Human-Robot Collaboration: Hand-in-Hand Gripper

Human/robot collaboration requires intelligent and safe grippers. In technology studies, Schunk shows what is important for HRC-capable actuators, which minimum standards must be fulfilled and what is already possible today. And what is more: with the Schunk Co-act Gripper JL1, the gripping technology specialist sets a new benchmark for HRC grippers of the future.

A touchscreen in the gripper housing and LED panels in the fin-gers enable direct communication with the operator on the Schunk Co-act Gripper JL1.

When Schunk presented the world’s first certified safety gripping system around three years ago, it was to be expected that the competence leader for clamping technology and gripping systems would soon build on this success. At the time, Ralf Steinmann, Director Business Unit Gripping Systems at Schunk, had already defined the barrier-free collaboration of human and robot as a target photo for the production of the future. Just 36 months later, the development engineers of the innovative high-tech forging delivered on this promise with the technology studies of the SCHUNK Co-act Gripper. These have the potential to catapult the gripper into a new dimension.

In doing so, Schunk remains true to the success principle of the modular gripper system. Users also ought to be able to achieve customized solutions from the standard, without this resulting in costly over-engineering. They are expected to do their service in separate machining areas, in which pneumatic modules have been established for years. Proven components such as the flagship Schunk PGN-plus are therefore consistently being further developed and subjected to technological updates. The new Schunk PGN-plus, which is being launched right now, thus has an enlarged supporting dimension between the six load-bearing shoulders of the patented multi-tooth guidance, which enables even higher moments to be accommodated and longer fingers used. Furthermore, continuous lubrication by means of through-hole lubricant pockets in the multi-tooth guidance ensure that the gripper is lifelong maintenance-free under normal, clean operating conditions. And last but not least, an expanded surface of the drive piston enables further increased gripping forces. In addition, Schunk electrically transfers the performance package of its pneumatic all-rounder with the new PGN-plus to the world of mechatronic gripping system components.

Graduated safety concepts

As the machining areas of human and robot are growing closer to each other, for instance when operators step onto the automated system in order to remove defective components, load part storage conveyors or to eliminate malfunctions, the Schunk safety gripping systems EGN and EZN in combination with the Schunk ECM controller and the Schunk ECS safety module enable the SLS, SOS and STO functionalities. In combination with safety mats, door switches, light curtains or 3D cameras with area monitoring, it is possible to define graded protection zones without completely interrupting the production process using emergency shutdown operations when human/machine contact becomes too close. Instead, the grippers go into either a safely limited speed or a safe operating stop, depending on which protection zone is activated. In safe operating stop the grippers are continuously supplied with power, so that gripped parts are held safely even without mechanical gripping force. As soon as the safety zone is released, they directly switch back to regular operating mode without delay and without having to restart the system.

Soft shell – intelligent core: the Schunk Co-act Gripper JL1 is a milestone on the pathway to human/robot collaboration.

Where full automation of production or assembly lines is only economically possible in certain conditions, or human capabilities are indispensable for the process, sub-processes are separated and divided up between man and robot more distinctly in the future. In such situations, autonomous cobots, meaning robots used in the worker’s immediate environment, can handle tasks that are ergonomically awkward or particularly monotonous. As intelligent lifting or positioning aids for instance, they reduce the physical exertion on humans and ensure high efficiency within the process chain. Compared with full automation, the space requirements for man and robot reduce with hand-in-hand work and the process can be shaped with considerably more flexibility. According to the specialists at SCHUNK, the number of robot-assisted systems, particularly in assembly applications, will therefore rapidly increase in future.

