Gait Planning for a Quadruped Robot with One Faulty Actuator

Fault tolerance is essential for quadruped robots when they work in remote areas or hazardous environments. Many fault-tolerant gaits planning method proposed in the past decade constrained more degrees of freedom(DOFs) of a robot than necessary. Thus a novel method to realize the fault-tolerant walking is proposed. The mobility of the robot is analyzed first by using the screw theory. The result shows that the translation of the center of body(Co B) can be kept with one faulty actuator if the rotations of the body are controlled. Thus the DOFs of the robot body are divided into two parts: the translation of the Co B and the rotation of the body. The kinematic model of the whole robot is built, the algorithm is developed to actively control the body orientations at the velocity level so that the planned Co B trajectory can be realized in spite of the constraint of the faulty actuator. This gait has a similar generation sequence with the normal gait and can be applied to the robot at any position. Simulations and experiments of the fault-tolerant gait with one faulty actuator are carried out. The Co B errors and the body rotation angles are measured. Comparing to the traditional fault-tolerant gait they can be reduced by at least 50%. A fault-tolerant gait planning algorithm is presented, which not only realizes the walking of a quadruped robot with a faulty actuator, but also efficiently improves the walking performances by taking full advantage of the remaining operational actuators according to the results of the simulations and experiments.     

A Precise Localization Method for a High Speed Mobile Robot Using iGS and Dual Compass

This paper proposes a precise localization algorithm for a quickly moving mobile robot.In order to localize a mobile robot with active beacon sensors,a relatively long time is needed,since the distance to the beacon is measured by transmitting time of the ultrasonic signal.The measurement time does not cause a high error rate when the mobile robot moves slowly.However,with an increase of the mobile robot’s speed,the localization error becomes too high to use for accurate mobile robot navigation.Therefore,in this research into high speed mobile robot operations,instead of using two active beacons for localization,an active beacon and dual compass are utilized to localize the mobile robot.This new approach resolves the high localization error caused by the speed of the mobile robot.The performance of the precise localization algorithm is verified by comparing it to the conventional method through real-world experiments.     

APPROACH TO IMPROVEMENT OF ROBOT TRAJECTORY ACCURACY BY DYNAMIC COMPENSATION

Some dynamic factors, such as inertial forces and friction, may affect the robot trajectory accuracy. But these effects are not taken into account in robot motion control schemes. Dynamic control methods, on the other hand, require the dynamic model of robot and the implementation of new type controller. A method to improve robot trajectory accuracy by dynamic compensation in robot motion control system is proposed. The dynamic compensation is applied as an additional velocity feedforward and a multilayer neural network is employed to realize the robot inverse dynamics. The complicated dynamic parameter identification problem becomes a learning process of neural network connecting weights under supervision. The finite Fourier series is used to activate each actuator of robot joints for obtaining training samples. Robot control system, consisting of an industrial computer and a digital motion controller, is implemented. The system is of open architecture with velocity feedforward function. The proposed m     

Adaptive walking of a quadrupedal robot based on layered biological reflexes

A multiple-legged robot is traditionally controlled by using its dynamic model.But the dynamic-model-based approach fails to acquire satisfactory performances when the robot faces rough terrains and unknown environments.Referring animals’ neural control mechanisms,a control model is built for a quadruped robot walking adaptively.The basic rhythmic motion of the robot is controlled by a well-designed rhythmic motion controller(RMC) comprising a central pattern generator(CPG) for hip joints and a rhythmic coupler(RC) for knee joints.CPG and RC have relationships of motion-mapping and rhythmic couple.Multiple sensory-motor models,abstracted from the neural reflexes of a cat,are employed.These reflex models are organized and thus interact with the CPG in three layers,to meet different requirements of complexity and response time to the tasks.On the basis of the RMC and layered biological reflexes,a quadruped robot is constructed,which can clear obstacles and walk uphill and downhill autonomously,and make a turn voluntarily in uncertain environments,interacting with the environment in a way similar to that of an animal.The paper provides a biologically inspired architecture,with which a robot can walk adaptively in uncertain environments in a simple and effective way,and achieve better performances.     

