Bionic lightweight design of limb leg units for hydraulic quadruped robots by additive manufacturing and topology optimization

Galloping cheetahs,climbing mountain goats,and load hauling horses all show desirable locomotion capability,which motivates the development of quadruped robots.Among various quadruped robots,hydraulically driven quadruped robots show great potential in unstructured environments due to their discrete landing positions and large payloads.As the most critical movement unit of a quadruped robot,the limb leg unit(LLU)directly affects movement speed and reliability,and requires a compact and lightweight design.Inspired by the dexterous skeleton–muscle systems of cheetahs and humans,this paper proposes a highly integrated bionic actuator system for a better dynamic performance of an LLU.We propose that a cylinder barrel with multiple element interfaces and internal smooth channels is realized using metal additive manufacturing,and hybrid lattice structures are introduced into the lightweight design of the piston rod.In addition,additive manufacturing and topology optimization are incorporated to reduce the redundant material of the structural parts of the LLU.The mechanical properties of the actuator system are verified by numerical simulation and experiments,and the power density of the actuators is far greater than that of cheetah muscle.The mass of the optimized LLU is reduced by 24.5%,and the optimized LLU shows better response time performance when given a step signal,and presents a good trajectory tracking ability with the increase in motion frequency.

Dynamic Bending of Bionic Flexible Body Driven by Pneumatic Artificial Muscles(PAMs) for Spinning Gait of Quadruped Robot

The body of quadruped robot is generally developed with the rigid structure. The mobility of quadruped robot depcnds on the mechanical properties of the body mechanism, It is difficult for quadruped robot with rigid structure to achieve better mobility walking or running in the unstructured environment. A kind of bionic flexible body mechanism for quadruped robot is proposed, which is composed of one bionic spine and four pneumatic artificial muscles（PAMs）. This kind of body imitates the four-legged creatures＇ kinematical structure and physical properties, which has the characteristic of changeable stiff＇hess, lightweight, flexible and better bionics. The kinematics of body bending is derived, and the coordinated movement between the flexible body and legs is analyzed. The relationship between the body bending angle and the PAM length is obtained. The dynamics of the body bending is derived by the floating coordinate method and Lagrangian method, and the driving tbrce of PAM is determined. The experiment of body bending is conductcd, and the dynamic bending characteristic of bionic flexible body is evaluated. Experimental results show that the bending angle of the bionic flexible body can reach 18. An innovation body mechanism for quadruped robot is proposed, which has the characteristic of flexibility and achieve bending by changing gas pressure of PAMs. The coordinated movement of the body and legs can achieve spinning gait in order to improve the mobility of quadruped robot.

Bionic Mechanism and Kinematics Analysis of Hopping Robot Inspired by Locust Jumping

A flexible-rigid hopping mechanism which is inspired by the locust jumping was proposed, and its kinematic characteris- tics were analyzed. A series of experiments were conducted to observe locust morphology and jumping process. According to classic mechanics, the jumping process analysis was conducted to build the relationship of the locust jumping parameters. The take-offphase was divided into four stages in detail. Based on the biological observation and kinematics analysis, a mechanical model was proposed to simulate locust jumping. The forces of the flexible-rigid hopping mechanism at each stage were ana- lyzed. The kinematic analysis using pseudo-rigid-body model was described by D-H method. It is confirmed that the proposed bionic mechanism has the similar performance as the locust hind leg in hopping. Moreover, the jumping angle which decides the jumping process was discussed, and its relation with other parameters was established. A calculation case analysis corroborated the method. The results of this paper show that the proposed bionic mechanism which is inspired by the locust hind limb has an excellent kinematics performance, which can provide a foundation for design and motion planning of the hopping robot.

Motor Driving Leg Design for Bionic Crab-like Robot

The paper presents the design of walking leg for bionics crab-like robot, which is driven with micro servo motor. The kinematic characteristics of the bionics machine are analysed for optimized structure parameters, which has been used in the robot design. A three closed loop motor control system structure for joint driver is also given, as well as the multi-joint driving system for walking robot leg.

Analysis on pivot turning of quadruped robot with bionic flexible body driven by the PAMs

The pivot turning function of quadruped bionic robots can improve their mobility in unstructured environment.A kind of bionic flexible body mechanism for quadruped robot was proposed in this paper,which is composed of one bionic spine and four pneumatic artificial muscles(PAMs).The coordinated movement of the bionic flexible body and the leg mechanism can achieve pivot turning gait.First,the pivot turning gait planning of quadruped robot was analyzed,and the coordinated movement sequence chart of pivot turning was presented.Then the kinematics modeling of leg side swing and body bending for pivot turning was derived,which should meet the condition of the coordinated movement between bionic flexible body and leg mechanism.The PAM experiment was conducted to analyze its contraction characteristic.The study on pivot turning of the quadruped robot will lay a theoretical foundation for the further research on dynamic walking stability of the quadruped robot in unstructured environment.

