Design Schemes and Comparison Research of the End-effector of Large Space Manipulator

The end-effector of the large space manipulator is employed to assist the manipulator in handling and manipulating large payloads on orbit.Currently,there are few researches about the end-effector,and the existing end-effectors have some disadvantages,such as poor misalignment tolerance capability and complex mechanical components.According to the end positioning errors and the residual vibration characters of the large space manipulators,two basic performance requirements of the end-effector which include the capabilities of misalignment tolerance and soft capture are proposed.And the end-effector should accommodate the following misalignments of the mechanical interface.The translation misalignments in axial and radial directions and the angular misalignments in roll,pitch and yaw are ±100 mm,100 mm,±10°,±15°,±15°,respectively.Seven end-effector schemes are presented and the capabilities of misalignment tolerance and soft capture are analyzed elementarily.The three fingers-three petals end-effector and the steel cable-snared end-effector are the most feasible schemes among the seven schemes,and they are designed in detail.The capabilities of misalignment tolerance and soft capture are validated and evaluated,through the experiment on the micro-gravity simulating device and the dynamic analysis in ADAMS software.The results show that the misalignment tolerance capabilities of these two schemes could satisfy the requirement.And the translation misalignment tolerances in axial and radial directions and the angular misalignment tolerances in roll,pitch and yaw of the steel cable-snared end-effector are 30mm,15mm,6°,3° and 3° larger than those of the three fingers-three petals end-effector,respectively.And the contact force of the steel cable-snared end-effector is smaller and smoother than that of the three fingers-three petals end-effector.The end-effector schemes and research methods are beneficial to the developments of the large space manipulator end-effctor and the space docking mechanism.

Development of space end-effector with capabilities of misalignment tolerance and soft capture based on tendon-sheath transmission system

The essential requirements of the end-effector of large space manipulator are capabilities of misalignment tolerance and soft capture.According to these requirements,an end-effector prototype combining the tendon-sheath transmission system with steel cable snaring mechanism was manufactured.An analysis method based on the coordinate transformation and the projection of key points of the mechanical interface was proposed,and it was a guideline of the end-effector design.Furthermore,the tendon-sheath transmission system was employed in the capture subassembly to reduce the inertia of the capture mechanism and enlarge the capture space.The capabilities of misalignment tolerance and soft capture were validated through the dynamic simulation in ADAMS software.The results of the capture simulation and experiment show that the end-effector has outstanding capabilities of misalignment tolerance and soft capture.The translation misalignments in radial directions are±100 mm,and angular misalignments about pitch and yaw are±15°.

Development of Chinese large-scale space end-effector

In order to achieve large tolerance capture and high stiffness connection for space payload operations,a Chinese large-scale space end-effector (EER) was developed.Three flexible steel cables were adopted to capture the payload with large capture allowance.Ball screw transmission mechanism and plane shape-constraint four bar linkage mechanism were utilized to connect the payload with high stiffness.The experiments show that capture tolerances in X,Y,Z,Pitch,Yaw,Roll directions are 100 mm,100 mm,120 mm,10.5°,10.5°,12°,respectively.The maximum connection stiffness is 4 800 N·m.The end-effector could meet the requirements for space large tolerance capture and high stiffness connection in the future.

Design and experimental study of the end-effector for broccoli harvesting

The end-effector is an important part of the broccoli harvesting robot.Aiming at the physical characteristics of a large broccoli head and thick stem,a spherical cutting tool broccoli harvesting end-effector was designed in this study.First,the physical characteristics of broccoli were tested,and physical parameters such as the broccoli head diameter and stem diameter of broccoli were measured.The maximum cutting force of broccoli stems under different cutting angles was tested.Second,according to the physical characteristics and harvesting process of broccoli,the end-effector was designed,and the mathematical model of kinematics and dynamics was established.Based on the results of dynamic analysis,the end-effector rod was optimized,and the unilateral width of the slider was 40 mm,the length of the connecting rod was 120 mm,and the length of the crank was 42 mm.The mechanism needed an external driving force of 140.54 N to cut the broccoli stem.Therefore,a 32 mm cylinder with a load rate of 50%was selected as the power source.Finally,the feasibility of the broccoli harvesting end-effector was verified by the harvesting test.Experiments showed that the overall harvesting success rate of the end-effector is 93.3%,and the smoothness rate of the stem section is 83.3%.The harvesting performance of the broccoli end-effector was verified.This lays a foundation for agricultural robots to harvest broccoli.

