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外文翻译---基于PLC电梯控制系统的设计与实践

外文翻译---基于PLC电梯控制系统的设计与实践
外文翻译---基于PLC电梯控制系统的设计与实践

翻译部分

英文原文

Design and Practice of an Elevator Control System Based on PLC

Abstract

This paper describes the development of 2 nine-storey elevators control system for a residential building.The control system adopts PLC as controller,and uses a parallel connection dispatching rule based on"minimum waiting time"to run 2 elevators in parallel mode.The paper gives the basic structure,control principle and realization method of the PLC control system in detail. It also presents the ladder diagram of the key aspects of the system.The system has simple peripheral circuit and the operation result showed that it enhanced the reliability and performance of the elevators.

1.Introduction

With the development of architecture technology,the building is taller and tallerand elevators become important vertical transportation vehicles in high-rise buildings.They are responsible to transport passengers, living,working or visiting in the building,comfortable and efficiently to their destinations.So the elevator control system is essential in the smooth and safe operation of each elevator.It tells the elevator in what order to stop at floors,when to open or close the door and if there is a safety-critical issue.

The traditional electrical control system of elevators is a relay-controlled system.It has the disadvantages such as complicated circuits,high fault ratio and poor dependability;and greatly affects the elevator’s running quality.Therefore,entrusted byan enterprise,we have improved electrical control system of a relay-controlled elevator in a residential building by using PLC.The result showed that the reformed system is reliable in operation and easy for maintenance.

This paper introduces the basic structure,control principle and realization method of the elevator PLC control system in detail.

2.System structure

The purpose of the elevator control system is to manage movement of an elevator in response to user’s requests.It is mainly composed of 2 parts:

2.1.Electric power driving system

The electric power driving system includes:the elevator car,the traction

motor,door motor,brake mechanism and relevant switch circuits.

Here we adopted a new type of LC series AC contactors to replace the old ones,and used PLC’s contacts to substitute the plenty of intermediate relays. The circuits of traction motor are reserved.Thus the original control cabinet’s disadvantages,such as big volume and high noise are overcome efficiently.

2.2.Signal control system

The elevator’s control signals are mostly realized by PLC.The input signals are:operation modes,operation control signals,car-calls,hall-calls,safety/protect signals, door open/close signal and leveling signal,etc.All control functions of the elevator system are realized by PLC program,such as registration,display and elimination of hall-calls or car-calls,position judgment of elevator car, choose layer and direction selection of the elevator,etc.The PLC signal control system diagram of elevator is showed in Figure 1.

Figure 1 PLC signal control system diagram

2.3.Requirements

The goal of the development of the control system is to control 2 elevators in a 9-storey residential building.

For each elevator,there is a sensor located at every floor.We can use these sensors to locate the current position of the elevator car.The elevator ar door can be opened and closed by a door motor.There are 2 sensors on the door that can inform the control system about the door’s position.There is another sensor on the door can detect objects when the door is closing.The elevator car’s up or down movement is controlled by a traction motor.

Every floor,except the first and the top floor,has a pair of direction lamps indicating that the elevator is moving up or down.

Every floor,has a seven segment LED to display the current location of the elevator car.

The first step for the development of the elevator control is to define the basic

https://www.wendangku.net/doc/0417578971.html,rmally,the elevators behavior is defined as follows.

(1)Running with a single elevator

Generally,an elevator has three operation states: normal mode,fire-protection mode and maintenance mode.The maintenance mode has the highest priority. Only the maintenance mode is canceled can the other operation modes be implemented.The next is fire-protection mode,the elevator must return to the bottom floor or base station immediately when the fire switch acts.The elevator should turn to normal operation mode when the fire switch is reset.Under normal operation mode,the control system’s basic task is to command each elevator to move up or down,to stop or start and to open and close the door.But is has some constraints as follows: Each elevator has a set of 9 buttons on the car control panel,one for each floor.These buttons illuminate when they are pressed and cause the elevator to visit the corresponding floor.The illumination is canceled when the corresponding floor is visited by the elevator.

