Abstract-One of the best nonlinear robust controllers which can be used in uncertain nonlinear systems is sliding mode controller (SMC), but pure SM C results in chattering in a noisy environment. This effect can be eliminated by optimizing the sliding surface slope. This paper investigates a novel methodology in designing a SMC by a new heuristic search, so called -colonial competitive algorith m -in order to tune the sliding surface slope and the switching gain of the discontinuous part in SMC structure. This process decreases the integral of absolute errors which results in tracking the desired inputs by the outputs in designing a controller for robot manipulator. Simu lation results prove that the optimized performance obtained through CCA significantly reduces the chattering phenomena and results in better trajectory tracking compared to typical trial and error methods.

Evaluating the Effectiveness of Cranial Molding for Treatment of Positional Plagiocephaly Using Finite Element AnalysisMaziyar KeshtgarSince the advent of recommendations for placing infants in the supine position during sleep to reduce the incidence of sudden infant death syndrome, clinicians have noted an increase in the frequency of cranial asymmetry due to deformation of suture sections of the infants' skulls as a result of constant concentrated stress in one area at the back of their head.This specific form of cranial deformation is known as positional plagiocephaly and its rate of occurrence has increased from 0.3% in 8.2% within the past 30 years.Current treatments and methodologies for preventing and correcting positional plagiocephaly such as stretching exercises, bedding pillows, and cranial molding are not optimized for effectiveness and comfort. Literature surrounding the implementation of these methodologies or devices often assesses the relative effectiveness of each treatment through statistical means, or studies complications associated with their use. There is a lack of quantified mechanical analysis for determining the effectiveness of each treatment or engineered solutions.In this study, a finite element model was created and validated to study the effect of wearing a cranial helmet, as the most effective non-surgical device for treatment of positional plagiocephaly, on reducing concentrated stress from the back of the baby's head during sleep.The results from this model were then compared to two other finite element models with a healthy baby sleeping in supine position on a pillow, and a patient diagnosed with a severe case of positional plagiocephaly sleeping on the flat side of his head in supine position. The geometries representing the head of the babies in these models are the refined 3D laserv scanned file of a patient's head contour at Hanger Clinic as well as the cavity inside the cranial helmet that was used for treatment of the baby.After successfully assigning section and contact properties to different regions of the models, applying proper loading and boundary conditions, and performing mesh convergence studies for each of the three models, the average Von Mises stress values of each of the 13 different suture segments of each model were summarized in tables and evaluated using mathematical and qualitative methods.The stress value data obtained from different suture regions of the model with the cranial helmet resulted in the smallest standard deviation among all three populations which supports that wearing the cranial helmet helps to reduce stress concentrations. Use of the cranial helmet during sleep also showed a significant decrease of the average Von Mises stress within the posterior fontanelle by 90% compared to the healthy baby sleeping in supine position and 73.4% compared to the deformed head sleeping on the flat surface of the head.The major limitations of this study are correlated with the simplifying assumptions and geometries in generating and validating t...

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