Inverted Modelling:An Effective Way to Support Motion Planning of Legged Mobile Robots

This paper presents an effective way to support motion planning of legged mobile robots—Inverted Modelling,based on the equivalent metamorphic mechanism concept.The difference from the previous research is that we herein invert the equivalent parallel mechanism.Assuming the leg mechanisms are hybrid links,the body of robot being considered as fixed platform,and ground as moving platform.The motion performance is transformed and measured in the body frame.Terrain and joint limits are used as input parameters to the model,resulting in the representation which is independent of terrains and particular poses in Inverted Modelling.Hence,it can universally be applied to any kind of legged robots as global motion performance framework.Several performance measurements using Inverted Modelling are presented and used in motion performance evaluation.According to the requirements of actual work like motion continuity and stability,motion planning of legged robot can be achieved using different measurements on different terrains.Two cases studies present the simulations of quadruped and hexapod robots walking on rugged roads.The results verify the correctness and effectiveness of the proposed method.

Research on Biologically Inspired Hexapod Robot's Gait and Path Planning

Realistically there are many robot joints in the biologically inspired hexapod robot, so they will generate many complexities in the calculations of the gait and the path planning and the control variables. The software Solidworks and MSC. ADAMS are adopted to simulate and analyze the prototype model of the robot. By the simulations used in our design, the applicability of the tripod gait is validated, and the scheme which uses cubic spline curve as the endpoint of foot＇s path is feasible. The principles, methods, and processes of the simulation of hexapod robot are illustrated. A methodology is proposed to get the robot inverse solution in ADAMS, and to simplify the theoretical calculation, and further more to improve the efficiency of the design.

Application of Optimal-Jerk Trajectory Planning in Gait-balance Training Robot

To accommodate the gait and balance disorder of the elderly with age progression and the occurrence of various senile diseases,this paper proposes a novel gait balance training robot(G-Balance)based on a six degree-of-freedom parallel platform.Using the platform movement and IMU wearable sensors,two training modes,i.e.,active and passive,are developed to achieve vestibular stimulation.Virtual reality technology is applied to achieve visual stimulation.In the active training mode,the elderly actively exercises to control the posture change of the platform and the switching of the virtual scene.In the passive training mode,the platform movement is combined with the virtual scene to simulate bumpy environments,such as earthquakes,to enhance the human anti-interference ability.To achieve a smooth switching of the scene,continuous speed and acceleration of the platform motion are required in some scenarios,in which a trajectory planning algorithm is applied.This paper describes the application of the trajectory planning algorithm in the balance training mode and the optimization of jerk(differential of acceleration)based on cubic spline planning,which can reduce impact on the joint and enhance stability.

Novel algorithm of gait planning of hydraulic quadruped robot to avoid foot slidingand reduce impingement

In order to solve kinematic redundancy problems of a hydraulic quadruped walking robot,which include leg dragging,sliding,impingement against the ground,an improved gait planning algorithm for this robot is proposed in this paper.First,the foot trajectory is designated as the improved composite cycloid foot trajectory.Second,the landing angle of each leg of the robot is controlled to satisfy friction cone to improve the stability performance of the robot.Then with the controllable landing angle of quadruped robot and a geometry method,the kinematic equation is derived in this paper.Finally,agait planning method of quadruped robot is proposed,a dynamic co-simulation is done with ADAMS and MATLAB,and practical experiments are conducted.The validity of the proposed algorithm is confirmed through the co-simulation and experimentation.The results show that the robot can avoid sliding,reduce impingement,and trot stably in trot gait.

