Robotics and Biology Laboratory

Soft Hands

Soft Hands represent a departure from classical robot hand design, which often relies on exact models and precise planning of contact points. Instead, we aim to increase robustness and safety through the use of soft materials and flexible mechanics. This softness allows us to exploit contact with the environment and use it in robust grasping and manipulation strategies. 

We developed the RBO Hand 3 to understand the necessary soft-robotic aspects, and formulate the concept of morphological-computation.

RBO Hand 3

Contact Persons

Steffen Puhlmann, Adrian Sieler

The RBO Hand 3 is a highly dexterous and versatile soft hand based on pneumatic actuation. It advances on its predecessor by combining 16 actuated degrees of freedom with intrinsic mechanical compliance in an anthropomorphic design. Special attention was paid to the design of the opposable thumb. The RBO Hand 3 is inherently safe and highly robust for externsive real-world experimentation. It closely replicates the functioning of its human counterpart to facilitate transfer of insights to human dexterity, and it is capable of dexterous grasping and manipulation


RBO Hand 2

Contact Persons

Raphael Deimel, Vincent Wall, Steffen Puhlmann

The RBO Hand 2 is a hand made from PneuFlex actuators mounted on a flexible, printed scaffold. The hand was developed to investigate the capabilities and limits of hands when relying only on soft, deformable structures. The unique deformability provides several advantageous benefits to robots trying to interact with the environment: 

  • very robust against blunt collisions
  • very low impact energies
  • passively compliant fingers and palm decouple contact from the robot arm, stabilizing force control
  • mechanical adaptability to object shapes simplifies finger control
  • the pneumatic actuation makes it easy to create complex hand and actuator geometries

The result of our research are several hand prototypes, which we refer to collectively as Soft Hands. RBO Hand 2 is the latest model and used in our lab for research into grasping strategies.

If you want to build your own, you are welcome to do so! We have published the CAD models for the PneuFlex actuators


RBO Hand 1

Contact Persons

Raphael Deimel, Vincent Wall, Steffen Puhlmann

The RBO Hand (published in 2013) was the first soft hand that employed PneuFlex actuators. It uses 3 pairs of parallel and straight PneuFlex actuators. The finger are also partially connected to each other. The hand has a passively bendable rubber sheet acting as a palm in opposition to the fingers.

Pneumatic Box

Contact Persons

Raphael Deimel, Vincent Wall

For the control of the pneumatic RBO Hand 2 we had to create our own hardware. We developed the "PneumaticBox", which consists of valve array, a single-board computer, and a custom printed circuit board. 

A detailed description of the hard- and software can be found in the Tutorial section.


PneuFlex Actuators

Contact Persons

Raphael Deimel, Steffen Puhlmann

We develop a set of production processes and a complete design toolchain for soft continuum actuators under the name PneuFlex. The toolchain consists of several components:

  • unified process to create PneuFlex actuators of diverse shape from a given mold
  • A method to automatically create PneuFlex molds from a parametric description of shape.
  • A method to automatically create PneuFlex molds from a description of mechanical parameters
  • A system to simulate a PneuFlex actuator or to simulate arrangements of actuators (i.e. soft hands)
  • pneumatic control hardware tailored to the requirements of finger-size soft continuum actuators
  • Controllers to enable complex, synchronized actuation across PneuFlex actuators

Morphological Computation

Contact Person

Steffen Puhlmann

The term Morphological Computation emphasizes the notion, that the way a robot is built (its morphology) provides a substantial contribution to the computation of reactive behavior. Intuitively, controlling a robot on the higher level gets simpler when the robot's body provides more Morphological Computation to the task.

At RBO Lab, we investigate methods to quantify the contribution of a robot's morphology to a specific task, and ways of increasing that share. We use soft hand design as a use case that provides sufficient complexity and cooperate with MPI Leipzig on the supporting theory.


Deutsche Forschungsgemeinschaft (DFG, German Research Foundation) under Germany's Excellence Strategy - EXC 2002/1 "Science of Intelligence" - project number 390523135

German Priority Program DFG-SPP 2100 “Soft Material Robotic Systems” - project number 405033880.

Soft Manipulation (SoMa) -  funded by the European Commission in the Horizon 2020 program, award number 645599, May 2015 - April 2019.  

Alexander von Humboldt professorship - awarded by the Alexander von Humboldt foundation and funded through the Ministry of Education and Research, BMBF, July 2009 - June 2014



[english] Puhlmann, Steffen; Harris, Jason; Brock, Oliver
RBO Hand 3: A Platform for Soft Dexterous Manipulation
IEEE Transactions on Robotics :1-16
April 2022
ISSN: 1941-0468


Bhatt, Aditya; Sieler, Adrian; Puhlmann, Steffen; Brock, Oliver
Surprisingly Robust In-Hand Manipulation: An Empirical Study
Proceedings of Robotics: Science and Systems
Publisher: Virtual
July 2021


Deimel, Raphael; Brock, Oliver
A Novel Type of Compliant, Underactuated Robotic Hand for Dexterous Grasping
Robotics:Science and Systems (RSS)


Deimel, Raphael; Brock, Oliver
A Compliant Hand Based on a Novel Pneumatic Actuator
Proceedings of the IEEE International Conference on Robotics and Automation (ICRA), Page 2047–2053
May 2013