Stability margin of the quadruped bionic robot with spinning gait

Spinning gait is valuable for quadruped robot,which can be used to avoid obstacles quickly for robot walking in unstructured environment. A kind of bionic flexible body is presented for quadruped robot to perform the spinning gait. The spinning gait can be achieved by coordinated movement of body laterally bending and legs swing,which can improve the mobility of robot walking in the unstructured environments. The coordinated movement relationship between the body and the leg mechanism is presented. The stability of quadruped robot with spinning gait is analyzed based on the center of gravity( COG) projection method. The effect of different body bending angle on the stability of quadruped robot with spinning gait is mainly studied. For the quadruped robot walking with spinning gait,during one spinning gait cycle,the supporting polygon and the trajectory of COG projection point under different body bending angle are calculated. Finally,the stability margin of quadruped robot with spinning gait under different body bending angle is determined,which can be used to evaluate reasonableness of spinning gait parameters.

Modelling of thrust generated by oscillation caudal fin of underwater bionic robot

A simplified model of the thrust force is proposed based on a caudal fin oscillation of an underwater bionic robot. The caudal fin oscillation is generalized by cen- tral pattern generators （CPGs）. In this model, the drag coefficient and lift coefficient are the two critical parameters which are obtained by the digital particle image velocimetry （DPIV） and the force transducer experiment. Numerical simulation and physical experi- ments have been performed to verify this dynamic model.

Planning on Bionic Walking Gait of Quadruped Robot over Rough Terrain

A quadruped robot is more adjustable to a complex terrain than a wheeled or caterpillar robot to realize the continuous adjustable motions characterized by submissiveness and low energy consumption in basic control of the quadruped robot over rough terrain. This paper presents a static walking mode of ＂altitude hold＂, which means to keep absolute altitude by controlling limbs adjustably on the basis of which biokinetics studies have shown that quadrupeds can move with almost the same body altitude over rough terrains characterized by a nearly horizontal relief. The gait design specifies several characteristic states of stance phase and swing phase for a quadruped robot and controls the phase sequence and phase of four legs through change of characteristic states. Furthermore, we design a robot control system to generate adjustable gaits and control the coordinative movement of robot joints. This planning method is tested through ADAMS and MATLAB interactive co-simulation; the quadruped robot which has 8 degrees of freedom （8-DOF） is used to simulate the motion over a terrain character- ized by randomly arranged humps. The results show that this method can make the quadruped robot capable to walk over certain rough terrain.

四足机器人腾空跳跃的轨迹优化与控制方法

针对四足机器人难以跨越大尺寸障碍物的问题,提出了一种仿生腾空跳跃的轨迹优化控制方法 .首先,对马里努阿犬的越障运动进行测试和仿生学分析,得到腾空跳跃的参考轨迹.其次,根据摩擦锥、轨迹平滑、运动学和动力学等约束条件,基于轨迹优化的方法对仿生参考轨迹进行离线优化,生成四足机器人的期望跳跃轨迹,得到跳跃所需的足端位置、关节力矩和关节角度序列.再次,设计分阶段的跳跃控制器,采用关节和质心PD(Proportional Derivative)的组合控制策略,实现对期望跳跃轨迹的跟踪,采用变刚度虚拟模型控制实现对落地姿态的调整和足底力的缓冲.最后,在Webots仿真环境中完成了1 m高度的自由落地和跳跃0.75 m高度桌子的仿真实验.研究结果表明:仿生轨迹优化与控制算法能够使四足机器人跳跃大尺寸障碍物并且具有平稳落地的效果,对于提高四足机器人的高性能运动能力以及拓展其应用环境具有参考价值.

仿生六足折纸机器人结构设计与运动分析

针对现有折纸机器人组成结构单一,运动不够灵活的问题,将折纸结构与多足机器人设计相结合,耦合三浦折纸和六折痕折纸,提出新型的仿螃蟹六足折纸机器人设计方案,扩展了折纸机器人的运动构型,提升了折纸机器人的运动灵活性.在面对称假设下,该机器人单足具有2个自由度,此时将机器人腿部顶点等效为关节,轴线折痕等效为连杆,建立机器人腿部的平面连杆等效模型,并以折面夹角为运动变量,通过仿真计算得出机器人足端的理论运动范围.利用楔形面板技术对折面增厚并避免相邻折面发生物理干涉,建模得到折纸仿螃蟹六足机器人的三维模型.基于平面连杆的等效模型,分析折面夹角与足端运动之间的联系,设计确定机器人的足端运动轨迹与运动步态.利用3D打印技术设计并制作折纸仿生六足机器人试验样机,基于STM32单片机控制实现了机器人三横向角步态运动.结果表明,该折纸仿生机器人可以实现平面构型到仿螃蟹构型的转换,在6条腿的协同运动下,机器人可以平稳地左右横向移动.

