一类全方位移动机器人的不确定扰动数学模型

本文针对一类正交轮全方位移动机器人的机构特点 ,分析了运行中由于其结构因素引起机器人运动不稳定的主要原因 .针对此类结构运动过程存在的不确定扰动问题 ,分析了它的产生机理及其变化规律 ,并推导出在该种不确定性扰动影响下的移动机器人动力学模型 .该模型可为正交轮全方位移动机器人运动控制提供理论依据 ,具有较强的理论意义和应用价值

自动化制造系统的产生与发展

探讨了自动化与制造业的产生和互促发展过程 ,论述了自动化制造系统的形成和不同发展阶段的内涵及重大作用 ,指出自动化技术与制造技术是驱动自动化制造系统发展的两个轮子 ,不能忽视任何一个侧面 ,自动化研究与制造技术研究相结合是发展先进制造技术的必由之路

两轮驱动自动引导车辆定位停车研究

建立了两轮独立驱动自动引导车辆的运动学模型，计算了两轮以不同速度行驶时的运动轨迹。基于所建的运动学模型，提出了两轮驱动自动引导车的定位控制策略。通过试验证实，这种定位控制策略具有很快的停车速度和较高的定位精度。

基于滑转率的六轮纵列式月球车驱动控制研究

基于车轮滑转率和车轮地面力学,研究了月球车在松软月面行驶时的车轮过度下陷问题.将月球车车轮下陷和车轮—土壤作用力表达为车轮滑转率的函数,结合车辆地面力学理论并考虑纵列式车轮多通过性土壤参数的修正,建立了月球车的动力学模型.判断车轮是否发生过度下陷的标准为土壤所提供给驱动轮的土壤推力能否克服土壤对车轮的阻力.利用建立的动力学模型,计算出能够保证车轮不会过度下陷的期望滑转率.考虑到月球车动力学系统的非线性和不确定性,设计了以车轮滑转率为状态变量的滑模驱动控制器.仿真结果表明,采用该控制器可以较快地跟踪期望滑转率,避免车轮的过度滑转下陷,保证月球车能够在软质路面上正常行驶.

滑转率对月球车车轮驱动力学特性的影响分析

应用车辆地面力学理论研究滑转率对月球车车轮挂钩牵引力、驱动效率以及功率消耗的影响。建立刚性车轮与松软月壤交互作用的动力学模型。通过实例对月球车车轮驱动动力学特性进行仿真分析。研究结果表明,车轮的挂钩牵引力、驱动效率以及驱动能耗均受到车轮滑转率的制约。存在一个最优的滑转率区间,在此区间内车轮可获得较大的挂钩牵引力、较高的驱动效率以及较低的驱动能耗。求取轮、地相对速度,对月球车车轮的地面摩擦力功率进行了估算。

轮式移动机器人沙地行驶控制建模与仿真研究

结合车轮沙土相互作用的力学分析,研究解决轮式移动机器人沙地行驶车轮过度滑转下陷问题。考虑纵列式重复通过车轮沙土力学参数的修正,建立六轮式沙地移动机器人的动力学模型,以车轮滑转率为状态变量,设计了移动机器人沙地行驶的滑模驱动控制器跟踪车轮期望滑转率。MATLAB/Simulink仿真结果表明,采用该控制器可以较快地跟踪期望滑转率,有效地限制机器人车轮的滑转,避免车轮的过度下陷。

Whole-Vehicle modelling of exhaust energy recovery on a diesel-electric hybrid bus

Hybrid vehicles can use energy storage systems to disconnect the engine from the driving wheels of the vehicle. This enables the engine to be run closer to its optimum operating condition, but fuel energy is still wasted through the exhaust system as heat. The use of a turbogenerator on the exhaust line addresses this problem by capturing some of the otherwise wasted heat and converting it into useful electrical energy.

This paper outlines the work undertaken to model the engine of a diesel-electric hybrid bus, coupled with a hybrid powertrain model which analysed the performance of a hybrid vehicle over a drive-cycle. The distribution of the turbogenerator power was analysed along with the effect on the fuel consumption of the bus. This showed that including the turbogenerator produced a 2.4% reduction in fuel consumption over a typical drive-cycle.

The hybrid bus generator was then optimised to improve the performance of the combined vehicle/engine package and the turbogenerator was then shown to offer a 3.0% reduction in fuel consumption. The financial benefits of using the turbogenerator were also considered in terms of fuel savings for operators. For an average bus, a turbogenerator could reduce fuel costs by around £1200 per year.

