meng483 mini blinds

7/28/2019 MENG483 Mini Blinds

1/21

1

Mini Blinds Control System Project

Mechatronics MENG 483

Course Project

Group 4

Michael Carmody

David Sonny Cooper

Patrick Murray

12/12/06

ABSTRACT

The project objective was to create a system that opens and closes mini blinds accordingto two defined settings, temperature and light intensity. The system will maintain thetemperature/light intensity in the room by opening and closing the blinds. The blinds and astepper motor will be mounted on a constructed wooden frame. The program asks the user tochoose a setting and define a specific value for that option. The program maintains the desiredrange by opening and closing the blinds using a stepper motor.


2/21

30-Dec-06 Mini Blinds Control System

2

TABLE OF CONTENTS

1. INTRODUCTION..............................................................................................................................................3

2. SYSTEM DESIGN.............................................................................................................................................3Functions................................................................................................................................. 4

2.1 Mechanical design .......................................................................................................... 4

2.2 Electrical design.............................................................................................................. 7

2.3 Software design............................................................................................................. 12

2.4 System assembly........................................................................................................... 15

3. SYSTEM TESTING ........................................................................................................................................16

4. MATERIAL COST AND TOTAL EXPENSES............................................................................................16

5. CONCLUSION.................................................................................................................................................17

6. ACKNOWLEDGEMENTS.............................................................................................................................17

7. REFERENCES.................................................................................................................................................17

8. APPENDIX.......................................................................................................................................................18

8.1 Appendix A: Mechanical Components......................................................................... 18

8.1.1 Materials Used ...................................................................................................... 18

8.1.2 Tools Used ............................................................................................................ 18

8.2 Appendix B: Electronic components ............................................................................ 19

8.2.1 Materials and Components Used .......................................................................... 19

8.3 Appendix C: Software components .............................................................................. 20


3/21


3

1. INTRODUCTIONThe team project was to design and build an automatically adjustable mini blind system. The

blinds will open and close according to a user defined setting. The user will set a desired

temperature or light intensity in the room where the blinds are installed. The system will

maintain the temperature/light intensity in the room by opening and closing the blinds.

The opening and closing mechanism of the mini blinds will be driven by a Shinano Kenshi STP-

42D241 stepper motor. This motor will be controlled by the MRK Board with the Motorola

MC9HCS12 Microcontroller. The MRK board will be receiving inputs via the analog in pins

from two PN 168 photo transistor light sensors and one TMP36 integrated circuit temperature

sensor. The motor requires a control circuit that will be set up on a 3M solder less bread board.

The team acquired and assembled a simple wooden frame with the mini blinds attached. The

stand alone frame was constructed using 1 x 2 boards. A generic set of mini blinds measuring

24 x 48 were affixed to the frame. The completed setup is shown in Appendix A. The MRK

board, bread board, and sensors were also attached to the frame.

2. SYSTEM DESIGNEquipment

Microcontroller - Board with Motorola MC9HCS12 Microcontroller

Motor Shinano Kenshi STP-42D241 stepper motor

Temperature Sensor TMP36 Integrated Circuit Temperature Sensor Light sensor 2 PN 168 photo transistors

Mini blinds Basic store bought mini blinds Wood test stand Fabricated basic wood planks


4/21


4

Functions

Sense lighting conditions and open/close blinds to maintain a certain user defined lightintensity in room

Sense temperature and open/close blinds to maintain a certain user defined temperature in

room Open/close blinds on a timer Open/close blinds from direct user input

2.1 Mechanical designFor the mechanical aspect of this project, the team decided to construct a model window frame.

The team chose to use 1 x 2 boards and also purchased a set of blinds measuring 24 by 48. The

frame was constructed by making a square frame measuring 26 x 47and adding two horizontal

boards for support. The blinds were mounted on this frame 3.5 from the top of the frame to

allow for the motor to be mounted. A stepper motor was zip tied to the frame directly above the

blind turning mechanism. This mechanism was removed from the original setup, inverted, and

then placed in the track on the top of the blinds. The inverted mechanism was situated directly

beneath the stepper motor and connected using bushings and electrical tape. Using the existing

mechanism prevented the team from having to fabricate a linkage or modifying the blinds

structure. Also, there are 2 light sensors and 1 temperature sensor mounted on the frame. A light

sensor was mounted at the midpoint of the frame on each side. A temperature sensor is located

on the top of the frame. The MRK board and 3M breadboard are also secured at the top of the

frame.

