Third–Generation Pleated Pneumatic Artificial Muscles for Robotic Applications: Development and Comparison with McKibben Muscle

This paper introduces the third generation of Pleated Pneumatic Artificial Muscles (PPAM), which has been developed to simplify the production over the first and second prototype. This type of artificial muscle was developed to overcome dry friction and material deformation, which is present in the widely used McKibben muscle. The essence of the PPAM is its pleated membrane structure which enables the muscle to work at low pressures and at large contractions. In order to validate the new PPAM generation, it has been compared with the mathematical model and the previous generation. The new production process and the use of new materials introduce improvements such as 55% reduction in the actuator’s weight, a higher reliability, a 75% reduction in the production time and PPAMs can now be produced in all sizes from 4 to 50?cm. This opens the possibility to commercialize this type of muscles so others can implement it. Furthermore, a comparison with experiments between PPAM and Festo McKibben muscles is discussed. Small PPAMs present similar force ranges and larger contractions than commercially available McKibben-like muscles. The use of series arrangements of PPAMs allows for large strokes and relatively small diameters at the same time and, since PPAM 3.0 is much more lightweight than the commong McKibben models made by Festo, it presents better force-to-mass and energy to mass ratios than Festo models.     

微小气动机器人系统的模糊自适应PID控制

基于尺蠖的移动机理,研制了一种具有柔性移动机构的微小气动机器人内窥镜诊疗系统。描述了微机器人系统的本体结构和运动机理,并通过分析机器人系统的驱动力学特性和机器人的移动控制特性,给出了基于模糊自适应PID的气压-位置伺服控制方法,计算机仿真实验结果表明基于模糊自适应PID算法可实现机器人系统的有效控制。     

The Development, Control and Operation of an Autonomous Robotic Excavator

The excavation of foundations, general earthworks and earth removal tasks are activities which involve the machine operator in a series of repetitive operations, suggesting opportunities for the automation through the introduction of robotic technologies with subsequent improvements in machine utilisation and throughput. The automation of the earth removal process is also likely to provide a number of other benefits such as a reduced dependence on operator skills and a lower operator work load, both of which might be expected to contribute to improvements in quality and, in particular, the removal of the need for a local operator when working in hazardous environments.The Lancaster University Computerised Intelligent Excavator or LUCIE has demonstrated the achievement of automated and robotic excavation through the implementation of an integrated, real-time, artificial intelligence based control system utilising a novel form of motion control strategy for movement of the excavator bucket through ground. Having its origins in the systematic observation of a range of machine operators of differing levels of expertise, the control strategy as evolved enables the autonomous excavation of a high quality rectangular trench in a wide variety of types and conditions of ground and the autonomous removal of obstacles such as boulders along the line of that trench.The paper considers the development of the LUCIE programme since its inception and sets out in terms of the machine kinematics the evolution and development of the real-time control strategy from an implementation on a one-fifth scale model of a back-hoe arm to a full working system on a JCB801 360° tracked excavator.     

气动人工肌肉拮抗关节的力与刚度独立控制

针对柔性仿生关节难以实现力与刚度独立控制的问题,建立了一种新的气动人工肌肉等效弹簧模型及关节力和刚度模型,设计了一种双输入双输出滑模控制器,来实现对气动人工肌肉拮抗关节力与刚度的独立控制．最后,搭建了气动人工肌肉驱动的拮抗关节实验平台,在关节位置固定和开放两种状况下进行了实验研究,验证所提方法的有效性;在不同负载情况下进行了对比实验,验证所提方法的通用性．所提出的建模和控制方法综合考虑了仿生关节位置、力和刚度相对独立控制,在机器人与人或环境互相作用的场合有很好的应用前景．     

垂直气动人工肌肉系统的模型参考自适应逆补偿控制

与传统刚性驱动系统相比, 气动人工肌肉系统具有质量轻、人机交互友好等优势, 近年来在生产生活中受到广泛关注. 然而, 该类系统的运动呈现出复杂的迟滞特性, 这给针对该类系统的跟踪控制研究带来了挑战. 本文针对垂直气动人工肌肉系统, 提出一种模型参考自适应逆补偿控制策略, 可有效克服迟滞特性以及控制过程中外界扰动和参数摄动等不确定因素对系统运动状态的影响, 实现系统高精度跟踪控制. 具体而言, 本文首先对系统的运动特性以及影响系统控制精度的不确定因素进行分析; 然后, 基于分析结果建立一个描述系统运动特性的参考模型; 进而采用逆补偿思想, 通过对所建立的参考模型求逆来构造一个逆补偿控制器, 克服迟滞特性对系统运动状态产生的影响; 随后, 基于最小均方误差算法设计自适应律, 在线辨识参考模型的权值, 同时估计逆补偿控制器的设计参数, 克服外界扰动和参数摄动等不确定因素对系统运动状态的影响; 最后, 通过实验验证所提控制策略的有效性.     

