Four Elevator COntroller

1

Department of Electronics and Communication

Jaypee Institute of Information Technology

Noida

Four Elevator Controller

A Project Report submitted in partial fulfillment of the course of Digital Hardware Design

Submitted to:

Mr. Sidhartha S. Rout

Submitted by:

Siddharth 9911102336

Mehul Garg 9911102255

Devyani Gera 9911102210

Abhas Vijayvargiya 9911102153

2

Table of Contents 1.Abstract 3

2.Role Distribution Among Group Members 4

3.Theory

3.1 Dual Elevator Control 5

3.2 Basic Principal 5

4.Elevator Control & Its Working

4.1 General Description 6

4.2 Control & Working 6

4.3 Assumptions 7

4.4 Working of Elevators 7

5.Block Diagram & State Machine Diagrams

5.1 Model Simple Elevator Control system Inputs & Outputs 9

5.2 From the point of View of an Individual User 9

5.3 From the point of view as a System Being acted on by Many users 10

5.4 Finite State Machine for Elevator System 11

6.Limitations of the System 12

7.Verilog Code 13

8.Simulation Results 23

9.Conclusion 25

References

3

Abstract

The elevator control system is one of the important aspects in electronics control module in

automotive application. In this investigation elevator control system is designed with different

control strategies. First the elevator control system is implemented for multi-storage building.

This implementation is based on FPGA based logic controller for intelligent control of elevator

group system. This proposed approach is based on algorithm which is developed to reduce the

amount of computation required by focusing only on relevant rules and ignoring those which

are irrelevant to the condition for better performance of the group of elevator system. Here we

have designed controller for four elevators group.

4

Role distribution among Group Members

The project was completed with contributions from all the group members equally. However

the breakdown of the work completed by each member has been summarized below.

Mehul Garg

Verilog Coding for Four Elevator System

Documentation

Finite State Machine

Siddharth


Documentation

Abhas Vijayvargiya

Theory

Elevator Control & its Working

Devyani Gera

Block Diagram


5

Theory

1. Dual Elevator Controller

An elevator or lift is a kind of transport device used to move people between building

floors. Whenever a passenger presses the call button for an elevator, a computer

receives the request and logs it for future reference. There are actually two sets of doors,

which allow passengers safely to exit and enter the lift. One set of doors remains shut

until an elevator car's presence is detected and the elevators computer controls the other

door. Once both doors are open, passengers should leave quickly to allow new

passengers to board and more calls to be answered. Elevator doors also contain motion

detectors and other presence-sensing devices to keep doors from trapping passengers.

Another issue want to be considered is the weight capacity. Overload in elevator will

lead to accident and using the load sensor can control it. In modern life elevators have

become an integral part of any public or commercial complex. It does not only ease the

faster movement between any two floors and provide a way for movement of disabled,

but has also become a status symbol. Elevators work on a gearless traction system in

which the movement of the elevator is controlled by several steel hoist ropes and a

counter-weight. The weight of the car and counterweight provides sufficient traction

between the sheaves and the hoist ropes so that the sheaves can grip the hoist ropes and

move and hold the car without excessive slipping. The machinery to drive the elevator

is located in a machine room usually directly above the elevator hoist way. To feed

electricity to the car and receive electrical signals from it, a multi-wire electrical cable

connects the machine room to the car.

2. Basic Principle

Elevators themselves are simple devices and the basic lifting systems have not changed

much in over 50 years. The control systems however, have changed substantially to

improve safety and speed of operation. Elevators are designed for a specific building

taking into account such factors as the height of the building, the number of people

traveling to each floor and the expected periods of high usage.

Controllers can also be programmed to respond differently at different times of the day.

For example the elevator controller in a busy office building will receive a

preponderance of calls from the ground floor in the morning. When workers are arriving

and need to go to their workplaces on the upper floors, in that case, the controller will

be programmed to send all unassigned cars to the ground floor rather than have them

return to a home floor in their sector. Later in the day a different set of instructions can

be used to send unassigned elevators to different sectors since passengers leaving the

building will be much more evenly distributed among the floors than in the morning.

6

Elevator Controller and Its Working

1. General Description

Elevators as usually been called as cars come in dual or quad groups. The

coordination of a group of cars in elevator systems for satisfying the demands of

passengers is called the Elevator Group Control. The Elevator controller provides this

control by monitoring the position of all the elevators. When a request comes, the

controller checks the position of the request and assigns the elevator nearest to it to

address the request. Generally it stores an algorithm to take the action according to the

request position, and positions of the cars. It has proximity switches to sense the

position of the elevators. Amongst the many factors included in the selection of the car

wait time of the user is dominant.

Figure 1 : Elevator Group Control

2. Control and Working

Elevator controller controls the entire operation of the Dual elevator system. The

proximity sensors located to sense the positions of the cars provide the current state

storing it in register. The obstruction sensors provide the status of obstruction. The

elevator controller also reads the requests if any from any of the request positions

through the flip-flops.

