【作者】 丰飞；

【导师】 蔡鹤皋；

【作者基本信息】 哈尔滨工业大学 ， 机械电子工程， 2013， 博士

【摘要】 空间在轨服务是一项意义深远的空间前沿技术。在轨服务可以实现航天器的在轨组装、日常维护、系统升级、燃料加注、零部件更换以及轨道转移等操作，从而延长航天器的使用寿命，甚至恢复失效航天器的设计功能。因此，在轨服务具有不可估量的经济价值和应用前景。在轨捕获是实现在轨服务操作的前提，而基于机械臂的在轨捕获以其灵巧性和广适性，是在轨捕获的主要手段。此外，随着空间技术的发展，空间站等大型空间设施的组装和日常维护将变得越来越频繁，而这些大型设施的组装和维护仅仅依靠宇航员是很难实现的，因此需要空间大型机械臂的辅助。为了提高大型机械臂对载荷操作的可靠性和效率，本文致力于对空间大型机械臂的末端执行器的方案和捕获策略研究，并力图研制一套性能优异的空间大型机械臂末端执行器，以提高在轨载荷捕获的可靠性和快速性。本文的主要研究工作如下：基于大型机械臂在轨操作载荷的特点和大型机械臂“大容差，软捕获”和“硬连接”的设计准则。本文以“大容差”和“软捕获”作为末端执行器的基本性能要求，提出了多种末端执行器设计方案，并对其中具有代表性和可行性的三指-三瓣式和钢丝索缠绕式这两类末端执行器进行了详细设计。通过对两类末端执行器容差能力的理论量化比较分析，并结合ADAMS动力学仿真对两类末端执行器基本性能的对比分析可知，钢丝索缠绕式末端执行器的性能要优于三指-三瓣式。此外，腱-鞘传动系统在钢丝索索缠绕式末端执行器捕获环节设计中的应用，可以使末端执行器外径最小化，而容差空间最大化；而且还能进一步提高钢丝索缠绕式末端执行器的软捕获能力。此外，对钢丝索索缠绕式末端执行器的外形进行了优化设计，提出了正方形横截面的末端执行器外形方案，在保证容差空间的前提下，使末端执行器的外形包络直径最小化。本文研制了基于腱-鞘传动的钢丝索缠绕式末端执行器。以“大容差”性能为前提，结合质量轻、体积小等技术要求，确定了末端执行器的容差空间。此外完成了末端执行器驱动系统的模块化设计以及传感器配置，并分析了捕获环节的腱-鞘传动系特性。通过分析腱-鞘传动系统的传递特性，并提出了多段腱-鞘传动系统的分析模型，对捕获环节的多曲率腱-鞘传动进行了分析，从而完成了腱-鞘传动系统的路径设计和材料选择；容差空间的分析则确定了末端执行执行器的整体外形尺寸和容差性能；传感器的配置则提高了末端执行器各环节的智能性和载荷捕获的独立性；模块化的驱动系统设计以及将三个环节的驱动系统外置，便于实现驱动系统的在轨维护和更换。此外，分析了末端执行器锁紧环节的展开性能，并建立了末端执行器捕获环节和拖动环节的动力学模型，为末端执行器在轨捕获策略的实施提供了理论基础。基于钢丝索缠绕捕获末端执行器的特点，提出了末端执行器的捕获接触分析模型和接触点预测模型，并对在轨漂浮载荷的动力学特性进行分析。通过腕关节力/力矩信息，结合末端执行器与目标接口的接触点分析模型，建立了腕关节力矩传感器测量的力/力矩与漂浮载荷运动之间的数学模型。由漂浮载荷的动力学分析可知，关键点的位移要远远大于载荷质心点的位移，影响关键点位移的主要因素是载荷的惯量，以及接触点到载荷质心的距离。基于漂浮载荷的动力学关系，提出基于试探性接触的漂浮载荷动力学参数辨识方法，为未来空间未知参数载荷的捕获提供理论依据。成本较高的地面微重力模拟装置难以模拟载荷的质量和惯量等参数，而质量和惯量等动力学参数对末端执行器的捕获操作影响较大。因此，基于动力学仿真是研究末端执行器捕获操作性能的主要手段。本文根据钢丝索缠绕式末端执行器的载荷捕获特点，提出变刚度柔顺捕获域的概念。此外，基于钢丝索的离散建模方法，建立了末端执行器捕获环节的ADAMS虚拟样机模型，并通过在不同位姿偏差状态下，对不同质量/惯量的漂浮载荷实施捕获仿真，以验证末端执行器的“大容差”和“软捕获”性能。在捕获仿真的基础上，对末端执行器的捕获模式和捕获策略进行分析和研究，寻找能提高末端执行器捕获效率和捕获可靠性的捕获策略。此外，提出了基于机械臂末端位置控制的固定载荷和机械臂重定位操作的捕获策略。为进一步验证末端执行器的基本性能，研制了吊丝悬挂方式的微重力模拟装置，用于容差能力测试及载荷捕获等试验。通过容差试验及载荷捕获试验结果，并结合动力学仿真结果，验证了所研制的末端执行器的性能达到设计标准，机构设计合理，达到预期目标。更多还原

