In every high rise buildings lift has become an inevitable part. Generally all lifts are operated using switches. For physically challenged person or blind reach their floor without aid is quite difficult. This project is designed to overcome such problem.
The main idea behind this project is to develop a lift which can be operated using voice. It will be helpful for wheelchair bound persons, blind persons to reach their destination. For example if a person wants to visit a certain department but doesn’t know which floor it has, he can just say the department name and lift will take there.
The controller or the heart of this project is Peripheral Interface Controller (PIC) microcontroller. The programs are written in MPLAB, Microchip’s ‘Integrated Development Environment’.
- IR distance sensor
- Voice module
- Motor Driver
- DC Motor
- PIC microcontroller
Here the aim is to develop a lift or elevator which will be operated using voice. The whole system depends on the efficient human machine interaction. Lift will move upward or downward depending on the voice instruction provided by the user. The user can also control the electric fan in the lift using the voice command. For the voice section, a voice recognition module, V2 is used. V2 supports up to 80 voice commands. The user has to train the module first to accept any voice command. It can be operated using two modes: manual and CPU control mode. Here manual mode is used. It is interfaced with the PIC using UART. The PIC microcontroller selected for this project is 16F877A. The pin out of the PIC is provided below:
The ease of use, flexibility, many inbuilt peripherals, low cost etc. are some of the factors to opt this one. The V2 module is interfaced with the PIC microcontroller through its UART. PIC has inbuilt USART in it which is configured as UART for serial communication. The voice module has to be trained to understand the commands being said. The procedure of the voice module training will be provided in the datasheet. Voice module has a mike using which we will be providing the voice commands to the module for training purpose. Voice module should be designed in such a way that it could manipulate the speech. While speech recognition the following things should be kept in mind that each speaker has unique voice, dialect etc. The words will sound different at different surroundings and the speaking rate and style of saying them will vary. So the voice module has to be trained accordingly. If the user inputs an invalid floor or his diction is not clear then the voice module will ask the speaker to repeat the request in slow and clear manner. The commands will be small one like floor, department, stop, go etc. but it should be clear.
DC motor is used to drive the lift. To drive them a motor driver is used. Generally L239D is used as motor driver as it can control 2 motors simultaneously and supports bidirectional rotation. It has 4 channel drivers with high current and voltage. It has a H-bridge configuration which makes it possible to drive the load connected to the IC move in either direction i.e. by reversing the current flow the direction of rotation of motor will be reversed. L239D has 2 H-bridges making it possible to drive 2 DC motors simultaneously and independently.
L239D pin layout
An IR sensor is placed to check whether the doors are closed or anybody is standing in between the door. IR sensor will have an IR transmitter and receiver. IR rays are continuously emitted from the transmitter which upon hitting any object will be reflected back to the receiver. This time duration of transmitting and receiving will give the presence of objects. If doors are closed the duration will be less compared to when it is open. If a person is standing in between the door it will wait till it gets closed. Once it is ensured the doors are closed the lift will ask for which floor. The user can say or can press the limit switches provided. The limit switches contains the number panel, fan, emergency button etc. LCD will display the current position of lift.
Pin out of LCD
It will display 16 characters in each row. It has 2 rows. To adjust the contrast a potentiometer is connected to 1, 2, 3 pins of the microcontroller. 29th pin of the microcontroller is connected to the register select pin of the LCD. It has two registers, when RS = 1 data register is selected and the data will be displayed on the LCD and when RS=0 command register is selected were other operations of LCD is selected. The 5th pin will be grounded as we will be writing to LCD. 6th pin is connected to 30th pin of microcontroller. Usually 29th and 30th pin are kept high for valid data transmission. From 7 to 14 they are 8-bit data pins which are connected to any port of the microcontroller.
The limit switches are the switches generally seen in the side of the lift to hint the lift.