A Real-time Look-ahead Trajectory Planning Methodology for Multi Small Line Segments Path

When a robot is required to machine a complex curved workpiece with high precision and speed,the tool path is typically dispersed into a series of points and transmitted to the robot.The conventional trajectory planning method requires frequent starts and stops at each dispersed point to complete the task.This method not only reduces precision but also causes damage to the motors and robot.A real-time look-ahead algorithm is proposed in this paper to improve precision and minimize damage.The pro...     

Effect of Spine Motion on Mobility in Quadruped Running

Most of current running quadruped robots have similar construction： a stiff body and four compliant legs. Many researches have indicated that the stiff body without spine motion is a main factor in limitation of robots’ mobility. Therefore, investigating spine motion is very important to build robots with better mobility. A planar quadruped robot is designed based on cheetahs’ morphology. There is a spinal driving joint in the body of the robot. When the spinal driving joint acts, the robot has spine motion; otherwise, the robot has not spine motion. Six group prototype experiments with the robot are carried out to study the effect of spine motion on mobility. In each group, there are two comparative experiments： the spinal driving joint acts in one experiment but does not in the other experiment. The results of the prototype experiments indicate that the average speeds of the robot with spine motion are 8.7%–15.9% larger than those of the robot without spine motion. Furthermore, a simplified sagittal plane model of quadruped mammals is introduced. The simplified model also has a spinal driving joint. Using a similar process as the prototype experiments, six group simulation experiments with the simplified model are conducted. The results of the simulation experiments show that the maximum rear leg horizontal thrusts of the simplified mode with spine motion are 68.2%–71.3% larger than those of the simplified mode without spine motion. Hence, it is found that spine motion can increase the average running speed and the intrinsic reason of speed increase is the improvement of the maximum rear leg horizontal thrust.     

WALK-ASSISTING BALANCE SYSTEM OF THE EXOSKELETON ROBOT FOR DISABLED PEOPLE

A novel methodology for a walk-assisting balance system of the exoskeleton robot for dis-abled people is presented. The experiment on the walk-assisting balance system is implemented using amini-type ropewalker robot. The mechanism of the ropewalker robot is designed, its dynamic model isbuilt, and its control system based on PWM is developed. The emulations in Matlab and the results ofexperiments prove that this methodology is effective.     

Kinematics and dynamics analysis of a quadruped walking robot with parallel leg mechanism

It is desired to require a walking robot for the elderly and the disabled to have large capacity,high stiffness,stability,etc.However,the existing walking robots cannot achieve these requirements because of the weight-payload ratio and simple function.Therefore,Improvement of enhancing capacity and functions of the walking robot is an important research issue.According to walking requirements and combining modularization and reconfigurable ideas,a quadruped/biped reconfigurable walking robot with parallel leg mechanism is proposed.The proposed robot can be used for both a biped and a quadruped walking robot.The kinematics and performance analysis of a 3-UPU parallel mechanism which is the basic leg mechanism of a quadruped walking robot are conducted and the structural parameters are optimized.The results show that performance of the walking robot is optimal when the circumradius R,r of the upper and lower platform of leg mechanism are 161.7 mm,57.7 mm,respectively.Based on the optimal results,the kinematics and dynamics of the quadruped walking robot in the static walking mode are derived with the application of parallel mechanism and influence coefficient theory,and the optimal coordination distribution of the dynamic load for the quadruped walking robot with over-determinate inputs is analyzed,which solves dynamic load coupling caused by the branches’ constraint of the robot in the walk process.Besides laying a theoretical foundation for development of the prototype,the kinematics and dynamics studies on the quadruped walking robot also boost the theoretical research of the quadruped walking and the practical applications of parallel mechanism.     