Artificial evolution and real robots

Artificial evolution as a design methodology allows the relaxation of many of the constraints that have held back conventional methods. It does not require a complete prior analysis and decomposition of the task to be tackled, as human designers require. However, this freedom comes at some cost; there are a whole new set of issues relating to evolution that must be considered. Standard genetic algorithms may not be appropriate for incremental evolution of robot controllers. Species adaptation genetic algorithms, (SAGA) have been developed to meet these special needs. The main cost of an evolutionary approach is the large number of trials that are required. Simulations-especially those involving vision in complex environments, or modeling detailed semiconductor physics—may not be adequate or practical. Examples of evolved robots will be discussed, including a specialized piece of equipment which allows a robot to be tested using simple vision in real time, and what is believed to be the first successful example of an evolved hardware controller for a robot. Presented at the International Symposium on Artificial Life and Robotics, Oita, Japan, February 18–20, 1996     

柔顺双稳态机构的研究现状与进展

由于柔顺机构和双稳态机构分别所具有的独特优势,已使柔顺双稳态机构成为目前国内外研究的新热点.综合论述了基于MEMS技术的柔顺双稳态机构的最新研究成果,根据柔顺双稳态机构的驱动机制,系统介绍了机械锁定型、电热锁定型、磁致锁定型、多耦合场锁定型等柔顺双稳态机构,针对其原理、性能及应用等各个方面进行了综合比较.最后展望了柔顺双稳态机构的研究前景和可能遇到的问题与挑战.     

扁平气动人工肌肉的设计和分析

传统的气动人工肌肉受结构和制造手段的限制,很难同时满足高收缩率、高收缩力和全柔性等应用需求。针对这些问题,本文基于约束层、收缩层与扁平气囊正交混合编织的工艺,提出了一种扁平编织型气动人工肌肉（扁肌）。通过建模分析了最小收缩层长度、收缩率以及扁肌最大厚度与气囊层数及气囊手指数量之间的关系,并通过数值拟合获得了收缩力的近似解析解。扁肌的各主要部件均采用激光切割而成,组装完成的扁肌质量仅为8.1g,厚1.2mm。收缩实验表明,扁肌在5%的收缩率下最大收缩力可达280 N,是其自重的3527倍。在0.5 kg的负载下最大收缩率42.8%,最大收缩速度1216.2mm/s。迟滞实验表明,扁肌存在一定的位移迟滞,而力迟滞并不明显。在采用闭环控制时,扁肌对0.25 Hz的正弦信号具有良好的位置跟踪能力,最大位移误差2.5mm。当频率为0.5 Hz时,受放气速度的影响,扁肌存在较大位移延迟。     

多模式刚柔结合欠驱动抓取机构的设计、分析与实验测试

结合刚性欠驱动抓取机构与柔顺机构,提出一种多模式刚柔结合欠驱动抓取机构,并对所提出的机构进行分析与实验研究。基于刚体替代法,设计了二指多模式欠驱动抓取机构的刚柔结合方案。运用正运动学分析与载荷平衡方程,对驱动单元进行静力学建模。结合伪刚体模型法、载荷平衡方程与操作对象平衡位置枚举搜索,建立两点抓取与包络抓取模式下抓取力与驱动力矩的关系式。将驱动单元静力学建模与抓取单元静力学建模相结合,可以得到完整的多模式抓取力模型。进一步地,考虑由于接触引起的柔性杆件变形,结合线性插值,对抓取力模型进行修正。基于修正后的抓取力模型,对机构尺寸参数进行优化设计,综合提升机构在两点抓取模式和包络抓取模式下的载荷输出性能。RecurDyn仿真结果显示,在两点抓取模式和包络抓取模式下,修正后完整的抓取力模型与仿真值的最大相对误差为7.62%,并且所提出的优化算法有效提升了机构的两点抓取力与综合包络抓取力。实验结果显示,优化后的抓取机构抓取力有较大的提升,修正后完整的抓取力模型与实验值的最大相对误差为1.87%,验证了抓取力建模、优化设计的有效性。     

煤矿用防爆柴油机冷却风扇液压驱动系统研究

防爆柴油机是煤炭开采设备使用的主要动力源。当前防爆柴油机冷却系统风扇主要采用传统曲轴定转动比驱动,无法完全适应煤矿井下复杂的工作条件,造成风扇功耗大,冷却效果差,空间布置受限等问题。本文研究了防爆柴油机冷却系统结构,提出了采用液压驱动方式,分别对冷却系统中的不同组成进行独立控制的解决方案,从而改善了系统过热、过冷情况。将风扇与防爆柴油机分开布置,使得系统设计更加灵活,可以适应更多的应用场合。     

Two-stage compliant microleverage mechanism optimization in a resonant accelerometer

Compliant microleverage mechanisms can be used in micro-electro-mechanical systems (MEMS) to transfer an input force/displacement to an output to achieve mechanical/geometrical advantages. By stacking multiple stages of microlevers together, a compound microleverage mechanism is obtained with a higher amplification factor. This paper presents the analysis and optimization of a two-stage microleverage mechanism in a resonant output micro-accelerometer for force amplification. It is found that the compliance of the two-stage mechanism needs to be appropriately distributed in order for both stages to have the desired amplification effect. June 13, 2000     

Cooperative Mobile Robotics: Antecedents and Directions

There has been increased research interest in systems composed of multiple autonomous mobile robots exhibiting cooperative behavior. Groups of mobile robots are constructed, with an aim to studying such issues as group architecture, resource conflict, origin of cooperation, learning, and geometric problems. As yet, few applications of cooperative robotics have been reported, and supporting theory is still in its formative stages. In this paper, we give a critical survey of existing works and discuss open problems in this field, emphasizing the various theoretical issues that arise in the study of cooperative robotics. We describe the intellectual heritages that have guided early research, as well as possible additions to the set of existing motivations.