查看更多>>摘要：A new control scheme is proposed for the nonlinear system with unmodeled dynamics based on HJI and adaptive neural network L_2-gain controller. The aim is to make the closed-loop system a finite gain L_2 stable between the disturbance and output of the system. The approach will avoid the limit of precise modelling, only need the unmodeled dynamics to be bounded without the other transcendent information. The simulation results show that the control system designed can satisfy the performance indicators proposed.
查看更多>>摘要：Designing a visual tracking system to track an object is a complex task because a large amount of video data must be transmitted and processed in real time. In this study, a stereo vision system is used to acquire the 3D positions of the target, tracking can be achieved by applying the CAMSHIFT algorithm, then apply the fuzzy reasoning control to steer the mobile robot to follow the selected target and avoid the in-path obstacles. The adopted obstacle avoidance component is based on the Harris corner detection and the binocular stereo imaging, which performs the correspondence calculation. Therefore a depth map is created and showing the relative 3D distances of the detected substantial features to the robot, which provides the information of the in-path obstacles in front of the wheeled mobile robot. The designed visual tracking and servo system is less sensitive to lighting influences and thus performs more efficiently. Experimental results showed that the mobile robot vision system successfully finished the target-following task by avoiding obstacles.
查看更多>>摘要：Designing a visual tracking system to pick-and-place an object is a complex task because a large amount of video data must be transmitted and processed in real time. In this work, a mobile robot visual control system is proposed which uses a stereo vision to acquire the 3D positions of a target color ball and to control an end-effector to pick the ball up and place it in the specified location. This mobile robotic system is based on the Open Source Computer Vision Library for programming framework with portable components, off-the-shelf commercial hardware, and minimal programming. Two calibrated web cameras are used to track the color ball and a 2-axis end-effector is controlled to pick up the tracked color ball. The visual tracking and servo system as designed in this work is less sensitive to lighting influences and thus performs more efficiently. Experimental results show that the open platform based robot vision system successfully finishes the pick-and-place task and could be scalable to many diverse areas of robotics research.
查看更多>>摘要：This paper presents an adaptive controller based on the passivity theorem to control the position of an induction machine. Firstly, an open-loop flux observer estimates the rotor flux linkages, and then adaptive laws are designed to estimate the inverse rotor time constant, mechanical parameters, and load torque. The passive properties of the feedback connection of the rotor flux observer to the inverse rotor time constant estimator, and the adaptive controller are analyzed by the passivity theorem. The overall control system is formally verified to be globally stable by the theorem instead of Lyapunov-like functions. Experimental results show that the parameter estimation errors converge to zero when the position command is a sinusoidal signal with two distinct frequencies. Furthermore, good position tracking responses can be obtained, and the approach is robust with regard to the variation of the parameters and load torque disturbances.
查看更多>>摘要：The aim of this study was to investigate the firing test properties of NiCr alloy thin film bridge electro-initiators(detonators). The function time of firing test was characterized in terms of their area, shape, resistance, and thickness of thin film bridge electro-initiators(detonators). It is found that samples with small film bridge area show profound and positive influence on the function time of firing test. The shortest function time is 120 μs (3.165 Ω).
查看更多>>摘要：A PROFI-BUS based industrial robot control system is introduced from the viewpoint of both software and hardware. It is discussed about how to use PC technology and field-bus technology to design an open robot control system. The system adopts a three- layer structure, which is mainly configured with universal control devices, to realize a modular and universal design. A high-speed field-bus is designed for connecting servo system and IPC, to ensure real-time capability; another low-speed Field-bus is used to connect IPC and PLC, HMI, teaching panel and other devices for data exchange, while reducing the occupancy of system resources. The software system adopts the modular design with Windows NT and RTX, which fully exploits the powerful functions of Window NT system and meets the requirements of real-time system. This open structure greatly enhances the system's flexibility and openness.
查看更多>>摘要：Kinematics and dynamics calculation is meaningful both in the design stage and the movement control stage of a manipulator. After the comparison among different methods of manipulator kinematics and dynamics, this paper adopts homogeneous coordinate transformation to analyze and research positive solutions of the space 5-DOF manipulator kinematics, applies mathematics in the approximate calculation to solve the equations' inverse problems because of the explicit difficult nature to derive analytic solution; conducts dynamics analysis to the manipulator and adopts the Lagrange dynamics method to establish an ideal model, i.e., a dynamics model integrating with corresponding computer algorithm without considering the influences of friction force, to complete the research on the simulation calculation of dynamics inverse solution.
查看更多>>摘要：The designing method of filtering, fault-tolerating, and fusing PID control is put forward, concerning multisensor time-delay system with colored noise disturbance. First of all, this method detects fault and isolate the data by the weighted square sum of residuals (WSSR) method which is measured by multisensors, then the data which is detected right will be measurement fused, and the fused data will be optimally filtered basing on modern time series analysis method. Finally, the global optimal estimation of measured data will be got, which will be brought back to the input endian in order to improve PID controlling accuracy. A 3-sensor servomotor control example shows the effectiveness of the method.
查看更多>>摘要：Nonholonomic wheeled mobile service robot's posture error model denoted by polar coordinates in global coordinates is established .Based on the inherent discontinuousness of the closed-loop system model, a novel nonlinear state feedback stabilization control law is proposed, which causes closed-loop system state space equation of robot to have isolated equilibrium state at origin. By Lyapunov candidate function method, this paper concludes that the closed-loop system is global uniformly asymptotically stable at origin. Simulation results indicate that the proposed control law is effective.
查看更多>>摘要：Harmonic drive has widespread applications for its compact size and high reduction ratios. It is often favored for electro-mechanical systems with space and weight limitation. In order to minimize the volume and improve its transmission capacity, more and more aborative design technologies are adopted. For structural analyses in assembly state and in transmission stage, Finite Element Analysis (FEA) can be widely applied to get proper parameters and performance. Flexspline usually endures large deformation under assembly force from wave generator. In transmission state. driving force leads to multiple tooth mesh contact between flexspline and circular spline teeth. In this paper, shell element is applied to build flexspline cone, and tapered beam element is used to model the teeth on the flexspline. Contact relation between flexspline and wave generator is simulated by contact element. Forced displacement of flexspline is imposed by contact analysis. Transmission forces are acted at the teeth tips on the flexspline in mesh state, whose values are determined according to experimental distribution. Simulations of assembly state and transmission state are computed in ANSYS. Deformation and stress distribution in assembly state are compared with that in transmission state. Some suggestions for long life and high performance design are present.
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