The paper presents some of the biomechanical tools available for the forensic bioengineering expert. The tools range from the simple three-dimensional modeling environment to represent the geometries ...up to the analytical models based on the free-body diagram and the multibody numerical models of rigid bodies. Through these tools the forensic bioengineering expert is able to solve complex problems by providing quantitative results based on a scientific approach. In this work three case studies, representing real cases that were treated in court, are presented. They relate to accidents which occurred in different contexts. The first relates to an accident in a filament factory where a worker remained with her body stuck in the production line, the second the hit of a pedestrian, and the last concerning a worker who fell from a wall on a construction site. It is shown that the approach to modeling may not always be necessarily complex. It was possible to solve the first case with a simple three-dimensional geometric model that clearly highlighted the development of the facts. In the second case it was possible to set up a simple analytical model based on a free body diagram to search for the relationship between the forces developed on the invested leg, demonstrating the relationship between the accident and the injuries reported. The third case, with the need for more complex modeling, was instead treated with a kinematic and dynamic multibody model which allowed the dynamics of the accident to be traced, starting from the final position in which the victim was found. In each case, the competence of the forensic bioengineering expert was crucial in identifying the correct modeling for the case in question, with the choice of the right data, in order to arrive at reliable quantitative results.
Oh Capitano Vecoli, Rudolph J; Durante, Francesco; Gabaccia, Donna R ...
06/2018
eBook
Plays out across an international arena but centered in the U.S. and Hawaii for the second half of his life."Celso Cesare Moreno was a schemer on an international level involved in the Hawaiian ...revolution, a promoter of colonialism in Southeast Asia to the governments of Italy, France, and the U.S., and involved also as a lobbyist in Washington in the "little slaves" /padrone controversies of the 1870s.The story of Celso Cesare Moreno, one of the most famous of the emigrant Italian elites or "prominenti." Moreno traveled the world lying, scheming, and building an extensive patron/client network to to establish his reputation as a middleman and person of significance. Through his machinations, Moreno became a critical player in the expansion of western trade and imperialism in Asia, the trafficking of migrant workers and children in the Atlantic, and the conflicts of Americans and natives over the fate of Hawaii, and imperial competitions of French, British, Italian and American governments during a critically important era of imperial expansion.Offers a detailed illustration of the well-known but poorly understood pattern of the Italian prominenti--their relationships, their polemics, their intense battles over disappearing causes, and their personal idiosyncrasies.
This paper illustrates an experimental activity for the closed-loop position control of an actuator made using shape memory alloy (SMA) wire. A solution with the self-sensing effect was implemented ...to miniaturize the systems, i.e., without external sensors. A proportional control algorithm was initially used, demonstrating the idea's feasibility; the wire can behave simultaneously as an actuator and sensor. An experimental investigation was subsequently conducted for the optimization of the developed actuator. As for the material, a Flexinol wire, Ni-Ti alloy, with a diameter of 0.150 mm and a length of 200 mm, was used. Preliminarily, characterization of the SMA wire at constant and variable loads was carried out; the characteristics detected were elongation vs. electric current and elongation vs. electrical resistance. The control system is PC based with a data acquisition card (DAQ). A drive board was designed and built to read the wire's electrical resistance and power it by pulse width modulation (PWM). A notable result is that the actuator works with good precision and in dynamic conditions, even when it is called to support a load up to 65% different from that for which the electrical resistance-length correlation has previously been experimentally obtained, on which the control is based. This opens up the possibility of using the actuator in a counteracting configuration with a spring, which makes hardware implementation and control management simple.
Powered ankle-foot prostheses for walking often have limitations in the range of motion and in push-off power, if compared to a lower limb of a healthy person. A new design of a powered ankle-foot ...prosthesis is proposed to obtain a wide range of motion and an adequate power for a push-off step. The design methodology for this prosthesis has three points. In the first one, a dimensionless kinematic model of the lower limb in the sagittal plane is built, through an experimental campaign with healthy subjects, to calculate the angles of lower limb during the gait. In the second point a multibody inverse dynamic model of the lower limb is constructed to calculate the foot-ground contact force, its point of application and the ankle torque too, entering as input data the calculated angles of the lower limb in the previous point. The third point requires, as input of the inverse dynamic model, the first dimensioning data of the ankle-foot prosthesis to obtain the load acting on the components of the prosthesis and the angle torque of the actuator during the gait cycle. Finally, an iteration cycle begins with the inverse dynamic model modifying the ankle torque and angle until these quantities during the gait are as close as possible to the physiological quantities. After the mechanical design and the construction of the prototype of the prosthesis, an experimental methodology was used for preliminary validation of the design. The preliminary tests in the laboratory on the prototype alone show that the range of motion of the ankle angle during the gait is close to a healthy person's: 27.6° vs. 29°. The pushing force of the distal area of the prototype is 1.000 N, instead of 1.600 N, because a budget reduction forced us to choose components for the prototype with lower performance.