The following pictures show the completed frame with blinds, MRK board and 3M breadboard

locations, motor mount, and light sensor locations. Figure 1 is the completed frame before

system components have been mounted. Figure 2 shows the stepper motor connection to the


5/21


5

blind turning mechanism. Figure 3 shows the frame with the MRK board and 3M breadboard

attached. Figure 4 shows the location of the 2 light sensors on the frame.

Figure 1: Frame Assembly


6/21


6

Figure 2: Mounted Motor

Figure 3: Mounted MRK Board and Breadboard


7/21


7

Figure 4: Location of Light Sensors

2.2 Electrical designThe electrical components of the system included two light sensors, one temperature sensor, one

motor and integrated controlling circuit, the MRK controller board, and a bread board. The

MRK board shown in Figure 5 acts as the brains of the system. It performs all operations for

the components, and executes the C++ code.

Figure 5: MRK Board with the Motorola MC9HCS12 Microcontroller


8/21


8

The temperature and light sensors used in the system are shown in Figures Figure 6 andFigure 7.

All three sensors were connected to separate channels on the ANALOG IN pins of the MRK

board. The signals from the three sensors are converted using the A/D converter. The converted

signals are then processed by the Motorola microprocessor according to the C++ code contained

in section 2.3.

Figure 6: TMP36 Temperature Sensor

Figure 7: PN 168 Photo Transistor

Depending to the outcome of the program, the MRK board will send an output signal to the

DIGITAL OUT pins to be received by the stepper motor shown in Figure 8. The motor is


9/21


9

connected to the DIGITAL OUT pins and its integrated controlling circuit via the bread board.

The Motor receives its power via the LEFT MOTOR connection of the MRK board. In order for

an adequate amount of energy to be received, the MRK board must be set on HIGH POWER

mode. Further descriptions of electrical components can be seen in Appendix B.

Figure 8: Shinano Kenshi STP-42D241 Stepper Motor

The full electrical assembly of these components is seen in Figures Figure 9 and Figure 10.

Figure 9: Components Connected to MRK Board


10/21


10

Figure 10: Components Connected to Bread Board

The electrical connection diagram can be seen on the following page. It shows the connection of

the sensors, motor, power, and computer to the MRK board.


11/21

11

ANALOG

IN

MBOAPOW

SERIALPORT

MO(LE

DIGITAL OUT

MRK BOARD

GROUND

POWER

SIGNAL

GROUND

POWER

SIGNAL

GROUND

POWER

SIGNAL

TO COMPUTER

SERIAL PORT

SIGNALS

LIGHTSENSOR 1

LIGHTSENSOR 2

TEMPERATURE

SENSOR

STEPPER MOTOR


12/21

12

2.3 Software designThe two main functions of the program are to control temperature and light of the room. The

first operation performed is a prompt to the user to select which mode to execute put the program

in, light control or temperature control. Before the program displays the user menu, the blinds

are opened 800 motor steps which place the blinds in the fully open position. Because of this,

the blinds must always be place in the fully closed position in a particular direction before

running the program.

For the light control mode, the user will select a desired light intensity level: low, medium, or

high. These light levels will correspond to a predetermined light sensor value. Two light sensors

are used to get a representative value of the light level in a room. The average of all the sensor

readings is taken and compared to the user chosen light level. If the light intensity measured is

higher than the desired, the blinds will be closed until the conditions met. If the measured

intensity is lower than the desired, the blinds will open until the conditions are met. This

operation will run continuously until the user ends the loop by hitting the Q key, which will

send the program back to the main menu. During a control process, the program will

remember the number of steps taken by the motor. Because of this, the user can exit the

program by pressing the E key, after which the program will return the blinds to the fully

closed position.

For the temperature control mode, the user will set the desired temperature of the room. One

sensor is used to measure the temperature of the room. Like the light intensity mode, the

measure temperature will be compared to the desired temperature and either open or close the


13/21


13

blinds accordingly. The user can also press the E key to exit the program and return the blinds

to the fully closed position.

A logic flow diagram can be seen on the following page. It follows the steps and decisions that

the program makes once it is executed.


