The design and construction of a soft robot are challenging tasks on their own. When the robot is supposed to operate without a tether, it becomes even more demanding. While a tethered operation is sufficient for a stationary use, it is impractical for wearable robots or performing tasks that demand a high mobility. Choosing and implementing an on-board pneumatic pressure source are particularly complex tasks. There are several different pressure generation methods to choose from, each with very different properties and ways of implementation. This review paper is written with the intention of informing about all pressure generation methods available in the field of soft robotics and providing an overview of the abilities and properties of each method. Nine different methods are described regarding their working principle, pressure generation behavior, energetic considerations, safety aspects, and suitability for soft robotics applications. All presented methods are evaluated in the most important categories for soft robotics pressure sources and compared to each other qualitatively and quantitatively as far as possible. The aim of the results presented is to simplify the choice of a suitable pressure generation method when designing an on-board pressure source for a soft robot.

This paper presents a soft passive gripper consisting of six fluidic soft bending actuators arranged in a star-shaped manner. The actuators are oriented such that, upon pressurization, they bend against gravity. Gripping is realized by a commercial tape with mushroom-shaped adhesive structures that is glued to the bottom patches of the gripper. In this way, the object is released by peeling away the actuators from the object’s surface. In contrast to active grippers, which require continuous pressurization during gripping and holding, the presented passive gripper only requires energy for the release process. However, due to its working principle, the gripper is restricted to only flat objects or objects with at least one flat surface.

This paper presents a fully coupled fluid-structure interaction (FSI) simulation model of a soft pneumatic actuator (SPA). Previous research on modelling and simulation of SPAs mostly involves finite element modelling (FEM), in which the fluid pressure is considered as pressure load uniformly acting on the internal walls of the actuator. However, FEM modelling does not capture the physics of the fluid flow inside an SPA. An accurate modelling of the physical behaviour of an SPA requires a two-way FSI analysis that captures and transfers information from fluid to solid and vice versa. Furthermore, the investigation of the fluid flow inside the flow channels and chambers of the actuator are vital for an understanding of the fluid energy distribution and the prediction of the actuator performance. The FSI modelling is implemented on a typical SPA and the flow behaviour inside the actuator is presented. Moreover, the bending behaviour of the SPA from the FSI simulation results is compared with a corresponding FEM simulation.

In addition to the general advantages of additive manufacturing technologies, such as the resource-efficient production of highly complex components, the metal binder jetting (MBJ) process enables a more cost-effective manufacturing of metal additive components. However, the design freedoms gained by additive manufacturing, and MBJ in particular, are also accompanied by new design restrictions for component design. While a large number of design guidelines are already available for the established additive manufacturing processes, the metal binder jetting process imposes additional requirements on component design, which are currently only inadequately covered in the literature. Therefore, this paper presents the development and derivation of first design rules for the metal binder jetting process using martensitic stainless steel (17–4 PH). In this way, the paper also provides a methodology for deriving guidelines regardless of the material. In total, 13 guidelines have emerged from this, which in part both confirm existing guidelines, but also extend them.

Soft robotics is an emerging field in the robotics community which deals with completely new types of robots. However, often new soft robotic designs depend on the ingenuity of the engineer rather being systematically derived. For this reason, in order to support the engineer in the design process, we present a design methodology for general technical systems in this paper and explain it in depth in the context of soft robotics. The design methodology consists of a combination of state-of-the-art engineering concepts that are arranged in such a way that the engineer is guided through the design process. The effectiveness of a systematic approach in soft robotics is illustrated on the design of a new gecko-inspired, climbing soft robot.