A gait planning method applied to hexapod biomimetic robot locomotion

In order to fulfill the goal of autonomous walking on rough terrain,a distributed gait planningmethod applied to hexapod biomimetic robot locomotion is proposed based on the research effort of gait co-ordination mechanism of stick insect.The mathematical relation of walking velocity and gait pattern wasdepicted,a set of local rules operating between adjacent legs were put forward,and a distributed networkof local rules for gait control was constructed.With the interaction of adjacent legs,adaptive adjustmentof phase sequence fluctuation of walking legs resulting from change of terrain conditions or variety of walk-ing speed was implemented to generate statically stable gait.In the simulation experiments,adaptive ad-justment of inter-leg phase sequence and smooth transition of velocity and gait pattern were realized,andstatic stableness was ensured simultaneously,which provided the hexapod robot with the capability ofwalking on rough terrain stably and expeditiously.

Gait planning and intelligent control for a quadruped robot

We present a method for designing free gaits for a structurally symmetrical quadruped robot capable of performing statically stable, omnidirectional walking on irregular terrain. The robot＇s virtual model is constructed and a control algorithm is proposed by applying virtual components at some strategic locations. The deliberative-based controller can generate flexible sequences of leg transferences while maintaining walking speed, and choose optimum foothold for moving leg based on integration data of exteroceptive terrain profile. Simulation results are presented to show the gait＇s efficiency and system＇s stability in adapting to an uncertain terrain.

Study on Gait Planning of Dynamic Walking of Biped Robots Based on Optimization Theory

In this paper. two important problems in the gait planning of dymamic walking of biped robot, i. e., finding inverse kinemdtic solution and constructing joint trajectories, are studied in detail’by adopting complex optimization theory. The optimization algorithm for finding the inverse kinematic solution is developed, the construction method of joint trajectories is given, and the gait planning method of dynamic walking of biped robots is proposed.

A Humanoid Robot Gait Planning and Its Stability Validation

Gait planning based on linear inverted pendulum (LIPM) on structured road surface can be quickly generated because of the simple model and definite physical meaning. However, over-simplifi- cation of the model and discontents of zero velocity and acceleration boundary conditions when robot starts and stops walking lead to obvious difference between the model and the real robot. In this paper, parameterized gait is planned and trajectories’ smoothness of each joint angle and centroid are ensured using the 3-D LIPM theory. Static walking method is used to satisfy zero velocity and acceleration boundary conditions. Besides, a multi-link model is built to validate the stability. Simulation experiments show that: despite of some deviation from the theoretical solution, the actual zero-moment point (ZMP) is still within the support polygon, and the robot walks steadily. In consequence, the rationality and validity of model simplification of LIPM is demonstrated.

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。

月基装备行走运动学分析与连续步态规划

针对缓冲行走功能一体的月面探测器构型设计困难、步态分析复杂等问题,提出了一种基于相同支链构型的四足月基装备(LBE)设计分析方法与连续步态规划方案。设计复合功能着陆腿机构及整机多状态位姿;构建LBE在行走状态下的单腿运动学模型,对其进行正逆运动学求解,分析单腿与整机工作空间和运动性能;对LBE整机进行水平月面的连续步态规划,并设计单步足端轨迹,通过动力学仿真,验证LBE行走步态稳定性。仿真结果表明:LBE沿前进方向连续稳定运行,质心竖直方向浮动仅占整器高度的0.24%,俯仰角最大摆动幅度为0.34°,翻滚角最大摆动幅度为0.27°。

十二杆张拉整体结构动态分析及路径规划研究

张拉整体因其区别于传统结构的特点在土木和可动结构领域有广泛的发展前景,目前学者对于多步态或更复杂的球形张拉整体研究较少,且一些传统路径规划方法不适用于多面体张拉整体结构.因此,本文采用几何方法找寻了一种多步态的十二杆球形张拉整体结构(Snub-12)的合理构型,并用找形方法进行了验证.定义并分析了Snub-12的多种基本步态和各步态形成的理论路径空间,并将其与单步态的6杆球形张拉整体结构(TR-6)进行对比,明确了两种结构运动的特点和区别.对快速搜索随机树算法进行改进并利用其产生引导路径,结合Snub-12步态组合的情况,生成适合不同场景的合理运动路径,最后通过仿真分析验证了方法的可行性和有效性.分析结果表明:同等条件下,不论是路径空间中盲区占比还是独立滚动步态的翻滚步长,Snub-12均优于TR-6,更适宜开展长距离运动.基于引导策略的路径规划方法可以解决多步态张拉整体结构的路径规划问题,这丰富了球形张拉整体结构的运动理论,可以为该类球形张拉整体可动结构的实际应用提供了理论支撑.