Each floor,except the first and the top floor,has two buttons on the floor control panel,one to request an up- elevator,one to request a down-elevator.These buttons illuminate when they are pressed.The illumination is canceled when an elevator visits the floor,then moves in the desired direction.

The buttons on the car control panel or the floor control panel are used to control the elevator’s motion.

The elevator cannot pass a floor if a passenger wants to get off there.

The elevator cannot stop at a floor unless someone wants to get off there.

The elevator cannot change direction until it has served all onboard passengers traveling in the current direction, and a hall call cannot be served by a car going in the reverse direction.

If an elevator has no requests,it remains at its current floor with its doors closed.

(2)Parallel running with two elevators

In this situation,there are two elevators to serve the building simultaneously.It runs at 7am to 9am and 5pm to 7pm every day.

When an elevator reaches a level,it will test if the stop is required or not.It will stop at this level when the stop is required.

At the same time,to balance the number of stops,the operation of two elevators will follow a certain dispatching principle.

An elevator doesn’t stop at a floor if another car is already stopping,or has been stopped there.

The normal operation of elevators is implemented by cooperation of its electric power driving system and logic control system.

3.Software design

Due to the random nature of call time,call locations and the destination of passengers,the elevator control system is a typical real-time,random logic control system. Here we adopted collective selective control method with siemens PLC S7-200 CPU226 and its extension modules. There are 46 input points and 46 output points in the system.The I/O points are showed in Table1 and Table 2.

Table 1 Input points

Table 2 Output points

About software designing,we adopt the modularized method to write ladder diagram programs.The information transmission between modules is achieved by intermediate register bit of PLC.

The whole program is mainly composed of 10 modules: hall-call registration and display module,car-call registration and display module,the signal combination module,the hall-call cancel module,the elevator-location display module,the floor selection module,the moving direction control module,the door open/close module,the maintenance operation module and the dispatching module under parallel running mode.

The design of the typical modules is described as follows:

3.1.Hall-call registration and display

There are two kinds of calls in an elevator:hall-call and car-call.When someone presses a button on the floor control panel,the signal will be registered and the corresponding lamp will illuminate.This is called hall-call registration.

When a passenger presses a button in the elevator car, the signal will be registered and with the corresponding lamp illuminated.This is called car-call registration.

Figure2 shows the ladder diagram of up hall-calls registration and display.The self-lock principle is used to guarantee the calls’continuous display.

Figure 2 up hall-call registration and display

3.2.The collective selection of the calls

Here the collective selection control rules are used.As showed in Figure3,M5.1-M5.7,M6.0 and M6.1 are auxiliary relays in PLC.They denote the stopping request signal of 1st to 9th floor respectively.The auxiliary relay M6.2 denotes the elevator driver’s operation signal.When there is a call in a certain floor,the stopping signal of corresponding floor will output.When the elevator is operated by the driver,the hall-calls will not be served. And the elevator cannot pass a floor at which a passenger wishes to alight.

3.3.The cancellation of the calls

The program of this module can make the elevator response the hall-calls which have the same direction as the car’s current direction,and when a hall-call is served, its registration will be canceled.The ladder diagram of up hall-calls’cancellation is showed in Figure4.

Figure 3 The combination of the calls

Figure 4 The cancellation of up calls

In Figure4,the auxiliary relay M4.0 is the up moving flag of the elevator.When the current direction of the elevator is up,M4.0’s contacts are closed;on the contrary, when the current direction of the elevator is down,M4.0’s contacts are opened.M0.1 to M0.7 denotes the car-calls’ stopping request signal of floor 2 to floor 8 respectively.

This program has two functions:

(1)Make the elevator response the normal down hall-calls when it is moving down,and when a down hall-call is served,its registration is canceled.

(2)When the elevator is moving up,the corresponding floor’s down hall-call it passing by is not served and the registration is remained.

The cancellation of down hall-calls is reversed with up hall-calls.

