Review. Technologies for robot grippers in pick and place operations for fresh fruits and vegetables

Abstract

Robotics has been introduced in industry to replace humans in arduous and repetitive tasks, to reduce labour costs and to ensure consistent quality control of the process. Nowadays robots are cheaper, can work in hostile and dirty environments and they are able to manipulate products at high speed. High speed and reliability and low robot gripper costs are necessary for a profitable pick and place (P&P) process. However, current grippers are not able to handle these products properly because they have uneven shapes, are flexible and irregular, have different textures and are very sensitive to being damaged. This review brings together the requirements and phases used in the process of manipulation, summarises and analyses of the existing, potential and emerging techniques and their possibilities for the manipulation of fresh horticultural products from a detailed study of their characteristics. It considers the difficulties and the lack of engineers to conceive of and implement solutions. Contact grippers with underactuated mechanism and suction cups could be a promising approach for the manipulation of fresh fruit and vegetables. Ongoing study is still necessary on the characteristics and handling requirements of fresh fruit and vegetables in order to design grippers which are suitable for correct manipulation, at high speed, in profitable P&P processes for industrial applications.Additional key words: food manipulation; horticulture grasp; postharvest science and technology; robotic product handling. ResumenRevisión. Tecnologías en garras robotizadas para operaciones de coger y dejar productos hortofrutícolas frescos La robótica ha sido introducida en la industria para reemplazar a los humanos en tareas arduas y repetitivas, reducir mano de obra y para asegurar una calidad constante de los procesos. Actualmente los robos son más baratos, capaces de manipular productos a alta velocidad y de trabajar en ambientes hostiles. Por tanto, los robots pueden trabajar en operaciones de "coger y dejar" (pick & place, P&P) con frutas y hortalizas frescas. Para un proceso rentable de P&P, son necesarias una alta velocidad y fiabilidad, así como un bajo coste de los sistemas de agarre. Este artículo de revisión recopila las necesidades y fases empleadas en el proceso de manipulación, reuniendo y analizando las técnicas existentes, potenciales y emergentes y sus posibilidades de aplicación para la manipulación de productos hortofrutícolas frescos a partir del estudio detallado de sus características. Considera las dificultades y la falta de ingenieros para concebir e implementar soluciones. Los autores proponen las alternativas más prometedoras para acometer este difícil problema y consideran la necesidad de seguir estudiando las características de frutas y vegetales frescos y las necesidades de manipulación. Las garras de contacto con mecanismos infra-actuados y ventosas o agarrar el producto sin contacto pueden ser las alternativas más prometedoras para manipular frutas y vegetales frescos. Es necesario continuar e...

Assessment of eggplant firmness with accelerometers on a pneumatic robot gripper

“…The lack of robot grippers able to adapt to the product and the inability of sensors to sort products like operators makes it difficult to introduce robots into the horticultural packaging sector. Robot grippers for handling horticulture products can be designed on the basis of different technologies (Blanes et al, 2011). Multifingered robot hands are the most promising approach to human dexterity but most of them are both too fragile and complex, as well as too expensive, have a low operating speed, and are not robust enough for industrial applications, where far less complex solutions do accomplish the requirements.…”

Non-Destructive Assessment of Mango Firmness and Ripeness Using a Robotic Gripper

“…To achieve the objective, robot grippers need to improve their ability for handling irregular and sensitive products like mango fruit and incorporate tactile sensing. Different solutions regarding the development of robot grippers for handling fruits and vegetables have been proposed by Blanes et al 2011. In this study, gripper finger should be adapted to the product for achieving an adequate manipulation by means of the actuation on the gripper mechanisms (Meijneke et al 2011).…”

Task and Context Sensitive Gripper Design Learning Using Dynamic Grasp Simulation

“…The design objectives include amongst others: small gripper footprint, small weight, secure grasping, small finger length, avoiding tool changes and aligning grasped objects. Furthermore, reviews on the gripper design problem are presented in [7,8]. In [7] a general overview of early work on gripper designs and control is presented, whereas grippers designed specifically for handling fruits were presented in [8].…”