1、附录 1 文献翻译 A Design of Elevator Positioning Control System Model Zhang Yajun, Chen Long, Fan Lingyan School of Electronics & Information， Hangzhou Dianzi University Hangzhou, Zhejiang, 310018 The Peoples Republic of China ABSTRCT This paper presents a design of elevator positioning control system mo
2、del based on the ATmega128 microcontroller. The model mainly includes MCU control module, stepper motor drive module, infrared detection module, LCD display module and keys module. The elevators running path is set by keys； the elevators running location is detected by the infrared binate tubes. Ste
3、pper motor is the executive component. MCU controls the speed and direction of the stepper motor by inputting pulse signals to its drive chip L298. LCD displays the real-time information of elevators running status. Key Words: ATmega128 microcontroller, stepper motor, drive chip L298, infrared detec
4、tion circuit. 1. INTRODUCTION A four-floor elevator system module is designed in this paper. The object of elevator system module is shown in figure 1. The size of the model and the distance between the layers are shown in the figure. The system model provides an intuitional and thorough description
5、 for the construction and action principle of elevator, and gives a platform for the further research of the new elevator control technologies. It has a certain reference in relevant professional experiments teaching. It can be chosen as a teaching model for university teachers when they instruct st
6、epper motors drive and control. In addition, the model has a certain value for research and development of high-rise elevator control software. 2. SYSTEM STRUCTURE AND WORKING PRINCIPLE The basic structure diagram of the elevator positioning control system model is shown in Figure 2. The model inclu
7、des MCU control module, stepper motor drive module, infrared detection module, LCD module and keys module. The elevators running path is set up by keys； the real-time information of the elevators location is detected by infrared detection circuits and is fed back to the MCU. Thespeed and direction o
8、f the stepper motor are controlled by MCU inputting timing pulse signals to its drive chip L298(internal circuits are H-bridge drive circuits).The elevator stops when the information input by the key and the feedback signals of the infrared detection circuits are the same and the elevators real-time
9、 running status is displayed by the LCD1602. 3. SYSTEM HARDWARE DESIGN 3.1 Stepper motor drive module design Stepper motor drive circuit is shown in Figure 3. L298 integrated chips input ports connect with the system MCU I/O ports and its output ports connect with the signal input ports of two-phase
10、 four wires stepper motor. MCU I/O ports output certain timing pulse signals to drive chip to control its outputs, which makes the stepper motor rotate positively or reversely. Stepper motor rotational speed is directly proportional to the frequency of input pulse, which means the higher frequency o
11、f the input pulse, the faster stepper motor rotate speed, and vice versa. The internal circuits of L298 chip are H-bridge driver circuits, as shown in Figure 4. VD1, VD2, VD3, VD4 are continued flow diodes for protecting the drive circuit. When Q1, Q4 binate tubes in the H-bridge circuit turn from o
12、n to off, the current cant change immediately and flows as original direction, VD2, VD3 provide loop circuit at this time. When Q1, Q4 disconnect the current forms a continued flow loop as follows: GND VD3 stepper motor VD2 VCC. Similarly, VD1, VD4 provide flow loop when Q2, Q3 turn from on to off,
13、the current forms a continued flow loop as follows: GND VD4 stepper motor VD1 VCC. D1 and D6, D2 and D5, D3 and D8, D4 and D7 are quadruplet binate tubes of continued flow in the drive circuit. 3.2 Infrared detection module design The infrared detection circuit is composed of infrared emitting and r
14、eceiving tubes and comparator as shown in figure 5. The infrared emitting tubes are installed at the point of O, A, B, C. The infrared receiving tubes are installed at the point of O, A, B, C. When the infrared receiving tube receives infrared signals, its resistance is quite small； the voltage at p
15、oint A is about 4V. When the infrared receiving tube doesnt receive infrared signals, its resistance is very large, at this time the voltage at A point is about 0.8V.The voltage of point B is the reference voltage which is about 1.5V(realized by adjusting 10K potentiometer) and the comparator output
16、 port connect with 10K pull-up resistor. When the voltage at point A is higher than point B, LM339 outputs high-level signal to MCU I/O port. Otherwise, LM339 outputs low-level signal to MCU I/O port. MCU achieves the exact location of the elevator through detecting high or low level signal output b
17、y comparator and the key input signal in the system module. 3.3 MCU control module and key module design Figure 6 MCU control module and keys module circuits MCU control module and keys module circuit is shown in Figure 6. Keys are defined as follows: key P1.3 is a start key and the elevator start t
18、o rotate when key P1.3 is pressed. When the elevator is rotating, it will enter to state of emergency (elevator stops at last point along the moving direction) if we press key P1.3. P1.4, P1.5, P1.6, P1.7 are keys for O floor, A floor, B floor, C floor individually. Key P3.0 is a shift key and the m
19、odification item starts flashing and the flashing information can be amended when key P3.1 is pressed. Key P3.2 is the enter key. The modification item stops flashing, amendments is over and the elevator runs according to the revised information when key P3.2 is pressed. We can make more flexible de
20、finition of the keys during the course of designing the system software in order to achieve more functions. 3.4 Display module design LCD1602 display module are adopted and used to display model running status. The information displayed mainly includes the elevators current location, operation order
21、, operation time, running status (UP, DOWN, STOP) and so on. 4. SYSTEM SOFTWARE DESIGN The basic idea of the program design is as follows: Firstly, the operation of pressing keys can set the running path of the elevator model. Secondly, infrared binate tubes carry out the real-time detection of the
22、elevators location after the elevator starts. Thirdly, MCU scans the infrared circuit I/O ports real-time detection results. The detection result is low-level when the elevator reaches the target floor. Meanwhile, the elevator stops and the array of indicators move back a bit. The elevator will rest
23、art if the comparison result of the current and the next floor (position of the array indicator) are not consistent. The process repeats until the array bits pointed by array indicator become zero, and then the elevator stops. In addition, the elevator should increase speed slowly after it starts an
24、d reduce speed gradually before it stops in order to smooth the operation of the elevator and avoid vibration or swing. To achieve this goal in the program design, we can control the drive circuits pulse signal frequency given by MCU. The elevators rotation speed is directly proportional to the puls
25、e signal frequency, which means the higher the pulse signal frequency, the quicker the elevator rotation speed, and vice versa. In the process of the elevator running from zero to maximum speed, the MCU output higher and higher pulse signal frequency to the drive circuit to realize the elevators acc
26、eleration. Similarly, the MCU input lower and lower pulse signal frequency to the drive circuit to realize the elevators deceleration. 5. CONCLUSION We choose ATmega128 microcontroller as the core control component and stepper motor as the implementation component, use L298 integrated chip to drive
27、stepper motor and infrared binate tubes to detect the location of the elevator and acquire real-time information to achieve a position control system model for teaching. This model has the characteristics are as follows: (1) The operation order of elevator can be preset and the real-time information
28、 of the elevators running order and running time can be displayed by LCD. The running order and running time can be modified by pressing certain keys. The system can enter into the emergency situation by pressing certain keys. The elevator is smooth and uniform during the course of acceleration and
29、deceleration. (2)Integrated L298 driver chip which used in the motor driver circuit is simple, high integrated, convenient to control. (3)The design of infrared binate tubes detection circuit makes elevator accurate positioning. Information displayed by LCD is rich and the display interface is user-friendly. The experiment shows that the system model has the characteristics of stability and high reliability. It can be used in teaching relevant professional course and designing practical elevator control software.
