-serial. Table 1 summarizes the specifications of the Arduino UNO board.
Figure 7 Picture of Arduino UNO.
The Arduino can be described as the hub of the magnetic levitation device and will be responsible for controlling the power input of the electromagnet, retrieving data from the device’s sensor, and returning the retrieved data back to MATLAB/Simulink to be plotted and displayed on a PC. Consequently, the Arduino will be responsible for executing the function of controllers designed in MATLAB/Simulink. For the Arduino to be controlled using MATLAB/Simulink, special I/O integration toolboxes are needed. These toolboxes allow users to interface with and command the Arduino using MATLAB syntax or by uploading controllers through Simulink.
Table 1 Arduino UNO specification summary
MCU Component / SpecificationMicrocontroller / ATmega328
Operating Voltage / 5V
Input Voltage (recommended) / 7-12V
Input Voltage (limits) / 6-20V
Digital I/O Pins / 14 (of which 6 provide PWM output)
Analog Input Pins / 6
DC Current per I/O Pin / 40 mA
DC Current for 3.3V Pin / 50 mA
Flash Memory / 32 KB (ATmega328) of which 0.5 KB used by bootloader
SRAM / 2 KB (ATmega328)
EEPROM / 1 KB (ATmega328)
Clock Speed / 16 MHz
7. Signal Conditioning : Control Circuit
7.1. Component Description
Now that the processing control and sensing components of the apparatus are defined, some form of signal conditioning is needed for the input current to the electromagnet and the retrieval of the output voltage (data) coming from the sensor. Signal conditioning is crucial to the manipulation of the raw I/O signals for further processing. For instance, a smooth electrical signal is required to provide stable magnetic polarity and also a stable magnetic field strength in the electromagnet. Additionally, it is required to amplify the electrical output of the sensor for further use by MATLAB/Simulink for graphical display of data.
7.2. Component Design
As mentioned in the description, the electromagnet requires a steady current flow through its coils to be able to provide stable magnetic polarity and also a stable magnetic field strength. However, current is transmitted in the form of an analog signal; thus, its signal varies or oscillates during transmission. Consequently, a raw current signal would not be most suitable for powering the electromagnet. Therefore, it is necessary to implement a form of signal conditioning that would allow for a relatively steady flow of current into the electromagnet and hence a relatively steady magnetic field strength. This conditioning can be supplemented by the use of a capacitor which is often used in electrical circuits to smooth the output of power supplies (i.e. the power supplied by the Arduino). In addition to this some form of switch is required to control the magnetic field strength based on position of the levitating object (provided by the sensor). Figure 8 shows a configuration of an electromagnet coil driving circuit that makes use of the above signal conditioning methods (Mekonikuv).