Design stable robust intelligent nonlinear controller for 6- DOF serial links robot manipulator

In this research parallel Proportional-Derivative (PD) fuzzy logic theory plus Integral part (I) is used to compensate the system dynamic uncertainty controller according to highly nonlinear control theory sliding mode controller. Sliding mode controller (SMC) is an important considerable robust nonlinear controller. In presence of uncertainties, this controller is used to control of highly nonlinear systems especially for multi degrees of freedom (DOF) serial links robot manipulator. In opposition, sliding mode controller is an effective controller but chattering phenomenon and nonlinear equivalent dynamic formulation in uncertain dynamic parameters are two significant drawbacks. To reduce these challenges, new stable intelligent controller is introduce

New methodology of online sliding surface slope tuning PID like fuzzy sliding mode controller for robust control of robot manipulators

Designing a robust controller for uncertain multi input-multi output (MIMO) nonlinear dynamical system (e.g., robot manipulator) can be a challenging work in this research. Robot manipulators are set of links which connected by joints, they are multiple-input and multiple-output (MIMO), nonlinear, time variant, uncertain dynamic systems and are developed either to replace human work in many fields such as in industrial or in the manufacturing. According to the dynamic formulation of robot manipulators, they are uncertain and have strong coupling effects between joints. To solve this challenge, sliding mode controller is selected since it is robust, stable and it works very well in certain and fairly uncertain condition. Although this controller works incredibly efficient, but still, it has two important challenges, namely the high frequency chattering and working in uncertain situation. To reduce the chattering with respect to stability and robustness; linear controller is added to discontinuous (switching) part of sliding mode controller. In this methodology linear controller is used in parallel with discontinuous part to reduce the role of sliding surface slope and switching (sign) function. To modify chattering free sliding mode controller in uncertain situation PID like fuzzy logic theory is recommended in estimating the robot manipulator's nonlinear dynamic formulation and on-line tuning sliding surface slope.As a result, this controller improves the stability and robustness, reduces the chattering as well and reduces the level of energy due to the torque performance as well

Chatter-free and equivalent estimator fuzzy model-based sliding mode controller for serial links 6 dof robot manipulator

Design of a robust controller for multi input-multi output (MIMO) nonlinear uncertain dynamical system could be a challenging work. This thesis focuses on the design and analysis of a high performance Proportional-Integral-Derivative (PID)-like fuzzy sliding mode control for second order nonlinear uncertain system, in presence of uncertainties. In this research, sliding mode controller is a robust and stable nonlinear controller, which selected to control of robot manipulator. The proposed approach effectively combines of design methods from switching sliding mode controller, adaptive controller, fuzzy logic theory and linear Proportional-Derivative (PD) control to improve the performance,stability and robustness of the sliding mode controller. This sliding mode controller has two important subparts, switching and equivalent. Switching part (discontinuous part) is very important in uncertain condition but it causes chattering phenomenon. To solve the chattering, the most common method used is linear boundary layer saturation method, but this method lost the stability. To reduce the chattering with respect to stability and robustness; linear controller is added to the switching part of the sliding mode controller. The linear controller is to reduce the role of sliding surface slope and switching (sign) function. The nonlinearity term of the sliding mode controller is used to eliminate the decoupling and nonlinear term of link’s dynamic parameters. However nonlinearity term of sliding mode controller is very essential to reliability but in uncertain condition or highly nonlinear dynamic systems it can cause some problems. To solve this challenge the PID fuzzy logic controller is used as a modelbased PID like fuzzy sliding mode controller. The PID like fuzzy sliding mode controller is updated based on online tuning sliding surface slope. In order to reduce the online computation burden, the PID like fuzzy logic controller is also used to sliding surface slope online tuning. As a result, in proposed method fuzzy logic controller is used to dynamic estimation and also online tuning. This controller improves the stability and robustness, reduces the chattering as well and reduces the level of energy due to the torque performance as well

Synthesis, Characterization, and Evaluation of Anti-Helicobacter Activity of Chitosan and Pectin Microparticles Containing Zataria multiflora Extract In Vitro: H. pylori suppression by bioactive compounds

Background and Objective: Helicobacter pylori infection is of widespread diseases in the world. The most common treatment for remediation of its symptoms is administration of antibiotics, which are not efficient enough in some patients and resulted in antibiotic resistance. Given the adverse effects arising from antibiotics in clinical studies, we aimed to fabricate chitosan- and pectin-based micro-particles containing Zataria multiflora extract for suppression of Helicobacter pylori in the laboratory. Materials and Methods: Chitosan and pectin micro-capsules alone and in combination with Zataria multiflora extract were prepared by spray dryer. The powders were further characterized by FT-IR, zeta sizer, and scanning electron microscope. Simulated gastric fluid was also prepared for evaluation of anti-Helicobacter potency of the samples. Results and Conclusion: Chitosan 1% w v-1 + 0.5 ml Zataria multiflora extract (CE0.5), pectin 1% w v-1 + 0.3 ml Zataria multiflora extract (PE0.3), and pectin 1% w v-1 (P1) could significantly suppress the bacteria under simulated gastric condition. The least survivability of Helicobacter pylori was 45.4% and achieved for CE0.5, followed by 45.70% and 46.6% for PE0.3 and P1, respectively. Electrostatic charge of the biopolymers and phenol compounds of the extract greatly affected the integrity of bacterial cell wall. According to FT-IR spectra, Zataria multiflora extract was physically entrapped in chitosan and pectin layers, which helped its better antimicrobial activity in vitro. Regarding the significant anti-Helicobacter activity of our selected formula, they would be considered as complementary treatment for antibiotics in eradication of Helicobacter pylori infection. Although further in vivo experiments are required to validate the current findings. Conflict of interest: The authors declare no conflict of interest