Bipedal robotic mechanisms are unstable due to the unilateral contact passive joint between the sole and the ground. Hierarchical control layers are crucial for creating walking patterns, stabilizing locomotion, and ensuring correct angular trajectories for bipedal joints due to the system’s various degrees of freedom. This work provides a hierarchical control scheme for a bipedal robot that focuses on balance (stabilization) and low-level tracking control while considering flexible joints. The stabilization control method uses the Newton–Euler formulation to establish a mathematical relationship between the zero-moment point (ZMP) and the center of mass (COM), resulting in highly nonlinear and coupled dynamic equations. Adaptive approximation-based feedback linearization control (so-called adaptive computed torque control) combined with an anti-windup compensator is designed to track the desired COM produced by the high-level command. Along the length of the support sole, the ZMP with physical restrictions serves as the control input signal. The viability of the suggested controller is established using Lyapunov’s theory. The low-level control tracks the intended joint movements for a bipedal mechanism with flexible joints. We use two control strategies: position-based adaptive approximation control and cascaded position-torque adaptive approximation control (cascaded PTAAC). The interesting point is that the cascaded PTAAC can be extended to deal with variable impedance robotic joints by using the required velocity concept, including the desired velocity and terms related to control errors such as position, force, torque, or impedance errors if needed. A 6-link bipedal robot is used in simulation and validation experiments to demonstrate the viability of the suggested control structure.
Postmodern arguments, formed a critic case of what modernity brought in several levels. Postmodern practice was considered as a proactive case having amorphous concepts and features to what entiled as an intellectual trends postmodern philosophically and intellectually. But, what postmodernism architecture broughts in it essence, was not isolation from the intellectual context and entrepreneurship case, and it was not disconnecting from the intellectual and philosophical era of that period. Lliteratures and philosophical argument precede what (Robert Venturi) and (Charles A Jencks) had brought, albeit it was closer to critics and correction the path of modernity from crystallizing a direction that exceeds modrinity to wh
... Show MoreUnsaturated polyester was used as a matrix which was filled with different percentages of cobalt ferrite using hand lay-up method. Cobalt ferrite was synthesized using solid state ceramic method with reagent of CoO and Fe2O3. Mechanical properties such tensile strength, Young's modulus and shore D hardness of the composite have been studied. All these properties have increased by 10% with increasing cobalt ferrite contents. Also the thermal properties such thermal conductivity and specific heat capacity are highly increased as the ferrite content increased, while the thermal diffusivity increased by 22 %. On the other hand dielectric strength of composite has been measured which increased by 50% by increasing the cobalt ferrite content.&
... Show MoreGenus Salix is among family Salicaceae, distributing in the northern hemisphere. It is represented in Egypt by two species (Salix mucronata and Salix tetrasperma). The classification of Salix at the generic and infra-generic levels is still outstanding. We have agreed to list the Egyptian species of this genus. We collected them during field trips to most Egyptian habitats; fresh and herbarium specimens were subjected to taxonomic revision based on morphological characters; scanning electron microscope (SEM) for pollen grains; isozyme analysis using esterase and peroxidase enzymes and genetic diversity using random amplified polymorphic DNA (RAPD). We recorded that both sexes of S.
I have written my most important findings in my research are as follows:
The book forty nuclear is one of the writings of the nuclear imam "God's mercy" in which he had collected ahaadeeth from several different sections and diverse, has been described by scientists as the orbit of Islam are all valid conversations.
the duty to pay attention to the Sunnah of the Prophet from the linguistic point of view because it is very rich news and constructional evidence in all sections contained the forty nuclear talks on the news sentences in (30) places divided between the news request, as stated in (13)
home and primary news in (14) home and the news denial in (3) c
... Show MoreBiosorption is an effective method to remove toxic metals from wastewaters. In this
study biosorption of lead and chromium ions from solution was studied using
Citrobacter freundii and Citrobacter kosari isolated from industrial wastewater. The
experimental results showed that optimum grwoth temperature for both bacteria is 30oC
and the optimum pH is 7 &6 for C. freundii and C. kosari respectively. While the
optimum incubation period to remove Pb and Cr for C. freundii and C. kosari is 4 days
and 3days respectively. Also the biosorption of Pb and Cr in mixed culture of bacteria
and mixed culture of Pb and Cr was investigated. Result indicate that uptake of Cr and
Pb for C.freundii, C. kosari and in mixes cultu
Venus orbit around the Sun is an ellipse inside the Earth orbit. The elements of Venus orbit and its position are affected by the gravitational force of near planets therefore the elements were determined with Julian date through ten years 2011-2020. The orbital elements used to calculate Venus distance from the Sun, the heliocentric and geocentric equatorial coordinates. From the results the orbit of Venus and its position were described and show the gravity effect of near planets on it. The results get the values and their variation through ten years for the eccentricity, semi-major axis, inclination, longitude of ascending node, argument of perihelion, mean anomaly and distance from the Sun. The variation is very small through 10 year
... Show MoreThis paper aims to study the asymptotic stability of the equilibrium points of the index 2 and index 3 Hesenberg differential algebraic equations. The problem reformulated to an equivalent explicit differential algebraic equations system, so the asymptotic stability is easily investigated. The singular points such as impasse points and singularity induced bifurcation points are identified in this kind of differential algebraic equations by using conclusion of the explicit differential algebraic equations.
A transdermal drug delivery system (TDDS) is characterized by the application of medications onto the skin's surface to deliver drugs at a controlled and predefined rate through the skin. Spanlastics, an elastic nanovesicle capable of transporting various pharmacological substances, shows promise as a drug delivery carrier. It offers numerous advantages over traditional vesicular systems applied topically, including enhanced stability, flexibility in penetration, and improved targeting capabilities. This study aims to develop meloxicam (MX)-loaded spanlastics gel as skin delivery carriers and to look into the effects of formulation factors like Tween80, Brij 35, and carbopol concentration on the properties of spanlastics gel, like pH, drug
... Show MoreThe present work involved preparation of new hetro cyclic polyacrylamides (1-9) using reaction of polyacryloyl chloride with 2-aminobenzothiazole which prepeard by thiocyanogen method in the presence of a suitable solvent and amount tri ethyl amine (Et3N) with heating. The structure confirmation of polymers were proved using FT-IR,1H-NMR,C13NMR and UV spectroscopy.Other physical properties including softening and melting points, and solubility of the polymers were also measured.