Despite extensive use of robots nowadays in automation factories, practical success of robots on harvesting tasks is still limited. The aim of these kind of robots is to assist farmers in the laborious harvesting work. In order to accomplish this, two main difficulties have to be faced: time, robots have to help farmers save time during the harvesting period; and quality, the plantation or fruits shall not be damaged or misplaced.
The purpose of this report is to present all the work done in order to develop an automatic robot able to recognize and harvest ripe tomatoes.
Since it is not possible to build a fully automatic harvesting robot during the time that lasts the European Project Semester, this project is divided in various stages. This report will be about the first part of the project.
First, the requirements are set up and along with it, a research about existing harvesting robots is conducted and several solutions to meet the requirements are proposed.
Following the mentioned above, a prototype is realised by designing a gripper that can be mounted on a ABB IRB1600 robot arm. The gripper is made up of three fingers and each finger has two phalanxes that closes around the tomato. The opening and closing movement is realised by a servomotor. This gripper is equipped with two mechanical switches to detect the maximum open or closed position which are all connected with an Arduino Uno processor.
The tomatoes are detected with a web camera mounted on the robot arm in combination with the SICK 3D camera placed on a fixed position. The web camera takes a picture and through different image processing the ripe tomatoes are detected. Given that a single camera is not able to determine the depth, the 3D camera is used to obtain the third missing coordinate. All three coordinates are adjusted to the robot coordinate system and finally packed together with the other tomato coordinates in a string. This information is sent to the robot controller.
The robot controller moves the arm to the given coordinates and gives the order to close the gripper. When it is closed, the robot arm moves to a fixed position and gives the order to open the gripper. The picked tomato falls in the basket and the sequence is repeated until all the tomatoes are picked.
The prototype built during this project is able to harvest ripe tomatoes but it is far from being ready for the commercial market, hence some valuable recommendations are given at the end of the report.
Treball desenvolupat dins el marc del programa 'European Project Semester'.