14/21

14

Motor Steps toFully Open

Position

Main Menu1. Light2. Temp3. Exit

Li ht Intensit Mode Tem erature Mode

User Selects:1. High2. Medium3. Low

User Selects:4. Warmer5. Same6. Cooler

Sensor Value:Averages the values

from both sensor

Acquires Temp fromsensor

Steps motor incompensating

direction (if needed)while recording

position

Steps motor incompensating

direction (if needed)while recording

position

Checks if desiredvalue is within +/- 50units of sensor value

Checks if desiredvalue is within +/- 3

of sensor value

Motor Steps to fullyclosed position

User exits program


15/21

15

2.4 System assemblyCombining the mechanical and electrical components of the system was quite simple. The

connection of the MRK microcontroller, bread board, and stepper motor and its corresponding

integrated circuit were essentially laid out in the same manner as Lab 10 from the MENG 483

Lab. This system was modified to accept two types of sensors and move the stepper motor

according to the code discussed in section 2.3.

Getting the stepper motor to move one way or another depending on the sensor inputs was

proven to be much easier than expected. The major problem seen by the system was telling the

program when the blinds were fully closed. Without a set of boundaries, the motor might

continue to turn while the blinds are already closed, possibly breaking the rotational mechanism

on the blinds or the stepper motor itself.

Difficulties met in the C++ code were mostly associated with program flow. Problems were met

in getting the program to immediately start the main menu upon running. Another difficulty

was getting the program to return to the main menu after a user exits a control mode instead of

having to run the program each time a mode change is desired. Without a return to main menu,

the MRK board would have to be reset and the program run fresh for each change. It would be

much more convenient for the code to run continuously and allow changes without the need to

reset the system.


16/21


16

3. SYSTEM TESTINGThe sensors and motor functions work properly in the system. The group attempted to add a set

of boundaries so that the blinds would stop opening or closing to keep from breaking the blind or

motor components. The program is set up in such a way that the blinds must be fully closed in a

certain position when beginning the program. The program implements a certain amount of

motor steps from the closed position to the middle position. The group created a user-defined

option for the light and temperature settings. The light intensity controller option allows a low,

medium, or high setting while the temperature option required a value to be entered. These

additional controls only partially worked, as the system would randomly freeze up from time to

time. The group used flashlights to vary the intensity of the light sensor. Body heat was used to

increase the temperature of the temperature sensor and was allowed to cool. When the program

is running, it keeps a count of the position relative to the closed position. When the program is

exited the blinds return to the fully closed position. The delay was set to be very low so that the

blinds would open or close quickly. In reality the delay will be higher so only small changes in

position are made. This makes it convenient for the user without the annoyance of the blinds

opening and closing rapidly.

4. MATERIAL COST AND TOTAL EXPENSESThe MRK board, stepper motor, and sensors were provided by the mechatronics lab. The group

purchased the mini blinds and wood required to make a mounting frame. The total cost of these

items was $7.23. The team also purchased zip ties and shrink fit tubing to secure several

components of the system and frame.


17/21


17

5. CONCLUSIONThe group was able to successfully create the circuitry necessary to drive the stepper motor and

utilize the light and temperature sensors. The stepper motor was attached to the top of the frame

using zip ties. To open and close the blinds, the shaft of the motor was taped to the rotation

mechanism on the blinds. The program performs as desired for major system actions but requires

further development for stability and limitation factors. Further coding and/or mechanical

features will be needed to ensure that the motor does not keep trying to rotate the blinds beyond

the fully closed and fully open positions. Also, the user input settings require further

development to ensure functionality and practicality.

6. ACKNOWLEDGEMENTSWe would like to acknowledge our professor of the mechatronics class Dr. Zagrei, the teaching

assistants Jonathan Berg, Hakan Cakan, and Jason Matthews for helping us with constructing our

circuitry and providing us with the tools necessary to complete the project.

7. REFERENCESAlciatore D.G. and Histand, M.B., (2005) Introduction to Mechatronics and Measurement

Systems, McGraw-Hill, third edition.

Bishop, R.H., (Editor) (2002) The Mechatronics Handbook, CRC press, first edition.


18/21


18

8. APPENDIX

8.1 Appendix A: Mechanical Components

8.1.1 Materials Used Mini Blinds A standard set of mini blinds for household use. Blinds measured 24 x

48 when fully lowered

Lumber Standard 1 x 2 pine boards to create a stand for the mini blinds to simulate a

window frame

Wood Screws Standard 2 deck screws to assemble boards into frame

Wood Glue Standard wood glue to add rigidity to wooden frame

Zip ties Standard 8 zip ties to secure motor and breadboard to test stand

Electrical Tape Standard electrical tape used in securing motor to rotation mechanism

