Evaluation of the Electroglottographic Signal Variability in Organic and Functional Dysphonia.

OBJECTIVES: To confirm the data reported in our previous studies on the analysis of the variability of the electroglottographic signal in the pathological voice; to evaluate possible differences in variability between organic and functional pathologies; to identify any distinctive/typical EGG patterns for these pathologies. METHODS: One hundred twenty-five subjects were enrolled (36 euphonic and 89 pathological: 24 functional dysphonia, 21 bilateral vocal nodules, 23 unilateral polyps and 21 unilateral cysts). All subjects were studied with videolaryngostroboscopy, spectrographic analysis of voice and electroglottography (EGG). The EGG signal variability was then investigated using amplitude-speed combined analysis, by means of a proprietary software algorithm. Amplitude and Speed variation were expressed as a new parameter, the Variability Index (VI), calculated both for the whole EGG signal recorded (VI-tot) and in each phase of the glottic cycle (VI-Q, absolute value; VI-Q%, percentage value). RESULTS: In the comparison of VI values between pathological and normal groups, VI-tot and VI-Q2% (which corresponds to the final phase of vocal fold contact) were significantly greater in pathological subjects (P= 0.002). The comparison of VI values among subgroups of the various pathologies showed a difference for VI-tot (P< 0.0001) and VI-Q2% (P= 0.001); this difference was more marked in the cysts than in the functional dysphonia. The cut-off values of VI-tot and VI-Q2% were 0.191 and 18.17%, respectively (sensitivity and specificity 65.2% and 66.7% for VI-tot and 84.3% and 77.8% for VI-Q2%). CONCLUSIONS: The variability of the EGG signal investigated through the combined analysis of the amplitude and the speed of vibration using a proprietary algorithm software has proved useful not only to distinguish the normal voice from the pathological voice, but also to characterize which phases are more altered in the various voice pathologies studied, both functional and organic. Furthermore, the analysis of the VI parameter allowed to propose cut-off values characterized by a good sensitivity and specificity to discriminate dysphonia from the euphonic voice. Larger groups of patients will be needed to confirm these results.

Fiber Jamming Transition as a Stiffening Mechanism for Soft Robotics.

Robots made of soft materials are demonstrating to be well suited in applications where dexterity and intrinsic safety are necessary. However, one of the most challenging goals of soft robotics remains the ability to change the stiffness of body parts to guarantee stability and to produce significant forces. Among soft actuation technologies reported in literature, the jamming phenomenon is now achieving resounding interest. The jamming transition was observed and studied both with granular and laminar material; however, there is a third possibility that is not gaining the attention that probably would deserve: the fiber jamming. The aim of this study was an attempt to analyze the main parameters influencing the fiber jamming transition as promising stiffening solution for soft robotics. A preliminary analysis to choose the most suitable filling material and the external membrane that compose the system was performed and three possible configurations were designed. The prototypes thus assembled were experimentally investigated by using two different setups: one for conducting comparative bending tests on the systems and another for assessing the mechanical properties of single filling fibers. The results of the tests are used to feature the correlation between the arrangement and the material properties of the fibers and the stiffening capability of the fiber jamming systems. The investigation has shown performances comparable with those obtained with granular and layer jamming, demonstrating that fiber jamming is a good candidate for integration in soft robotic devices.

Toward a Variable Stiffness Surgical Manipulator Based on Fiber Jamming Transition.

Soft robots have proved to represent a new frontier for the development of intelligent machines able to show new capabilities that can complement those currently performed by robots based on rigid materials. One of the main application areas where this shift is promising an impact is minimally invasive surgery. In previous works, the STFF-FLOP soft manipulator has been introduced as a new concept of using soft materials to develop endoscopic tools. In this paper, we present a novel kind of stiffening system based on fiber jamming transition that can be embedded in the manipulator to widen its applicability by increasing its stability and with the possibility to produce and transmit higher forces. The STIFF-FLOP original module has been re-designed in two new versions to incorporate the variable stiffness mechanism. The two designs have been evaluated in terms of dexterity and variable stiffness capability and, despite a general optimization rule did not clearly emerge, the study confirmed that fiber jamming transition can be considered an effective technological approach for obtaining variable stiffness in slender soft structures.

Learning Closed Loop Kinematic Controllers for Continuum Manipulators in Unstructured Environments.

This article introduces a machine-learning-based approach for closed loop kinematic control of continuum manipulators in the task space. For this purpose, we propose a unique formulation for learning the inverse kinematics of a continuum manipulator while integrating end-effector feedback. We demonstrate that this model-free approach for kinematic control is very well suited for nonlinear stochastic continuum robots. The article addresses problems that are vital for practical realization of machine-learning techniques. The primary objective is to solve the redundancy problem while making the algorithm scalable, fast, and tolerant to stochasticity, requiring minimal sensor elements and involving few open parameters for tuning. In addition, we demonstrate that the proposed controller can exhibit adaptive behavior in the presence of external forces and in an unstructured environment with the help of the morphological properties of the manipulator. Experimental validation of the proposed controller is done on a six-degree-of-freedom tendon-driven manipulator for pose control of the end effector in three-dimensional space with and without external forces. The experimental results exhibit accurate, reliable, and adaptive behavior of the proposed system, which appears suitable for the field of continuum service robots.

Design and development of a bio-inspired, under-actuated soft gripper.

The development of robotic devices able to perform manipulation tasks mimicking the human hand has been assessed on large scale. This work stands in the challenging scenario where soft materials are combined with bio-inspired design in order to develop soft grippers with improved grasping and holding capabilities. We are going to show a low-cost, under-actuated and adaptable soft gripper, highlighting the design and the manufacturing process. In particular, a critical analysis is made among three versions of the gripper with same design and actuation mechanism, but based on different materials. A novel actuation principle has been implemented in both cases, in order to reduce the encumbrance of the entire system and improve its aesthetics. Grasping and holding capabilities have been tested for each device, with target objects varying in shape, size and material. Results highlight synergy between the geometry and the intrinsic properties of the soft material, showing the way to novel design principles for soft grippers.