If the door of any elevator is open, the timer signals from the elevator keep the controller

informed of being busy. The control state machine receives all these signals. It is

programmed to the algorithm by which it should control the system. The CSM then

generates control signals for the next position and movement of the elevators. Elevators

on receiving the signal address to the request that has been asked by the controller.

7

Figure 2 : Block Diagram for Dual Elevator Controller

3. Assumptions

The Dual Elevator System does face some conflict in the operation that which car

should take the request when both are at the same positions. So some assumptions are

implemented in the elevator algorithm. The assumptions considered are:

Default State:

The default position provides quick response to the request coming at any of the

four floors. The default positions of the elevators are specified below

E1 first floor

E2 second floor

E3 third floor

E4 fourth floor

Closing the Elevator Door:

Door of the elevator closes after some time duration defined by the timer. By default

the timer should be 0 and when to close the door it should be 1. The system also

checks for any obstruction if present between the doors. Both the timer and

obstructions is implemented using switch.

4. Working of Elevator

In this general block diagram there are two main blocks are available. One is controller

and other is door operator. A sensor is connected between these two main blocks so that

if there any sensor signal goes high, the operation on all four elevators will be carried

out.

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Figure 3 : Block Diagram of Elevator Controller

Every elevator has inside buttons for 1 to 4 floors and outside call button at every floor.

The sensor signal will sense the obstruction and timer, so that the signal from controller

will be send to door operator and hence the door operator will control the elevator

according to the request.

9

Block Diagrams and State Machine Diagram

1. Model Simple elevator control system inputs and outputs[1]

Figure 4 : Control System Input Output

2. From the point of view of an individual user[2]

Figure 5 : Individual Users Point of View

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3. From the point of view as a system being acted on by many users[3]

Figure 6 : Many users at a time

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4. Finite State Machine for Elevator System

The Finite state machine for Elevator System is done below. The state encodings are

mentioned below. The input are 2-bit binary.

State 00: floor 1

State 01: Floor 2

State 10: Floor 3

State 11: Floor 4

Figure 7: Finite State Machine for Elevator 1

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Limitations of the Project

This project has a few limitations that must be highlighted:

The project does not account for obstacles to sensor or any other interruption to the

movement of the elevator system.

The project does not account for a real life elevator system in the sense that various

functions of the elevator such as the hold door button, fire alarm button, stop etc. have

not been inducted in the code

The project assumes the opening and closing of the door and does not show it their

function in the simulation.

The functions of the lift operator such as scheduling a maintenance etc. have also been

avoided.

13

Verilog Code

`timescale 1ns /1ps // time scale of 1ns and resolution 0.01 ns

module elevator_demo( input clk, reset, req_1F, req_2F, req_3F, req_4F, req_E1_1,

req_E1_2, req_E1_3, req_E1_4, req_E2_1, req_E2_2, req_E2_3, req_E2_4, req_E3_1,

req_E3_2, req_E3_3, req_E3_4, req_E4_1, req_E4_2, req_E4_3, req_E4_4,output reg [1:0]

E1_pos, E2_pos, E3_pos, E4_pos,output reg [7:0] o1, o2, o3, o4);

reg [1:0] E1_next_pos, E2_next_pos, E3_next_pos, E4_next_pos;

reg dg;

parameter firstfloor= 2'b00, secondfloor = 2'b01, thirdfloor = 2'b10, fourthfloor = 2'b11;

always@(posedge clk, reset)

begin

if (reset)

begin

E1_pos

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dg=4'b1110;

end

if (E1_pos==secondfloor)

begin

o1=8'b00100101;

dg=4'b1110;

end

if (E1_pos==thirdfloor)

begin

o1=8'b00001101;

dg=4'b1110;

end

if (E1_pos==fourthfloor)

begin

o1=8'b10011001;

dg=4'b1110;

end

if (E2_pos==firstfloor)

begin

o2=8'b10011111;

dg=4'b1101;

end


begin

o2=8'b00100101;

dg=4'b1101;

end


begin

o2=8'b00001101;

dg=4'b1101;

end


begin

o2=8'b10011001;

dg=4'b1101;

end\

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begin

o3=8'b10011111;

dg=4'b1011;

end


begin

o3=8'b00100101;

dg=4'b1011;

end


begin

o3=8'b00001101;

dg=4'b1011;

end


begin

o3=8'b10011001;

dg=4'b1011;

end


begin

o4=8'b10011111;

dg=4'b0111;

end


begin

o4=8'b00100101;

dg=4'b0111;

end


begin

o4=8'b00001101;

dg=4'b0111;

end

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begin o4=8'b10011001;

dg=4'b0111;

end

end

always@(posedge clk, reset, E1_pos, E2_pos, E3_pos, E4_pos, req_1F, req_2F, req_3F,

req_4F, req_E1_1, req_E1_2, req_E1_3, req_E1_4,req_E2_1, req_E2_2, req_E2_3,

req_E2_4, req_E3_1, req_E3_2, req_E3_3, req_E3_4, req_E4_1, req_E4_2, req_E4_3,

req_E4_4)

begin

begin

if (req_1F==1)

begin

E1_next_pos

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begin

if (req_E1_1==1)

