Getting a grip on end-of-arm tooling
End-of-arm tooling, or end effectors, play a crucial role in enhancing productivity through automation. They provide the specific functionality a robot or pick-and-place system requires to interact with its environment and complete tasks effectively. Peter Potters, product manager at Festo, explores the latest developments in automated gripping and handling.
There are many reasons for the tremendous growth in demand for industrial robots, including labour shortages, rising energy costs and the need for higher flexibility and productivity. These commercial pressures are creating exciting opportunities to push the boundaries of end-of-arm tooling (EOAT) design, taking into account critical factors such as moving mass and surface form and texture, while improving accuracy and safety.
EOAT evolution
Traditionally, a vacuum generated by pumps or venturi nozzles and applied via flexible cups or porous plates has been used for most pick-and-place applications, with specialist Bernoulli non-contact grippers being specified for very delicate substrates. Mechanical grippers have emerged as an alternative. Usually two- or three-fingered, these devices move in a parallel or angled motion with the fingers and mechanically squeeze or engage with the profile of the component to be moved.
Vacuum-based EOAT has evolved to offer vacuum generators that are weight and cost optimised, and which can be mounted on highly dynamic robotic arms close to the vacuum cups, enabling faster evacuation times and increased operating cycles. Improvements in pneumatic valve technology, such as Festo’s VTUX valve terminal, are part of this evolution. The VTUX valve terminal addresses both the mechanics/pneumatics and the electrical connectivity requirements within a single platform. It enables a mix of standard valves and vacuum slices, or 100% vacuum, for reduced installation space and costs.
Developments in mechanical grippers have driven the technology in two directions. Design reviews have removed material, not only reducing cost but, more importantly, reducing moving mass. Higher technology grippers offer more flexible control over position and force using fieldbus protocols. One example is the Festo HEPP electric gripper, which features an integrated motor controller for easy integration into control architecture (Profinet, Ethernet/IP, Ethercat). This powerful electric gripper is also highly flexible, offering precise control of positioning stroke, speed, acceleration and gripping force.
Another development in robotic end-effectors is the evolution of soft grippers or fingers. Festo has demonstrated several solutions for flexible grippers inspired by nature that wrap around the product more dextrously. These range from flexible gripper fingers that mount onto standard mechanical grippers or wholly soft devices more akin to a gecko’s tongue or an octopus’s tentacle. Compliant materials allow these grippers to adapt to non-uniform and differing work pieces, enabling reliable handling of complex components using automated systems.
A major influence on EOAT development is the desire for greater human-robot collaboration. ISO/TS 15066 provides guidelines for designing and implementing collaborative workspaces, focusing on risk assessment and control. It includes advice on limiting robot power and force, monitoring speed and separation, and implementing safety measures to protect workers from potential hazards.
It uses four levels to define the human-robot relationship. Level 1 (Coexistence) sees humans and robots operating in the same workspace, but without direct interaction. For example, a human might be working on one part of an assembly line while a robot works on another, without physical contact. Level 2 enables humans and robots to share a workspace, but not at the same time. Level 3 sees some cooperation, with humans and robots working on different tasks with some degree of interaction. Level 4 defines requirements for full collaboration, where humans and robots work together on the same task or product simultaneously, with a high degree of interaction and communication.
Level 4 requires sophisticated robot systems with advanced sensing, control and communication capabilities to ensure safety and coordination. In addition, grippers must limit the gripping force per jaw as well as meet compatible gripper and finger design.
Ease of deployment
While EOAT design is becoming increasingly sophisticated, automation manufacturers are working hard to ensure that the technology remains quick and simple to specify and deploy.
For example, the ability to optimise the sizing of mechanical or vacuum-based grippers is critical to energy-efficient operations. Over-sizing end-of-arm components not only costs more but results in considerably higher lifetime operating costs, which outweigh the purchase price many times over. Software that guides selection and considers all the key application criteria provides system designers and machine builders with assurance that the correct parts have been calculated and the right safety factor applied without waste.
For end-users, flexibility and responsiveness to fluctuations in demand are key considerations. But when the objects to be picked vary, it is challenging to provide a ‘one-size-fits-all’ gripper. Festo has developed a standalone software package called GripperAI that works with a vision system and deep learning algorithms to support blind bin picking operations. It determines the best gripper to use on a multi-headed tool, enabling fast, reliable, object-dependent gripper selection.
Gripped and sorted
The Würth Group, the global market leader in the development, manufacture and sale of assembly and fastening materials, was among the first to put Festo’s GripperAI software to the test. Würth wanted to comprehensively test the software at the Reinhold Würth Innovation Centre Curio, discuss it with employees and, if everything proved successful, implement it in its logistics centres worldwide.
The logistics centre at Würth’s headquarters in Künzelsau, Germany, includes final packaging stations where a wide variety of products arrive in trays on sorter conveyors. Employees remove the objects from the trays and pack them into shipping cartons. Würth has around 1,000,000 products in its portfolio – from small and light products to very heavy parts. Working with heavy parts is particularly demanding for the employees. As the proposed alternative to manual handling, the GripperAI needed to instruct a robot to handle parts weighing up to 20 kilograms.
Over two years, Festo built a copy of Würth’s sorter conveyors in its own research and development laboratory to develop the various capabilities of the robot: object-dependent gripper selection, gripping any objects from the trays, packing shipping cartons, and handling the cartons and trays. The robot cell is equipped with a special tool station, allowing the robot to use various suction cups and grippers. GripperAI determines which tool is most suitable depending on the type of object, its shape and surface finish. An integrated camera in the robot recognises the various objects, enabling precise selection. The Festo GripperAI solution can grip almost anything that is presented to it, for which the gripper and robot are designed. The grippers specially developed for this project set new standards in robot technology, while the suction cups come from Festo’s existing portfolio.
The customised AI robot solution enables Würth to handle heavy parts and other objects efficiently, which significantly reduces the workload for employees and increases operational efficiency. Importantly, it requires no teaching or training before deployment. It also works with any robot and vision system.
The robot cell has been in use at Würth since spring 2023 and can serve all the intended lanes. Further development work and optimisation steps have already been defined, such as higher speed, better packing, and optimisation of the overall process. Würth is convinced that this project will significantly improve their logistics processes, facilitate further growth, and support their employees.
Whether your application demands higher precision, faster cycle times, more flexibility, gentler touch, or lower costs, continuing new developments in EOAT mean there is likely to be a tool to meet your needs.
As the range of mechanical and vacuum EOAT options expands, correct selection will be even more important in delivering safe, efficient and optimised robotic solutions. Festo’s team of Grip-It application engineers supports customers by providing practical application advice and guidance, backed by powerful software tools and the well-equipped Customer Application Centre for proof-of-concept trials and backup to theoretical calculations. Online software sizing tools are also invaluable, allowing specifiers to simulate different gripping solutions before they buy.
Visit the Festo website for more information
