Virtual Simulation System with Path-following Control for Lunar Rovers Moving on Rough Terrain

Virtual simulation technology is of great importance for the teleoperation of lunar rovers during the exploration phase, as well as the design of locomotion systems, performance evaluation, and control strategy verification during the R&D phase. The currently used simulation methods for lunar rovers have several disadvantages such as poor fidelity for wheel-soil interaction mechanics, difficulty in simulating rough terrains, and high complexity making it difficult to realize mobility control in simulation systems. This paper presents an approach for the construction of a virtual simulation system that integrates the features of 3D modeling, wheel-soil interaction mechanics, dynamics analysis, mobility control, and visualization for lunar rovers. Wheel-soil interaction experiments are carried out to test the forces and moments acted on a lunar rover’s wheel by the soil with a vertical load of 80 N and slip ratios of 0, 0.03, 0.05, 0.1, 0.2, 0.3, 0.4, and 0.6. The experimental results are referenced in order to set the parameters’ values for the PAC2002 tire model of the ADAMS/Tire module. In addition, the rough lunar terrain is simulated with 3DS Max software after analyzing its characteristics, and a data-transfer program is developed with Matlab to simulate the 3D reappearance of a lunar environment in ADAMS. The 3D model of a lunar rover is developed by using Pro/E software and is then imported into ADAMS. Finally, a virtual simulation system for lunar rovers is developed. A path-following control strategy based on slip compensation for a six-wheeled lunar rover prototype is researched. The controller is implemented by using Matlab/Simulink to carry out joint simulations with ADAMS. The designed virtual lunar rover could follow the planned path on a rough terrain. This paper can also provide a reference scheme for virtual simulation and performance analysis of rovers moving on rough lunar terrains.

Following Control for a UUV using Temporary Path Generation Guidance

A path following control algorithm for an unmanned underwater vehicle（UUV） using temporary path generation guidance was proposed in this paper.Owing to different initial states of the vehicle,such as position and orientation,the path following control in the horizontal plane may yield a poor performance.To deal with the negative effect induced by initial states,a temporary path generation was presented based on the relationship between the original reference path and the vehicle’s initial states.With different relative positions between the vehicle and reference path,including out of straight lines,as well as inside and outside a circle,the related temporary paths guiding the vehicle to the reference path were able to be generated in real time.The vehicle was guided to steer along the temporary path until it reached the tangent point at the reference path,where the controller was designed using the input-output feedback linearization method.Simulation results demonstrated that the proposed algorithm is effective under the three different situations mentioned above.

Path following control of underactuated ships based on nonswitch analytic model predictive control

A path following controller is developed for underactuated ships with only surge force and yaw moment available to follow a predefined path.The proposed controller is based on nonswitch analytic model predictive control.It is shown that the optimal control law for a nonlinear path following system with ill-defined relative degree is continuous and nonsingular.The problem of ill-defined relative degree is solved.The path-following ability of the nonlinear system is guaranteed.Numerical simulations are provided to demonstrate the effectiveness of the proposed control law.

Serret-Frenet frame based on path following control for underactuated unmanned surface vehicles with dynamic uncertainties

The path following problem for an underactuated unmanned surface vehicle(USV) in the Serret-Frenet frame is addressed. The control system takes account of the uncertain influence induced by model perturbation, external disturbance, etc. By introducing the Serret-Frenet frame and global coordinate transformation, the control problem of underactuated system(a nonlinear system with single-input and ternate-output) is transformed into the control problem of actuated system(a single-input and single-output nonlinear system), which simplifies the controller design. A backstepping adaptive sliding mode controller(BADSMC)is proposed based on backstepping design technique, adaptive method and theory of dynamic slide model control(DSMC). Then, it is proven that the state of closed loop system is globally stabilized to the desired configuration with the proposed controller. Simulation results are presented to illustrate the effectiveness of the proposed controller.

Inverse Optimal Control for Speed-varying Path Following of Marine Vessels with Actuator Dynamics

A controller which is locally optimal near the origin and globally inverse optimal for the nonlinear system is proposed for path following of over actuated marine crafts with actuator dynamics. The motivation is the existence of undesired signals sent to the actuators, which can result in bad behavior in path following. To attenuate the oscillation of the control signal and obtain smooth thrust outputs, the actuator dynamics are added into the ship maneuvering model. Instead of modifying the Line-of-Sight (LOS) guidance law, this proposed controller can easily adjust the vessel speed to minimize the large cross-track error caused by the high vessel speed when it is turning. Numerical simulations demonstrate the validity of this proposed controller.

PREDICTIVE CONTROL FOR OPTIMAL PATH TERRAIN FOLLOWING SYSTEM

In this paper output predictive algorithm is applied to the design of predictive controller for an optimal path terrain following system. In this way, the error of path tracking is decreased to a minimum degree simply and efficiently and the computation time for the optimal path is shortened greatly. Therefore, the real-time processing of the optimal path terrain following system is made to be very helpful.