E1_next_pos

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if (req_E3_3==1)

E3_next_pos

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reg req_E2_1, req_E2_2, req_E2_3, req_E2_4;



//OUTPUTS

wire [1:0] E1_pos;

wire [1:0] E2_pos;

wire [1:0] E3_pos;

wire [1:0] E4_pos;

wire [7:0] o1;

wire [7:0] o2;

wire [7:0] o3;

wire [7:0] o4;

//Instantiate FE_Test

elevator_demo test1(.clk(clk), .reset(reset), .req_1F(req_1F), .req_2F(req_2F),

.req_3F(req_3F), .req_4F(req_4F), .req_E1_1(req_E1_1),

.req_E1_2(req_E1_2),

.req_E1_3(req_E1_3),.req_E1_4(req_E1_4),.req_E2_1(req_E2_1),.req_E2_2(req_E2_2),.req

_E2_3(req_E2_3),

.req_E2_4(req_E2_4),.req_E3_1(req_E3_1),.req_E3_2(req_E3_2),.req_E3_3(req_E3_3),.req

_E3_4(req_E3_4),.req_E4_1(req_E4_1),

.req_E4_2(req_E4_2), .req_E4_3(req_E4_3), .req_E4_4(req_E4_4), .E1_pos(E1_pos),

.E2_pos(E2_pos), .E3_pos(E3_pos), .E4_pos(E4_pos),

.o1(o1), .o2(o2), .o3(o3), .o4(o4));

initial begin

// Initialize Inputs

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clk = 0;

end

always clk=#10 ~clk;

initial

begin

reset = 1;

req_1F = 0;

req_2F = 0;

req_3F = 0;

req_4F = 0;

req_E1_1=0;

req_E1_2=0;

req_E1_3=0;

req_E1_4=0;

req_E2_1=0;

req_E2_2=0;

req_E2_3=0;

req_E2_4=0;

req_E3_1=0;

req_E3_2=0;

req_E3_3=0;

req_E3_4=0;

req_E4_1=0;

req_E4_2=0;

req_E4_3=0;

req_E4_4=0;

#10

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reset = 1;

req_1F = 0;

req_2F = 0;

req_3F = 0;

req_4F = 0;

req_E1_1=0;

req_E1_2=1;

req_E1_3=0;

req_E1_4=0;

req_E2_1=0;

req_E2_2=0;

req_E2_3=0;

req_E2_4=1;

req_E3_1=1;

req_E3_2=0;

req_E3_3=0;

req_E3_4=0;

req_E4_1=0;

req_E4_2=0;

req_E4_3=1;

req_E4_4=0;

#10

// ALL FLOORS ARE NOW ONE

reset = 1;

req_1F = 1;

req_2F = 1;

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req_3F = 1;

req_4F = 1;

req_E1_1=0;

req_E1_2=0;

req_E1_3=0;

req_E1_4=0;

req_E2_1=0;

req_E2_2=0;

req_E2_3=0;

req_E2_4=0;

req_E3_1=0;

req_E3_2=0;

req_E3_3=0;

req_E3_4=0;

req_E4_1=0;

req_E4_2=0;

req_E4_3=0;

req_E4_4=0;

end

endmodule

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Simulation Results

Figure 8: Simulation Results

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The simulation results corresponds to the above mentioned testbench. The following requests

were made to all the four elevators. Their output can be discerned in the four status values o1,

o2, l3, & o4 which mention the position of the elevators E1, E2, E3 & E4 respectively.

Each floor is decoded in the elevator status using eight bit numbers mentioned below:

Floor 1 10011111 8h9F

Floor 2 00100101 8h25

Floor 3 00001101 8h0D

Floor 4 10011001 8h99

The output Ex_pos gives the floor on which the elevator is located as per the earlier

mentioned values.

The input were given as follows:

E1- 2nd floor

E2- 4th floor

E3- 1st floor

E4- 3rd floor

The output is decided after 1 clock period, after which the values are reflected in the Ox

register.

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Conclusion

This project has designed a four elevator system for as many floor. The output proves that

each lift gives priority to the internal inputs as compared to the external outputs.

The design can also be altered to suit the need for as many floors as required.

The simulation results have been successful.

26

References

[1] http://www.electrical-knowhow.com/2012/04/elevator-control-system.html

[2] http://image.slidesharecdn.com/fourelevatorcontroller-140216134421-phpapp01/95/four-

elevator-controller-3-638.jpg?cb=139255837

[3] http://image.slidesharecdn.com/fourelevatorcontroller-140216134421-phpapp01/95/four-

elevator-controller-3-638.jpg?cb=139255837

Four Elevator COntroller

Documents

group of elevator system

elevator doors

dual elevator controller

elevator cars presence

electronics control

elevators group

different control strategies

group members