In the case of humanoid robotics, and in comparison with a rigid design, a robot with soft links has the following main advantages: a) simplicity of design, favouring an underactuated architecture without the need of increasing the number of degrees of freedom; b) increased accessibility and adaptability to complex environments, with a postural control that can hardly be implemented in rigid robots; and c) safer interaction with the human and the environment, with a high level of absorption of possible impacts, increasing the stability of the robot.

The main objective of this research topic is the development of a new type of links to create softer humanoid robots that meet the characteristics of simplicity, accessibility and safety. These soft links may be used interchangeably in various limbs of the humanoid robots, like arms, neck and spine, under the constraints of scalability, controllability of their stiffness and integration. To achieve this goal, this research proposes the following sub-objectives: 1) design and development of a prototype of soft link with definition of its material and its actuation system. As a result the electromechanical prototype will be obtained with the premise of easy integration into the rigid structure of a humanoid robot; 2) reconfigurable embedded control system for the soft link, using fractional order and robust control techniques. As a result a controller easily implementable in the humanoid robot TEO will be obtained; 3) substitution (integration) of various links of the life-size humanoid robot TEO by soft links properly scaled to act like arms, neck and spine. As a result a new soft humanoid will be available; and 4) final evaluation of the system, developing new metrics for the analysis of the behaviour of the soft robot, especially in human-robot interaction.