Path Following Control of A Deep-Sea Manned Submersible Based upon NTSM

In this paper, a robust path following control law is proposed for a deep-sea manned submersible maneuvering along a predeterminated path. Developed in China, the submersible is underactuated in the horizontal plane in that it is actuated by two perpendicular thrusts in this plane. The advanced non-singular terminal sliding mode （NTSM） is implemented for the design of the path following controller, which can ensure the convergence of the motion system in finite time and improve its robustness against parametric uncertainties and environmental disturbances. In the process of controller design, the close-loop stability is considered and proved by Lyapunov＇ s stability theory. With the experimental data, numerical simulations are provided to verify the control law for path following of the deep-sea manned submersible.

Autopilot Control Synthesis for Path Tracking Maneuvers of Underwater Vehicles

This paper is concerned with the robust control synthesis of autonomous underwater vehicle （AUV） for general path following maneuvers. First, we present maneuvering kinematics and vehicle dynamics in a unified framework. Based on H∞ loop-shaping procedure, the 2-DOF autopilot controller has been presented to enhance stability and path tracking. By use of model reduction, the high-order control system is reduced to one with reasonable order, and further the scaled low-order controller has been analyzed in both the frequency and the time domains. Finally, it is shown that the autopilot control system provides robust performance and stability against prescribed levels of uncertainty.

Risk Control of Transmission Line Overload for Wind-Integrated Power Systems

With the rapid development of the wind generation,uncertainties of random wind and load bring some inevitable impacts on the security of power system. Once the uncertainty causes line power to exceed its limit, line overload will occur. The paper presents the risk control of transmission line overload for windintegrated power systems. Firstly, a risk control model of line overload is proposed considering the uncertainties of loads,generator outputs and wind powers. The generation cost and security level of system associated with overload can be optimally controlled. Then path following interior point method is employed to carry out the optimal control. Finally the simulation is made on the modified IEEE-30 bus system. Results show that the risk of line overload is effectively reduced through the optimization of control variables.

基于Leader-Follower策略的双联AGV协同运载控制方法

针对面向大部件协同运载的双联AGV系统,融合单台全向移动AGV的路径跟踪运动学模型与Leader-Follower策略下的队形保持方法建立了一种双联AGV的协同偏差模型。基于该模型,采用Lyapunov反演法,提出一种双联AGV协同运载的运动学控制模型。最后通过软件仿真和系统实验验证了该控制模型的运行稳定性、精确性和协调性。

基于多模型自适应方法的智能汽车路径跟踪控制

路径跟踪控制是智能汽车的一项核心技术,跟踪效果的精确性和在各种路面附着条件下的鲁棒性是该技术的两大关键要素。但汽车动力学模型的不确定性,尤其是轮胎侧偏刚度的摄动使这两者难以同时得到满足。针对这一问题,将多模型自适应理论引入到智能汽车运动控制中处理不确定性系统的控制。首先,推导了多模型自适应控制律,提出了凸包构架下各个顶点的子模型对真实模型的自适应逼近律,并通过李雅普诺夫函数证明了所提出自适应律的收敛能力。在此基础上建立了汽车动力学模型和车辆-路径联合模型,并由多个顶点子模型构建可覆盖汽车轮胎侧偏刚度摄动范围的凸多面体,利用汽车动力学模型求解自适应率,通过车辆-路径联合模型,基于线性二次型方法(linear quadratic regulator,LQR)求解各个顶点的子模型处的反馈控制律,并通过所得出的自适应权重进行加权。基于Carsim/Simulink的联合仿真结果表明,所提出的多模型自适应路径跟踪控制器在保证鲁棒性的同时克服了传统鲁棒控制方法的保守性问题,与基于名义模型的LQR控制器和鲁棒保性能控制器相比,在高附着路面和低附着路面上都可以取得更好的控制效果,很好地解决了路径跟踪控制中精确性与鲁棒性之间的两难问题。最后,通过快速原型测试平台对算法进行了进一步的实验验证。结果表明,所提出的多模型自适应算法实时性良好,具有较好的工程应用潜力。

面向海底管道巡检的AUV三维自适应路径跟踪

针对面向海底管道巡检任务的欠驱动自主水下航行器(AUV)三维路径跟踪控制问题进行研究。首先,在固定坐标系和机体坐标系下建立AUV的运动学模型,为设计适宜运动控制的三维路径跟踪控制器,建立流体坐标系,并在Serret-Frenet坐标系下建立AUV的路径跟踪误差模型;其次,将可变前视距离引入传统视线(LOS)制导策略,提出一种自适应LOS制导策略以提高制导精度,并基于此设计面向海底管道巡检的AUV三维路径跟踪控制器,使得AUV可有效跟踪设定的参数化路径;最后,基于李雅普诺夫稳定性理论证明了闭环系统的稳定性。仿真结果验证了所提面向海底管道巡检的三维路径跟踪控制器的有效性。研究成果能够改善AUV的操纵性,可为面向海底管道巡检的无人水下航行器路径跟踪控制方法提供参考。

