Heuristics for determining a patrol path of an unmanned combat vehicle

We consider a problem of finding a path of an unmanned combat vehicle that patrols a given area by visiting a given set of checkpoints with the objective of minimizing possibility of enemy’s infiltration. In this study, we focus on a situation in which the possibility of enemy’s infiltration at (through) each checkpoint is increased nonlinearly as time passes and the checkpoint may be patrolled multiple times during a planning horizon. We develop two-phase heuristics in which an initial path is constructed in the first phase and then it is improved in the second phase. For evaluation of the performance of the proposed heuristics, computational experiments are performed on randomly generated problem instances, and results show that the heuristics give good solutions in a reasonably short time.     

Immersion and invariance-based integrated guidance and control for unmanned aerial vehicle path following

An integrated guidance and control scheme is proposed on path following for the unmanned aerial vehicle. It is capable of handling the coupled non-linearities of the path's kinematics and the aircraft's dynamics independently. In the path coordinate, the guidance law is designed based on a nominal model, and the non-linearity of the path's kinematics is taken into full consideration. In the time coordinate, the flight control law is designed as a feed-forward controller, and it can guarantee the robustness of the guidance law with respect to the actual aircraft's dynamics. Instead of only employing Lyapunov method, the concept of immersion and invariance is also applied to explicitly analyse the stability in both time and path coordinates, and the asymptotic stability of the closed-loop system can be guaranteed. What is more, the regulation-based and immersion-based adaptive technologies are synthetically utilised to handle the unknown parameters. Finally, the numerical simulations demonstrate the effectiveness of the developed integrated guidance and control scheme.     

固定双桨驱动的无人水面艇自主直线路径跟踪系统

针对直流电机驱动固定双桨的无人水面艇,介绍了一种自主直线路径跟踪系统,该系统由岸基监控系统和艇载控制系统组成,具有自主航行和遥控航行两种工作模式,可在自主航行出现危险时切换到遥控模式,保证航行安全。岸基监控系统通过数传电台与艇载控制系统通信,向艇载控制系统发送控制命令,接收并显示其传回的状态信息;艇载控制系统以工控机为主控单元,进行数据采集与解算,与岸基监控系统通信,并为直线路径跟踪控制算法提供程序接口;GPS双天线高精度测向定位系统为直线路径跟踪控制算法提供位置和航向信息,直线路径跟踪控制算法根据距离偏差和航向偏差计算出左右两侧电机电压,进而控制无人水面艇航行。实验分别采用了PID、模糊控制和模糊PID三种控制方法,系统实际水上实验表明,在风力2~3级,晴到多云天气条件下,无人水面艇对目标路径的最大跟踪误差小于0.6 m。     

无人机电源地面测试系统设计

为了实现对某型无人机电源系统的快速检测,设计了一种基于Labwindows/CVI的无人机电源地面测试系统。测试系统的硬件部分能够实现数据的快速采集,软件部份分为数据采集软件和数据处理软件。实际应用表明,该系统测试结果达到设计要求,具有运行稳定可靠、操作方便、维护简单的特点,能够满足无人机电源系统的维护保障需要。     

The influence of camouflage,obstruction, familiarity and spatial ability on target identification from an unmanned ground vehicle

The purpose of this study was to examine the effects of environmental and cognitive factors on the identification of targets from an unmanned ground vehicle (UGV). This was accomplished by manipulating obstruction, camouflage and familiarity of objects in the environment, while also measuring spatial ability. The effects of these variables on target identification were studied by measuring performance of participants that observed pre-recorded video from a 1:35 scaled military operations in urban terrain facility. Analyses indicated that a combination of camouflage and obstruction caused the most detrimental effects on performance, and that there were differences in the recognition of familiar and unfamiliar targets. Further analysis indicated that these detrimental effects could only be overcome with a combination of target familiarity and spatial ability. The findings highlight the degree to which environmental factors hinder performance and the need for a multidimensional approach for improving performance under these conditions. Areas in need of future research are also discussed.

Practitioner Summary: Cognitive theory is applied to the problem of perception from UGVs. Results from an experimental study indicate that a combination of camouflage and obstruction caused the most detrimental effects on performance, with differences in the recognition of both familiar and unfamiliar targets. Familiarity and spatial ability interacted to predict the performance.     

Design and analysis of lateral motion control algorithms for an unmanned aerial vehicle with two control surfaces

This paper considers control of an unmanned aerial vehicle with two horizontal aerodynamic control surfaces in the modes of angular stabilization and coordinated turn. We analyze the linear yaw angle control algorithms based on roll angle variation in terms of their performance. In addition, we suggest an algorithm that ensures a required performance of yaw angle control. Some simulation results are given.     

Exponential stabilization of an underactuated autonomous surface vessel

This paper studies the problem of controlling the planar position and orientation of an autonomous surface vessel using two independent thrusters. It is first shown that although the system is not asymptotically stabilizable to a given configuration using a time-invariant continuous feedback, it is strongly accessible and small-time locally controllable at any equilibrium. Time-invariant discontinuous feedback laws are then constructed to asymptotically stabilize the system to the desired configuration with exponential convergence rates. A simulation example is included to demonstrate the results.     