Dynamic axle force and road profile identification using a moving vehicle

The axle forces applied by a vehicle through its wheels are a critical part of the interaction between vehicles, pavements and bridges. Therefore, the minimisation of these forces is important in order to promote long pavement life spans and ensure that bridge loads are small. Moreover, as the road surface roughness affects the vehicle dynamic forces, the monitoring of pavements for highways and bridges is an important task. This paper presents a novel algorithm to identify these dynamic interaction forces which involves direct instrumentation of a vehicle with accelerometers. The ability of this approach to predict the pavement roughness is also presented. Moving force identification theory is applied to a vehicle model in theoretical simulations in order to obtain the interaction forces and pavement roughness from the measured accelerations. The method is tested for a range of bridge spans in simulations and the influence of road roughness level on the accuracy of the results is investigated. Finally, the challenge for the real-world problem is addressed in a laboratory experiment.

A Novel Approach for Axle Detection in Bridge Weigh-In-Motion Systems

Bridge weigh-in-motion (B-WIM), a system that uses strain sensors to calculate the weights of trucks passing on bridges overhead, requires accurate axle location and speed information for effective performance. The success of a B-WIM system is dependent upon the accuracy of the axle detection method. It is widely recognised that any form of axle detector on the road surface is not ideal for B-WIM applications as it can cause disruption to the traffic (Ojio & Yamada 2002; Zhao et al. 2005; Chatterjee et al. 2006). Sensors under the bridge, that is Nothing-on-Road (NOR) B-WIM, can perform axle detection via data acquisition systems which can detect a peak in strain as the axle passes. The method is often successful, although not all bridges are suitable for NOR B-WIM due to limitations of the system. Significant research has been carried out to further develop the method and the NOR algorithms, but beam-and-slab bridges with deep beams still present a challenge. With these bridges, the slabs are used for axle detection, but peaks in the slab strains are sensitive to the transverse position of wheels on the beam. This next generation B-WIM research project extends the current B-WIM algorithm to the problem of axle detection and safety, thus overcoming the existing limitations in current state-of–the-art technology. Finite Element Analysis was used to determine the critical locations for axle detecting sensors and the findings were then tested in the field. In this paper, alternative strategies for axle detection were determined using Finite Element analysis and the findings were then tested in the field. The site selected for testing was in Loughbrickland, Northern Ireland, along the A1 corridor connecting the two cities of Belfast and Dublin. The structure is on a central route through the island of Ireland and has a high traffic volume which made it an optimum location for the study. Another huge benefit of the chosen location was its close proximity to a nearby self-operated weigh station. To determine the accuracy of the proposed B-WIM system and develop a knowledge base of the traffic load on the structure, a pavement WIM system was also installed on the northbound lane on the approach to the structure. The bridge structure selected for this B-WIM research comprised of 27 pre-cast prestressed concrete Y4-beams, and a cast in-situ concrete deck. The structure, a newly constructed integral bridge, spans 19 m and has an angle of skew of 22.7°.

The Triveneto transhumance: law, land, movement

North Italy's nomadic shepherds are a phenomenon unique in the world. Their nomadic nature is taken to the extreme since they move constantly rather than solely in the winter or the summer, as in the usual nomadism. Their home is on wheels and their territory is the tightly regulated yet sprawling Triveneto area. The Triveneto transhumance moves beyond private/public property divides, and indeed beyond lawful/unlawful distinctions, giving rise to what I have called an animal normativity. Relying on Valentina De Marchi's text 'Fame d'Erba' on the Triveneto transhumance, I show how territory becomes a question of animal hunger, and movement becomes an atmospheric, silent and imperceptible affect that crosses private property boundaries, state law limitations, reservation areas and road networks. This way of being, beyond the usual distinctions, offers an example of an alternative political and legal organisation that brings forth the continuum between the human, the natural and the legal/political.

