The perception of an object's surface is important for robotic applications enabling robust object manipulation. The level of accuracy in such a representation affects the outcome of the action planning, especially during tasks that require physical contact, e.g. grasping. In this paper, we propose a novel iterative method for 3D shape reconstruction consisting of two steps. At first, a mesh is fitted on data points acquired from the object's surface, based on a single primitive template. Subsequently, the mesh is properly adjusted to adequately represent local deformities. Moreover, a novel proactive tactile exploration strategy aims at minimizing the total uncertainty with the least number of contacts, while reducing the risk of contact failure in case the estimated surface differs significantly from the real one. The performance of the methodology is evaluated both in 3D simulation and on a real setup.

In this paper we introduce a novel technique that aims to control a two-module bio-inspired soft-robotic arm in order to qualitatively reproduce human demonstrations. The main idea behind the proposed methodology is based on the assumption that a complex trajectory can be derived from the composition and asynchronous activation of learned parameterizable simple movements constituting a knowledge base. The present work capitalises on recent research progress in Movement Primitive (MP) theory in order to initially build a library of Probabilistic MPs (ProMPs), and subsequently to compute on the fly their proper combination in the task space resulting in the requested trajectory. At the same time, a model learning method is assigned with the task to approximate the inverse kinematics, while a replanning procedure handles the sequential and/or parallel ProMPs' asynchronous activation. Taking advantage of the mapping at the primitive-level that the ProMP framework provides, the composition is transferred into the actuation space for execution. The proposed control architecture is experimentally evaluated on a real soft-robotic arm, where its capability to simplify the trajectory control task for robots of complex unmodeled dynamics is exhibited.

In this paper we introduce a novel technique that aims to dynamically control a two-module bio-inspired soft-robotic arm in order to qualitatively reproduce a path defined by sparse way-points. The main idea behind this work is based on the assumption that a complex trajectory may be derived as a combination of a discrete set of parameterizable simple movements, as suggested by Movement Primitive (MP) theory. Capitalising on recent advances in this field, the proposed controller uses a Probabilistic MP (ProMP) model which initially creates an abstract mapping in the primitive-level between the task and the actuation space, and subsequently guides the movement’s composition by exploiting its unique properties - conditioning and blending. At the same time, a learning-based adaptive controller updates the composition parameters by estimating the inverse kinematics of the robot, while an auxiliary process through replanning ensures that the trajectory complies with the new estimation. The learning architecture is evaluated on both a simulation model, and a real soft-robotic arm. The research findings show that the proposed methodology constitutes a novel approach that successfully manages to simplify the trajectory control task for robots of complex dynamics when high-precision is not required.

In this paper we introduce a novel technique that aims to dynamically control a modular bio-inspired soft-robotic arm in order to perform cyclic rhythmic patterns. Oscillatory signals are produced at the actuator's level by a central pattern generator (CPG), resulting in the generation of a periodic motion by the robot's end-effector. The proposed controller is based on a model-free neurodynamic scheme and is assigned with the task of training a policy that computes the parameters of the CPG model which generates a trajectory with desired features. The proposed methodology is first evaluated with a simulation model, which successfully reproduces the trained targets. Then experiments are also conducted using the real robot. Both procedures validate the efficiency of the learning architecture to successfully complete these tasks.