Current Issue : October - December Volume : 2020 Issue Number : 4 Articles : 6 Articles
Abstract: The appropriate selection of arrows in the sport of archery is important to the achievement\nof high-quality results. In this regard, a shooting machine that is compatible with the wide variety\nof available bows and arrows is necessary. However, bow strength and arrow length vary among\ndifferent athletes. It is also important to develop a shooting machine that reproduces the movement\nof the right fingers that releases an arrow, and the forward jump of a bow after shooting an arrow.\nIn this study, a shooting machine was developed that considered these factors. Its efficacy was\nexamined in terms of its ability to determine the characteristics of each arrow, and to distinguish\nbetween normal and flawed arrows. Based on the experimental results, we identified the factors\nthat affected the shooting accuracy of arrows. In addition, the developed shooting machine was able\nto distinguish between normal and flawed arrows....
Hydraulic drive mode enables legged robots to have excellent characteristics, such as greater power-to-weight ratios, higher load\ncapacities, and faster response speeds than other robots. Nowadays, highly integrated valve-controlled cylinder, called the\nhydraulic drive unit (HDU), is employed to drive the joints of these robots. However, there are some common problems in the\nHDU resulted from hydraulic systems, such as strong nonlinearity, asymmetry dynamic characteristics between positive and\nnegativemoving directions of the piston rod, and time-varying parameters. It is difficult to obtain the desired control performance\nby just using classical control methods such as the traditional PID control. In this paper, a position controller that combines fuzzy\nterminal sliding mode control (FTSMC) and time delay estimation (TDE) is proposed, in which FTSMC adopts a compound\nreaching law which combines the tangent function and the exponential reaching law.Moreover, the fuzzy control is introduced to\nadjust the parameters of the reaching law in real time to improve the adaptability of FTSMC. Based on FTSMC, the external\nuncertain disturbance of the HDU position control system is estimated by TDE, which ensures the simplicity of system modeling\nand the normal application of FTSMC. Finally, the control effects of the controller combining FTSMC and TDE are verified on the\nHDU performance test platform and the load simulation experiment platform. The experimental results show that the proposed\ncontroller greatly improves the system position control performance and has a strong disturbance rejection ability and a good\nadaptability under different working conditions. The above research results can provide an important reference and experimental\nbasis for the inner loop of compliance control of legged robots....
Despite early enthusiasm in robotic-assisted NOTES, several technical challenges exist. Various spinopelvic anatomical constraints\ncan significantly act as obstacles and affect entry and space availability for the deployment of straight and rigid\ntransvaginal/transanal NOTES instruments. Anatomical constraints such as the sacral slope, position, and distance to the target\norgans are defined. Transvaginal access to the surgical site required a high insertion angle between...............
In view of the nonlinearity and time-varying characteristics of the electrohydraulic servo system of the robotic excavator, a\nnonlinear adaptive identification and control algorithm based on improved Hammerstein model is proposed. The Hammerstein\nalgorithm model can approximate the nonlinear system with enough precision, but for the time-varying systems is not satisfactory.\nIn order to compensate for the influence of time-varying factors, the fuzzy control module is designed to adaptively update\nthe forgetting factor. The experimental results show that the improved Hammerstein model error is about 40.11% less than the\nclassical Hammerstein model error. This proves that the improved Hammerstein model is feasible and effective to describe the\nelectrohydraulic servo system of the robotic excavator....
A new trajectory tracking control method based on the U-model is proposed to improve the trajectory tacking speed of robot\nmanipulators. The U-model method is introduced to relieve the requirement of the dynamic mathematical model and make the\ndesign of trajectory tracking controller of robot manipulators simpler. To further improve the trajectory tacking speed, an\nimproved iterative learning control algorithm is used to suppress the influence of the initial state error with less computation time.\nExperimental results show that the proposed control method is effective and practical for the trajectory tracking control of robot\nmanipulators, especially with a high real-time requirement....
In this paper we present two different, software and reconfigurable hardware,\nopen architecture approaches to the PUMA 560 robot controller implementation, fully document them\nand provide the full design specification, software code and hardware description. Such solutions are\nnecessary in todayâ??s robotics and industry: deprecated old control units render robotic installations\nuseless and allow no upgrades, advancements, or innovation in an inherently innovative ecosystem.\nFor the sake of simplicity, just the first robot axis is considered. The first approach described is a PC\nsolution with data acquisition I/O board (Humusoft MF634). This board is supported with Matlab\nReal-TimeWindows Toolbox for real-time applications and thus whole controller was designed in\nMatlab environment. The second approach is a robot controller developed on field programmable\ngate arrays (FPGA) board. The complexity of FPGA design can be overcome by using a third party\nsoftware package, such as self-developed Matlab FPGA Real Time Toolbox. In both cases, parameters\nof motion controller are calculated by using simulation of the PUMA 560 robot first axis motion.\nSimulations were conducted in Matlab/Simulink using Robotics Toolbox....
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