月球软着陆避障段定点着陆导航方法研究

我国正在实施月球软着陆工程,月球软着陆避障段是着陆器动力下降过程的关键阶段.在该阶段,导航系统除了需要提供着陆器的位置、速度和姿态测量信息外,还需要识别月表障碍、寻找安全着陆点并将着陆器导引到该着陆点.软着陆避障段的自主导航以惯性导航为基础,为了克服惯性导航的累积误差,并实现对安全着陆点的高精度相对导航,需要引入图像敏感器与测距仪的测量信息对惯导系统加以修正.为此,本文提出了一种基于图像信息的高精度相对导航方法,首先用图像处理技术选择着陆区,然后通过跟踪自主选择的特征点序列实现精确的相对导航.仿真计算表明,该方法能够有效地修正惯性导航误差,实现安全避障和精确定点软着陆.     

自动泊车轨迹生成方法的研究

轮式移动机器人是机器人学的重要分支,广泛地应用于消防,军事等领域.轮式移动机器人属于非完整约束系统,也是典型的强非线性系统,一般的控制理论很难能够适用.根据重复变换法对轮式移动机器人自动泊车轨迹的生成作了尝试,通过移动机器人的两驱动轮的9种可能的微小移动组合,利用顺运动学计算出与其对应机器人的位置和姿态,选取最优解,实现了机器人在障碍及非障碍环境下的自动泊车,对移动机器人优化路径,提高姿态性能,通过仿真证明了算法的可行性,生成的泊车轨迹同人操纵下泊车的轨迹非常相似.     

Guidance in the main deceleration section during a lunar landing of a spacecraft with an integrated propulsion system

An algorithm is developed for terminal guidance during the main deceleration section of the lunar landing trajectory of a spacecraft with an integrated propulsion system, which has a main engine with variable thrust and four auxiliary nonthrottleable engines. A method of guidance adaptation to the actual motion conditions by measuring the thrust acceleration with jumps in time is proposed.     

Bioinspired design of a landing system with soft shock absorbers for autonomous aerial robots

One of the main challenges for autonomous aerial robots is to land safely on a target position on varied surface structures in real‐world applications. Most of current aerial robots (especially multirotors) use only rigid landing gears, which limit the adaptability to environments and can cause damage to the sensitive cameras and other electronics onboard. This paper presents a bioinpsired landing system for autonomous aerial robots, built on the inspire–abstract–implement design paradigm and an additive manufacturing process for soft thermoplastic materials. This novel landing system consists of 3D printable Sarrus shock absorbers and soft landing pads which are integrated with an one‐degree‐of‐freedom actuation mechanism. Both designs of the Sarrus shock absorber and the soft landing pad are analyzed via finite element analysis, and are characterized with dynamic mechanical measurements. The landing system with 3D printed soft components is characterized by completing landing tests on flat, convex, and concave steel structures and grassy field in a total of 60 times at different speeds between 1 and 2 m/s. The adaptability and shock absorption capacity of the proposed landing system is then evaluated and benchmarked against rigid legs. It reveals that the system is able to adapt to varied surface structures and reduce impact force by 540N at maximum. The bioinspired landing strategy presented in this paper opens a promising avenue in Aerial Biorobotics, where a cross‐disciplinary approach in vehicle control and navigation is combined with soft technologies, enabled with adaptive morphology.     

A geometric optimization method for the trajectory planning of flexible manipulators

Multibody System Dynamics - Lightweight and flexible robots offer an interesting answer to industrial needs for safety and efficiency. The control of such systems should be able to deal properly...     

Evolutionary algorithms with deterministic mutation operators used for the optimization of the trajectory of a four-bar mechanism

In this paper, we propose an Evolutionary Algorithm (EA) with a deterministic mutation operator which is a combination of EA with the Broyden, Fletcher, Goldfarb and Shanno (BFGS) method. The advantages of both optimization algorithms are retained and interconnected. The proposed algorithm shows faster convergence as well as increased reliability in the search for the global optimum. Results referring to the Fletcher and Powel test function in comparison with EA (Evolution Strategies, Evolutionary Programming, and Genetic Algorithms), provide sufficient indication for the performance of the new method. Finally, the proposed method is successfully implemented for the trajectory optimization of a four-bar mechanism.     

