scholarly journals Adaptive Fuzzy Type-II Controller for Wheeled Mobile Robot with Disturbances and Wheelslips

2021 ◽  
Vol 2021 ◽  
pp. 1-11
Author(s):  
Viet Quoc Ha ◽  
Sen Huong-Thi Pham ◽  
Nga Thi-Thuy Vu
Keyword(s):  
Mobile Robot ◽  
Wheeled Mobile Robot ◽  
Lyapunov Theory ◽  
Reference Trajectory ◽  
Type I ◽  
Type Ii ◽  
Control Loops ◽  
Adaptive Fuzzy ◽  
Fuzzy Type Ii ◽  
The Stability

This paper proposed adaptive fuzzy type-II controllers for the wheeled mobile robot (WMR) systems under conditions of wheel slips and disturbances. The system includes two control loops: outer loop for position tracking and the inner loop for velocity tracking. In each loop, the controller has two parts: the feedback which keeps the system stable and the adaptive type-II fuzzy part which is used to compensate the unknown components that act on the system. The stability of each loop as well as the overall system is proven mathematically based on the Lyapunov theory. Finally, the simulation is setup to verify the effectiveness of the presented algorithm. The simulation results show that, in comparison with the corresponding fuzzy type-I controller, the performance of the adaptive fuzzy type-II controller is better, i.e., the position error is smaller and the velocity is almost smooth under the conditions that the reference trajectory is changed, and the system is affected by wheel slips and external disturbances.

scholarly journals Robust adaptive controller for wheel mobile robot with disturbances and wheel slips

2021 ◽  
Vol 11 (1) ◽  
pp. 336
Author(s):  
Nga Thi-Thuy Vu ◽  
Loc Xuan Ong ◽  
Nam Hai Trinh ◽  
Sen Thi Huong Pham
Keyword(s):  
Mobile Robot ◽  
Adaptive Controller ◽  
Lyapunov Theory ◽  
Control Loops ◽  
Proposed Model ◽  
Control Scheme ◽  
System Uncertainties ◽  
Robust Adaptive ◽  
The Stability ◽  
Adaptive Control Algorithm

In this paper an observer based adaptive control algorithm is built for wheel mobile robot (WMR) with considering the system uncertainties, input disturbances, and wheel slips. Firstly, the model of the kinematic and dynamic loops is shown with presence of the disturbances and system uncertainties. Next, the adaptive controller for nonlinear mismatched disturbance systems based on the disturbances observer is presented in detail. The controller includes two parts, the first one is for the stability purpose and the later is for the disturbances compensation. After that this control scheme is applied for both two loops of the system. In this paper, the stability of the closed system which consists of two control loops and the convergence of the observers is mathematically analysed based on the Lyapunov theory. Moreover, the proposed model does not require the complex calculation so it is easy for the implementation. Finally, the simulation model is built for presented method and the existed one to verify the correctness and the effectiveness of the proposed scheme. The simulation results show that the introduced controller gives the good performances even that the desired trajectory is complicated and the working condition is hard.

scholarly journals Adaptive Fuzzy Integral Terminal Sliding Mode Control of a Nonholonomic Wheeled Mobile Robot

2017 ◽  
Vol 2017 ◽  
pp. 1-12 ◽  
Author(s):  
Shuying Peng ◽  
Wuxi Shi
Keyword(s):  
Mobile Robot ◽  
Sliding Mode ◽  
Kinematic Model ◽  
Small Neighborhood ◽  
Wheeled Mobile Robot ◽  
Fuzzy Integral ◽  
Control Input ◽  
Parameter Uncertainties ◽  
Terminal Sliding Mode ◽  
Adaptive Fuzzy

In this paper, the trajectory tracking problem is investigated for a nonholonomic wheeled mobile robot with parameter uncertainties and external disturbances. In this strategy, combining the kinematic model with the dynamic model, the actuator voltage is employed as the control input, and the uncertainties are approximated by a fuzzy logic system. An auxiliary velocity controller is integrated with an adaptive fuzzy integral terminal sliding mode controller, and a robust controller is employed to compensate for the lumped errors. It is proved that all the signals in the closed system are bounded and the auxiliary velocity tracking errors can converge to a small neighborhood of the origin in finite time. As a result, the tracking position errors converge asymptotically to zeros with faster response than other existing controllers. Simulation results demonstrate the effectiveness of the proposed strategy.

scholarly journals Microfilament modification by dihydrocytochalasin B causes retinoic acid-modulated chondrocytes to reexpress the differentiated collagen phenotype without a change in shape.