3.4.Elevator’s direction

The elevator may be moving up or down,depending on the combination of hall-calls and car-calls.The following ladder diagram in Fig.5 illustrates that the elevator will move up.

Figure 5 Up moving of the elevator

Figure5 shows that when the calls corresponding floor is higher than the elevator’s current location,the ele vator will go up.Here the auxiliary relay M4.0 is used as the up-moving flag.When the elevator is moving up,the up-moving lamp is illuminated,so the M4.0 is connected

on.When the elevator arrives the top floor,the up-moving lamp is off and the timer starts.After 0.2s,the M4.0 is disconnected,the up-moving display is off.Here we used M4.0 to replace Q3.1 which can ensure the cancellation’s reliability.

3.5.Elevator’s floor-stopping

Figure6 shows the ladder diagram of the elevator’s floor-stopping function.

As showed in Figure6,M6.4 is the flag of floor-stopping signal.M6.6 is the floor-stopping signal sent by the driver.M7.0 is the fire signal sent by the fire switch.And M6.7 is the forced speed changing signal. When either of these contacts act,the system should send out the floor-stopping signal.

4.Minimum waiting time algorithm

In traffic of elevator systems,there are two types of control task usually.The one is the basic control function to command each elevator to move up or down,to stop or start and to open and close the door.The other is the control of a group of elevators.

The main requirements of a group control system in serving both,car and hall calls,should be:to provide even service to every floor in a building;to minimize the time spent by passengers waiting for service;to minimize the time spent by passengers to move from one floor to another;to serve as many passengers as possible in a given time[1]

.

Figure 6 The elevator’s floor-stopping

There are many dispatching algorithms f or elevator’s group control.Such as Nearest-neighbor Algorithm[2], which the elevator always serve the closet request next; Zoning Algorithm[3] which by analyzing the traffic of elevator system with unequal floor and population demand to dispatch the elevator;and Odd-even rule, which an elevator only serves the odd floor and the other only serves the even floor.

The Nearest-neighbor Algorithm minimizes the length of the elevator’s empty move to the next request.it usually has very small average waiting times,but individual waiting times can become quite large[2].The Zoning Algorithm usually used in buildings which has heavy traffic situations,such as the office building at lunch time.

Compared to the office building and shopping mall, the traffic flow of residential buildings is relatively low and even in every floor.Secondly,people usually think of elevators as purely functional objects and the experience of riding an elevator is time waited for most of them. Furthermore,there exist immense problems when attempting to satisfy all requirements.

Considering all of the reasons above,we adopted the “minimum waiting time”algorithm to realize the 2elevators’parallel running[4].

4.1.Evaluation function

The goal of the“minimum waiting time”algorithm is to predict the each

elevator’s response time according to all calls,and select the elevator which has the shortest response time to serve.

When there is a call,the system calculates out the function values of each elevator according the evaluation function showed in(1)and(2):

J(*)=Min[J(1),J(2),…,J(n)](1)

J(i)=Tr(i)+KTd(i)+KTo(i)i=1,2,...,n (2)

J(i)is the evaluation index of each elevator;Tr(i) denotes the time of the elevator directly moving to the destination corresponding the latest call from its current floor;To(i)denotes the additional acceleration and deceleration time of a floor-stop of the elevator;Td(i) denotes the average time of the passenger boarding and alighting the elevator;and K is the sum of hall-calls and car-calls.But when a hall-call and a car call corresponds the same floor,the K is only calculated one time.

4.2.Calculation of minimum waiting time

In equation(2),K is a certain value,To and Td can be obtained by means of statistics.Tr=T*L,where T denotes the average time of the elevator passing by one floor;L denotes the desired floors of the elevator from current floor to the hall-call floor.

In order to calculate the L value,we defined the 2 elevators are A and B respectively;YA,YB denotes the current floor of elevator A and B respectively.H is the corresponding key value when a hall-call button is pressed,and H=floor number of the hall-call.

We defined 4 tables for the PLC realization:up hall-call registration table,down hall-call registration table,car-call registration table of A and car-call registration table of B.When a certain call button is pressed,its floor value is recorded in corresponding table.