【Abstract】 On-Orbit Servicing is a leading and promising technology for space exploration.It is applied to the structure assembly, dialy maintance, system upgrading, refuelingspace vehicle, replacement of compenents and orbit transfer and so on. It is helpfulfor extending life of space vehicles and recovering the space vehicle in malfunction.The space manipulator with dexterity and multifunction is the predominant methodfor On-Orbit Servicing. Moreover, the construction and maintenance of lagre spaceinfrastructure will become frequent as the development of space exploration. Thelarge space manipulators will be imminently imployed to these construction andmaintenance, because the Extravehicular Activities of astronauts are insufficient. Inordert to promote the manipulation efficiency and reliability of large spacemanipulator, many end-effector design schemes and capture strategies are presentedand studied in this paper. Finally, an end-effector prototype with capabilities ofpromoting the reliability and rapidity of on-orbit capture is developed.Basing on the characteristics of large space manipulator, the design guidelingswith large misalignment tolerance, soft capture and hard connecting for spaceend-effector schemes are proposed. And the basic requirements are largemisalignment tolerance and soft capture. According to these two requirements, manydesign schemes are presented. The three fingers-three petals and the steelcable-snared end-effector which are designed in detail are most representative andfeasible. According to the comparison of basic requirements through theory analysisof misalignment tolerance and the ADAMS dynamic simulation analysis, the steelcable-snared end-effector is superior to the three fingers-three petals end-effector.The tendon-sheath system is employed as the transmission mechanism of the capturesubassembly. It maximizes the capture space with strict limitation of outsideenveloped diameter. Moreover, the flexibility of the tendon-sheath system willenhance passive compliance of the capture subassembly to promote the soft capturecapability. The cross section with foursquare shape of the end-effector is proposed,and it will minimize the enveloped diameter and maximize the capture space.An end-effector prototype with cable-snared mechanism is developed. Itscapture space is determined by the precondition of large misalignment tolerancecombined with requirements of light-weight and small-volume. The modularizationdesign of actuator systems and sensor collocation are presented, and the features ofthe tendon-sheath are analysed. And then the tendon-sheath system with multi-curvatures are modeled and analysed. Therefore, the transmission route and material of the tendon-sheath system are designed and chosen. The outside shell dimensionand the misalignemnt tolerance performance are obtained by the analysis of thecapture space. The sensor collocation is beneficial to the intelligence andindependence of payload capture. There actuator units of the end-effector aremodularization design, and all of the three actuator units are fixed on the outsideshell of the end-effector, it is useful for the replacement and repair on orbit. Thedeployment of latching loop is analysed. And the dynamics models of the captureand rigidizing loop are modeled to offer a theory support for capture strategies.The contact model of the end-effecor is proposed based on the capture principleof the end-effector. And the motion of the free-floating target is analysed. Themathematical model of the relationship between the force/moment of the wrist jointand the motion of the free-floating target is constructed, according to the contactmodel of capture subassembly and the force/moment information of the wrist joint.The dynamics parametes identification method is obtained based on this model. Themodel and method of dynamics parameters identification is vital to the captureoperation of free-floating targets of which the dynamics parameters are unknown.It is difficult for the micro-gravity simulation device with high cost to simulatethe mass and inertia parameters of the free-floating target on ground. Morever, thedynamic parametes are important for the capture operation. Therefore, the dynamicssimulation is the main method to study the capture operation and capture strategy.The capture field with variable stiffness is presented, according to the flexibility andstiffness change as the rotating ring rotates. The dynamics model and virtualprototype of the capture subassembly are proposed by a discrete model of threecapture cables in ADAMS. The end-effector performance of large misalignment andsoft capture are validated by capture simulation of free-floating target with differentparameters. And the capture mode and strategy are also studied by simulations tosearch for the capture strategy to promote the capture efficiency and reliability.Therefore, the capture strategy with trajectory tacking control is presented for themanipulation of fixed payload and self-relocation of the large manipulator. Amicro-gravity simulation decive is developed to test the capability of misalignmenttolerance and carry out the capture experiment. The performance of the end-effectorprototype meets the requirements, and it is validated by the dynamics simulations inADAMS software and the experiments on the micro-gravity simulation decive.更多还原