An Automatic Implementation of Oropharyngeal Swab Sampling for Diagnosing Respiratory Infectious Diseases via Soft Robotic End-Effectors

The most widely adopted method for diagnosing respiratory infectious diseases is to conduct polymerase chain reaction(PCR)assays on patients’respiratory specimens,which are collected through either nasal or oropharyngeal swabs.The manual swab sampling process poses a high risk to the examiner and may cause false-negative results owing to improper sampling.In this paper,we propose a pneumatically actuated soft end-effector specifically designed to achieve all of the tasks involved in swab sampling.The soft end-effector utilizes circumferential instability to ensure grasping stability,and exhibits several key properties,including high load-to-weight ratio,error tolerance,and variable swab-tip stiffness,leading to successful automatic robotic oropharyngeal swab sampling,from loosening and tightening the transport medium tube cap,holding the swab,and conducting sampling,to snapping off the swab tail and sterilizing itself.Using an industrial collaborative robotic arm,we integrated the soft end-effector,force sensor,camera,lights,and remote-control stick,and developed a robotic oropharyngeal swab sampling system.Using this swab sampling system,we conducted oropharyngeal swab-sampling tests on 20 volunteers.Our Digital PCR assay results(RNase P RNA gene absolute copy numbers for the samples)revealed that our system successfully collected sufficient numbers of cells from the pharyngeal wall for respiratory disease diagnosis.In summary,we have developed a pharyngeal swab-sampling system based on an“enveloping”soft actuator,studied the sampling process,and imple-mented whole-process robotic oropharyngeal swab-sampling.

分体刀具式名优茶采摘末端执行器设计与试验优化

针对名优茶机械化采摘过程中侧芽无法采摘的问题,根据顶芽、侧芽及茶梗的相关参数并结合茶园环境设计了一种末端执行器,利用分体式刀具的刀齿弯曲变形适应茶梗的干扰从而采摘侧芽。通过有限元仿真刀具切割侧芽得到采摘成功率的影响因素为刀齿宽度、刀齿长度及刀具厚度;采用三因素三水平的中心组合设计与响应面分析法研究各因素对采摘成功率的交互影响;以采摘成功率为响应值建立二次回归模型,确定各因素对采摘成功率的影响显著性主次排序为:刀齿长度、刀齿宽度、刀具厚度。以采摘成功率为目标对各试验因素进行优化,得到优化后的刀齿宽度、刀具厚度、刀齿长度分别为2.6、0.9、20.0 mm。采用优化后的参数进行茶园采摘试验,结果表明,末端执行器能够有效完成茶叶采摘工作,顶芽、侧芽采摘成功率分别为93%、63%,试验值与预测值的相对误差小于5%,优化模型结果可靠。

柑桔采摘机器人末端执行器设计与试验

针对现有柑桔采摘机器人末端执行器单果采摘时间长、采摘成功率低等问题,以20SiMnMoV合金结构钢为材料,设计制作了一款柑桔采摘末端执行器。该末端执行器主要由抓取机构、剪切机构、连接架及控制系统等部分组成,通过控制系统,抓取机构可以实现柑桔无损抓取,剪切机构可将果梗与柑桔快速分离。应用CATIA软件建立末端执行器的三维模型,借助UG与ABAQUS软件对其进行模态分析与静强度分析,得到末端执行器在采摘柑桔过程中不会发生共振,最大变形量为0.077 mm,最大应力为853.1 Mpa、小于材料屈服强度。在脐橙园田间采摘试验结果表明,在采摘机器人机械臂姿态的采摘角度为45°,切割刀刃角度为45°,空压机气压为6 kPa时,采摘成功率最高,单果采摘时间接近最小。该柑桔采摘机器人末端执行器采摘速度高,控制难度低,与机械臂集成度高。

植物工厂岩棉块种苗移植机移植部件设计与试验

目前植物工厂岩棉块种苗移植装备自动化程度低,作业时大多依赖于人工,劳动强度大,效率低。基于植物工厂水培叶菜种苗移植现状设计了一种二级变间距的高速移植部件,并配备有一种拨指式定植杯分离辅助机构。对移植手取苗过程中岩棉块种苗进行受力分析,为移植手设计提供依据;开展拨指式定植杯分离辅助机构落杯试验,为后续植苗至栽培槽孔的定植杯中奠定基础。搭建移植机构试验平台,以取苗深度、岩棉块含水率、移植部件横移速度、移植手升降速度、移植手夹苗间距为试验因素进行五因素三水平正交试验,通过方差分析各因素对移植成功率的影响。试验结果表明:当取苗深度为24 mm、岩棉块含水率为90%、移植部件横移速度为0.8 m/s、移植手升降速度为0.24 m/s、移植手夹苗间距为14 mm时,机构移植成功率为97.9%,移植速度为3132株/h,能够满足高速、高效、稳定的植物工厂岩棉块叶菜种苗移植机械化作业的技术需求。