SCHUNK Co-act Grippers facilitate interaction and communication

The closer human and robot work together, the higher the safety requirements become. Whilst in the lowest stage, i.e. in separate machining areas, a risk assessment in accordance with DIN EN ISO 12100 and for the area of functional safety a certification of the machine safety in accordance with DIN EN ISO 13849 are sufficient, the principles of protection of DIN EN ISO 10218-1/-2 and DIN EN ISO/TS 15066 must additionally be taken into consideration for direct human/robot collaboration. This is precisely what the SCHUNK Co-act Gripper family stands for. Even at a basic level, Schunk Co-act Grippers will satisfy the three most critical requirements of safe human-robot collaboration in the future, as stipulated by their goal: they never lose grip of an object, they always detect contact with humans and they will never cause injury when gripping. With the aid of various sensors, the gripping process can be adjusted in real time. Various “senses” are used to record, evaluate and communicate situational, ambient and operational conditions. Thus, in the future, SCHUNK Co-act grippers will be able to transmit all relevant data about processes and surroundings to the control and production systems. The focus will be on the intelligent flow of materials, process optimization and continuous documentation. Typical of SCHUNK: the modules of the Co-act series are designed to be manufacturer-independent and can be used on all relevant HRC robots.

The Schunk Co-act Gripper JL1 makes it clear where the development is headed. This is the first intelligent HRC gripper, which directly interacts and communicates with the humans. Schunk consciously chose the initials of the brand ambassador Jens Lehmann for the technology carrier. The world class goalkeeper stands for safe, precise gripping and holding like no one else. Five features are characteristic for the JL1: first, a safe drive, which facilities a wide gripping force range and simultaneously ensures functional safety. It is therefore continuously ensured that gripped parts are held reliably if a process is interrupted. Secondly, environmental sensors which record the environment of the gripper. Thirdly, a software that evaluates and processes the signals of the sensors. Fourthly, a limitation of the gripping force, which is deployed immediately after unintentional contact with a human. And last but not least, a smooth external contour without sharp, angular or cutting edges.

Sensoric aura for environmental monitoring

 Whether it’s a soft covering, flowing form, protection from loss of workpiece or communication interface over an LED panel integrated into the gripper: SCHUNK impressively demonstrates with the Co-act Gripper JL1 what is important for HRC applications. With the help of particularly designed gripping techniques and force-measuring jaws in its fingers, the gripper can adjust its behavior in real time depending on whether it is gripping a workpiece or a human hand – and given the magnitude of its gripping force, this is by no means an insignificant decision. Mechanically, the gripper facilitates both a parallel and also an angular grip, meaning it is able to reliably handle a wide variety of objects.

Using a complex interplay between various sensors, the Schunk Co-act Gripper JL1 constantly records its surroundings.

Adjusted to suit the respective application, plant planners and users will have at their disposal a complex interplay between various sensors and safety mechanisms. Force-measuring jaws and visual monitoring by means of cameras will be incorporated as well as skins made of tactile and capacitive sensors or current-based force control. Similarly to humans, who as a rule combine several senses in order to evaluate a situation, a sensoric aura facilitates a redundant perception of the environment with the Co-act Gripper JL1. A special software bundles the various information from the individual sensor sources and derives the correct information from this. Furthermore, via OPC UA interface, the gripper is able to communicate both with robots and with the higher-level system control. In doing so, it creates the prerequisite to flexibly shape processes as envisioned in Industry 4.0. At the same time, the gripper acts as a direct means of communication between the plant controller and the operator: using LEDs and a corresponding color coding system, it provides information as to whether the system is ready for operation or if the correct workpiece is gripped. Depending on the application, the components can be identified using defined machining areas, RFID or visual codes. An integrated touchscreen also enables direct communication with the gripper as well as teaching or switching to various operating modes.

 

Bundling HRC competence in the Schunk Co-act team

The Schunk Co-Act team is able to implement HRC grippers to-day already as customized solutions. For example the force-sensitive Schunk WSG was equipped as a HRC gripper for in-specting cast-iron parts.

Based on the technology carrier, Schunk will now put the finishing touches on the development of the individual standard modules of the SCHUNK Co-act Gripper family. Until the standard program comes onto the market SCHUNK is already able to deliver HRC grippers individually adjusted to the respective application as a customer-specific solution right now. Schunk formed the interdisciplinary SCHUNK Co-act team specifically for this, with specialists trained for precisely this purpose from the fields of design, product management, assembly and distribution. The team of specialists ensures a unique concentration of compentence in the field of gripping, regardless of the HRC robots deployed. It enables swift and needs-based technical implementation as well as active support for the required risk assessment.

 

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