Here we take elevator A as an example.First,define the variable MA,MB and MW.Where MA,MB denotes the extreme value of car-calls with same direction of A or B’s movement respectively.

When elevator A is up-moving,set MA is equal to the maximum value in car-call registration table A;when elevator A is down-moving,set MA is equal to the minimum value in car-call registration table A.

MW denotes the extreme value of hall-calls with same direction of A’s movement.

When elevator A is up-moving and up-hall-call value≥YA,set MW=0;otherwise,set MW is equal to the minimum value in up-hall-call registration table A.When elevator A is down-moving and up-hall-call value≤YA,set MW=0;otherwise,set MW is equal to the maximum value in down-hall-call registration table A.

Thus,we can determine the L value according to YA,H, MA and MW.There are 3 situations:

(1)When the hall-call’s direction is opposite to elev ator A’s movement:

L=|YA-MA|+|MA-H|(3)

(2)When the hall-call’s direction is same as elevator A’s movement and it is in the front of elevator A:

L=|YA-H|(4)

(3)When the hall-call’s direction is same as the elevator A’s movement and it is in the back of elevator A:

L=|YA-MA|+|MA-MW|+|H-MW|(5)

So the i-th floor’s minimum waiting time can be calculated by(6)as follows:

Time(i)=TL(i)+KTd(i)+KTo(i)i=1,2,...,n(6)

When the calls change during the operation of elevators,the system calculates the minimum waiting time of each elevator.Then it allocates the current call to the elevator which has small value.When the each elevator has the same value,then the current call is prior to elevator A.

When an elevator is wrong or not in service,the system can exit the dispatching algorithm and turns to a single elevator running mode.

4.3.Algorithm realization

Compared with single elevator running mode,the parallel running mode is mainly different at the processing method about hall-calls.The former uses collective selective control method,and the latter uses dispatch rule combined with collective selective control method.

Here the system is to control a 9-storey building,so we choose two Siemens S7-200 PLCs(CPU226)and its Extensive Modules to control the single elevator respectively.And by using PPI Protocol to realize the communication between 2 PLCs.

The PPI Protocol adopts master-slave communication mode,so we defined elevator A as the master and elevator B as the slave.By communication program,the 2 PLCs can exchange the massage such as the current position, hall-calls or car-calls and moving direction.Then by using“minimum waiting time”algorithm,the system realizes the optimal operation of 2 elevators.

Figure7 shows the ladder program of the car-calls extreme value calculation of elevator A.

In Figure7,VB121~VB130 is the register address of elevator A’s car-call corresponding to each floor,Q3.1 is the up-moving lamp of elevator A,and the car-calls extreme value is

saved in VB120.

Figure 7 The car-calls extreme value calculation of elevator A

5.Conclusions

In this paper,we have improved an old elevator control system by using PLC,and realized the group control of 2 elevators.The new control system has been operated for 1 year,and its operation scenarios are as follows:

(1)Down–Peak

This traffic condition concerns people out of the building in the morning between 7am to 9am.

(2)Up–Peak

This condition concerns people entering the building between 5pm to 7pm.

(3)Other

It covers the day from 6:00 to 0:00 except the two situations above.And in this situation,there is only one elevator running.

The results are expressed via an average waiting time and maximum waiting time(both given in seconds)are collected in Tables 3 and 4.

Table 3

Average and maximum waiting time(before reformed)

Due to the nonparallel running before the reform,so the average waiting time and maximum waiting time of down–peak and the up–peak are very longer than the reformed.The practice results have showed the better performance of the improved control system.

References

[1]Ricardo Gudwin,Fernando Gomide,Marcio(1998).“A Fuzzy Elevator Group Controller With Linear Context Adaptation”.IEEE World Congress on Computational Intelligence.V ol.12,No.5,pp.481-486.

[2]Philipp Friese,Jorg Rambau(2006).“Online-optimization of multi-elevator transport systems with reoptimization algorithms based on set-partitioning models”.Discrete Applied Mathematics.No.154,pp.1908-1931.

