The fast-growing human–robot collaboration predicts that a human operator could command a robot without mechanical interface if effective communication channels are established. In noisy, vibrating ...and light sensitive environments, some sensors for detecting the human intention could find critical issues to be adopted. On the contrary, biological signals, as electromyographic (EMG) signals, seem to be more effective. In order to command a laboratory collaborative robot powered by McKibben pneumatic muscles, promising actuators for human–robot collaboration due to their inherent compliance and safety features have been researched, a novel modeling-based electromyographic signal (MBES) classifier has been developed. It is based on one EMG sensor, a Myotrac one, an Arduino Uno and a proper code, developed in the Matlab environment, that performs the EMG signal recognition. The classifier can recognize the EMG signals generated by three hand-finger movements, regardless of the amplitude and time duration of the signal and the muscular effort, relying on three mathematical models: exponential, fractional and Gaussian. These mathematical models have been selected so that they are the best fitting with the EMG signal curves. Each of them can be assigned a consent signal for performing the wanted pick-and-place task by the robot. An experimental activity was carried out to test and achieve the best performance of the classifier. The validated classifier was applied for controlling three pressure levels of a McKibben-type pneumatic muscle. Encouraging results suggest that the developed classifier can be a valid command interface for robotic purposes.
Different from the McKibben pneumatic muscle actuator, the straight fibers one is made of an elastomeric tube closed at the two ends by two heads that ensure a mechanical and pneumatic seal. High ...stiffness threads are placed longitudinally into the wall of the tube while external rings are placed at some sections of it to limit the radial expansion of the tube. The inner pressure in the tube causes shortening of the actuator. The working mode of the muscle actuator requires a series of critical repeated contractions and extensions that cause it to rupture. The fatigue life duration of a pneumatic muscle is often lower than traditional pneumatic actuators. The paper presents a procedure for the fatigue life prediction of a straight-fibers muscle based on experimental tests directly carried out with the muscles instead of with specimens of the silicone rubber material which the muscle is made of. The proposed procedure was experimentally validated. Although the procedure is based on fatigue life duration data for silicone rubber, it can be extended to all straight-fibers muscles once the fatigue life duration data of any material considered for the muscles is known.
In the landscape of Industry 4.0, advanced robotics awaits a growing use of bioinspired adaptive and flexible robots. Collaborative robotics meets this demand. Due to human–robot coexistence and ...interaction, the safety, the first requirement to be satisfied, also depends on the end effectors. End effectors made of soft actuators satisfy this requirement. A novel pneumatic bending soft actuator with high compliance, low cost, high versatility and easy production is here proposed. Conceived to be used as a finger of a collaborative robot, it is made of a hyper-elastic inner tube wrapped in a gauze. The bending is controlled by cuts in the gauze: the length and the angular extension of them, the pressure value and the dimensions of the inner tube determine the bending amplitude and avoid axial elongation. A design methodology, oriented to kinematically mirror the shape of the object to be grasped, was defined. Firstly, it consists of the development of a non-linear parametric numerical model of a bioinspired finger; then, the construction of a prototype for the experimental validation of the numerical model was performed. Hence, a campaign of simulations led to the definition of a qualitatively predictive formula, the basis for the design methodology. The effectiveness of the latter was evaluated for a real case: an actuator for the grasping of a light bulb was designed and experimentally tested.
In recent years, robotics and automation technology have spread significantly throughout the agricultural harvesting sector. The increased productivity and the high cost of labour are some of the ...main reasons for this phenomenon. However, the harvesting of some crops is still carried out manually. One such crop is radicchio, which ripens at various times, thus requiring selective harvesting. This paper presents the development of an innovative modular system which aims at automating the harvesting of radicchio. Each module adopts a mechanical sensor to recognize the ripening status of the plant, on the basis of the hardness/compliance of its core. The module contains a cutting system, made of pneumatically actuated blades, and a harvesting system, made of two electrically powered tape conveyors. The module is intended to be used for a single row of radicchio cultivations using a tractor to move it. In laboratory tests the module prototype was manually moved. For this reason, the prototype is equipped with a control panel for monitoring and commanding. The conceived design, technical specifications and the prototype of the module are presented in detail. In addition, performances and functional tests are discussed. Finally, the functionality of the whole system is validated.
