Robot hand with fingertip sensitivity

Article of 29 March 2019 

BionicSoftHand

Holding a coffee cup, typing an email on the keyboard or playing rock paper scissors with friends: we use our hands intuitively in different life situations. The pneumatic universal gripper BionicSoftHand not only looks similar to the natural model, but also learns human movement patterns through artificial intelligence. Combined with the lightweight pneumatic robot BionicSoftArm, it can work together with humans.

One hand holds a cube with 12 different-coloured sides. It turns the cube until the blue side is facing up. It is an easy task to solve for a human – often associated with considerable programming effort for robots.

Training with artificial intelligence

Thanks to artificial intelligence, the BionicSoftHand learns independently and quickly to move the desired side of the cube to face upwards, using the method of reinforcement learning. Instead of a concrete action that the hand must imitate, it is given the objective. It tries to achieve this through trial and error. Based on the feedback received, the hand gradually optimises its actions until it solves the task successfully.

Thanks to reinforcement learning, the BionicSoftHand learns human movement patterns independently and quickly.
Thanks to reinforcement learning, the BionicSoftHand learns human movement patterns independently and quickly.

The teaching takes place in a virtual environment using a simulation – the so-called digital twin. With the help of the data from a depth camera and the algorithms of artificial intelligence, the control is trained in the simulation to the desired motion strategy and then transferred to the real SoftHand. In this way, the learned knowledge elements can also be shared with other robot hands around the world.

Sensitive down to the fingertips

The fingers of the robot hand are comprised of flexible bellows structures with air chambers, which are enclosed in a special 3D textile cover which is knitted from both elastic and high-strength fibres. This means that the textile can be used to exactly determine at which points the structure expands, thereby generating force, and where it is prevented from expanding. This makes the hand light, flexible, adaptable and sensitive, yet capable of exerting strong forces. In addition, position sensors are installed as well as tactile force sensors that register pressure.

Sensitive and powerful at the same time: the fingers can act flexibly thanks to a special 3D textile knit.
Sensitive and powerful at the same time: the fingers can act flexibly thanks to a special 3D textile knit.

In order to keep the effort for tubing the BionicSoftHand as low as possible, the developers have specially designed a small, digitally controlled valve terminal, which is mounted directly below the hand. This means that the tubes for controlling the gripper fingers do not have to be pulled through the entire robot arm. In this way, the BionicSoftHand can be quickly and easily connected and operated with only one tube each for supply air and exhaust air. With the proportional piezo valves used, the movements of the gripper fingers can be precisely controlled.

Flexible arm for working together

The BionicSoftHand can be mounted on the BionicSoftArm – a lightweight pneumatic robot – for working together with humans. It is flexible from the ground up and can machine a workpiece at the same time as a person with no danger to the human. The strict separation between human work and the automated actions of robots is thus increasingly being abolished and their areas of work are merging into a collaborative working space.

Human and robot work hand in hand – the BionicSoftArm makes it possible.
Human and robot work hand in hand – the BionicSoftArm makes it possible.

The BionicSoftArm is a compact further development of Festo’s BionicMotionRobot, whose range of applications has been significantly expanded. This is made possible by its modular design: It can be combined from up to seven pneumatic bellows segments and rotary actuators. This gives it maximum flexibility in terms of reach and mobility and allows it to work around obstacles even in the tightest of spaces if required.

Modular design: the BionicSoftArm can be combined with up to seven pneumatic bellows segments and rotary actuators.
Modular design: the BionicSoftArm can be combined with up to seven pneumatic bellows segments and rotary actuators.

The bionic arm is very versatile. Depending on the task, grippers other than the BionicSoftHand can also be mounted. In addition, it easily adapts to different tasks and changing locations. The elimination of costly safety devices such as cages and light barriers shortens conversion times and thus enables flexible use – completely in accordance with adaptive and economical production.