Biped walking robot based on a 2-UPU+2-UU parallel mechanism

Existing biped robots mainly fall into two categories： robots with left and right feet and robots with upper and lower feet. The load carrying capability of a biped robot is quite limited since the two feet of a walking robot supports the robot alternatively during walking. To improve the load carrying capability, a novel biped walking robot is proposed based on a 2-UPU＋2-UU parallel mechanism. The biped walking robot is composed of two identical platforms（feet） and four limbs, including two UPU（universal-prismatic-universal serial chain） limbs and two UU limbs. To enhance its terrain adaptability like articulated vehicles, the two feet of the biped walking robot are designed as two vehicles in detail. The conditions that the geometric parameters of the feet must satisfy are discussed. The degrees-of-freedom of the mechanism is analyzed by using screw theory. Gait analysis, kinematic analysis and stability analysis of the mechanism are carried out to verify the structural design parameters. The simulation results validate the feasibility of walking on rugged terrain. Experiments with a physical prototype show that the novel biped walking robot can walk stably on smooth terrain. Due to its unique feet design and high stiffness, the biped walking robot may adapt to rugged terrain and is suitable for load-carrying.     

Localization of Small Mobile Robot by Low-Cost GPS Receiver

This article deals with a problem of the robot localization in the outdoor environment by using the GPS （global positioning system） data. In order to navigate the robot, it is necessary to transform the global position into the local map in the form of two-dimensional Cartesian coordinate system. The transformation is based on the model of the Earth-WGS 84 reference ellipsoid. The aim of this article is to experimentally evaluate a set of low-cost GPS receivers applicable as position sensors for small outdoor mobile robots. The evaluation is based on series of measurements executed in different times and places. The measured data is processed by given procedure and acquired positions are transformed into the local coordinate system. Accordingly the accuracy of the measured positions is statistically evaluated. The evaluation of used GPS receivers is done by comparison with data acquired by high-end geodetic GPS system Leica 1200, which is used as a reference GPS system.     

大型17R“加藤一郎”机器人仿人行走控制研究

针对大型17R"加藤一郎"结构双足机器人仿人行走控制问题,从仿人机器人的机械结构、控制系统、步态仿真、动力学参数等方面对机器人的影响进行了研究,采用仿生学原理,参考了人体上、下半身比例特点,对机器人的机械结构进行了设计;对机器人控制系统进行了设计,提出了一种基于DSP+FPGA的主控系统,将多CPU协同工作、分布式远程控制技术应用到仿人机器人行走控制中;利用人类行走过程中各关节的转动参数为输入的控制方法,在ADAMS上进行了步态行走试验,分析了动力学参数对机器人步态的影响。研究结果表明,以人类行走方式控制机器人步态行走,机器人行走步态稳定可行,可应用于大型双足步行机器人步态行走控制。     

“穿地龙”机器人及其位姿检测系统的研究

在讨论了“穿地龙”机器人的结构和工作原理的基础上,提出“自主式”机器人位姿检测的方法,并建立了机器人位姿检测的软硬件系统,推导了机器人在土中位姿计算的数学模型。土中穿孔实验证明这种位姿检测的方法可准确、方便、可靠地检测机器人位姿,这对“穿地龙”机器人工况条件下的实际轨迹控制和进行“穿地龙”机器人的应用分析打下了一定的理论基础。     

基于模糊算法的机器人行进控制

针对亚广联（ABU）第四届机器人电视大赛，搭建一台由单片机控制的轮式机器人，依靠光纤传感器感知场地内白线而前进。山于比赛场地所铺设的白线宽度会存在较大的误差，而且赛场上外界光线变化较大，容易对传感器产生影响。因而提出了高鲁棒性的控制要求，故对其寻线算法采用了模糊算法，取得了很好的控制效果，在大赛中获得了冠军。     

第五届全国大学生机器人电视大赛参赛机器人的研制

本文以第五届全国大学生机器人电视大赛题目为研究对象，阐述了参赛机器人的设计和研发过程。针对参赛机器人抗干扰、智能化等要求，我们研发了一套基于C8051F020单片机的具有多路输出和输入且能同时控制五台电动机的控制电路和与此适应的控制软件。实践证明。该设计满足了大赛要求。     

