While grippers for industrial automation have so far been designed primarily for robustness, durability and performance, the focus with gripper hands is on the aspect of flexibility of movement. The closer humans and robots work together, the greater the relevance of humanoid five-fingered hands. "In extreme cases, humans and service robots will share one and the same workplace, including all tools and aids," says Dr. Martin May, Head of Research/Advanced Technologies at Schunk, with conviction.

For this reason, Schunk had the SVH five-finger hand certified by the DGUV for collaborative operation back in 2017 as the world's first gripper. With the help of a total of nine drives, its five fingers can perform different gripping operations. In addition, numerous gestures can be displayed, which facilitates visual communication between humans and service robots and can also increase acceptance for use in a human environment.

Desksharing with the robot
"In our research projects, we found that the human hand is much more than a highly flexible instrument for manipulation. In contrast to industrial grippers, users always associate emotional aspects with humanoid gripping hands," explains May. "Gripper hands are always in demand when a robot needs to imitate human behavior."

The SVH 5-finger hand opens up many possibilities in assistance and service robotics. © Schunk

This applies to manipulation as well as gestures. Schunk's research projects focus primarily on household-related applications of service robotics as well as assembly-related applications of industrial assistance robotics. "Gripping hands make sense wherever an activity environment is designed for humans to be supported by a robot, for example in the kitchen at home, but also at industrial assembly workstations or in order picking and logistics applications."

Different variants
The company has different gripper hands in its portfolio to suit the respective application, ranging from a two-finger hand for service robotics that is reduced to the basic functions of gripping to the industrial three-finger hand SDH and the complex SVH five-finger hand. The latest model, the SIH, also has five human-like fingers, but differs fundamentally from the SVH in terms of drive and kinematics.

While the SVH, which is driven by nine motors, fulfills the typical aspects of a precisely working robotic hand, the SIH, which is equipped with five motors and operated by cable pulls, is more closely based on its human model with its tendons and muscles. Three of its fingers can be moved independently of each other, while the two smallest can be moved together as a team. According to Schunk, this makes the SIH more flexible to use than other gripping hands with cable pull mechanisms on the market, and it is also more robust and attractively priced. According to Martin May, the latter aspect in particular was a key requirement in the research project, as service robotics applications in the domestic environment in particular require strict cost management if they are to be successful on the market.

Autonomous gripping
In its Smart Labs, Schunk is devoting itself to the gripping process as a whole and is looking for ways to complete handling tasks autonomously. The complex programming of the robot, which has so far been carried out manually by the user or integrator, is to be replaced in future by a learning, autonomous component network.

In this application, the SVH five-finger hand autonomously grips any object that has been placed anywhere. © Schunk

Instead of individually defining positions, speeds and gripping forces step by step, intelligent gripping systems will in future detect their target objects via cameras and take over the gripping planning independently. Based on data sets and algorithms, gripping systems will be able to recognize regularities and derive appropriate reactions. Researchers are also working on algorithms to classify different geometries and arrangements and develop optimal gripping strategies. The aim is to enable gripping systems to handle parts independently and to continually refine the underlying gripping processes.

Independent evaluation of gripping quality
The greater the variance of the parts to be gripped and the more complex the task, the more likely it is that gripper hands will be used. Using appropriate sensors in the gripper fingers, the motor current and intelligence integrated into the gripper hand, it should be possible to record and evaluate the quality of a grip and readjust it if necessary. In addition, object characteristics such as geometry, size or flexibility can be recorded via the gripper alone and transmitted to higher-level systems or upstream or downstream stations.

"With the help of artificial intelligence methods, it will also be possible to train service and assistance robots intuitively and to create and enrich individual libraries for gripping planning," Martin May is convinced. "Flexible gripping hands in particular will no longer be used only for repetitive tasks, but will be able to continuously adapt to new objects and contexts and constantly optimize their gripping strategies." as