Proceedings of the Conference on Engineering Research, Innovation and Education 2011 CERIE 2011, 11-13 January 2011, Sylhet, Bangladesh
DESIGN AND IMPLEMENTATION OF A MICROCONTROLLER BASED ELEVATOR CONTROL SYSTEMS 1
Muhibul Haque Bhuyan*, 2Md. Maidul Haque, 2M. Abdur Rauf and 2Md. Mazharul Islam Khan 1
Department of Electrical and Electronic Engineering Daffodil International University, Shukrabad, Dhaka, Bangladesh 2 Department of Electrical and Computer Engineering Presidency University, Banani, Dhaka, Bangladesh E-mail:
[email protected],
[email protected] Abstract In this paper, we have designed and implemented a prototype elevator and its control systems using a very low cost microcontroller (PIC16F84) based circuit. Thus the conventional analog control circuit has been replaced. The elevator is operated by using DC motors and gears along with timing belt. Forward and reverse direction of motion of the DC motor is obtained by using a MOSFET bridge. An assembly language program has to be developed for the microcontroller for implementing different logic operations, such as, floor selection, sensor signal detection, alarm signal transmission and reception etc. Different mechanical parts, such as, cabin, doors, gears, guide, timing belt etc. have also been designed for the prototype system. Before implementation of the system, we have simulated the microcontroller based control circuit using ‘Proteus’ software. It was found that the simulation results are satisfactory and practical systems work very well. We also expect that this will save our valuable foreign currency if we go for practical implementation. Key words: Microcontroller, DC motor, elevator, gear, control circuit.
1. INTRODUCTION An elevator (or lift in British English) is vertical transport equipment that efficiently moves people or goods between floors or levels of a building [1]. At present, many high rise buildings are being built in Bangladesh to be used as apartments, offices, shopping malls, hospitals etc. So, all these high rise buildings require elevator. But these are very costly because they are being imported from different foreign countries. Elevators are generally powered by electric motors that either drive traction cables and counterweight systems like a hoist, or pump hydraulic fluid to raise a cylindrical piston like a jack. So, these motors need to be controlled by sophisticated control circuits. If the costs of these control circuits and other parts can be reduced then the overall costs of the elevator will be reduced. In this work, we have developed a low cost elevator system using microcontroller based control circuit. Because microcontroller has emerged as one of the low cost controller IC and many works have been found in the literatures using microcontroller for minimizing the cost [2-5]. The whole system and
the controller circuit have been tested for various conditions of the elevator operation and it has been observed that the system works very well.
2. HARDWARE DESCRIPTION The overall system architecture is shown in Fig. 1 as a block diagram. The circuit configuration is each component is briefly described in this section. The 8-bit PIC microcontroller IC 16F877 was chosen to obtain the analog data from the sensor circuit in transmitting to control the DC motors. This microcontroller has a 25 MHz processor (the current compiler runs the processor at 20 MHz), 33 input/output (I/O) pins, (8k*14 words) of Enhanced FLASH program memory, (386*8bytes) of RAM, (256*8bytes) of data EEPROM. The PIC does not have an operating system and simply runs the program in its memory when it is turned on. This PIC microcontroller has several hardware features that are very useful for use in a UAV and simplify the interfacing of sensors and motors with the microcontroller, such as an analog to digital converter (ADC), interrupts, timers, and
*
Corresponding Author: Muhibul Haque Bhuyan, E-mail:
[email protected]
ISBN: 978-984-33-2140-4
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capture/compare/pulse width modulation (CCP) channels. One microcontroller circuit produces the required signals for controlling the levels and another microcontroller produces the control signals for the car. For each floor, one board is needed and for car control each level requires one such board.
Fig. 2 Program architecture
Fig. 1 Block diagram of microcontroller based elevator control system Our designed system has the various electrical and mechanical parts. The main components are the two DC motors with gear, one motor for the car operation and the other motor for the door open/close. Besides, motors’ driver circuits have to be designed. There are various sensors for the transmitter (Tx) and the receiver (Rx) circuit, one microcontroller (PIC16F84) circuit. Power supplies for various controller circuit and motors have also been designed. Since this system is a prototype system, therefore, only a +12V DC power supply was required.