中型组足球机器人控球系统的设计与实现

针对RoboCup中型组足球机器人在比赛过程中,被动式控球机构不具备断球功能、持球不稳定,以及带球不能进行小角度转弯等问题,将红外传感技术与机电一体化技术应用到中型足球机器人控球机构中,设计了基于Atmegal28的主动式控球机构,通过串口从上位机读取机器人的行进姿态,结合红外传感器探测到的控球区域信息,选择了左右持球臂传动电机的控制方式,实现了比赛过程中机器人的断球、带球转身和持球等关键技术。采用模块化架构理念,设计了DC—DC电源电路、红外传感器电路、空心杯直流电机驱动电路、持球臂机械构件以及系统软件。实验结果表明,中型足球机器人控球系统的输出电压、PWM波、红外探测距离等参数误差均小于2％,RisingSun机器人在实际比赛中的有效控球时间达到了56％。     

2V2足球机器人设计

介绍了足球机器人的构思过程、软件设计、硬件使用及制作机器人过程中遇到的问题和战术的运用。基于比赛场地和比赛规则,重点说明软件的编程思想和使用的语言并附有流程图,对传感的选择,机器人的改造和对机器人改造及编程技巧和遇到的问题的分析,也对足球机器人2V2比赛的规则、使用的足球、场地简单的说明。     

手动机器人设计与可靠性分析

依据第二届全国大学生机器人电视大赛规则，从创新机器人设计的角度对手动机器人的设计及其关键机构的工作机理进行了细致分析。并针对竞赛中对系统的高稳定性的要求，详细阐述了在设计改进与系统维护中所用的故障树分析法。设计分析和参赛效果证明了论文内容的有效性。     

机器人导航路径的多种群博弈蚁群规划策略

为了降低移动机器人工作路径长度、减少算法迭代次数、提高路径平滑性,提出了多种群博弈蚁群算法的规划方法。建立了机器人工作环境的栅格模型;提出了由1个主种群和2个从种群组成的多种群蚁群算法;将博弈论应用于种群的协同与竞争中,设计了合作博弈机制、奖惩机制、针锋相对机制和协调博弈机制;针锋相对机制和协调博弈机制应用于从种群间的交流与竞争,以帕累托最优为目的提高整个从种群的搜索多样性;合作博弈机制和奖惩机制应用与主从种群之间的交流与合作,使从种群将搜索经验和较优路径片段传递给主种群,从而提高主种群搜索效率和质量。经仿真验证,多种群博弈蚁群算法的路径多样性在迭代过程中保持较高水平;多种群博弈算法规划的路径长度比最大最小蚂蚁系统减小了5.98%,搜索迭代次数和路径平滑性也优于最大最小蚂蚁系统,证明了多种群博弈蚁群算法在路径规划中的有效性。     

一种简单的行走助力机器人的设计与仿真

行走助力机器人是近年来兴起一新的研究领域,它属于特种机器人的范畴。行走助力机器人可以增强人体下肢的力量,可以为老年人、残疾人、士兵和消防员等提供增强行走能力的服务。在本篇论文中,首先是在分析人体行走特定的基础上设计了一款简单的行走助力机器人,并通过运动学逆求解得到了各个关节的角位移计算方程。然后采用微分变换法来求取雅可比矩阵来对速度运动学进行分析。最后采用Pro/E和ADAMS对机器人进行了动力学仿真,并对仿真中出现的问题和测量所得曲线进行了分析。     

分层递阶的足球机器人决策系统的设计

MiroSot的决策子系统是一个多智能体的协调控制系统,主要由信息处理、协调策略、角色分配、动作实现等组成,决策子系统的优劣直接关系到机器人足球比赛的胜负。采用四层推理的决策模型对MiroSot(3vs3)决策子系统进行了设计,并采用Petri网的方法对其角色转换进行了描述,最后应用面向对象的编程方法实现了所设计的决策子系统。将这个模型应用于机器人足球实际比赛中,实验证明该系统是可行的、有效的。