基于改进LADRC的突变载荷无人艇路径跟踪控制

本文针对上述问题提出一种基于改进线性自抗扰控制的控制架构来提高无人艇路径跟踪控制的抗干扰能力及跟踪精度。首先,采用积分视距制导法来为无人艇路径跟踪制导提供依据;其次,针对跟踪微分器固有的超调问题,基于一种改进的线性自抗扰控制方法设计了无人艇转首力矩控制器,以控制无人艇受到突变载荷时突变的航向角,从而提高路径跟踪精度;然后采用潜射导弹发射反力曲线模拟无人艇受到突变载荷情况,并且考虑无人艇在风、浪、流联合作用下的干扰作用力;最后,使用Simulink进行仿真试验,并与PID控制器进行了对比。在无人艇突变载荷工况下,该方法能够在满足系统的速度约束条件下对给定的直线路径进行快速响应并精确跟踪;与传统PID控制器相比,其收敛速度提高了约50%,其最大横向误差响应幅值减小了约53%,针对风、浪、流的联合干扰,本文设计的控制器的抗干扰能力显著优于PID控制器。仿真结果表明本文提出的改进线性自抗扰路径跟踪控制器具有优良的抗干扰能力和控制效果。

基于CTNN算法的智能小车路径跟踪控制研究

针对目前路径跟踪控制检测方法精度低、实时性能差的问题,提出一种基于深度机器学习的构建树形神经网络CTNN(Constructing Tree shaped Neural Net)的深度学习算法。该算法通过深度机器学习,构建针对性强的学习集,同时在模型车中实现。将传统机器学习算法与文章所提出的算法在相同行驶条件下的实时响应进行比较,仿真结果表明,CTNN算法在恶劣的行驶环境中,实时性、鲁棒性均得到一定程度的提高。

无人驾驶汽车路径跟踪控制的算法综述

国内外对无人驾驶车辆运动控制问题的研究,主要分为纵向运动控制、路径跟踪控制和轨迹跟踪控制。其中,路径跟踪控制是无人驾驶汽车运动控制的重点研究方向,路径跟踪控制中控制器设计是重点和难点。路径跟踪控制的研究主要集中在常规工况,对复杂路况、恶劣天气、突发事件等非常规工况的研究较少,增强控制算法的鲁棒性以应对非常规工况是无人驾驶汽车路径跟踪控制算法未来的发展重点。

基于矢量场制导法和模型预测控制的船舶路径跟踪与避碰

为提高船舶路径跟踪和避碰效果,提出了一种基于矢量场制导法的模型预测控制方法.首先,采用矢量场制导算法将船舶的路径跟踪和船舶避碰问题转换为航向控制问题;然后,采用一阶Nomoto响应模型作为模型预测控制的动力学模型,考虑船舶的舵角输入受限问题,引入干扰观测器对模型误差项和环境扰动进行补偿,并应用Lyapunov理论证明了所设计的路径跟踪控制系统的稳定性;最后,设计了基于矢量场制导法的避碰策略,使船舶在路径跟踪的过程中同时完成自主避碰.仿真计算结果表明,开发的方法可以使船舶在波浪干扰作用下准确地跟踪目标路径并有效实现避碰.

速度矢量场二阶滑模无人艇引导律

针对航速和航道未知扰动等因素,提出一种速度矢量场二阶滑模无人水面艇(USV)引导律。首先,建立无人艇运动学和航向角动力学模型;其次构造路径误差(y_(e))模型,设计基于航速(V_(g))的路径误差矢量场,速度越大,航向角变化越小;再结合二阶滑模面设计一种速度矢量场二阶滑模无人艇引导律,并考虑未知扰动因素Δ分析速度矢量场二阶滑模无人艇引导律的稳定性。仿真结果表明:相比于经典矢量场,速度矢量场有效实现航速V_(g)越快,航向角变化率越小,矢量场越平缓,提高了USV航行安全性和稳定性;基于速度矢量场二阶滑模无人艇引导律的路径跟踪控制系统鲁棒性更强,路径跟踪准确度更高,能够较好地完成路径跟踪。

基于扰动观测的USVs协同路径跟踪控制

论文针对多无人艇协同控制系统中出现的通信资源有限、存在外界环境扰动及收敛速度慢等问题,提出了一种基于扰动观测器的固定时间无人艇协同路径跟踪控制算法。首先,结合固定时间算法、参数协同算法及事件触发通信机制,设计了固定时间事件触发参数协同模块,以此协同期望路径上的参数、计算无人艇在各自期望路径上的理想位置并降低通讯资源消耗。其次,为了使无人艇不受外界环境干扰并令其固定时间内实现轨迹跟踪控制,设计了固定时间轨迹跟踪控制模块,其中包括固定时间扰动观测器以及固定时间跟踪控制器。文中各模块算法都能保证固定时间收敛,因而整个系统能够实现固定时间收敛。仿真结果验证了论文设计算法的有效性。