A influência da idade nos parâmetros metabólicos durante a marcha com andarilho

Introdução: Estruturalmente, a marcha é modificada de acordo com as características de cada individuo, sua natureza morfológica, tipo de atividade, idade e a presença de determinadas doenças, entre outros fatores. Devidas as alterações fisiológicas de envelhecimento, o custo energético da marcha normal por si só é superior nos idosos comparativamente com os jovens. Objetivo: Analisar a influência do uso de andarilho com rodas e fixo nos parâmetros metabólicos de indivíduos com mais de 60 anos e em jovens. Metodologia: realizou-se um estudo analítico transversal numa amostra de 21 voluntários, sendo 11adultos jovens (idade compreendida entre 18 e 25 anos) e 10 são adultos com idade superior a 60 anos. Utilizou-se o sistema K4b2 COSMED de forma a recolher os dados relativos ao consumo energético, quociente respiratório e volume de CO2 produzido. Os participantes realizaram os diferentes tipos de marcha (marcha normal, a três pontos com andarilho fixo, a três pontos modificada com andarilho fixo, a três pontos com andarilho com rodas e a três pontos modificada com andarilho com rodas) durante 10 minutos num percurso rectilíneo de 20 metros. Para a análise estatística recorreu-se ao software IBM SPSS Statistics v20 com um nível de significância de 0,05. Resultados: observou-se que á exceção da marcha normal em todos os outros tipos de marcha com andarilho, os participantes com mais de 60 anos, apresentam valores significativamente superiores aos dos jovens, nomeadamente nas marchas com andarilho fixo, a 3 pontos e a 3 pontos modificada e com andarilho de rodas, na marcha a 3ponto modificada. Verificaram-se diferenças apenas no grupo dos jovens, pois a marcha normal apresentou valores significativamente maiores que as restantes. Conclusão: A idade influenciou os parâmetros metabólicos da marcha normal e com andarilhos fixo e móvel apresentando os idosos um maior gasto energético, bem como os METS utilizados.

Robótica móvel: sistema de condução autónoma

Dissertação para obtenção do grau de Mestre em Engenharia Electrotécnica Ramo Automação e Electrónica Industrial

A literature review on the optimization of legged robots

Over the last two decades the research and development of legged locomotion robots has grown steadily. Legged systems present major advantages when compared with ‘traditional’ vehicles, because they allow locomotion in inaccessible terrain to vehicles with wheels and tracks. However, the robustness of legged robots, and especially their energy consumption, among other aspects, still lag behind mechanisms that use wheels and tracks. Therefore, in the present state of development, there are several aspects that need to be improved and optimized. Keeping these ideas in mind, this paper presents the review of the literature of different methods adopted for the optimization of the structure and locomotion gaits of walking robots. Among the distinct possible strategies often used for these tasks are referred approaches such as the mimicking of biological animals, the use of evolutionary schemes to find the optimal parameters and structures, the adoption of sound mechanical design rules, and the optimization of power-based indexes.

The Portuguese Administrative Elite, 1851-1910

The aim of this article is to examine the composition and patterns of recruitment of the ministries’directors-general, as well as to assess the interconnections between bureaucracy and politics, from the beginnings of Regeneração (1851) until the breakdown of Monarchy (1910). The post of director-general was considered one of “political trust”, that might be filled by individuals from outside the civil service, and the selection and de-selection of officeholders depended exclusively on the ministers’ will. Nonetheless, most directors-general were experienced bureaucrats, boasting a steady career as civil servants, and remained in office for long terms, regardless of ministerial discontinuities. In other words, High Administration became relatively immune to party-driven politics. Due to their professional background and lengthy tenure, directors-general were usually highly skilled specialists, combining technical expertise and practical knowledge of the wheels of state bureaucracy. Hence, they were often influential actors in policy-making, playing an active (and sometimes decisive) part behind the scenes, in both designing and implementing government policies. As regards their social profile, directors-general formed a cohesive and homogeneous elite group: being predominantly drawn from urban middle class milieus, highly educated, and appointed to office in their forties.

A Realization Of An Fpga Sub System For Reducing Odometric Localization Errors In Wheeled Mobile Robots

This paper introduces a simple and efficient method and its implementation in an FPGA for reducing the odometric localization errors caused by over count readings of an optical encoder based odometric system in a mobile robot due to wheel-slippage and terrain irregularities. The detection and correction is based on redundant encoder measurements. The method suggested relies on the fact that the wheel slippage or terrain irregularities cause more count readings from the encoder than what corresponds to the actual distance travelled by the vehicle. The standard quadrature technique is used to obtain four counts in each encoder period. In this work a three-wheeled mobile robot vehicle with one driving-steering wheel and two-fixed rear wheels in-axis, fitted with incremental optical encoders is considered. The CORDIC algorithm has been used for the computation of sine and cosine terms in the update equations. The results presented demonstrate the effectiveness of the technique