1988 ◽  
Vol 106 (1) ◽  
pp. 161-170 ◽  
Author(s):  
P D Benya ◽  
P D Brown ◽  
S R Padilla
Keyword(s):  
Retinoic Acid ◽  
Cell Shape ◽  
Articular Chondrocytes ◽  
Type Ii Collagen ◽  
Phenotypic Change ◽  
Type Iii Collagen ◽  
Type I ◽  
Type Ii ◽  
The Stability ◽  
Rabbit Articular Chondrocytes

Primary monolayers of rabbit articular chondrocytes synthesize high levels of type II collagen and proteoglycan. This capacity was used as a marker for the expression of the differentiated phenotype. Such cells were treated with 1 microgram/ml retinoic acid (RA) for 10 d to produce a modulated collagen phenotype devoid of type II and consisting of predominantly type I trimer and type III collagen. After transfer to secondary culture in the presence of RA, the stability of the RA-modulated phenotype was investigated by culture in the absence of RA. Little reexpression of type II collagen synthesis occurred in this period unless cultures were treated with 3 X 10(-6) M dihydrocytochalasin B to modify microfilament structures. Reexpression of the differentiated phenotype began between days 6-8 and was essentially complete by day 14. Substantial reexpression occurred by day 8 without a detectable increase in cell rounding. Colony formation, characteristic of primary chondrocytes, was infrequent even after reexpression was complete. These data suggest that the integrity of microfilament cytoskeletal structures can be a source of regulatory signals that mechanistically appear to be more proximal to phenotypic change than the overt changes in cell shape that accompany reexpression of subculture-modulated chondrocytes in agarose culture.

scholarly journals Decoding the Structure of Non-Proteinogenic Amino Acids: The Rotational Spectrum of Jet-Cooled Laser-Ablated Thioproline

Molecules ◽  
2021 ◽  
Vol 26 (24) ◽  
pp. 7585
Author(s):  
Juan Carlos López ◽  
Alberto Macario ◽  
Andrés Verde ◽  
Alfonso Pérez-Encabo ◽  
Susana Blanco
Keyword(s):  
Interaction Analysis ◽  
Noncovalent Interaction ◽  
Coupling Constants ◽  
Cooh Group ◽  
Stable Form ◽  
Equatorial Position ◽  
Type I ◽  
Rotational Spectrum ◽  
Type Ii ◽  
The Stability

The broadband rotational spectrum of jet-cooled laser-ablated thioproline was recorded. Two conformers of this system were observed and identified with the help of DFT and ab initio computations by comparison of the observed and calculated rotational constants and 14N quadrupole coupling constants as well as the predicted energies compared to the observed relative populations. These conformers showed a mixed bent/twisted arrangement of the five-membered ring similar to that of the related compound thiazolidine with the N–H bond in axial configuration. The most stable form had the COOH group in an equatorial position on the same side of the ring as N-H. The arrangement of the C=O group close to the N-H bond led to a weak interaction between them (classified as type I) characterized by a noncovalent interaction analysis. The second form had a trans-COOH arrangement showing a type II O–H···N hydrogen bond. In thioproline, the stability of conformers of type I and type II was reversed with respect to proline. We show how the conformation of the ring depends on the function associated with the endocyclic N atom when comparing the structures of isolated thioproline with its zwitterion observed in condensed phases and with peptide forms.

scholarly journals Influence of coracoglenoid space on scapular neck fracture stability: biomechanical study

2022 ◽  
Vol 23 (1) ◽  
Author(s):  
Junfeng Chen ◽  
Wei Zhang ◽  
Gang Pang ◽  
Qingling Meng ◽  
Youyu Zhu ◽  
...  
Keyword(s):  
Failure Load ◽  
Anatomical Variation ◽  
Biomechanical Study ◽  
Interindividual Variation ◽  
Type I ◽  
Type Ii ◽  
Average Maximum ◽  
Neck Fracture ◽  
The Stability ◽  
Scapular Neck Fractures

Abstract Background The anatomical variation of the coracoglenoid space has the potential to influence the stability of scapular neck fractures. This paper aimed to investigate the mechanical mechanism underlying the influence of different coracoglenoid space types on scapular neck fractures by morphometric analysis and biomechanical experiments. Methods The morphology of 68 dried scapulae (left: 36; right: 32) was studied. Two variables, the length of the coracoglenoid distance (CGD) and the coracoglenoid notch (CGN), were measured. The distribution of CGN/CGD × 100% was used to identify the morphology of the coracoglenoid space. Each specimen was tested for failure under static axial compression loading. The average failure load, stiffness, and energy were calculated. Results Two coracoglenoid space types were identified. The incidence of Type I (‘‘hook’’ shape) was 53%, and that of Type II (‘‘square bracket’’ shape) was 47%. The CGD and CGN were significantly higher for type I than type II (13.81 ± 0.74 mm vs. 11.50 ± 1.03 mm, P < 0.05; 4.74 ± 0.45 mm vs. 2.61 ± 0.45 mm, P < 0.05). The average maximum failure load of the two types was 1270.82 ± 318.85 N and 1529.18 ± 467.29 N, respectively (P = 0.011). The stiffness and energy were significantly higher for type II than type I (896.75 ± 281.14 N/mm vs. 692.91 ± 217.95 N/mm, P = 0.001; 2100.38 ± 649.54 N × mm vs. 1712.71 ± 626.02 N × mm, P = 0.015). Conclusions There was great interindividual variation in the anatomical morphology of the coracoglenoid space. Type I (hook-like) spaces bore lower forces, were less stiff, and bore less energy, which may constitute an anatomical predisposition to scapular neck fractures.

