离轴式拖车移动机器人的反馈镇定

由于离轴式拖车移动机器人的模型不能转化为非完整链式模型, 因而无法采用针对非完整链式模型的控制方法. 针对有多节离轴式拖车的移动机器人, 给出了一种基于时间–状态能控形的反馈镇定控制算法. 首先推导出系统的线性化时间–状态模型, 并证明了其能控性; 进而设计了一种线性切换反馈镇定控制律, 该控制律可以保证系统的状态在有限时间内收敛到原点的任意小邻域内. 仿真结果证实了所提控制算法的有效性.     

Robustification of the modular tracking control system for non-Standard N-Trailers of uncertain kinematics

The paper is devoted to the problem of control performance robustification for the modular cascade-like tracking controller, recently devised for the N-Trailer vehicles equipped solely with off-axle hitching (called the non-Standard N-Trailers). It has been shown that the control performance degradation due to parametric uncertainty of the N-Trailer kinematics can be treated as an effect of an external input-matched disturbance acting on the closed-loop system dynamics. One proposes to suppress this detrimental effect by redesigning of the original cascade-like tracking controller combining it with an additional disturbance observation-compensation loop. It is revealed under which conditions the new robustified control law guarantees uniform ultimate boundedness of tracking errors for arbitrarily small ultimate bounds. Forecasts of a theoretical analysis have been validated by numerical examples and practically verified with a laboratory-scale three-trailer robotic vehicle. The results illustrate control performance improvement achievable with the new robust controller, even in the case of substantial parametric uncertainty of a vehicle model.     

浅析梳棉机弹性盖板针布充塞挂花起因

为提高梳棉机弹性盖板针布对纤维的分梳、除杂、均匀、混合等梳理效果,解析了弹性盖板针布分梳纤维的过程;通过建立理论模型,进一步分析了弹性盖板针布与锡林针布之间分梳纤维时的力学状态,归纳、建立数学关系式μ=tanα;联系生产实际,解析弹性盖板针布充塞挂花的起因.指出:弹性盖板针布充塞挂花的根源在于对针布与纤维之间的摩擦因数...     

剥棉罗拉针布工艺改进的实践

为解决剥棉罗拉针布挂花、返花的问题．采取改进剥棉罗拉针布齿型、原材料及加工工艺,试验证明：选用高碳低合金钢原料加工的等腰形薄齿剥棉罗拉针布齿条,经改进热处理、特殊表面处理工艺后,能有效防止挂花、返花,提高梳理质量。     

Forward tracking of complex trajectories with non-Standard N-Trailers of non-minimum-phase kinematics avoiding a jackknife effect

It is a common conviction that forward motion control of tractor-trailer vehicles is a substantially simpler problem relative to reversing with trailers. This opinion may be misleading when considering the N-trailer vehicles moving forward with positive hitching offsets when a guidance point is located on a trailer. Due to the non-minimum-phase nature of vehicle kinematics, closing a feedback from a trailer posture can lead to the jackknife effect in this case. So far, there has been no solution to this problem for the N-trailers admitting trajectories of a varying curvature. To fill this gap, we propose a scalable and modular control strategy applicable to the N-trailer vehicles equipped solely with off-axle interconnections. The concept relies on a transformation of the control problem posed for the non-minimum-phase kinematics into a corresponding problem formulated for a virtual vehicle of minimum-phase kinematics, which can be solved by using the recently proposed cascade-like controller.     

快速挂接器的分析与优化

选取了圆弧曲线、抛物线和余弦曲线三种典型的曲线形式对凸轮板与挂接销接触的曲线运用ANSYS的接触分析和优化功能进行了参数化建模和优化分析,优化效果明显。结果表明,凸轮板经优化后,挂接销推开凸轮板的接触力有了明显的减小,以优化后圆弧曲线的接触力为最小,优化效果明显。     

A highly scalable path-following controller for N-trailers with off-axle hitching

The paper presents a highly scalable nonlinear cascaded-like path-following feedback controller for N-trailer robotic vehicles equipped with arbitrary number of off-axle hitched trailers. In contrast to the other path-following control laws proposed in the literature for N-trailer robots, the presented control approach does not require determination of the shortest distance to a reference path. By introducing the so-called segment-platooning reference paths, and under the sign-homogeneity assumption for hitching offsets, the asymptotic following is guaranteed for both constant- and varying-curvature reference paths using either backward or forward vehicle motion strategy with a guidance point fixed on the last trailer. The paper contains experimental results obtained with a 3-trailer laboratory-scale vehicle.     

Application of the VFO method to set-point control for the N-trailer vehicle with off-axle hitching

In this article the cascaded set-point feedback controller has been proposed for kinematics of the articulated mobile vehicle equipped with arbitrary number of off-axle hitched trailers. The concept results from geometrical features of the vehicle model, and from application of the Vector-Field-Orientation method in the outer loop of the cascaded controller. Solution presented in this article is formulated in the original configuration space of the vehicle not involving any auxiliary state or input transformation. It guarantees convergence of the last vehicle segment to the prescribed neighbourhood of a desired posture along with approximate straightening of a vehicle kinematic chain during approaching the destination. Practical limits of the control input amplitudes have been taken into account during the control law derivation by the application of a simple on-line scaling procedure to the nominally computed control functions. Results of numerical simulations illustrate effectiveness of the method for a 3-trailer vehicle.     

离轴式带拖车移动机器人的路径跟踪控制

研究了离轴式拖车移动机器人系统任意一节车体的几何路径跟踪问题. 首先推导出系统的时间--状态线性化模型并证明了系统的能控性; 然后应用内模原理设计了线性动态反馈控制律, 该控制律可以保证路径跟踪误差有界和最终一致有界, 且最终一致界正比于期望路径函数变化率的立方. 仿真结果证实了控制律的有效性.