机器人灵巧手研究综述

机器人灵巧手可以模仿人类动作,完成复杂场景下的多种任务。机器人灵巧手的研究是开发智能人形机器人的关键技术之一。以机器人灵巧手的研究历程为核心,阐述了多指灵巧手的研究现状,分析了灵巧手的演化过程和研究进展。从自由度数目、驱动方式、机械传动方式和传感技术等方面探讨了灵巧手分类和特征,展望了灵巧手未来的发展趋势。

融合外形仿生与可拓创新方法的产品创新设计

为辅助设计人员创新,激发发散性思维,提出了融合外形仿生与可拓创新方法的产品创新设计方法。建立仿生样本库,通过意象相似度和功能相似度确定仿生对象;解构目标产品代表性样本,采用数量化Ⅰ类构建设计元素与设计目标的关联模型,选取对设计目标贡献度高的元素进行可拓建模;以仿生对象为基础,对可拓模型进行发散、变换,生成创意,并采用模糊综合评价法评估创意。融合外形仿生与可拓创新方法形成一种流程化的产品创新设计方法,以废墟搜救机器人为例,验证该方法的可行性。研究结果表明:该方法有助于生成创新方案,能为发散性思维提供指导方向,为设计人员提供有价值的参考。

基于改进YOLOv5的仿生机器鱼目标检测算法研究

为满足仿生机器鱼目标检测的需要,在YOLOv5基础上提出了一种轻量级检测算法,降低算法复杂度并提高精度。首先对YOLOv5s模型进行改进,通过GhostConv和C3Ghost模块降低参数量和计算量。其次,引入CA和CoordConv模块增强特征提取和目标位置感知能力,采用soft NMS减少使用传统非极大抑制(Non maximum suppression,NMS)带来的漏检、误检,同时使用MPDIoU简化相似性比较,提升检测精度和召回率。最后,所提出方法在目标检测数据集上的试验结果表明,改进的YOLOv5网络体积更小、精度更高,证明了该算法的有效性和优越性。

受海龟爬行与山羊行走启发的四足仿生移动机器人多步态规划及动力学分析

为解决救援机器人运动速度慢、环境适应性差和步态单一等问题,参照海龟与山羊的生理结构,设计了一种四足仿生移动机器人。首先,根据海龟能在松软地面上爬行以及山羊运动能力强的特点,为机器人规划了仿海龟爬行和仿山羊行走两种步态以适应不同环境,提高了机器人的运动性能。然后,对机器人支腿进行了动力学分析,通过建立动力学模型来获取机器人关节扭矩与运动性能参数之间的定量关系。最后,通过仿真和样机实验来验证机器人步态的可行性以及机器人的环境适应能力。结果表明,所设计的机器人结构稳定,步态规划合理,可适应不同的复杂地形。研究结果可为仿生机器人的设计与开发提供重要参考。

仿生系统动力学与应用专刊序

围绕仿生系统动力学建模、设计理论与方法、非线性振动特征、控制方法等研究主题,本专刊介绍了仿生系统动力学与控制的一些创新性研究和工程应用成果.

仿生机器鱼步态控制及闭环运动控制方法综述

鱼类所具有的推进效率高、机动性强、环境扰动小等优点引发了国内外学者对仿生机器鱼的研究。底层步态控制方法和闭环运动控制方法是当前机器鱼控制研究的两大热点。按照推进模式的分类方法概述各类机器鱼的样机研制情况以及其性能优劣,介绍机器鱼的推进机理及其水动力学研究进展,进而重点探讨轨迹逼近方法和中枢模式发生器这2种底层步态控制思路,综述机器鱼的典型闭环运动控制方法。中枢模式发生器具有更强的灵活性、稳定性和可操作性,易于引入反馈项而实现闭环控制,在机器鱼底层步态控制中占主导地位。针对机器鱼的显著特点改进后的基于学习的控制方法与多种方法相结合后的混合控制方法具有更为广阔的发展前景,符合仿生机器鱼智能化的发展方向。根据工作条件和运动要求建立合理的步态控制系统以及准确高效的闭环运动控制系统可提高机器鱼的整体性能。