丘陵果园自然环境下柑橘采摘机器人设计与试验

智慧果园是未来果园行业发展的趋势,智能化果实采摘是发展智慧果园的关键问题。为实现智能化果实采摘,本文搭建了一种适用于丘陵果园矮化栽培模式下的柑橘采摘机器人系统。针对丘陵果园垄间地面凹凸不平,存在地形倾斜角0°~20°,设计了一种自适应调平平台保持机械臂基座水平;通过视觉系统获取多幅点云图像建立果树的三维点云模型,获取果实位置信息;为避免采摘时造成果实损伤,结合柑橘类水果的采摘特点,设计了一种剪切夹持一体化的末端执行器完成柑橘采摘。针对果园自然环境的主要扰动因素(风和光照)进行分级,设置10组对比试验,结果表明:在低光照或正常光照条件下,平均果实定位准确率为82.5%,末端执行器夹取成功率为87.5%,平均采摘时间最短为12.3 s/个;高光照条件下平均果实定位准确率为72%,末端执行器夹取成功率为80%,平均采摘时间最短为12.5 s/个。

基于TRIZ的猕猴桃采摘机设计

针对猕猴桃采摘效率低、易损伤果实等问题,应用TRIZ理论指导猕猴桃采摘机的设计。通过需求分析,确定猕猴桃采摘机的作业流程。基于系统功能分析识别旋拧式猕猴桃采摘末端执行器的功能缺陷,应用因果分析、物场分析等TRIZ工具对采摘末端执行器求解创新方案,创新设计出一种自动定位果树—识别果实—剪断果梗—收集果实的猕猴桃采摘机。应用ADAMS对末端执行器采摘动作进行步态仿真、应用MATLAB对采摘机作业空间和采摘轨迹进行动态仿真,结果表明:猕猴桃采摘机采摘轨迹空间范围为X方向行程约1.4 m、Y方向行程约1.8 m和Z方向行程约2.3 m;采摘速度为8 s/个,末端执行器采摘过程作业动作平稳连贯,满足预期设计要求。在产品概念设计阶段应用TRIZ理论,有利于产生高质量、多层级的概念解,提高产品设计效率。

废旧锂离子电池搬运机器人末端执行器设计

为了解决废旧锂离子电池回收问题,针对回收过程中的分拣步骤,设计了一种可以承载电池质量并适应不同尺寸的机器人末端执行器。介绍了末端执行器各个机构,并针对肘杆六杆机构进行了进一步校核,建立了六杆机构的运动学模型;使用遗传-BFGS(Genetic Algorithm-BFGS,GABFGS)拟牛顿法和粒子群-BFGS(Particle Swarm Optimization-BFGS,PSO-BFGS)拟牛顿法对六杆机构的杆长及位置参数进行优化,建立了六杆机构的动力学模型,计算并仿真校核了空载所需的驱动力,以及极限条件下搬运过程的径向力。研究提供了一种六杆传动机构的新思路,可为废旧锂离子电池分拣设备的研发提供参考。

Contact detumbling toward a nutating target through deformable effectors and prescribed performance controller

Detumbling operation toward a rotating target with nutation is meaningful for debris removal but challenging. In this study, a deformable end-effector is first designed based on the requirements for contacting the nutating target. A dual-arm robotic system installed with the deformable end-effectors is modeled and the movement of the end-tips is analyzed. The complex operation of the contact toward a nutating target places strict requirements on control accuracy and controller robustness. Thus, an improvement of the tracking error transformation is proposed and an adaptive sliding mode controller with prescribed performance is designed to guarantee the fast and precise motion of the effector during the contact detumbling.Finally, by employing the proposed effector and the controller,numerical simulations are carried out to verify the effectiveness and efficiency of the contact detumbling toward a nutating target.

基于负压式苹果采摘机器人末端设计及仿真

为提高苹果采摘效率,实现无损化、高效化采摘。设计出一种基于负压式末端执行器的六自由度采摘机器人,并对基于负压式设计的末端结构进行验证。后基于SD-H参数法对机器人进行正逆运动学求解,运用ADAMS仿真软件对采摘机械臂进行运动学和动力学仿真分析。对末端吸口中心点和各关节点进行监控获取末端吸口位移、速度、加速度与各关节力矩曲线。分析曲线表明:机械臂运动过程平稳无突变,采摘苹果产生冲击力对机械臂各关节影响较小,机械结构设计合理,可满足采摘工作需求,并对后续路径规划提供基础依据。