Combination of predictive models with an optimal adaptive fuzzy controller for active suspension systems having control force constraints on front and rear tires

2020 ◽  
pp. 014233122094436
Author(s):  
Mohammad Javad Mahmoodabadi ◽  
Mohammad Javanbakht
Keyword(s):  
Predictive Models ◽  
Ride Comfort ◽  
Fuzzy Controller ◽  
Relative Displacement ◽  
Lyapunov Theory ◽  
The Body ◽  
Control Force ◽  
Adaptive Fuzzy ◽  
The Road ◽  
The Stability

This paper presents optimal adaptive fuzzy approaches combined by the predictive models for five degrees of freedom vehicle systems having a control force constraint of 1000 N on both front and rear suspensions in order to minimize the road disturbances. First, two separate adaptive fuzzy controllers are designed for the rear and front tires using the singleton fuzzifier, center average defuzzifier and product inference engine. The constructed fuzzy systems implement the adaptation laws based on the Lyapunov theory to guarantee the stability of the system. Afterward, a gravitational search optimization algorithm is applied to calculate the optimal values of the controller’s gains. The weighted summation of four objectives, as the relative displacement between the sprung mass and the front tire, the relative displacement between the sprung mass and the rear tire, the acceleration of the body and the acceleration of the seats, are regarded in the optimization process. Two different predictive models are employed to find the optimal design variables for the circumstances where the stability of the system is under variation. The first model is a fuzzy predictive system while the second one is based on the moving least squares interpolation. Eventually, the resultant online models are compared with the offline systems when the vehicle mass varies. These simulations obviously illustrate the efficiency and ability of the suggested strategy to remove the effect of the road disturbances on the ride comfort.

scholarly journals A Predictive Classification of Charcot Arthropathy of Foot and Ankle

2020 ◽  
Vol 5 (4) ◽  
pp. 2473011420S0008
Author(s):  
Mohamed Abdelaziz Elghazy ◽  
Hani M. El-Mowafi ◽  
Ahmed El-Hawary ◽  
Yasser R. Kandil ◽  
Samer Ali ◽  
...  
Keyword(s):  
Complication Rate ◽  
Classification Systems ◽  
Type I ◽  
Type Ii ◽  
Foot And Ankle ◽  
Charcot Arthropathy ◽  
Lateral Column ◽  
Lisfranc Joints ◽  
The Stability

Category: Diabetes; Other Introduction/Purpose: Charcot arthropathy of foot and ankle is a devastating, chronic and progressive destruction of bone and joint integrity affecting one or more joints. It is commonly associated with diabetes mellitus and is characterized by joint subluxations, dislocation, and pathological fractures in patients with peripheral neuropathy and results in a debilitating deformity, possibly leading to ulceration and amputation.Many classification systems exist for charcot arthopathy of foot and ankle. However, there is still lack of consensus regarding best classification. We are proposing a new classification for charcot arthropathy of foot and ankle based on our experience of large cohort of charcot patients. Our classification can guide treatment and prognosis of diabetic charcot arthropathy of foot and ankle, which we are following for the last decade. Methods: Patients with post-acute charcot who presented at our institution from January 2004 to October 2019 were reviewed and were further classified anatomically into Type I and Type II based on plain radiographs. Type I was characterized by charcot affection of one region. Regions were categorized anatomically as a modification of both Brodsky and Schon classifications into: ankle, Lisfranc (tarsometatarsal), naviculocuneiform, forefoot, and hindfoot which includes one of the following: talonavicular joint, calcaneocuboid joint or calcaneus. Type II was characterized by affection of more than one region like peritalar, perinavicular, transverse tarsal or any other combination. Peritalar complex involves at least two joints of the following: ankle, subtalar, and talonavicular. The perinavicular type includes talonavicular and naviculocuniform or tarsometatarsal and naviculocuniform, while the transverse tarsal involves the calcaneocuboid and talonavicu-lar. Both types were further classified into four stages according to the stability, deformity and associated mechanical ulcers. (Table 1) Results: 235 patients (242 feet) were presented with diabetic charcot arthropathy. Mean age was 56 years (range 22-84). Follow- up ranged from 6 months to 10 years, with a mean of 3.3 years.Types IA and IIA were managed conservatively. All patients in Type IIB, IC, IIC, ID, IID and the majority of type IB received fusion surgery to achieve stability and correction of deformity. Stage IB ankle were fixed, while IB lisfranc were observed, and fixed if transformed to IC.Type II D had the highest complication rate in the form of: infection, nonunion, nail protrusion, implant failure, revision including exostectomy after full union and recurrence of ulcer in midfoot 3-4 years after surgery. Five patients ended up with amputation, and all were stage IID. Conclusion: For post-acute charcot, stage A have the best prognosis and can be managed conservatively provided good diabetes control.Type IB can be managed conservatively but when the ankle is affected in type IB, it is better to be elected for surgery. When charcot affects the Lisfranc joints, it is usually stable unless the lateral column is affected.All cases of type IIB, IC and IIC, ID, IID should receive surgery to achieve stability, correction of deformity and prevent complications.Mechanical ulcer (stage D) carries the worst prognosis and highest complication rate. Type IID might predict the risk of amputation [Table: see text]

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