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Driven by performance criteria and requirements from specific applications in healthcare for instance, the soft robotics community have created a huge amount of different designs for pneumatically actuated soft robots. The assessment with regards to these criteria usually involves a full characterisation of the soft robotic system. In order to support these efforts during the prototyping phase and standardise assessment procedures, a physical platform is described in this paper that allows to gain essential insights into the characterisation and validation of control algorithms for pneumatically driven soft robots. The platform can be connected to a Matlab Graphical User Interface allowing to send pressure values as well as record and plot data, and, hence, it is able to actuate and characterise main features of soft robots, such as the kinematics/dynamics, stiffness and force capability. The user can chose between two control units including the NI USB-6341 and Arduino Due. These components facilitate implementing and validating control algorithms using different tools, e.g., Matlab/Simulink. To demonstrate the feasibility and functionalities of our platform, three soft robotic systems have been analysed. We present characterisation results for a variable stiffness joint, the kinematics results during the inflation of an elastic membrane and the validation of an open-loop control strategy for a soft continuum robot.

Soft robotic structures may play a major role in the 4th industrial revolution. Researchers have successfully demonstrated some of the advantages of soft robotics over traditional robots made of rigid links and joints in several application areas. In some applications, robots will need to work closely together with humans in a safe manner. However, soft robots have limited ability to exert larger forces when it comes to interaction with the environment, hence, changing their stiffness on-demand over a wide range. Variable stiffness links (VSL) and joints (VSJ) have been investigated to achieve on-demand forces and, at the same time, be inherently safe in interactions with humans.This paper investigates the influence of antagonistically actuated, stiffness-controllable joint-link units (JLUs) on the performance of collaborative robots (i.e. stiffness, load capacity, repetitive accuracy) and characterizes the difference compared with rigid units. A JLU is made of a combination of a VSL, a (VSJ) and their rigid counterparts. Experimental results show that the VSL has minor differences in terms of stiffness (0.62 ∼ 0.95), output force (0.93 ∼ 0.94) and repetitive accuracy compared with the rigid link. For the VSJ, our results show a significant gap compared with the servo motor with regards to maximum stiffness (0.14 ∼ 0.21) and repetitive position accuracy (0.07 ∼ 0.25). However, similar performance on repetitive force accuracy and better performance on the maximum output force (1.54 ∼ 1.55 times) are demonstrated.

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