A compact underactuated gripper with two fingers and a retractable suction cup

Modern industrial applications of robotics such as small-series production and automated warehousing require versatile grippers, i.e., grippers that can pick up the widest possible variety of objects. These objects must often be grasped or placed inside a container, which limits the size of the gripper. In this article, we propose to combine the two most popular gripper technologies in order to maximise versatility: finger grippers and suction-cup (vacuum) grippers. Many researchers and a few companies have followed this same idea in the past, but their gripper designs are often overly complex or too bulky to pick up objects inside containers. Here, we develop a gripper where the suction cup is lodged inside the palm of a two-finger robotic hand. The suction cup is mounted on a retractile rod that can extend to pick up objects inside containers without interference from the two fingers. A single actuator drives both the finger and sliding-rod motions so as to minimise the gripper complexity. The opening and closing sequence of the gripper is achieved by using a planetary gear train as transmission between the actuator, the fingers and the suction cup sliding mechanism. Special attention is paid to minimise the overall gripper size; its diameter being kept to 75 mm, which is that of the end link of the common UR5 robot. A prototype of the gripper is built and its versatility is demonstrated in a short accompanying video

Préhenseurs combinant doigts et ventouse entrainés par un seul actionneur

Titre de l'écran-titre (visionné le 22 juin 2023)Les robots interagissent souvent avec leur environnement et les objets à saisir via un préhenseur. Dans certaines applications comme une chaîne d'assemblage, un seul type d'objet est manipulé par ce robot. Choisir le bon préhenseur pour cette tâche est alors simple car les paramètres de l'objet sont connus. Dans une application où les objets à manipuler sont variés et inconnus, le choix de préhenseur est plus complexe. Parmi les technologies existantes, deux sont les plus fréquemment utilisées, soient les préhenseurs à doigts et les préhenseurs à vide utilisant des ventouses. Chacune des ces technologies a ses forces et ses faiblesses. L'objectif de ce mémoire est de combiner ces technologies dans un préhenseur pour exploiter leurs forces respectives et ce sans leurs faiblesses. Le premier concept présente un préhenseur ayant un mécanisme articulé pour chaque doigt et une ventouse fixe dans sa paume. Le mécanisme articulé des doigts est un mécanisme à quatre barres avec sous actionnement permettant une prise parallèle avec les phalanges distales ou une prise englobante en utilisant les phalanges proximales et distales. Le mécanisme à barres possède une plage de mouvements d'environ 180°, ce qui permet aux doigts de se rétracter suffisamment derrière le plan de travail de la ventouse a n de saisir des objets avec celle-ci. Le deuxième concept présente un préhenseur ayant des doigts suivant une trajectoire linéaire et une ventouse rétractable. Un train planétaire différentiel et un seul moteur sont utilisés pour actionner les mouvements des doigts et de la ventouse. Le mouvement des doigts est linéaire et entraîné par un pignon et une crémaillère. La ventouse est installée au bout d'une vis pour créer un mouvement linéaire entrant et sortant de la paume du préhenseur. Le diamètre maximal du préhenseur est contraint à 75 mm a n d'être compact et manœuvrable dans des espaces restreints. Un prototype de chaque concept a été conçu et testé.Robots often interact with their environment and the objects to be grasped via a gripper. In some applications such as an assembly line, only one type of object is handled by this robot. Choosing the right gripper for this task is then simple because the parameters of the object are known. In an application where the objects to be handled are varied and unknown, the choice of gripper is more complex. Among the existing technologies, two are the most frequently used, namely finger grippers and vacuum grippers using suction cups. Each of these technologies has its strengths and weaknesses. The objective of this thesis is to combine these technologies in a gripper to exploit their respective strengths without their weaknesses. The first concept presents a gripper having an articulated mechanism for each finger and a fixed suction cup in its palm. The articulated finger mechanism is a mechanism with underactuation allowing a parallel grip with the distal phalanges or an encompassing grip using the proximal and distal phalanges. The bar mechanism has a range of motion of approximately 180° , allowing the fingers to retract far enough behind the work surface of the suction cup to pick up objects with it. The second concept presents a gripper with fingers following a linear trajectory and a retractable suction cup. A di erential planetary gearset and a single motor are used to drive the fingers and suction cup movements. The finger movement is linear and driven by a rack and pinion. The suction cup is installed at the end of a screw to create a linear movement going in and out of the palm of the gripper. The maximum diameter of the gripper is constrained to 75 mm in order to be compact and maneuverable in tight spaces. A prototype of each concept was designed and tested

