Design of a Prototype Harvesting Robot for Greenhouses Products

Harvesting Robot for Greenhouses, Nowadays, according to the robust and effective harvesting management of greenhouse and agricultural fields products, using robotic systems seems to be necessary to increase the quality of harvesting and reduce manpower. In this research, a robot equipped with a tracked vehicle system and a mechanical arm is designed and constructed for harvesting greenhouse products.


Harvesting Robot for Greenhouses Products

At first, a robotic tracked vehicle system which was capable of maneuver on all levels between the crop rows in greenhouses was designed and developed. The stress-strain analysis of all the main parts of the robot was then carried out. The tracked vehicle system was able to be adjusted in height and width of the chassis, the angle of attack and the controller system.

Depending on the surface of the ground, the angle of the tracked vehicle system was adjustable from 45 to 60°. The tracked vehicle carrier is drived with two AC motors equipped with an Arduino system. Furthermore, sprocket wheel was used for power transmission with a ratio of 1:2 to raise the torque.


Mechanical Arm of Harvesting Robot for Greenhouses

Then, a mechanical arm with four degrees of freedom, capable of covering up the plants of the hydrophobic greenhouse, was designed and constructed. To reduce the weight of the robot arm and the maximum power transmission capacity, a combination of sprocket wheel and gear was used. This mechanical arm had four servomotors, four special drives and a programmable controller.

By calculating the torque required for each joint of the robot arm, servomotor type was selected for the arm. For high torque production, the selected servomotor had a gear ratio of 1:40. By calculating the direct and inverse kinematics of the arm, and with the writing of a special G-code, the direction of movement of the arm of the robot was determined and the mechanical arm was simulated in the designated path.


End-effector of Harvesting Robot for Greenhouses

According to this path, the end-effector of the robot arm reached the product on the crop row. The controller system of the Harvesting Robot for Greenhouses arm included a central controller and a computer on the robot, featuring an interface between the robot and the user. The computer then converted all commands into pulses after loading the G-codes for the type of arm movement, and drived servomotors through the controller. The tracked vehicle system was capable of crossing the the barriers at two angles of attack, i.e., 45 and 60°.



In order to accurately evaluate the performance of the Harvesting Robot for Greenhouses robot, a laboratory evaluation, with the motion of the tracked vehicle system and the mechanical arm of the robot in the laboratory was carried out in College of Abouraihan to determine the accuracy of the motion of the robot. Also, tomato, as a sample of greenhouse crops, cultivated in hydroponic greenhouse was selected to evaluate the performance of the image processing unit of the robot. The proposed image processing algorithm was used to differentiate ripe tomatoes that are suitable for harvest from premature tomatoes.



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