09-10-2010, 03:35 PM
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MICROCONTROLLER BASED PICK AND PLACE ROBOT
ABSTRACT
In this highly developing society; time and man power are critical constrains for completion of task in large scales. the automation is playing important role to save human efforts in most of the regular and frequently carried works e.g. most of the industrial jobs like welding, painting, assembly, container filling etc. one of the major and most commonly performed work is picking and placing of jobs from source to destination. For this purpose, ‘pick and place robot ‘maybe used.
The pick and place robot is a microcontroller based mechatronic system that detects the object, picks that object from source location and places at desired location. For detection of object, infrared sensors are used which detect presence of object as the transmitter to receiver path for infrared sensor is interrupted by placed object. As soon as robot senses presence of object, it moves towards object, picks it with end effectors, and moves along way gantry and finally place it on destination.
If another object causes interrupt, it again does the same job. Whole process is controlled by micro controller.
DESIGN SPECIFICATIONS:
ADC Interface ---- 4 channels (expandable) to detect object position.
Supply Voltage ---- 230V (AC).
8 bit microcontroller – P89V51RD2.
Motor interface – 3 motors : 2 motors in parallel.
MECHANICAL DESIGN:
This pick and place robot has two main mechanical components:
A] Robotic arm and end-effectors.
B] Gantry for moving the arm.
OPERATION OF ROBOT:
1. Initially we will assume the rest position of entire system, i.e. state when no object is placed.
2. At this stage, photo detector is having its output high, since receiver of sensor can receive photons from transmitter as no object I in its path to interrupt.
3. As soon as object is placed at the picking platform, the sensor gets interrupted and outputs low. This signal is sent to the microcontroller which is burnt with program which tells what operation is to be performed at this stage.
4. For understanding operation, let us rename the two motors used here. Let the name of gantry motor be M1 and that for end effecter motor is M2.
5. Now as microcontroller detects that object is placed, it moves motor M1 in say clockwise direction for a fixed time due to which whole arm moves towards picking platform.
6. As it reaches there, M1 stops and now motor M2 is started in say clockwise direction to hold the object by closing jaw. This motor also, is on for particular fixed time instant.
7. As M2 gets off, motor M1 is moved again in opposite (here anticlockwise) direction till the time it reaches the placing platform.
8. As it reaches placing platform, the motor M1 stops and M2 is switched ON in opposite (here anticlockwise) direction till it releases object properly on desired place.
9. If after this no object is detected, the robot is in rest position. Otherwise if another object is detected, steps from 3 are repeated till step 8.
