Distributed Architecture for Dynamic Role Behaviour in Humanoid Soccer Robots

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Pores Structure Change Induced by Heat Treatment in Cold-Sprayed Ti6Al4V Coating

In this study, the evolution of pores structure in cold-sprayed Ti6Al4V coating (TC4) was analyzed before and after 600-1100 °C heat treatment. It was found that almost no change happened to pores under the heat treatment temperature below 600 °C. When the heat treatment temperature was increased to 700 °C, the coating recrystallized, and pores turned to spheroid and healed because of the “bridging” effect. Some of the pores coarsened after 800 °C and 900 °C heat treatment. This kind of phenomenon grew severer when the heat treatment temperature increased to 1000 °C and 1100 °C. On the whole, with the increment of temperature, for the coating prepared at relatively low temperature, apparent porosity measured by image analysis method tended to go down first and then up, but it decreased all the time for the coating prepared at relatively high temperature. The reason for this phenomenon was contributed to the bonding state of particles in the coating. Only when there were fewer weakly bonded interfaces, the detachment between the particle interfaces which may be caused by release of residual stress did not occur, and there was no pores expansion and internal connectivity, so the porosity continuously decreased

Microstructure of Cross-Linked High Densification Network and Strengthening Mechanism in Cold-Sprayed Ti-6Al-4V Coating After Heat Treatment

In this study, Ti-6Al-4V (TC4) coating was prepared using an in situ shot peening-assisted cold spraying technology in which large shot peening particles were mixed with TC4 spraying powders to prepare the deposit. To improve its strength and toughness, the coating was heat-treated at 600-1000 °C in vacuum. The results demonstrated that the microstructure of the as-sprayed coating exhibited a special structure that was denser at the regions tamped by the shot peening particles and porous at the nontamped regions. When the coating was heat-treated at 800 and 1000 °C, the interface between the particles had largely disappeared and the local pores had interconnected with each other due to thermal diffusion and recrystallization. The coating hardness decreased slightly after annealing at 600 and 800 °C due to the released strain hardening effect. The bonding strength of the coating after annealing improved in comparison with that of the as-sprayed coating. The tensile strength of the coating improved significantly under annealing at 800 °C. A cross-linked high densification network was formed after annealing due to the effect of in situ shot peening, which served as a reinforced framework and enhanced the strength of the coating

Fuzzy-arithmetic-based Lyapunov synthesis in the design of stable fuzzy controllers: A computing-withwords approach

A novel approach to designing stable fuzzy controllers with perception-based information using fuzzy-arithmetic-based Lyapunov synthesis in the frame of computing with words (CW) is presented. It is shown that a set of conventional fuzzy control rules can be derived from the perception-based information using the standard-fuzzy-arithmetic-based Lyapunov synthesis approach. On the other hand, a singleton fuzzy controller can be devised by using a constrained-fuzzy-arithmeticbased Lyapunov synthesis approach. Furthermore, the stability of the fuzzy controllers can be guaranteed by means of the fuzzy version of Lyapunov stability analysis. Moreover, by introducing standard and constrained fuzzy arithmetic in CW, the “words ” represented by fuzzy numbers could be efficiently manipulated to design fuzzy controllers. The results obtained are illustrated with the design of stable fuzzy controllers for an autonomous pole balancing mobile robot

Robust Adaptive Fuzzy Control for Permanent Magnet Synchronous Servomotor Drives

A novel robust adaptive fuzzy control (RAFC) algorithm for the permanent magnet (PM) synchronous servomotor drives with uncertain nonlinearities and time-varying uncertainties is presented in this article. Takagi–Sugeno-type fuzzy logic systems are used to approximate uncertain functions. The RAFC algorithm is designed by use of the input-to-state stability (ISS) approach and small gain theorem. The closed-loop system is proven to be semiglobally uniformly ultimately bounded. In addition, the possible controller singularity problem in some of the existing adaptive control schemes met with feedback linearization techniques can be removed and the adaptive mechanism with only one learning parameterization can be achieved. The proposed methodology is applied to design the position control of the PM synchronous servomotor drives. Simulation results show the effectiveness of the proposed control scheme. © 2005 Wiley Periodicals, Inc. 1

A Fast Vision System for Soccer Robot

This paper proposes a fast colour-based object recognition and localization for soccer robots. The traditional HSL colour model is modified for better colour segmentation and edge detection in a colour coded environment. The object recognition is based on only the edge pixels to speed up the computation. The edge pixels are detected by intelligently scanning a small part of whole image pixels which is distributed over the image. A fast method for line and circle centre detection is also discussed. For object localization, 26 key points are defined on the soccer field. While two or more key points can be seen from the robot camera view, the three rotation angles are adjusted to achieve a precise localization of robots and other objects. If no key point is detected, the robot position is estimated according to the history of robot movement and the feedback from the motors and sensors. The experiments on NAO and RoboErectus teen-size humanoid robots show that the proposed vision system is robust and accurate under different lighting conditions and can effectively and precisely locate robots and other objects