ABSTRACT
Objective To design a notched flexible articulation applied to electric stapler and study its turning performance. Methods The notched flexible articulation was designed and modeled. The kinematics and statics models of the articulation were established for simulation calculations. The stress, deflection angle, top displacement and driving force of the articulation with 3 different turning structures were studied under equal and variable stiffness of symmetrical notches by using finite element simulation. An experimental platform for performance test of the turning structure was built to verify the simulation results and the model. Results The theoretical model of the turning structure in bending process was basically consistent with the experimental results. With the optimization of symmetrical notch stiffness, the maximum stress of the articulation with variable stiffness was reduced by 20.64% and 39.20%, respectively. The articulation with variable stiffness required the smallest tensile force during bending, which was 33.41% lower than that of the articulation with equal stiffness, and the tip displacement (30.8 mm) along the bending plane was the smallest. The maximum deflection angle for the articulation with 3 different turning structures all could reach 90°. Conclusions The kinematics and statics models of the articulation can be used for the calculation of its tensile force and position changes. The turning performance of the articulation with variable stiffness using symmetrical notch is better than that with equal stiffness. The notched flexible articulation meets the design requirements and the turning needs of electric stapler.
ABSTRACT
In this article, we focus on the importance of obtaining statics that stray from the usual probabilistic distribution, such as normal distribution. These statics, known as non-parametric, are especially adequate when analyzing small samples (less than 30 individuals) within biomedical research. We elaborate and show examples of their use in rehabilitation.
En este artículo, se enfatiza la importancia de la obtención de estadísticas que no se ajustan a alguna distribución de probabilidad conocida, como la distribución normal por ejemplo, que se denominan no paramétricas, adecuadas para analizar un conjunto de datos provenientes de muestras de tamaño relativamente pequeño, inferiores a 30 unidades de observación en una investigación biomédica. Se desarrollan y ejemplifican los escenarios más comúnmente encontrados en el área de la rehabilitación.
Subject(s)
Rehabilitation , Statistics, NonparametricABSTRACT
The purpose of this study was to increase knowledge about the landing posture that induces anterior cruciate ligament (ACL) injury. Analysis was done to determine the knee abduction moment during single limb landing using our previously proposed mathematical model. Our model has proven that the criterion of knee abduction occurring is when the acting line of the ground reaction force is directed laterally to the lower leg segment. Based on this, we predicted a medial shift of the knee joint and a lateral leaning of the trunk segment to induce the knee abduction moment. To verify the results of our model prediction, we conducted a motion analysis experiment with a single limb-landing task. Three male and four female subjects participated in the experiment. Subjects were instructed to fall from a 30 cm high box and land on a target which was assigned by PC-controlled laser pointers. Since the landing target was unexpectedly moved during landing, the subjects were perturbed and exhibited various landing postures. The results of the landing experiment showed that trunk leaning laterally towards the landing limb and medially shifted knee alignment induced the knee abduction moment. These results are consistent with the results predicted by our model. In conclusion, appropriate control of both lower limb alignment and trunk motion in the frontal plane in essential for reducing the risk of ACL injury.
ABSTRACT
Objective To study mechanics characteristics of two cooperative reconfigurable planetary robots when they get across an obstacle, and to find out the relationship between the maximum height of a stair with the configuration of the two-robot, and to find some restrictions of kinematics for the cooperation. Methods Multirobot cooperation theory is used in the whole study process. Inverse kinematics of the robot is used to form a desired configuration in the cooperation process. Static equations are established to analyze the relations between the friction factor, the configuration of robots and the maximum height of a stair. Kinematics analysis is used to find the restrictions of the two collaborative robots in position, velocity and acceleration. Results 3D simulation shows that the two cooperative robots can climb up a stair under the condition of a certain height and a certain friction factor between robot wheel and the surface of the stair. Following the restrictions of kinematics, the climbing mission is fulfilled successfully and smoothly. Conclusion The maximum height of a stair, which the two cooperative robots can climb up, is involved in the configuration of robots, friction factor between the stair and the robots. The most strict restriction of the friction factor does not appear in the horizontal position. In any case, the maximum height is smaller than half of the distance between the centroid of robot1 with the centroid of robot2. However, the height can be higher than the radius of one robot wheel, which profit from the collaboration.