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排序方式: 共有831条查询结果,搜索用时 46 毫秒
1.
《Mechatronics》2022
This paper considers the shared path following control of an unmanned ground vehicle by a single person. A passive measure of human intent is used to blend the human and machine inputs in a mixed initiative approach. The blending law is combined with saturated super-twisting sliding mode speed and heading controllers, so that exogenous disturbances can be counteracted via equivalent control. It is proven that when the proposed blending law is used, the combined control signals from both the human and automatic controller respect the actuator magnitude constraints of the machine. To demonstrate the approach, shared control experiments are performed using an unmanned ground vehicle, which follows a lawn mower pattern shaped path. 相似文献
2.
Ali Maghami Dominik Schillinger 《International journal for numerical methods in engineering》2020,121(5):967-989
We explore a truncation error criterion to steer adaptive step length refinement and coarsening in incremental-iterative path following procedures, applied to problems in large-deformation structural mechanics. Elaborating on ideas proposed by Bergan and collaborators in the 1970s, we first describe an easily computable scalar stiffness parameter whose sign and rate of change provide reliable information on the local behavior and complexity of the equilibrium path. We then derive a simple scaling law that adaptively adjusts the length of the next step based on the rate of change of the stiffness parameter at previous points on the path. We show that this scaling is equivalent to keeping a local truncation error constant in each step. We demonstrate with numerical examples that our adaptive method follows a path with a significantly reduced number of points compared to an analysis with uniform step length of the same fidelity level. A comparison with Abaqus illustrates that the truncation error criterion effectively concentrates points around the smallest-scale features of the path, which is generally not possible with automatic incrementation solely based on local convergence properties. 相似文献
3.
Long-Wen Chang Shui-kung Chuag Shang-shung Yu 《Multidimensional Systems and Signal Processing》1994,5(3):319-330
The compression of Chinese characters is very important for Chinese office automation and desktop publishing. In this paper, various methods are used to compress 13,051 Chinese characters losslessly by coding their skeleton points. The skeleton points are composed of isolated points and curves. To trace every point in a curve once and consecutively is a NP problem. Therefore, we use contour path following and revisiting algorithms to trace skeleton curves with chain codes. The remaining isolated skeleton points are encoded by an Elias code. Our coding method has a better compression rate than that of conventional skeleton coding. 相似文献
4.
5.
徐新鸣 《计算机光盘软件与应用》2012,(3):153-154
作为三维地图引擎中的重要一部分,地形跟踪算法起到了模拟各种不同地形与运动设备的作用。好的地形跟踪算法不仅可以实现水面、沙地、森林等在各种地形上行进的感受,还能模拟出船舶、车辆等各种不同载体的运动感受。在一款三维导航产品中,做好地形跟踪算法,对于用户体验的改善是相当大的。 相似文献
6.
We prove the existence of a P-type (proportional-type) space-learning control, which, on the basis of a kinematic third order nonlinear model of an autonomous nonholonomic vehicle and by a proper choice of the proportional control gain, guarantees asymptotic tracking of planar curves whose uncertain curvature is L-periodic in the curvilinear abscissa. The behavior of a human driver, who repetitively learns the correct action from the past experience in the space, is mathematically reproduced. A stability analysis is presented while simulation results demonstrate the effectiveness of the presented approach. 相似文献
7.
Choosing an appropriate control scheme to alleviate nonlinearities and uncertainties is not a trivial task, especially when models are not easily available and practical evaluation provides the only means for actual performance assessment. Various factors can contribute to these nonlinearities and uncertainties, such as friction and stiction. Thus, this article investigates four different control schemes, namely PID, adaptive, conventional sliding mode control (SMC) and integral sliding mode control (ISMC) which are implemented in the Bristol Elumotion Robot Hand (BERUL) to analyse and overcome the aforementioned problems. The hand has five fingers with 16 joints and all fingers are underactuated. The implementation of the proposed control schemes are challenging since the BERUL fingers have significant friction, stiction and unknown parameters. The fingers are light in weight and fragile. Comparative performance characteristics have shown that the ISMC is the most suitable candidate to provide good experimental trajectory following and positioning control for underactuated BERUL fingers. 相似文献
8.
This paper presents the trajectory tracking control of an autonomous underwater vehicle(AUV). To cope with parametric uncertainties owing to the hydrodynamic effect, an adaptive control law is developed for the AUV to track the desired trajectory. This desired state-dependent regressor matrix-based controller provides consistent results under hydrodynamic parametric uncertainties.Stability of the developed controller is verified using the Lyapunov s direct method. Numerical simulations are carried out to study the efficacy of the proposed adaptive controller. 相似文献
9.
针对固定参数PID方法在无人水面艇直线路径跟踪控制中出现的大迴转问题,提出一种基于模糊PID的直线路径跟踪方法。在系统中增加模糊推理模块,利用航向与跟踪直线之间的偏差角以及无人艇位置与跟踪直线之间的距离误差,根据模糊推理的方法动态地调整PID参数。通过PID控制器实时调整左右两侧推进电机的输入电压,实现对给定直线路径的自主跟踪。仿真结果表明,在初始航向偏差角较大时,该方法克服了采用固定参数PID控制方法时出现的大迴转现象;在初始航向偏差角较小时,该方法在超调量以及调节时间方面的直线跟踪性能优于固定参数PID控制方法。 相似文献
10.
The micro modeling for electric vehicle and its solution were investigated. A new car-following model for electric vehicle was proposed based on the existing car-following models. The impacts of the electric vehicle's charging electricity were studied from the numerical perspective. The numerical results show that the electric vehicle's charging electricity will destroy the stability of uniform flow and produce some prominent queues and these traffic phenomena are directly related to the initial headway, the distance between two adjacent charging stations and the number of charging stations. The above results can help traffic engineer to choose the position of charging station and the electric vehicle's driver to adjust his/her driving behavior in the traffic system with charging station. 相似文献