金属矿山井下采场六足机器人运动分析及步态规划

六足机器人因其结构特殊带来的良好越障能力成为仿生机器人研究的热点,然而,金属矿山井下采场矿石堆积、崎岖不平的特点,给这类机器人的行走稳定性、越障性带来更多的挑战。因此,为使六足机器人在井下具有更好的通过性,对其运动能力和步态规划进行了相关研究。首先仿照自然界六足生物,设计六足机器人结构,对其腿部进行运动学分析;然后规划了用于采场的直行步态,结合采场路面环境设计了一种直线—摆线复合轨迹提升越障性,同时分析了机器人爬坡稳定性,对爬坡步态进行了优选;最后对规划步态进行仿真和现场模拟试验。仿真和试验结果表明,所规划的足端轨迹能跨越抬腿高度85%的障碍物,并且对矿石堆积形成的采场路面有更好的避障能力;三角步态爬坡时在坡底和坡顶过渡阶段容易打滑,而横向步态可以实现平滑的过渡,爬坡性能更佳。

基于DRL和自由步态的六足机器人运动规划研究

为提高六足机器人在非结构环境下的通过率和运动性能,提出一种基于DRL和自由步态规划器的多接触运动规划算法。自由步态规划器获取目标状态下可达落足点从而输出最优步态序列;利用DRL训练得到六足机器人在随机生成的梅花桩环境中的质心运动策略。为了保证机器人在运动过程中相邻状态之间的可达性,利用状态转移可行性模型对状态转移可行性进行判定,实现六足机器人在不同宽度沟壑梅花桩环境下的落脚点规划。仿真与样机实验表明:多接触运动规划算法能够让机器人快速平稳地从起点到达目标区域,并自动调整步态模式以应对不同环境下随机分布的梅花桩。

基于四足并联脊柱3-RPS机构运动研究

为解决四足机器人在复杂地形运动的稳定性和适应性,提出基于腰部并联脊柱的结构设计。文中采用推导的运动学逆解,计算各驱动杆的长度,建立机构运动学方程,得到驱动杆的质心位移、速度和加速度曲线。建立简化四足腰部并联机器人模型,在ADAMS中运行,进行步态规划和步态仿真,并验证了该方案的可行性。

Design,Mobility Analysis and Gait Planning of a Leech-like Soft Crawling Robot with Stretching and Bending Deformation

Soft climbing/crawling robots have been attracting increasing attention in the soft robotics community,and many prototypes with basic locomotion have been implemented.Most existing soft robots achieve locomotion by planar bending deformation and lack sufficient mobility.Enhancing the mobility of soft climbing/crawling robots is still an open and challenging issue.To this end,we present a novel pneumatic leech-like soft robot,Leechbot,with both bending and stretching deformation for locomotion.With a morphological structure,the robot consists of a three-chambered actuator in the middle for the main motion,two chamber-net actuators that act as ankles,and two suckers at the ends for anchoring on surfaces.The peristaltic motion for locomotion is implemented by body stretching,and direction changing is achieved by body bending.Due to the novel design and two deformation modes,the robot can make turns and transit between different surfaces;the robot,hence,has excellent mobility.The development of the robot prototype is presented in detail in this paper.To control its motion,tests were carried out to determine the relationship between step length and air pressure as well as the relationship between motion speed and periodic delay time.A kinematic model was established,and the kinematic mobility and surface transitionability were analyzed.Gait planning based on the inflating sequence of the actuating chambers is presented for straight crawling,turn making,and transiting between surfaces and was verified by a series of experiments with the prototype.The results show that a high mobility in soft climbing/crawling robots can be achieved by a novel design and by proper gait planning.