of blinds and used in splicing wire connections

8.1.2 Tools Used Miter Saw 10 electric Makita miter saw used to section wooden boards for frame

Screw Drill 18V cordless DeWalt screw drill used to place deck screws in frame

Screw Drivers Assorted sizes and types of screwdrivers for several uses


19/21


19

8.2 Appendix B: Electronic components

8.2.1 Materials and Components Used TMP36 Temperature Sensor

o 2.7 to 5.5 V

o Calibrated Directly to C

o 2% Accuracy

o 5 C Linearity

o -40 C to +125 C Operation

PN 168 Photo Transistor

o 5 30V Collector/Emitter Voltage

o 3 mA photo current

o -25 C +85 C operation temperature

Shinano Kenshi STP-42D241 Stepper Motor

o 2 phase uni-polar 6 lead

o 12V, 3.1 ohm, 2.9 mH

o 3 degree step angle

o 120 steps/rev


20/21


20

8.3 Appendix C: Software components#include "MRK. h"

char mode, c;

void cr azy( void) {mode = f get char ( SCI 0) ;}void menu( void) {

f pr i nt f ( SCI 0, "Whi ch cont r ol mode do you wi sh t o use?\ n\ r " ) ;f pr i nt f ( SCI 0, "Li ght ( L) or Temper at ur e ( T) \ n\ r " , c ) ;f pr i nt f ( SCI 0, "Press q at any t i me t o r etur n t o mai n menu. \ n\ n\ n\ n\ r " ) ;

}

int di gi t al _val ue, l i ght 1, l i ght 2, l i ght _ l evel , l i ght _des i red, t emp,t emp_desi r ed, st ate, hi gh, l ow ;

intmai n( ) {

/ / Li ght I nt ens i t y Cont rol l i ngMode_____ _____ _____ _____ _____ _____ _____ _____ _____ __

anal og_i n(RESOLUTI ON, 10) ;di gi t al _i n( OUTPUT, ALL) ;motor_out ( LEFT, 255) ;const char st ep_sequence[ ] = {0x01, 0x04, 0x02, 0x08};while (1) {

menu( ) ;crazy();

if ( ( mode==' L' ) | | ( mode == ' l ' ) ) {setup_sci ( SCI 0, I NTERRUPT, &cr azy) ;

while (1) {

del ay ( 10) ;l i ght _desi r ed = 300;l i ght 1 = anal og_i n( I N, 2) ;l i ght 2 = anal og_i n( I N, 4) ;l i ght _l evel = ( l i ght 1+l i ght 2) / 2;l ow = l i ght _l evel - 50;hi gh = l i ght _l evel + 50;f pr i nt f ( SCI 0, "Li ght Aver age: %R4u Press Q t o r eturn t o

menu\ r " , l i ght _ l evel ) ;

if ( hi gh >= l i ght _desi r ed) {st at e = st ate - 1;di gi t al _i n( OUT, ALL, st ep_sequence[ st at e & 0x03] ) ;

}

if ( l ow < l i ght _desi r ed) {st at e = st at e + 1;di gi t al _i n( OUT, ALL, st ep_sequence[ st at e & 0x03] ) ;


21/21


21

}

if ( mode == ' q' ) {setup_sci ( SCI 0, I NTERRUPT, 0) ;break;

}

}}

/ / ___________________________________________________________________________

/ / Temperatur e Cont r olMode_____ _____ _____ _____ _____ _____ _____ _____ _____ _____ ____

if ( ( mode==' T' ) | | ( mode == ' t ' ) ) {setup_sci ( SCI 0, I NTERRUPT, &cr azy) ;

while (1) {

t emp_desi r ed = 85;

del ay ( 10) ;

di gi t al _val ue = anal og_i n( I N, 8) ;t emp=( 71 * di gi t al _val ue) / 100 + 29;l ow = t emp - 5;hi gh = t emp + 5;f pr i nt f ( SCI 0, "Sensor : %R4u Pr ess Q t o r eturn to

menu\ r " , t emp) ;

if ( hi gh >= t emp_desi r ed) {st at e = st ate - 1;di gi t al _i n( OUT, ALL, st ep_sequence[ st at e & 0x03] ) ;

}

if ( l ow < t emp_desi r ed) {st at e = st at e + 1;di gi t al _i n( OUT, ALL, st ep_sequence[ st at e & 0x03] ) ;

}

if ( mode == ' q' ) {setup_sci ( SCI 0, I NTERRUPT, 0) ;break;

}

}

/ / ___________________________________________________________________________

}}

}

meng483 mini blinds

Documents