Michele Gabrio Antonelli

Use of MMG signals for the control of powered orthotic devices: Development of a rectus femoris measurement protocol

ABSTRACT A test protocol is defined for the purpose of measuring rectus femoris mechanomyographic (MMG) signals. The protocol is specified in terms of the following: measurement equipment, signal processing requirements, human postural requirements, test rig, sensor placement, sensor dermal fixation, and test procedure. Preliminary tests of the statistical nature of rectus femoris MMG signals were performed, and Gaussianity was evaluated by means of a two-sided Kolmogorov-Smirnov test. For all 100 MMG data sets obtained from the testing of two volunteers, the null hypothesis of Gaussianity was rejected at the 1%, 5%, and 10% significance levels. Most skewness values were found to be greater than 0.0, while all kurtosis values were found to be greater than 3.0. A statistical convergence analysis also performed on the same 100 MMG data sets suggested that 25 MMG acquisitions should prove sufficient to statistically characterize rectus femoris MMG. This conclusion is supported by the qualitative characteristics of the mean rectus femoris MMG power spectral densities obtained using 25 averages.

An Innovative Brace With Pneumatic Thrusts For Scoliosis Treatment

Idiopathic scoliosis is the most common spinal deformity, and the brace treatment is the fundamental therapy. Brace works on the curve via the pressure they exert on the rib cage, usually on three points, to push against the progressive abnormal curvature of the spine and to reduce the local spasticity. Considering the possibility of the spine collapse, due to the six degrees of freedom of each vertebras with respect to the adjacent one, spine needs more thrusts relating to the curvature extension. This paper is focused on an innovative brace working by a three-dimensional thrusts system. The brace is internally covered by air pocket devices. Design and prototype of air pocket device is described. Air pockets apply the necessary corrective thrusts, at many levels of the spine, by compressed air at the specific pressure required in that area of the rib cage. Thrusts can be modified and checked. The design of the brace is presented together with a basic prototype, the design and the prototype of the air pocket device. First experimental tests on a simplified prototype of brace are also described. Finally, a pre-clinical test is performed by a healthy volunteer to validate the new brace concept.

Numerical modelling and experimental validation of a McKibben pneumatic muscle actuator

The McKibben muscle belongs to the type of muscles known as braided muscles. It is made of an inner hyper-elastic tube, surrounded by a braided shell made of inextensible threads; both ends provide mechanical and pneumatic seal. A finite element model of a McKibben pneumatic muscle was built and experimentally validated. The model is based on characteristic parameters of McKibben muscles. It takes into account the non-linearity of the constitutive material of the inner tube. It does not simulate backslashes between the tube and the shell at rest condition, but it models threads and rubber that are always connected. However, it does not consider friction among threads. In order to build and to validate the proposed numerical model, an experimental prototype of the muscle was designed and built. Both isotonic and isometric tests were carried out. Same tests were simulated in the finite element environment. The model validation was performed by comparison between experimental and numerical results.

Development and testing of a grasper for NOTES powered by variable stiffness pneumatic actuation

In natural orifice transluminal endoscopic surgery (NOTES) the peritoneal cavity is reached through natural orifices (mouth, rectus and transvaginal duct), by means of little cuttings in the walls of hollow organs. Due to narrow spaces, NOTES needs robotic systems to assure operation/movement precision and patient safety. Variable stiffness actuation (VSA) assures both requirements.

Experimental and Numerical Analysis of Pressure Waves Propagation in a Viscoelastic Hopkinson Bar

In this paper, the viscoelastic behaviour of PET is assessed in order to study the wave propagation in long SHPB made of polymeric materials.

Dynamic testing and constitutive modelling of NBR rubbers

The present work describes the compression behaviour of NBR rubber. Experimental tests have been conducted both in dynamic conditions. The latter ones, performed by a polymeric Split Hopkinson Bar, range from 100 to 500 1/s of strain rate. The long lasting pressure wave generated by the adopted SHB permitted to obtain a relatively high strain level in all the tests, up to 0.7–1.0 logarithmic strain. The experimental stress-strain curves were used to fit hyperelastic-perfect viscoelastic constitutive models; in particular, the Ogden and Mooney-Rivlin models were used for the hyperelasticity, while the Prony series was used for the viscoelastic part.

A new brace for the treatment of scoliosis

In this paper a new brace for the treatment of scoliosis is proposed. It uses pressurized air, by many air pockets, to apply the corrective thrusts to the rib cage and it can apply the thrusts at many levels of the spine. Moreover, the thrusts can be modified and monitored. In this way the corrective action on the spine can be more effective. The design of the prototype of the new brace is presented together with the design, the prototyping and the validation of the air pocket. Finally the first experimental tests on a simplified prototype of the brace are presented.

First clinical investigation on a pneumatic lumbar unloading orthosis

This paper deals with the first clinical investigation of a new designed orthosis to apply a traction force at lumbar spine. The objective is to verify the effect on healthy subjects and to assess the comfort of the orthosis. The results obtained are interesting. No negative feedback at spine level and many data on the comfort of the orthosis. The investigation suggests some modification to the prototype.

Development of a pneumatic soft actuator as a hand finger for a collaborative robot

Pneumatic soft actuators produce flexion and meet the new needs of collaborative robotics, which is rapidly emerging in the industry landscape 4.0. The soft actuators are not only aimed at industrial progress, but their application ranges in the field of medicine and rehabilitation. Safety and reliability are the main requirements for coexistence and human-robot interaction; such requirements, together with the versatility and lightness, are the precious advantages that is offered by this new category of actuators. The objective is to develop an actuator with high compliance, low cost, high versatility and easy to produce, aimed at the realization of the fingers of a robotic hand that can faithfully reproduce the motion of a real hand. The proposed actuator is equipped with an intrinsic compliance thanks to the hyper-elastic silicone rubber used for its realization; the bending is allowed by the high compliance of the silicone and by a square-meshed gauze which contains the expansion and guides the movement through appropriate cuts in correspondence of the joints. A numerical model of the actuator is developed and an optimal configuration of the five fingers of the hand is achieved; finally, the index finger is built, on which the experimental validation tests are carried out.

Battery-Powered Autonomous Robot for Cleaning of Dusty Photovoltaic Panels in Desert Zones

Storms in desert areas cause sand accumulation on the surface of photovoltaic panels so producing a decrease in the electrical conversion efficiency per day of solar farms ranging from about 0.6% up to 80%. Hence, continuous activities for cleaning the photovoltaic panels are required in total absence of water and under severe environmental conditions for the workers. In this communication we present a 12 V battery-powered autonomous robot for cleaning of dusty photovoltaic panels. The cleaning strategy adopts two helical brushes placed in front of and behind the robot. According to the robot movement direction, the forward brushes remove the sand until it falls out from the photovoltaic panels. The robot has been conceived to be moved as a half-track equipped with two independent rubber belts powered by two DC motors. The electronic on-board control system is based on ARDUINO DUE platform and employs ultrasonic sensors providing the real-time effective position of the robot, the movement regulations as well its direction and speed.