Here's is another one:
Elevator Lift control for three stories with microcontroller 8051
In this project, we will learn circuit design for a elevator, how to develop a three stories passenger lift or cargo lift using microcontroller at89c51. This is a modal of simple lift or elevator in which a building is assumed which have three floors :
Floor # 0 : The basement (A basement is one or more floors of a building that are either completely or
partially below the ground floor. )
Floor # 1: The ground floor
Floor # 2: The ist floor
There is a cabin of lift or elevator which will be moved up or down among different floors with the help of a motor. In this project of lift or elevator a single motor is used which will move the cabin up or down. Thus we have to learn about the control of this motor which is responsible of lift cabin movement on right time in right direction.
There are three floors in the building, thus lift cabin has to moves between these floor, for floor detection and to generate the arrival of any floor, some sensor are used. The floor detection sensors are limit switches which could be proximity switches. The proximity switches are sensors which changes the stat of a signal when metallic piece comes near them. The Principles of operation of inductive proximity sensors used in PC control, microcontroller or microprocessor projects and automation systems are as a proximity sensor is a sensor able to detect the presence of nearby objects without any physical contact. or in other words we can say that a proximity sensor often emits an electromagnetic or electrostatic field, or a beam of electromagnetic radiation and looks for changes in the field or return signal. The proximity sensors are the best for the detection of floor and could be used in this project. Thus, we will use three proximity sensors for three stories elevator project, one proximity sensor on each floor. These sensors have to be aligned with each other, such a way that, all sensors should be placed on equal distance from floor and these should be mounted to detect the bottom edge of lift cabin. By considering above precaution in the installation of sensors, lift cabin will stop on each floor correctly and doors of cabin and floor will be automatically aligned.
Three signals will be generated from within the lift cabin: these could be push buttons and will be used to request the lift to go on desire floor. The lift cabin will have three push switches for this purpose, one for each floor.7-segment led indication of lift system circuit design
Three signals will be generated outside the lift cabin, one from each floor. Again, these would be push buttons and there purpose will be to call the lift on desired floor, if it is not currently present there.
The status of lift will be indicated with the help of seven segment display. One seven segment display will be install on each floor; which will tell the current location of the lift. following display pattern could be visible on seven segment display of lift project:
0 : It means lift or elevator is on floor # 0 which is basement.
1: It means lift or elevator is on floor # 1 which is ground floor.
2: It means lift or elevator is on floor # 2 which is first floor.
3: This will indicate that lift is just powered up and it is going to its home position which basement. on reaching the basement, display will show 0.
The seven segment circuit is separate from main controller circuit of lift. The power supply of master controller circuit, and three floor indicator circuits (LED seven segment display) will be separate and communication between these will be through optocouplers.
In this project we can use L817 or 4n35 optocouplers. I used L817 optocoupler with no special reason. Please note that the inputs of the master controller will also be connected to microcontroller 8051 through optocouplers like L817. Although, i have not shown the optocouplers for input signals in the circuit diagram with the assumption that students will use these by their own.
The circuit diagram of Elevator Lift control for three stories with microcontroller 8051 is as under:-