Robust tracking control for an air-breathing hypersonic vehicle with input constraints

The focus of this paper is on the design and simulation of robust tracking control for an air-breathing hypersonic vehicle (AHV), which is affected by high nonlinearity, uncertain parameters and input constraints. The linearisation method is employed for the longitudinal AHV model about a specific trim condition, and then considering the additive uncertainties of three parameters, the linearised model is just in the form of affine parameter dependence. From this point, the linear parameter-varying method is applied to design the desired controller. The poles for the closed-loop system of the linearised model are placed into a desired vertical strip, and the quadratic stability of the closed-loop system is guaranteed. Input constraints of the AHV are addressed by additional linear matrix inequalities. Finally, the designed controller is evaluated on the nonlinear AHV model and simulation results demonstrate excellent tracking performance with good robustness.     

无人机飞控设备检测系统

介绍了一种无人机飞控设备检测系统,给出了系统的组成和硬件配置,讨论了系统软件设计和测试原理。该系统可以自动检测和校准无人机各种传感器、机载计算机及舵机的输出参数,具有一定的可靠性和准确性。     

Three-dimensional optimal path planning for waypoint guidance of an autonomous underwater vehicle

In this paper, optimal three-dimensional paths are generated offline for waypoint guidance of a miniature Autonomous Underwater Vehicle (AUV). Having the starting point, the destination point, and the position and dimension of the obstacles, the AUV is intended to systematically plan an optimal path toward the target. The path is defined as a set of waypoints to be passed by the vehicle. Four criteria are considered for evaluation of an optimal path; they are “total length of path”, “margin of safety”, “smoothness of the planar motion” and “gradient of diving”. A set of Pareto-optimal solutions is found where each solution represents an optimal feasible path that cannot be outrun by any other path considering all four criteria. Then, a proposed three-dimensional guidance system is used for guidance of the AUV through selected optimal paths. This system is inspired from the Line-of-Sight (LOS) guidance strategy; the idea is to select the desired depth, presumed proportional to the horizontal distance of the AUV and the target. To develop this guidance strategy, the dynamic modeling of this novel miniature AUV is also derived. The simulation results show that this guidance system efficiently guides the AUV through the optimal paths.     

Design and implementation of an autonomous flight control law for a UAV helicopter

In this paper, we present the design and implementation of an autonomous flight control law for a small-scale unmanned aerial vehicle (UAV) helicopter. The approach is decentralized in nature by incorporating a newly developed nonlinear control technique, namely the composite nonlinear feedback control, together with dynamic inversion. The overall control law consists of three hierarchical layers, namely, the kernel control, command generator and flight scheduling, and is implemented and verified in flight tests on the actual UAV helicopter. The flight test results demonstrate that the UAV helicopter is capable of carrying out complicated flight missions autonomously.     

MPC-based compensation control system for the yaw stability of distributed drive electric vehicle

Conventional yaw stability strategy of distributed drive electric vehicle (DDEV) is usually realised by torque distribution strategy. However, the instantaneous variations of four independent tyres slip ratio and the effect of disturbance have not been considered sufficiently. Therefore, it is difficult to realise the robustness of yaw stability for DDEV under various operating conditions. To solve this problem, a novel model predictive controller-based compensation control system (MPC-CCS) is proposed in this paper. The proposed MPC-CCS consists of two parts, an MPC based-feedback controller and a Kalman filter based-feedforward controller. In the feedback controller, a dual torque distribution scheme is adopted to obtain optimal torque values derived from the real-time signals of four independent tyres slip ratio, an MPC is designed to realise optimal torque values for vehicle yaw motion. In the feedforward controller, a Kalman filter is employed to attenuate the effect of the disturbance on yaw performance. In this way, the robustness of yaw stability for DDEV can be guaranteed by the proposed MPC-CCS. The proposed MPC-CCS is evaluated on eight degrees of freedom simulation platform and simulation results of different conditions show the effectiveness of the MPC-CCS.     

High accuracy path tracking for vehicles in presence of sliding: Application to farm vehicle automatic guidance for agricultural tasks

When designing an accurate automated guidance system for vehicles, a major problem is sliding and pseudo-sliding effects. This is especially the case in agricultural applications, where five-centimetre accuracy with respect to the desired trajectory is required, although the vehicles are moving on slippery ground. It has been established that RTK GPS was a very suitable sensor to achieve automated guidance with such high precision: several control laws have been designed for vehicles equipped with this sensor, and provide the expected guidance accuracy as long as the vehicles do not slide. In previous work, further control developments have been proposed to take sliding into account: guidance accuracy in slippery environments has been shown to be preserved, except transiently at the beginning/end of curves. In this paper, the design of this control law is first recalled and discussed. A Model Predictive Control method is then applied in order to preserve accuracy of guidance even during these curvature transitions. Finally, the overall control scheme is implemented, and improvements with respect to previous guidance laws are demonstrated through full-scale experiments.