This paper presents the design and analysis of a novel 3-degree-of-freedom (3-DOF) parallel manipulator equipped with self-sensing Ni-Ti (Nitinol) actuators. The manipulator’s architecture and ...mechanical design are elucidated, emphasizing the integration of Nitinol actuators. The self-sensing technique implemented in a previous work was extended to a 20 mm actuator length, and the actuator was used to design the 3-DOF manipulator. Kinematic analyses were conducted to evaluate the manipulator’s performance under various operating conditions. A dynamic model was implemented for the dynamic dimensioning of the actuators, which work synergistically with a bias spring. The manipulator was realized, and a control strategy was implemented. Experimental tests, although documenting some positioning accuracy issues, show the efficacy and potential applications of the proposed manipulator in robotics and automation systems, highlighting the advantages of self-sensing Nitinol actuators in small parallel manipulator designs.
In this paper, the designs and manufacturing process of a powered upper limb orthosis are presented. The orthosis is an exoskeleton worn on one arm by the user and fixed to the trunk. The orthosis’ ...architecture, design, and manufacturing process are presented and discussed. Estimations of the ranges of movement related to daily living activities are presented. The preliminary tests to verify the functionality of the design show encouraging results.
This study describes the activity of developing a force amplifier exoskeleton with one degree of freedom. The system was developed as a research prototype to conduct control system studies. The ...device consists of an arm with a pneumatic cylinder actuator controlled by a pressure regulator. As for the human–machine interface, the system has a force sensor. The idea is to verify the possibility of developing a simple system from the sensor system’s point of view and the control system’s architecture while simultaneously obtaining an effective, economical, and reliable device. The idea developed in this project is to use the user’s available ability to control movements in unknown environments. The user constitutes the central part of the entire control system: he defines the references for the speeds and forces to be applied to the environment and observes the rates of the controlled robotic system through his own sight and proprioceptive system. On the other hand, the machine produces and controls the forces applied to the environment by the actuator. In this way, the device shows an increased admittance. A mathematical system model was created to verify the idea’s feasibility. Following the results of the simulations, a prototype was built on which experimental tests were carried out. As stated above, it was possible to obtain the described behavior with the use of a force sensor, one-axis type, interposed between the machine and the user, to constitute the human–machine interface; using a pressure regulator, it was possible to avoid the sensors for the force feedback by the environment. The result is a simple architecture for the sensors and the control algorithm. Specific test protocols were proposed to test the performance of the human–machine “system”, and a test bench was developed that allows the tracking of variable signals represented on a monitor, which the user must follow. The system is intuitive to use, with a rapid learning curve, and the user can handle high loads according to the different signals to be followed with good precision, even at high speeds.
In this paper, the design of a 2-dof (degrees of freedom) rehabilitation robot for upper limbs driven by pneumatic muscle actuators is presented. This paper includes the different aspects of the ...mechanical design and the control system and the results of the first experimental tests. The robot prototype is constructed and at this preliminary step a position and trajectory control by fuzzy logic is implemented. The pneumatic muscle actuators used in this arm are designed and constructed by the authors’ research group.
Development of a Straight Fibers Pneumatic Muscle Durante, Francesco; Antonelli, Michele Gabrio; Zobel, Pierluigi Beomonte ...
International journal of automation technology,
05/2018, Letnik:
12, Številka:
3
Journal Article
Recenzirano
Odprti dostop
This paper presents the development and implementation of a pneumatic muscle actuator based on an idea proposed by a research group at the University of Warsaw. The muscle comprises a silicone rubber ...tube with plugs at the ends. The tube wall contains high-rigidity wires arranged parallel to the tube axis. Circular rings are present on the exterior of the tube. When air is introduced into the tube, the actuator becomes bulky and contracts. In order to establish a prediction model of muscle behavior, a finite element model was developed, and in this model, the Mooney-Rivlin formulation was implemented with two coefficients for rubber simulation and truss elements for the wires. Several prototypes were developed, and a test bench for the experimental characterization of muscle performance was set up. The results of comparison between prototype behavior and model prediction are presented. The finite element model can be used to design the actuator with different dimensions; hence, it was used to conduct a simulated test campaign to develop a quick actuator sizing procedure. Using dimensional analysis, few project parameters were identified on which the performance of the actuator depends. Through a complete simulation campaign using the finite element model, an abacus was constructed. It allows sizing the actuator as required based on the desired performances according to an established procedure.
Background
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.
Methods
The authors developed a grasper for NOTES, provided with VSA, to use as an end‐effector for snail robot devices. The present paper deals with basic concepts of VSA and describes the design and architecture of the grasper. Characterization and functional experiments were performed and results analysed.
Results
A finite element model developed for the actuator design was validated, performance grasper characteristic curves were obtained, VSA was validated, and the gripping capability of several objects was assessed.
Conclusion
The grasper satisfies technical design specifications. On the basis of the results obtained, a control system can be developed to test grasper in a simulated surgery environment.
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