[3]Zheng Yanjun,Zhang Huiqiao,Ye Qingtai,Zhu Changming.(2001).“The Research on Elevator Dynamic Zoning Algorithm and It's Genetic Evolution”.Computer Engineering and Applications,No.22,pp.58-61.

[4]Xiaodong Zhu,Qingshan Zeng(2006).“A Elevator Group Control Algorithm for Minimum Waiting Time Based On PLC”.Journal of Hoisting and Conveying Machiner,No.6, pp.38-40

中文译文

基于PLC电梯控制系统的设计

摘要

本文介绍了二组9层电梯的住宅楼宇控制系统的发展。

该控制系统采用可编程控制器作为控制器,并使用根据“最低等待时间”并联调度规则在并行模式下运行2台电梯。

本文给出了PLC控制系统的基本结构,控制原理和实现方法的细节。同时还介绍了改系统在关键方面的梯形图。

该系统具有简单的外围电路,其运算结果表明它增强了电梯的可靠性和性能。

1介绍

随着建筑技术的发展,建筑物越来越高,电梯已成为在高层建筑物中的重要的垂直运输工具。他们负责运送在高楼里生活,工作或者访问的乘客更舒适有效的到他们的目的地。因此,电梯控制系统是在保证每个电梯顺利和安全的运行的必要条件。它告诉了电梯在打开或关闭门和如果有一个安全的关键问题是为了什么停留在平层。

传统的电梯电气控制系统是继电器控制系统。它的缺点,例如复杂的电路,高故障率和低可靠性,并大大影响了电梯的运行质量。因此,由企业委托,我们已在一住宅楼的电梯使用PLC来改进电气控制系统。结果表明,改革了的系统运作可靠,易于维修。

本文详细介绍了的实现电梯的PLC控制系统的基本结构,控制原则和方法。2.系统结构

该电梯控制系统的目的是要按用户的请求去管理电梯的运动响应。它主要由两部分构:

2.1电力驱动系统

电力驱动系统包括:电梯轿厢,牵引电机,门机,刹车机制和有关开关电路。

在这里,我们采取了新型LC系列交流接触器以取代旧的并且用PLC的接触器来代替大量的中间继电器。牵引电机的电路被保留。因此,有效的客服了原控制柜的缺点,如大体积和高噪声。

2.2 信号控制系统

电梯的控制信号主要是通过PLC实现的。输入信号是:操作模式,操作控制信号,汽车电话,大厅唱出,安全/保护信号,门打开|关闭信号和流平信号等。所有的电梯系统的控制功能都是由PLC程序实现的,如外呼叫和内呼叫信号的登记,显示和消除,电梯轿厢位置的判断,选择电梯的层和方向等。PLC的电

梯信号控制系统图结果显示在图1。

图1 PLC的信号控制系统图

2.3 需求

该控制系统的发展目的是在一个9层住宅楼控制2组电梯。

对于每一个电梯,在每一个楼层上都有一个传感器,我们可以利用这些传感器来定位电梯轿厢的当前位置。电梯轿厢门可以用门电机来开启或关闭。在门上有2个传感器,可以通知有关的控制系统门的位置。在门上还有另外一个传感器可以当门是关闭时去检测对象。电梯轿厢的向上或向下运动时由一个牵引电机控制的。除了第一层和顶层,每层都有一对表明电梯向上或向下移动的方向灯。每层楼都有一个7段LED去显示电梯轿厢的当前位置。电梯控制发展的第一步是确定基本要求。非正式的,电梯行为的定义如下:

1)一个电梯运行

一般而言,一部电梯运行状态有三种:正常模式,防火保护模式和维修式。维护模式具有最高优先级。只有维护模式是可以取消其他运作模式的实施。其次是防火保护模式下,当防火开关动作时电梯必须立即返回底板或基站。当火开关复位时电梯应转向正常运作模式。在正常经营模式下,控制系统的基本任务是命令每个电梯上下移动,停止或启动并打开和关闭门。但是,有一些行为约束如下:

