Reconfigurable robotic handling devices
What it is: Technology for automated handling of cut fabric parts in garment industry where parts are singularly collected from flat and delivered to a transport system. The devices are:
- a reconfigurable passive hanger with 3 dof and 3 clamps on/off;
- a reconfigurable modular robotic gripper with an articulated redundant architecture with 3 fingers and 9 dof;
- 3 picking modules pneumatically actuated embedded into the gripper fingertips.
Picking technique: Each fabric part to be picked at exact locations decided part by part to avoid folding and minimize wrinkling in hung configuration. High flow-rate vacuum at each picking location to generate holding forces - safe, robust with porous materials like fabric, adaptation to curved contact regions
- Hanger architecture and
geometry defined from extensive analysis of cut part shapes to support.
- Minimum lateral space
- Overall cost very low (few
plastics and aluminum components).
- Suitable for both automatic and manual operation.
- 3 actuated arms each with one
picking/loading unit at tip.
- Central arm 1 dof; lateral arms
2dof accordingly to hanger motions.
- Distributed onboard generation
of vacuum by new micro turbine modules.
- Interface to robotic arm and
distributed control unit.
- Interface and docking system to
hanger; full hanger management including reset and configuration, part loading,
management of hanger graspers, release to transport system.
- 4bar linkages in lateral arms
to drive picking modules.
- Design solutions for minimum mass.
The robotic hand grasps and mates to the hanger, the group hand-hanger reconfigures positioning the hanger clamps to desired points on the fabric part, picks the part and connects to the hanger. The gripper is moved by a robotic arm. Robot, gripper and hanger cooperate to the task performing. Firstly the mechanisms back to the initial position, and then the grasping device detaches a hanger from the hanging conveyor, and enables its clamps to follow the fingers. Each finger of the hanger is bound to follow a tag placed on the corresponding grasping device clamp. The tips of the three fingers of the robotic gripper are equipped with picking modules whose turbine fans lift the fabric by mean of vacuum. The fingers lift up and retract, so that the fabric hems shift between the hanger clamps. After that the grasping device freezes the hanger and hands the pattern over it. As soon as the confirmation by the hanger comes, the gripper communicates to the controller that everything is ready to move towards the loading point in the hanging conveyor. The resetting of all I/O channels concludes the procedure. The main routine of the gripper fingers envelops the operative procedure into a while loop: the escape condition is determined by the robot controller.
What is the innovation/special feature
The robotic hand embeds high-flow vacuum picking modules with micro-compressors onboard. Fabric parts are grasped and handled by multi-functional fingers. Fabric porosity is not a problem as for other vacuum systems. Clamps are actuated using SMA.
The grasping solution proposed is a system including a reconfigurable gripper and a hanger. This allows concentrating movement dexterity and intelligence in the gripper while the hangers are passive and cheap. So the system cost is kept low because only one gripper serves a cutting table unloading cell but many hangers are used to run the cut parts to the sewing sections.
The metamorphic reconfigurable grasping device is able to handle cut parts of different sizes and shapes, made of different kind of fabric without damages.
The innovative architecture of the gripper offers a great dexterity in a working space suitable for a great variety of man and woman clothes; its modularity is very useful for quick maintenance, fast substitution of the picking modules on the fingertips (maybe adopting different picking technologies) and relative set-ups.
A further innovation is the gripper control that is integrated with the robot control so the information about the poses of the picking points on the cut parts are shared and the positioning can be achieved with the due accuracy on the basis of all the motilities of the robot and gripper. Many tricks have been adopted in order to make hangers simple, lightweight and cheap. With this purpose the clamps are actuated by SMA springs purposely designed and the electric circuitry used for SMA heating is embedded into the hanger structure.
Cutting table with automatic unloading
A robot equipped with robotized gripper grasps the cut parts and dispatches them in the plant. This system will satisfy the need of automation of the unloading operations of parts after cut. The robot can be a standard industrial arm or a special manipulator depending on specific requirements. The gripper can comprise fingers and different grasping units. A RFID-ZigBee labeler can be embedded as well.
The robot dialogs with the cutting table, learns the positions of the cut parts, knows the needs of manufacturing, decides which parts to grasp, grasps, unloads, realizes these parts to the transport.
The cutting table shares with the unloading system all information regarding part geometries and their nesting on the table, the material, the presence of plastics and paper, the number of plies, specific requirements regarding the fabric and its unloading. This information is used by the unloading system to plan the grasping and lift conditions.
Information about the unloading sequence is received from the cell or line control system. The unloading system dialogs also with the logistics of the plant either directly or through the cell/line controller.
The unloading sequence is carried out picking one or more parts at a time depending on dispatching requirements, size of the parts, specific architecture of the gripper.
The gripper is reconfigurable and can adapt to each part geometry. High-flow vacuum is used to generate the adhesion force. The working conditions can be modified to adapt to specific material requirements.
The gripper can embed equipment to transfer information in RFID-ZigBee markers onto the parts if required. The integration to the cell/line is complete.
The system realizes the automatic unloading of the fabric parts from the cutting table, operation done manually today. Accurate handling of fabric is difficult. The system allows extending automation to the following garment manufacturing sections.
The innovations in the system are in the adhesion technology adopted and in the level of flexibility which is higher than in any other previous technical experience.
The adhesion to fabric is obtained using a high-flow vacuum generator with depressor, control and every other functional component onboard to realize an independent module. Fabric is porous to air and delicate, especially garment types. The appearance of the surface is modified by any mechanical interaction comprising relative contact movements. Traditional vacuum solutions do not process an amount of air sufficient to obtain reasonable grasping force on fabric. Dynamic depressors are used to hold and grasp porous material but the architectures are generally centralized with one main generator and distribution channels. This limits the achievable flexibility. The innovation in the adhesion technology consists in the development of distributed dynamic depressors with low-cost that can be treated almost as Venturi-depressors in terms of complexity, size, mass, cost. These dynamic depressors can be distributed on any equipment with multiple picking points. The reliability of the overall system results improved because fail of one picking point does not compromise the overall functioning of the system as with centralized generators. A special features of the picking module developed is the adaptability to different materials with porosity to air in a large range without structural modifications to the module.
This article was originally published in the November issue of the New Cloth Market: the Complete Textile Magazine from Textile Technologists