A Comparative Evaluation of Adaptive and Non-adaptive Sliding Mode, LQR and PID Control for Platform Stabilization

During the uniform locomotion of compliant legged robots and other terrain vehicles, the body of the robot often exhibits complex oscillations which may have a disturbing effect on onboard sensors. For a camera mounted on such a robot, due to perspective projection, the effects of angular disturbances are particularly pronounced as compared to translational disturbances. This paper is motivated by the particular problem of legged robots exhibiting angular body motions and attempts to evaluate the performance of baseline and state-of-the-art controllers for compensating this undesired motion. For this comparative evaluation, a simplified planar camera platform is considered in a Matlab-Simulink based simulation environment but motion disturbances are collected on a physical experimental robot platform. Although the full stabilization problem is in 3D with three independent axes of rotation, we currently consider a planar case on the pitch axis with a kinematic structure very similar to many parallel actuated 3D platforms. We believe that despite the simplified analysis, the presented performance evaluation provides significant insight into the general problem. The work consist of the derivation of the planar platform model followed by the implementation and comparative testing of 4 different controllers, namely Proportional-Integral-Derivative (PID), Linear Quadratic Regulator (LQR), Sliding Mode (SMC) and Adaptive Sliding Mode (ASMC) controllers. Experimental setup, disturbance collection and finally, the controller performance test results are presented and discussed

A Nonlinear Dynamic Strategy for Mathematical Modeling and Simulation of Stabilized Platform in Planar Motion in One Body and Three Bodies

Abstract Mathematical modeling and simulation of a head stabilization platform. The stabilization platform is capable of moving on the pitch degree of freedom. The platform is modeled in two different approaches; considering only the mass of the platform (One-body) and considering platform, actuating shaft and actuator masses (Three-Body)

Does dual trigger improve euploidy rate in normoresponder? A cross-sectional study

Background: With the introduction of the dual triggering-gonadotropin-releasing hormone (GnRH) analog and recombinant human chorionic gonadotropin (hCG) combination, women with a history of low mature oocyte proportion and empty follicle syndrome were shown to benefit from the dual trigger. Objective: To investigate whether dual triggering of oocyte maturation with a GnRH agonist (GnRHa) combined with hCG can affect the euploidy rate and improve in vitro fertilization outcomes for normoresponder women. Materials and Methods: In this cross-sectional study, 494 women who underwent controlled ovarian stimulation with hCG (n = 274) or dual triggering (hCG+GnRHa, n = 220) at Acibadem Maslak hospital, Assisted Reproductive Unit, from January 2019- 2022 were enrolled in this study. Preimplantation genetic testing for aneuploidy was performed on all participants. Results: Both groups had similar baseline and clinical characteristics. Of the 881 embryos biopsied, 312 (35.4%) were reported as euploid in the hCG trigger group; in the dual trigger group, 186 (29.8%) of 623 screening embryos were reported as euploid. The hCG group had a higher euploidy rate per biopsied embryo, although the difference was not statistically significant (31.4 ± 26.5 vs. 26.5 ± 33.3, p > 0.05). Conclusion: In normoresponders, adding GnRHa for final follicular maturation to hCG did not improve the euploidy rate. Key words: Gonadotropin-releasing hormone, Chorionic gonadotropin, Preimplantation screening, Aneuploidy

PRIMER EPIPLOIC APPENDAGITIS MIMICKING APPENDIX DUPLICATION

Primary epiploic appendagitis (PEA) is a rare condition characterized by inflammation of subserosal colonic adipose tissue. It can mimic acute appendicitis or acute diverticulitis in elderly patients. Though previously relatively rare, surgical diagnosis is now being more frequently employed with an increasing use of computerized tomographic scans (CT) and ultrasound. We report here on a case of PEA mimicking an appendiceal duplication with acute ap- pendicitis. To the best of our knowledge, this is a very rare clinical entity in the literature. A 29-year-old female pa- tient was admitted to the emergency department. She had abdominal pain, was vomiting, and suffered from anorex- ia. The operative finding was double acute appendicitis in appendix duplication. PEA may mimic acute appendicitis and can be considered as an appendix duplication caused by a diagnostic dilemma. It may not be possible to diffe- rentiate during an operation; the distinction can be made only by histologic examination. Although both are very rare clinical entities, misdiagnosis of appendix duplication can cause serious health issues, and critical medico-legal issues must also be kept in mind

Vibro-acoustic radiation from a fluid-filled viscoelastic cylindrical shell with internal turbulent flow.

Vibro-acoustic radiation from a fluid-filled viscoelastic cylindrical shell with internal turbulent flow

Method for Dynamic Material Property Characterization of Soft-Tissue-Mimicking Isotropic Viscoelastic Materials Using Fractional Damping Models

Characterization of the mechanical properties of human-tissue-mimicking silicone elastomers is important for producing accurate tissue models for experimentation. However, the viscoelastic and frequency-dependent material properties of elastomers are difficult to quantify. We present a material characterization technique for a silicone elastomer used to mimic human soft tissue based on generalized-Maxwell-type material models with and without fractional dissipating mechanisms. The silicone specimens were prestressed and had the shape of cylindrical rods. It was possible to consistently identify material properties of all specimen samples from different batches of the material obtained from the manufacturer. As a general trend, material models with a higher number of parameters performed better, with the exception of models with fractional order damping mechanisms. Fractional models had the highest success for nearly all the samples in representing the dynamic behavior of the elastomer in the frequency range of 5-100 Hz, where the specimen structure displays a strong modal response