Stability-ensured topology optimization of boom structures with volume and stress considerations

The boom structure is a key component of giant boom cranes, and the stability-ensured topology optimization is critical to its lightweight design. The finite difference method, direct differentiation or adjoint method needs many time-consuming nonlinear analyses for this problem with a large number of design variables and constraints, and the last two methods are difficult to implement in off-the-shelf softwares. To overcome these challenges, this work first defines a global stability index to measure the global stability of the whole structure, and a compression member stability index to identify the buckling of compression members. Numerical and experimental verifications of these two stability indices are conducted by analyzing a simple three-dimensional frame. Next, the anti-buckling mechanism of boom structures is analyzed to develop the precedence order of freezing relative web members. The stability indices and the freezing measure are then utilized as a part of a novel Stability-Ensured Soft Kill Option (SSKO) algorithm, built upon the existing Soft Kill Option (SKO) method. The objective is to minimize the discrepancy between structural volume and predetermined target volume, while the global stability and stress are regarded as constraints. Lastly, the SSKO algorithm with different scenarios is applied to topology optimization problems of four-section frames and a ring crane boom; in both cases the consistent and stable topologies exhibit applicability of the proposed algorithm.     

Trailer truck trajectory optimization: the transportation of components for the Airbus A380

European aircraft manufacturer, Airbus, has started a program to develop the largest aircraft ever built, the Airbus A380, which would be able to carry between 550 to 800 passengers on two decks. The six components of the airplane are to be produced in different European cities. They need to be transported from these cities to Toulouse, France, for assembly, and several means of transportation have been investigated. The sizes of the freights, the length of the itinerary, and the narrowness of the critical passages constitute a challenge that classical transportation techniques in the domain of oversized convoys cannot easily overcome. Therefore, Airbus and the French national agency in charge of road management launched a research and development project divided into two parts. The objective of the first part is to adapt functions first to develop for mobile robots to the complex kinematics of trailer-truck systems and integrating these functions into a software platform. The second part of the project aims to define and develop a computer-aided driving system on board the vehicles in order to help the drivers carry out their task. This paper provides a brief overview of the state of the art in trajectory planning for mobile robots and vehicles, and discusses the development of original solutions to address both the kinematic complexity of one of the vehicles and the need to optimize the distance to obstacles.     

基于互信息操作变量曲线参数化的间歇过程批内修正优化

针对间歇过程批次内扰动影响最终优化效果的问题,提出一种基于互信息操作变量曲线参数化的间歇过程批内修正优化方法.首先根据操作变量与指标变量间互信息和相关系数划分出操作变量曲线上对指标变量作用近似的时段;然后,结合操作变量曲线的形态特征选择有代表性参数建立优化模型,以降低优化模型求解的复杂度.考虑到生产过程噪声干扰影响最终优化效果,在批次内设置决策点,并根据当前工况信息对决策点后未实施的操作变量曲线进行调整,以减弱批次内扰动对最终优化效果的影响.最后,将所提出方法用于某一化工厂双酚A结晶过程的优化研究,通过仿真结果验证了该方法的有效性.     

Building sustainable parking lots with the Web of Things

Peak-time traffic woes create considerable amount of stress and environmental pollution resulting in an economic loss. Research innovations in areas such as the Web of Things are able to curtail some of these issues by creating scalable and sustainable environments like parking lots, which provide motorists with access to convenient parking spots. We present a scalable parking lot network infrastructure that exposes parking management operations through a judicious mashup of physical things’ services within a parking lot. Our system uses service-oriented architecture, allowing motorists to reserve parking spots in advance. In doing so, our proposed system leverages the use of HTTP and Wi-Fi for the Web enablement and interoperability of things within a parking spot and elevates it as a Smart Parking Spot on the Web. Our suggested semantic Web-based structure for representing things makes it possible to query physical things’ states and services depending on their capabilities and other relevant parking-related parameters. Our performance evaluation reveals that a maximum of 40 % time is saved to find parking spots and also 40 % reduction in air pollution is observed.     

基于GPRS传输的车辆远程监控及行驶轨迹优化

为了远程监控和管理行驶的车辆,提高车辆运行效率,保障车辆驾驶安全,利用GPRS网络设计了基于C/S架构的车辆远程监控系统。根据GPS车辆定位数据,通过无线网络将数据传输至服务器。详细说明了数据传输和数据处理的过程,在客户端调用百度地图,并实时显示车辆位置和行驶轨迹。针对地图中车辆弯道行驶折线轨迹的问题,引入了二次B样条拟合算法,对车辆行驶轨迹进行有效拟合,改善折线轨迹的缺陷,反映车辆真实运动曲线。监控系统传输数据稳定,实现了实时显示车辆地理位置、精确跟踪的效果,达到了优化车辆折线轨迹的目的。     

Synthesis of decoupling laws for controlling the angular motion of landing module with solid-fuel landing engine minimizing the transient time

Application of the exact pole placement method and modal control to the problem of angular motion control of a landing module with a solid-fuel landing engine in the landing phase in the presence of deterministic external disturbances is considered. A technique for finding the poles that ensure the minimal transient time under the condition that the magnitude of the angular velocity of the landing module does not exceed a specified threshold is proposed. Examples of numerical simulation are discussed.     