In the present work, the activity of analyzing the breaking of the steerer tube of a bicycle is presented. After a description of the steering assembly of the bicycle, the problem is presented. The ...problem consists in the fact that the fork which consists of a head a steerer tube and 2 stems that make up the fork has a clear break at the junction between the head of the fork and the tube. The section has a typical case of fatigue failure. In fact, about three quarters of the section are hammered, while the remaining part is ripped. Then the observation under the electron microscope is presented for better understanding what was the real state of the surface of the fracture section of the tube, and then it presents the observation activity to the scanning electron microscope in order to identify the composition of the metallic material in order to check whether there is a discontinuity in the composition of the material. Finally, a structural-type finite element analysis is carried out to verify which was the stress state at the level of the breaking section. It results that given the open conformation of the tube, the geometrical discontinuity due to the opening creates a peak of tension that goes to about 1000 MPa which is sufficient to trigger a crack for fatigue failure. An estimation fatigue life of the joint was carried out and was demonstrated that the life duration had a reduction from unlimited to about 2500 cycles due to the presence of the notch. This way it was shown that the conformation of the tube was the cause of triggering the fatigue break.
A novel approach to the problem of grid-based path finding has been introduced. The method is a block-based search algorithm, founded on the bases of two algorithms, namely the quad-tree algorithm, ...which offered a great opportunity for decreasing the time needed to compute the solution, and the harmony search (HS) algorithm, a meta-heuristic algorithm used to obtain the optimal solution. This quad HS algorithm uses the quad-tree decomposition of free space in the grid to mark the free areas and treat them as a single node, which greatly improves the execution. The results of the quad HS algorithm have been compared to other meta-heuristic algorithms, i.e., ant colony, genetic algorithm, particle swarm optimization and simulated annealing, and it was proved to obtain the best results in terms of time and giving the optimal path.
This paper describes the control architecture of a 10 DOF (Degrees of Freedom) lower limbs exoskeleton for the gait rehabilitation of patients with gait dysfunction. The system has 4 double-acting ...rod pneumatic actuators (two for each leg) that control the hip and knee joints. The motion of each cylinder's piston is controlled by two proportional pressure valves, connected to both cylinder chambers.
The control strategy has been specifically designed in order to ensure a proper trajectory control for guiding patient's legs along a fixed reference gait pattern.
An adaptive fuzzy controller which is capable of compensating for the influence of the dry friction was successfully designed, implemented and tested on an embedded real-time PC/104.
In order to verify the proposed control architecture, laboratory experiments without a patient were carried out and the results are reported here and discussed.
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.
Research on extractivism has rapidly proliferated, expanding into new empirical and conceptual spaces. We examine the origins, evolution, and conceptual expansion of the concept. Extractivism is ...useful to analyze resource extraction practices around the world. 'Global Extractivism' is a new conceptual tool for assessing global phenomena. We situate extractivism within an ensemble of concepts, and explore its relation to development, the state, and value. Extractivism as an organizing concept addresses many fields of research. Extractivism forms a complex of self-reinforcing practices, mentalities, and power differentials underwriting and rationalizing socio-ecologically destructive modes of organizing life-through subjugation, depletion, and non-reciprocity.
Scuorno (Vergogna) Durante, Francesco
Delirious Naples,
12/2018
Book Chapter
People say: situation critical. It’s the suitcase expression into which we stuff the persistence of our problems, the full effort to forget about them and their sudden rising to intensity. We were ...the city of the last European cholera epidemic in 1973. The earthquake city of 1980. The city of the recurring feuds among the Camorra: Cutolo clan against the New Family (during the 1980s), Secondigliano Alliance against all the others (1990s), the Di Lauro clan against the secessionists (the “aughts” of the twenty-first century). Now, we’re the city of trash. The Futurists used to sing that “even after being
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