基于深度强化学习分层控制的双足机器人多模式步态系统研究

提出一种基于深度强化学习(DRL)分层控制的双足机器人多模式步态生成系统.首先采用优势型演员-评论家框架作为高级控制策略,引入近端策略优化(PPO)算法、课程学习(CL)思想对策略进行优化,设计比例-微分(PD)控制器为低级控制器;然后定义机器人观测和动作空间进行策略参数化,并根据对称双足行走步态周期性的特点,设计步态周期奖励函数和步进函数;最后通过生成足迹序列,设计多模式任务场景,并在Mujoco仿真平台下验证方法的可行性.结果表明,本方法能够有效提高双足机器人在复杂环境下行走的稳定性以及泛化性.

基于动作捕捉系统对下肢外骨骼运动分析及步态仿真

结合生物医学工程,设计出一种人体下肢外骨骼。通过光学动作捕捉系统采集人体正常行走时的位置坐标,分析采集数据,从而获得人体正常行走时的髋、膝和踝关节的角度变化;建立自由度为5的下肢外骨骼运动学模型,随后通过逆运动学求解出各个关节的角度变化,运用于步态规划中;在SolidWorks中建立下肢外骨骼三维模型,运用ADAMS进行动力学仿真,其中对仿真参数的设定为步态规划中求解的各关节角度,通过虚拟样机完成仿真动作,最后将所得的仿真数据与光学动作捕捉系统采集的数据进行对比。数据对比结果显示,下肢外骨骼能基本实现人体的正常行走,确定了模型建立的可适用性、运动学分析与动力学仿真准确性,为后期的研究提供基准。

机器鳄鱼运动的仿生步态规划方法

模仿真实动物的运动步态是仿生机器人步态规划研究的一个重点。针对一种新型仿生机器鳄鱼的步态规划问题,采用动作捕捉技术获取了真实鳄鱼的运动步态。在此基础上,利用高斯牛顿法求解出机器鳄鱼的腿部关节角度,拟合得到与真实步态轨迹相似性较好的仿生步态,并分析了机器鳄鱼在该步态下的运动稳定性。虚拟样机的运动仿真实验结果表明:机器鳄鱼能用与真实鳄鱼相似的步态,以0.3 m/s的速度向前爬行,且具备较高的稳定性。

可穿戴式下肢外骨骼康复机器人运动学分析

本文指出外骨骼康复机器人被广泛应用于下肢运动障碍患者的辅助行走,可大大增强肢体运动功能受损患者的康复效果。通过仿生学,本文设计了一种由绳索驱动的可穿戴式下肢外骨骼康复机器人。采用D-H法,对可穿戴式下肢外骨骼康复机器人进行了运动学建模,得到了各关节之间的运动学关系。采用五次多项式插值法进行步态规划,得出了步态运动方程,并将其所得的关节角速度数据导入到ADAMS软件中,对可穿戴式下肢外骨骼康复机器人进行了运动学仿真分析。最后得出,关节角位移变化平滑、稳定,表明了所设计康复机器人具有良好的效果。

四足机器人运动学分析与步态规划

四足机器人的稳定性好,灵活度高,在众多领域得到了应用。应用SolidWorks软件对四足机器人的机械结构进行三维建模,并进行运动学分析。基于复合摆线对四足机器人足端轨迹进行步态规划,并应用Simulink和Simscape Multibody软件对四足机器人对角步态进行运动仿真,获得四足机器人各个关节角及位置的轨迹。研究结果表明,基于复合摆线的四足机器人足端轨迹步态规划是合理和有效的,可以为后续四足机器人的运动控制提供参考。