复杂地形下仿生轮腿式机器人位姿控制研究

丘陵山地地势复杂、地形多变,农机装备作业环境以倾斜角度较大的斜坡为主,传统农机装备在丘陵山区复杂地形下作业时效率低、稳定性差,甚至会出现侧倾、翻车等现象。本文从仿生机械设计角度出发,提出一种在丘陵山地复杂地形下能够自主实现位姿调平控制的轮腿式机器人平台,提升复杂地形下的作业稳定性和安全性。以昆虫后足为仿生机械设计对象,并结合多连杆机构原理,完成新型变行程轮腿机构及机器人平台的整体架构设计。采用D-H参数法分析了轮腿机构运动学特性,结果显示轮腿式机器人离地间隙最大调整量为574mm,具备较强的越障能力。在空间坐标系上定义轮腿式机器人空间姿态参数,推导得到机身姿态角与轮腿伸缩量之间的空间姿态模型,并设计了基于NSGA-Ⅱ的机身空间姿态逆解算法。基于空间姿态逆解算法构建了轮腿式机器人全向位姿调平位姿控制系统,包含机身调平控制器、“虚腿”补偿控制器和质心高度控制器,在复杂地形下行驶时能够控制轮腿式机器人俯仰角、侧倾角、接地力、质心高度等空间姿态参数,然后通过搭建的轮腿式机器人ADAMS-Matlab联合仿真模型完成了位姿控制系统算法仿真验证。在机器人样机上开展了离地间隙自动调整和机身全向位姿调平试验,试验结果表明,试验样机离地间隙最大调整量为574mm,同时在复杂地形下能够实现机身位姿全向自动调平,调平平均时间约为1.2s,调平平均误差为0.8°,位姿控制响应速度与调平精度能够满足实际工作要求。

基于CPG控制的双髻鲨仿生机器人设计与实验研究

随着人类对自然的探索越来越深入,新型水下航行器的需求与日俱增,仿生机器人因其特殊的推进方式和高效的推进效率而受到越来越多的关注,而传统的仿生鱼类仅模拟了流线型外壳,少有提及仿生对象本身结构对于仿生性能的影响,本文提出了一种基于中央模式发生器(CPG)的类双髻鲨仿生机器人.以鱼类基本运动形态为基础,将鱼身抽象为关节连杆结构,建立了三关节四连杆的仿生机器鱼模型并进行了仿真计算.根据步态规律预估了其运动性能,随后通过实验验证了可行性.本仿生鱼旨在以简单的机械结构和较低的控制成本,实现对双髻鲨的最大限度模拟,得益于良好的仿生结构,中央模式发生器的引入,以及柔性硅胶材料在鱼身的应用,此机器人拥有体型小,控制简单,地形适应能力强,能量利用率高等特点,与传统水下推进器相比噪音更小,环境适应能力更强,在科研、农业等行业均具有广泛的应用前景,如野外勘测,水下救援,水域巡逻等.

轨迹可控的微型水母机器人研制

为解决微型机器人在较小机身尺寸下实现高效轨迹控制的难题,设计并研制了微型仿水母机器人JRT,其由气室、重心调整机构和仿水母推进器三部分组成,尺寸仅为6.8 cm×5.3 cm,可通过重心调整机构和仿水母推进器协同控制有效实现水下轨迹可控.水下实验验证了机器人JRT沿竖直方向游泳和悬停、水平定向游泳以及水平弹射功能,并通过对机器人JRT沿竖直方向和水平方向游泳过程中的力平衡关系和运动状态数据分析提出了轨迹控制方案,测得水平定向游泳的速度可达到1.7 cm/s,轨迹偏差为0~3.4 cm,展现了微型仿水母机器人JRT较好的轨迹控制能力,可见其在水下资源勘查、环境监测等领域的应用潜力.

仿人表情机器人的下颌机构设计与运动

针对目前仿人表情机器人口部运动模式单一的问题,基于人类下颌的解剖学运动机理,设计了一种新颖的多自由度仿生下颌机构.建立了仿生下颌机构的逆向运动学模型,分析了其运动模式,实现了仿生下颌机构在空间中的多自由度运动.对多自由度仿生下颌机构进行了多刚体仿真,并通过实验验证了其可行性.仿真和实验结果表明,基于逆向运动学模型,该机构可以模拟人类下颌的张合、前推、偏移3种基本运动模式,以及咀嚼、咬唇等口部复杂运动模式,弥补了现有仿人表情机器人口部运动模式受限的问题.