Since the early 1990s, Festo has been working intensively on the topic of bionics - the transfer of natural mechanisms and operating principles to technology. In 2006, the company set up an international research network with universities and institutes, development companies and private inventors: the Bionic Learning Network. The 'Future Concepts' of this network serve the manufacturer of pneumatic and electrical automation technology as development platforms that combine a wide variety of technologies and components - from manufacturing concepts and series products to software and control and regulation technology. To date, almost 60 projects have been developed within the Bionic Learning Network - such as the adaptive gripper finger 'DHAS'.

In the beginning was the fish fin

The adaptive gripper finger was the first object to go into series production as a catalog product. It is based on the amazing behavior of the fishtail fin: if you press against the side of the fin, it does not bend away but curves around the pressure point. The developers have technically implemented this so-called 'FinRay Effect' with the help of two flexible polyurethane bands that are connected to each other via intermediate bars. The stable but flexible gripper fingers adapt easily to the contour of the workpiece when gripping. This enables sensitive objects with irregular surfaces to be gripped gently and securely. The gripper finger is used in the food industry, for example when sorting fruit and vegetables. The adaptive gripper also handles tomatoes or raw eggs without crushing them.

The operating principle of the adaptive gripper was based on the 'Airacuda', one of the first stars of the Bionic Learning Network in 2006, which Festo floated in a giant water tank on its stand at the Hannover Messe. The Airacuda is pneumatically driven and follows its biological model in terms of construction, design and kinematics. Four fluidic muscles ensure the S-shaped movement and smooth steering of the tail fin.

As adaptable as a chameleon's tongue

Another series product that emerged from the development of the Bionic Learning Network is the adaptive form gripper 'DHEF'. Its operating principle is derived from the chameleon's tongue: To catch prey, the animal lets its tongue flick out like a rubber band. Shortly before the tip of its tongue reaches the insect, it retracts in the middle while the edges continue to move forward. In this way, the tongue adapts to the shape and size of the prey and can firmly enclose it.

The central element of the gripper is a silicone cap filled with slight overpressure, which is modeled on the chameleon tongue and fits flexibly and positively over the respective object to be gripped. This allows a gripped object to be enclosed and held. It is also possible to pick up several objects, such as screws from a bowl, using a corresponding control system with proportional valves.

Helpers for human-robot collaboration

The adaptive gripper arrived just in time for the development of a new flower bulb sorting machine. A Dutch company uses the gripper to sort flower bulbs according to size and quality. What previously had to be sorted laboriously and inefficiently by human hands is now done by a gripper with DHAS adaptive gripper fingers.

© Festo

In order for us humans to perform a movement, the interaction of opposing muscles is always necessary. Festo's developers have technically implemented this principle of agonist (player) and antagonist (opponent) in all seven joints of the 'BionicCobot'. There are three axes in the shoulder area, one each in the elbow and forearm and two axes in the wrist. Each axis contains a pivoting wing with two air chambers. These form a pair of drive units that can be continuously adjusted by filling them with compressed air like a mechanical spring. This drive concept allows the force potential and therefore the degree of rigidity of the robot arm to be precisely determined. In the event of a collision, the pneumatic arm yields automatically and poses no danger to humans.

The BionicCobot is operated intuitively via a specially developed graphical user interface. Using a tablet, the user can teach the actions to be performed and sequence them as required. Via the open source platform ROS (Robot Operating System), the programmed motion sequences are transferred to the integrated 'Festo Motion Terminal', which controls and regulates the kinematics. Controlled pneumatics with piezo technology forms the basis of the control and regulation technology.