A new parameter identification method of soft biological tissue combining genetic algorithm with analytical optimization

The main goal of this paper is to provide simple parameter identification process for most of hyperelastic constitutive laws in biomechanics of soft tissues. The advantage of our approach lies on its rapidity and effectiveness, by reducing analytically the number of parameters to identify in the model during the identification procedure. With the use of genetic algorithms, the search for an adequate initial guess point is avoided and the space solution of the objective function is reduced to meet only parameters that cannot be calculated analytically. As an example, we focus on models that predict arterial wall behaviour such as laws based on Fung’s type energy function (Holzapfel, 2006) [14] and (Holzapfel et al., 2000 model) [15]. Our approach is applied on uniaxial extension tests and the results are compared with available data in the literature.     

Optimization of variable blank holder force trajectory for springback reduction via sequential approximate optimization with radial basis function network

Springback is one of the major defects in sheet metal forming. Variable blank holder force (VBHF) approach is one of the effective ways for the springback reduction. In this paper, the VBHF trajectory is optimized to reduce the springback by a sequential approximate optimization (SAO) with radial basis function (RBF) network. The U-shaped forming in NUMISHEET’93 is employed to determine an optimum VBHF trajectory, for example. In this paper, the bending moment is taken as the objective function. The tearing of sheet during the forming is considered as the design constraint, and the forming limit diagram (FLD) is employed to evaluate the design constraint quantitatively. It has been found from numerical results that the optimal VBHF trajectory can drastically reduce the springback in comparison with various VBHF trajectories. Through the theoretical examination and numerical simulation, the springback reduction of metal forming by the VBHF trajectory is discussed.     

Particular features of the ocean glitter pattern observed from a sun-synchronous orbit

A simple analysis method is provided to locate the point of maximum sea surface glitter for a scanner on a sun-synchronous orbit. The method is easily extended to any type of scanning system. Sun glint avoidance methods are discussed.     

Local optimization of trajectory control of observations for mobile digital direction-finder in the location of discrete sources of radiation system

The procedure of local optimization of trajectory control of observations is discussed. The solution is obtained in relation to mobile digital direction-finder. The sources of radio emission (SRE), which radiation intensity satisfies to the regularities of the discrete Markov process with two states, as the objects of observation are considered. The sequence of consideration of probabilistic characteristics of the radiation intensity variations in the algorithm of control synthesis is shown. An example is given.     

定子斜槽月球车驱动电机性能的快速计算

通常采用3--D有限元方法分析斜槽电机的性能,但3--D模型剖分单元数目庞大、计算时间极长,对计算机性能要求也较高.为快速且准确地预测月表极限温度下月球车车轮驱动用斜槽电机的性能,提出了2--D几何模型耦合恒流源电路模型处理多截面模型中分段电机同槽导体电流相等以及定子斜槽的方法,并研究了计算精度的影响因素.针对一套永磁无刷直流电机方案,计算了齿槽转矩、空载感应电势和电磁转矩,并结合转子典型位置下气隙磁场沿电机轴向的分布特征以及谐波分析结果评估了计算精度.该方法的计算量较小,计算结果与3--D模型仿真结果、实测结果的比较表明了该方法的有效性.     

Novel hybrid optimization algorithm using PSO and MADS for the trajectory estimation of a four track wheel skid-steered mobile robot

Several optimization algorithms, such as the particle swarm optimization (PSO), genetic algorithm (GA), and ant colony optimization, have previously been applied in order to reliably obtain more accurate trajectory estimation for mobile robot. However, these optimization algorithms can get easily trapped in local optima when solving a complex system, which has many local optima and many input variables. This paper proposes a novel hybrid optimization algorithm-based tuning of the extended Kalman filter, which involves the PSO and mesh adaptive direct search algorithms, prior to operation. As demonstrated by our experimental results, the advantages of the novel hybrid optimization algorithm resolve the limitations of other algorithms in the trajectory estimation of a four track wheel skid-steered mobile robot (4-TW SSMR).     

Finite-source M/M/S retrial queue with search for balking and impatient customers from the orbit

The present paper deals with a generalization of the homogeneous multi-server finite-source retrial queue with search for customers in the orbit. The novelty of the investigation is the introduction of balking and impatience for requests who arrive at the service facility with a limited capacity and FIFO queue. Arriving customers may balk, i.e., they either join the queue or go to the orbit. Moreover, the requests are impatient and abandon the buffer after a random time and enter the orbit, too. In case of an empty buffer, each server searches for a customer in the orbit after finishing service. All random variables involved in the model construction are supposed to be exponentially distributed and independent of each other. The primary aim of this analysis is to show the effect of balking, impatience, and buffer size on the steady-state performance measures. Concentrating on the mean response time, several numerical examples are investigated by the help of the MOSEL-2 tool used for creating the model and calculating the stationary characteristics.