Shiny red peppers, succulent grapes and perfect apples:that is what customers prefer to pick up in the supermarket. So that fruit and vegetables make it to the shelves ripe and without bruises, they are carefully and laboriously harvested by hand.
It would be quicker with machines, but these first have to overcome a few challenges. “A robot first recognise the fruit hidden under leaves, which is not so easy. Grabbing and separating the fruit is also a difficult task due to the different shapes and sizes”, explains Dr. Wolfgang Gauchel, Festo Research and CROPS project manager for Festo.
Research project develops harvesting robot
The CROPS research project, “Clever Robots for Crops”, which is sponsored by the EU Commission, could provide a solution for an automated harvesting procedure. The aim is a configurable, modular and intelligent robot platform, which reliably recognises both the fruit as well as obstacles and other objects. In this way it can navigate and harvest on its own on plantations and in greenhouses. The robot platform is also intended to be able to treat selected areas with pesticides.
As an automation specialist and expert in handling technology, Festo is helping the project by developing gripping and cutting devices. Other partners are the Technical University of Munich, Wageningen University, the research institute, CSIC, and the company FORCE-A.
Apples and peppers as test objects
For the development of the right gripping and cutting device, the researchers are concentrating on the harvesting of apples and peppers. Dr. Wolfgang Gauchel: “To start with, we must clear up which framework conditions need to be observed: How strongly can the fruit be pressed with the gripping elements? What cutting strength is required? After four years of research work, we have now developed two prototypes. Both use an adaptive gripping technology to adapt to the fruit varying in size and shape.”
Adaptive gripping structures
The gripping element on the “pepper gripper” are passively adaptive FinRay fingers, which have already been used on the Festo Bionic Handling Assistant. A knife cuts the peppers off the plant. On the “apple gripper”, the gripping element consists of membrane jaws, which are filled with ceramic balls. The fruit is separated either by twisting and pulling or using a third finger, which presses on the apple's stalk.
Robot recognises ripe fruit
The grippers are fastened on a robot, which uses cameras and other sensor technology to not only detect the position of the fruit, but also its ripeness. Only the really ripe fruit is therefore harvested, with semi-ripe and overripe fruit being left on the plant.
Basis for automated harvesting
The CROPS research project with its demonstrators has developed a good basis for automated harvesting, says Dr. Gauchel: “With the adaptive fingers, Festo has been able to make an important contribution for the project – with these we have made the transition from a research demonstrator to an application fit for the future.”
We would like to thank the Crops research consortium for the friendly provision of the video film