机器人制孔末端执行器的设计及静动力学分析

提出了一种新型机器人制孔末端执行器的模块化结构设计方案,阐述了该末端执行器的主要模块结构设计、技术特点和技术参数。针对末端执行器整体和主要结构零件分别进行了有限元静力学及动力学分析计算,分析结果表明结构设计科学合理。同时,进一步揭示了高速制孔末端执行器与其匹配的机器人成本和制孔质量之间的关系,可以为其他类似机器人末端执行器设计提供参考。

一种搭载机械臂的瓷砖铺贴末端执行器的设计

针对手工铺贴瓷砖成本高、工作效率低、劳动强度大等问题,设计了一种搭载机械臂的瓷砖铺贴末端执行器。设计真空系统实现瓷砖吸放,设计惯性式激振器实现振动压实,利用激光测距传感器与边缘搜索方法检测定位。基于ROS开发了铺贴系统,实现了搭载机械臂的瓷砖铺贴实验。结果表明,该装置能够实现300 mm×300 mm的瓷砖铺贴作业,重复定位标准偏差小于0.343 mm。

水果采摘机械手关键技术研究现状与展望

采摘机器人的研究对推动水果产业的发展有着重要作用。采摘机械手的运动规划与其硬件结构是采摘机器人的关键技术,影响水果采摘的效率与水果品质。本文分析了传统运动规划算法、基于生物智能的运动规划算法、基于概率采样的运动规划算法以及基于深度强化学习的运动规划算法等运动规划算法的优点和不足。同时总结了采摘机械手硬件结构的研发现状,指出目前采摘机械手存在采摘效率低、规划算法效率低、系统成本高与采摘对象单一等问题,对未来水果采摘机器人的研究进行了展望。本文为未来采摘机器人的研发提供了参考。

莲蓬采摘末端执行器设计

针对目前人工收获莲蓬效率低,莲蓬机械化收获设备发展缓慢的问题,对莲蓬采摘末端执行器进行设计。为确定莲蓬茎秆的相关力学参数,以成熟期莲蓬茎秆作为试验材料,使用质构仪对莲蓬茎秆进行剪切力学特性试验。试验表明,剪切速度在500 mm/min以内时,剪切速度、茎秆直径对莲蓬茎秆剪切强度影响不显著。剪切位置对莲蓬茎秆剪切强度影响最大,剪切位置越靠近莲蓬,所需要的剪切力越小。成熟莲蓬的茎秆剪断所需的剪切力为10.29~132.17 N,剪切应力为0.20~2.71 MPa。由此确定莲蓬采摘末端执行器的最佳采摘范围及所需剪切力,并根据试验结果设计莲蓬采摘末端执行器。采摘试验表明,所设计的莲蓬夹持剪切装置的莲蓬剪切成功率为100%,但由于莲蓬从末端执行器滑落,导致整体采摘成功率为92%。

空间站机械臂末端执行器用导轨设计与验证

针对滚珠直线导轨用于空间机构时的空间环境适应性问题,提出了空间机构用导轨设计方案,经导轨地面试验和产品在轨试验验证,该设计方案可以满足在轨使用要求,实现了导轨在真空、高低温等空间复杂环境下的长寿命应用.以空间站机械臂末端执行器用滚珠直线导轨研制为例,开展了导轨设计,并进行了导轨试验验证,确定了导轨采用滚珠溅射沉积MoS_(2)复合薄膜的固体润滑方案,间隙为0.04~0.05 mm,满足末端执行器在轨工作2000次以上的使用寿命要求.通过末端导轨试验可知,固体润滑的导轨载荷能力和使用寿命均显著下降,在空间机构用导轨研制过程中,须进行专项寿命试验,以验证导轨能否满足在轨使用要求.

果蔬采摘机器人末端执行器研究现状

目前果蔬采摘大多以人工采摘为主,存在效率低、采摘成本大等缺点,同时随着人口老龄化问题的日益严重,劳动力紧缺,制约农业的快速发展。末端执行器作为果蔬采摘机器人的关键部件,在很大程度上影响着采摘机器人的采摘率和损伤率,对末端执行器的研究具有至关重要的意义。充分阐述当前国内外果蔬采摘机器人的研究现状。根据采摘方式和驱动方式的不同对采摘末端执行器进行归纳,总结出采摘过程中致损原因。通过列举典型采摘末端执行器,分析末端执行器在采摘过程中果实致损的原因;通过对现有采摘机器人末端执行器方案的具体参数对比梳理,提出存在识别定位不准、采摘效率低等问题,并从损伤率、采摘效率等方面对未来末端执行器进行展望。