Video2_A compact underactuated gripper with two fingers and a retractable suction cup.MP4

Modern industrial applications of robotics such as small-series production and automated warehousing require versatile grippers, i.e., grippers that can pick up the widest possible variety of objects. These objects must often be grasped or placed inside a container, which limits the size of the gripper. In this article, we propose to combine the two most popular gripper technologies in order to maximise versatility: finger grippers and suction-cup (vacuum) grippers. Many researchers and a few companies have followed this same idea in the past, but their gripper designs are often overly complex or too bulky to pick up objects inside containers. Here, we develop a gripper where the suction cup is lodged inside the palm of a two-finger robotic hand. The suction cup is mounted on a retractile rod that can extend to pick up objects inside containers without interference from the two fingers. A single actuator drives both the finger and sliding-rod motions so as to minimise the gripper complexity. The opening and closing sequence of the gripper is achieved by using a planetary gear train as transmission between the actuator, the fingers and the suction cup sliding mechanism. Special attention is paid to minimise the overall gripper size; its diameter being kept to 75 mm, which is that of the end link of the common UR5 robot. A prototype of the gripper is built and its versatility is demonstrated in a short accompanying video.</p

Video1_A compact underactuated gripper with two fingers and a retractable suction cup.MP4

Modern industrial applications of robotics such as small-series production and automated warehousing require versatile grippers, i.e., grippers that can pick up the widest possible variety of objects. These objects must often be grasped or placed inside a container, which limits the size of the gripper. In this article, we propose to combine the two most popular gripper technologies in order to maximise versatility: finger grippers and suction-cup (vacuum) grippers. Many researchers and a few companies have followed this same idea in the past, but their gripper designs are often overly complex or too bulky to pick up objects inside containers. Here, we develop a gripper where the suction cup is lodged inside the palm of a two-finger robotic hand. The suction cup is mounted on a retractile rod that can extend to pick up objects inside containers without interference from the two fingers. A single actuator drives both the finger and sliding-rod motions so as to minimise the gripper complexity. The opening and closing sequence of the gripper is achieved by using a planetary gear train as transmission between the actuator, the fingers and the suction cup sliding mechanism. Special attention is paid to minimise the overall gripper size; its diameter being kept to 75 mm, which is that of the end link of the common UR5 robot. A prototype of the gripper is built and its versatility is demonstrated in a short accompanying video.</p

Building food security in the Canadian Arctic through the development of sustainable community greenhouses and gardening

International audienceDisruptions in the way of life of indigenous peoples from the Far North have greatly affected their ability to meet their food needs. The implementation of community greenhouse and gardening projects is one of the initiatives taken to address this issue in Nunavik. Through a mixed-method approach, we analyze social benefits and challenges, as well as the potential food productivity and nutritional contributions of these projects. We discuss the potential of current greenhouse energy optimization scenarios and we address the benefits of Kuujjuaq's greenhouse in terms of carbon dioxide mitigation. Discussions with the local stakeholders highlighted technical challenges regarding the energy supply, its efficient management and the supply of soil in sufficient quantities. Our results highlight the interconnectedness and complexity of food and energy systems in Nunavik. They show that the establishment of local fresh food production corresponds to a need expressed by the residents and could bypass some of the difficulties associated with the conveyance and freshness of food sold at the supermarket. They also indicate that the implementation of such production poses many challenges that require taking into account the geographical isolation, the arctic climate and the availability of local resources