每个电梯在轿厢控制面板上有9个按钮,每层对应一个。当这些按钮被按下并导致电梯访问相应的楼层时照亮。当电梯访问了对应的楼层是光照被取消。每了除第一层和顶层,每层在楼层上的控制面板上都有两个按钮,一个请求电梯上行,另一个请求电梯下行。当这些按钮被按下时照亮。当电梯访问了对应的楼层是该照明取消,然后再按所需的方向动作。在轿厢的控制面板或楼层的控制面板上的按钮式用于控制电梯的议案的。

如果乘客要出这层电梯,那么电梯无法直接通过这个楼层。

如果没有人要在这个楼层出电梯,那么电梯不能停在这个楼层。

电梯直到它已送达在目前的方向行驶的机上所有乘客不能改变方向,当电梯

在行驶时

不能响应相反方向的呼叫。

如果电梯没有请求,那么仍保持其在当前楼层上并且门关闭。

2)平行运行的两部电梯在这种情况下,有两部电梯同时为大楼服务。它们每天在上午七时至上午九时和下午

五时至晚上七时运行。

当电梯到达的平层时,它将检测停止是否被请求。它将停在停止被请求的一层。

同时,为了平衡停止次数,两个电梯的运作将遵循一定的调度原则。

电梯不停在另一个电梯正在停在或已经停过的楼层。

该电梯的正常运行是通郭其电力驱动系统和逻辑控制系统的合作实施的。3.软件设计

由于呼叫时间,呼叫地点和乘客的目的地的随机性,电梯控制系统是一个典型的实时,随机逻辑控制系统。在这里,我们基于西门子PLC S7 - 200 CPU226和扩展模块来通过集体选择性控制。该系统有46个输入点和46个输出点。该I / O点,呈现于表1和表2

表1 输入点

描述地址

1到8层上行外呼叫2到9层下行外呼叫1到9层内呼叫

1到9层到达传感器电梯门开按钮

电梯门关按钮

电梯门关平层按钮电梯门开平层按钮上行传感器

下行传感器

防火开关

运行操作开关

触摸面板开关

超载

强迫变速开关

满载

I0.0-I0.7

I1.0-I1.7

I2.0-I2.7,I3.0

I3.1-I3.7,I4.0-I4.1

I4.2

I4.3

I4.4

I4.5

I4.6

I4.7

I5.0

I5.1

I5.2

I5.3

I5.4

I5.5

表2 输出点

描述地址

1到8层上行外呼叫灯2到9层下行外呼叫灯1到9层内呼叫灯

上行灯

下行灯

七段LED显示

电梯的位置

电梯门开

电梯门关

上行

下行

满载灯

高速运行

低速运行

加速开始

减速制动

蜂蜜器报警Q0.0-Q0.7

Q1.0-Q1.7

Q2.0-Q2.7,Q3.0 Q3.1

Q3.2

Q3.3-Q3.7

Q4.0-4.1

Q4.2

Q4.3

Q4.4

Q4.5

Q4.6

Q4.7

Q5.0

Q5.1

Q5.2-Q5.4

Q5.5

关于软件设计,我们采用模块化方法去写梯形图程序。该模块之间的信息传输是通过

PLC的中间寄存器实现的。

整个项目主要由10个模块组成:外呼叫注册和显示模块,轿厢内呼叫注册和显示模块

信号组合模块,外呼叫取消模块,电梯定位显示模块,楼层选择模块,运动方向控制模块,门打开/关闭模块,维护操作模块和在并联运行模式下的调度模块。

该典型模块的设计描述如下:

3.1外呼叫与显示

在电梯中有两种类型的呼叫:外呼叫和轿厢内呼叫。当有人在电梯的控制面板上按下

一个按钮时,该信号将被注册并且相应的灯将被照亮。这就是所谓的外呼叫登记。

当乘客在电梯轿厢内按下一个按钮式,该信号将被注册并且相应的灯照明。

这就是所

谓的轿厢内呼叫登记。

图2显示了外呼叫上行注册和显示的梯形图。自锁原理是用来保证了呼叫的连续显示。

图2 外呼上行注册和显示

3.2 呼叫的集体选择

这里是集体选择控制规则的使用。如在图3显示的,M5.0-M5.7,M6.0和M6.1都是

PLC的辅助继电器。他们分别表示了一到九层的请求停止的信号。辅助继电器M6.2表示该电梯运行的操作信号。当某层有呼叫时,相应的楼层停止信号将被输出。当电梯由驱动程序操作时,外呼叫将不会被响应,并且电梯不能通过乘客要下的楼层。

3.3呼叫的取消

该模块方案可以使电梯响应与当前电梯运行方向相同的外呼叫,并且当一个外呼叫被

响应了,其注册将被取消。外呼叫上行的取消的梯形图如图4。

图3组合的呼叫

图4上行呼叫的取消

在图4中,辅助继电器M4.0标志着电梯向上移动。当电梯的当前运行的方向是向上时,M4.0的触头关闭,相反,当电梯的当前运行的方向是向下时,M4.0的触头打开。M0.1至M0.7指2到8层的内呼叫停止信号。

这个方案有两个功能:

1当电梯下行时能够使电梯正常的响应外呼叫下行,并且当一个外呼叫被响应了,其

注册能够被取消。

2当电梯上行时所经过的楼层的外呼叫下行信号不被响应并且该信号能被保存。下行

外呼叫和上行外呼叫取消的信号被取消

3.4 电梯的方向

电梯可向上或向下移动,这取决于外呼叫和内呼叫的组合。下面的图5中的梯形图表明电梯将上行。

图5 电梯的上行

图5表明了当相应的呼叫楼层高于当前的电梯位置时,电梯将上行。这里辅助继电器M4.0是用作电梯上行的标志。当电梯正在上行是,上行的灯被照亮,所以M4.0置一。

当电梯到达顶层时,上行灯被关掉,同时定时器开始计时。0.2秒以后,M4.0置

零,上行显示关闭。这里我们用M4.0代替Q3.1能够增加取消的可靠性。

3.5电梯楼层止

图6的梯形图显示了电梯的楼层停职功能。

正如图6表明,M6.4是楼层停车信号的标志。M6.6是派出由驱动程序楼层停止信号。M7.0是由防火开关发送防火信号。M6.7是被迫变速信号。

当这些接触器中的一个动作时,系统将发送楼层停车信号。

4最低等待时间算法

在电梯交通系统中,通常有两种类型的控制任务。一个是指挥电梯上下移动,停止或启动并打开和关闭门的基本的控制功能。另一种是控制电梯群组。

一个群组控制系统在服务中的主要要求是不管在轿厢内或轿厢外,都应该为一个楼的

每个楼层的提供服务,减少乘客等待电梯花的时间,减少乘客从一层到另一层所花的时间,在给定的时间内尽可能的为更多的乘客服务。

图6 电梯的楼层停靠

有很多电梯群组控制的调度算法。如最近邻算法,该电梯总是服务于邻近的隐蔽的需

求。分区算法是通过分析人们要求派遣电梯与楼层不协调的电梯交通系统;以及奇偶规则是其中一个电梯只服务于奇数楼层和另一个只服务于偶数楼层。

最近邻算法把该电梯空移动到下一个请求的长度减小到最小。它通常有很小的平均等待时间,但是个别的等待时间会变得很大。分区算法通常用于有繁忙的情况的建筑如在午餐时间的办公楼。

相较于办公楼和商场,住宅楼的交通流量甚至在每个楼层都相对较低。其次,人们通

常认为电梯是纯功能性对象和大多数人乘坐电梯的经验就是等待的时间。此外,当电梯去试图满足所有要求时就存在着巨大的问题。

考虑到上述原因,我们采取了“最小的等候时间”的算法来实现了2组电梯的并行运行。

4.1 评价函数

而“最小等候时间”算法的目标是根据所有呼叫去预测每个电梯的响应时间,并选择具有

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