3. SOFTWARE DEVELOPMENT The program is developed for the microcontroller using the MPLAB software in assembly language and then debugged and edited as required. Finally the hex codes are generated to be loaded into the microcontroller by the TOP2049 Universal Programmer using the TOPWIN software [8]. MPLAB is an Integrated Development Environment (IDE) tool for this task. The architecture and flow chart of the developed program are shown in Figs. 2-4. The clock frequency used for this program is set at 4 MHz. The program is written in assembly language. A typical assembly language program consists of assembler directives, sub-routines (if needed) and the main program code. Assembler directives are a collection of commands that tell the assembler such things as the type of microcontroller being used, its clock speed, etc. They also allow names to be used for memory locations, ports and registers for making the program more readable [8]. In Figs. 3-4, we have shown two flow charts [9], one for the level board microcontroller’s and the other for the car board microcontroller’s. The flow charts are self explanatory.
Fig. 3 Flow chart of the program for level board
Fig. 4 Flow chart of the program for car board
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4. SYSTEM DESCRIPTION At first, we develop the motor control circuit as shown in Fig. 5. This circuit uses opto-couplers and relays to control the DC motor’s operation. The circuit is designed in such a way so that the motor can be driven in forward or reverse direction.
Then we have to design the mechanical parts of the system. Of them, the door control panel is shown in Fig. 8. This is a wooden frame where different switch boards and LEDs are connected. The photograph of the complete system is shown in Fig. 9. It is a 3-storied prototype elevator model.
Fig. 5 Motor control circuit diagram Fig. 8 Door control panel Then we design the sensor circuit for the car board and level board as shown in Fig. 6. In this circuit, the photo diode transmits the signal and the phototransistor receives it. Then we develop the microcontroller circuit to integrate these circuits. The complete hardware circuit is shown in Fig. 7.
Fig. 9 The complete system
5. CONCLUSIONS Fig. 6 Sensor circuit diagram
Fig. 6 Complete hardware circuit without microcontroller circuit
In this work, we have designed and implemented a prototype elevator and its control systems using a very low cost microcontroller based circuit. Thus the conventional analog control circuit has been replaced. The elevator is operated by using DC motors and gears along with timing belt. Forward and reverse direction of motion of the DC motor is obtained by using a MOSFET bridge. An assembly language program has been developed for the microcontroller for implementing different logic operations. Different mechanical parts have also been designed for the prototype system. Before implementation of the system, we have simulated the control circuit. It was found that the simulation results are satisfactory and practical systems work very well. We also expect that this will save our valuable foreign currency if we go for practical implementation. As future scopes, the main controller can be re-designed in such a way so that a three phase induction motor can be operated through a speed control circuit.
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http://en.wikipedia.org/wiki/Elevator. Mahbubul Hoq, Yasmeen Mawla, Mohammod A. S. Haque and Saleh M. Jahangir, “Design and Development of a Microcontroller Based Traffic Light Control System,” Proceedings of BES Conference, Dhaka, Bangladesh, April 2003, pp. 122-126. Muhibul Haque Bhuyan, Md. Anayet Rabby, Md. Anwar Parvez and Md. Mostayanul Gofur, “Microcontroller Based Display System Design using LED Array,” Proceedings of the Conference on Engineering Research, Innovation and Education (CERIE) held at Shahjalal University of Science and Technology, Sylhet, Bangladesh, 11-13 January 2010, pp. 417-420. Muhibul Haque Bhuyan, Md. Anayet Rabby and Md. Mostayanul Gofur Tarik, “Microcontroller based Automatic Traffic Light Control System Design,” Proceedings of the National Conference on Electronics and Telecommunications for Digital Bangladesh organized by the Bangladesh Electronics
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Society, Dhaka, Bangladesh, 2-3 June 2010, pp. 139-142. Md. Lutfor Rahman and Muhibul Haque Bhuyan, “Linearization of Voltage-Controlled Oscillator by Microcontroller Based PLL Frequency Synthesizer,” Proceedings of the Conference on Engineering Research, Innovation and Education (CERIE) held at Shahjalal University of Science and Technology, Sylhet, Bangladesh, 11-13 January 2011, accepted in this conference. Thomas E. Kissel, “Industrial Electronics – Applications for Programmable Controllers, Instrumentation and Process Control, and Electrical Machines and Motor Controls,” Prentice-Hall of India Pvt. Ltd., 3rd Edition, India, 2005. Charles A. Schuler and William L. McNamee, “Industrial Electronics and Robotics,” McGraw-Hill Book Co. International Edition, Singapore, 1986. Microchip Technology, Inc., USA, 2001, PIC16F877A Data Sheet, www.microchip.com D. V. Hall, “Microprocessors and Interfacing: Programming and Hardware,” McGraw-Hill International, 1997.
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