Perception of effective contact area distribution for humanoid robot foot

Maintaining dynamical stability for humanoid robots to walk or run in even environments has so far been achieved. However, it will become a challenge work to keep balance under rough terrains, because the effective contact area (ECA) between the feet and the uneven environments is less than that on even ground. Thus some control schemes are additionally needed for robot to keep dynamical balance, which increases the complexity of control. In view of that, flexible force sensor array (FFSA) system is adopted under robot feet to detect the ECA in the case of stepping on rough terrains. Structure optimum, data acquisition, processing methods, etc., of the FFSA system are all elaborately provided in this paper. And the feasibility and validity of the FFSA system mounted in the robot foot system are experimentally tested on the humanoid robot platform BHR-2.     

Dynamically adapt to uneven terrain walking control for humanoid robot

Dynamically adapt to uneven ground locomotion is a crucial ability for humanoid robots utilized in human environments.However,because of the effect of current pattern generation method,adapting to unkn...     

基于足端位置的六足机器人漫游地形感知与表征

未知复杂地形的精准感知与量化表征长期制约着六足机器人运动性能与作业效能的本质提升。针对传统基于外部传感的地形感知与表征方法普遍存在的感知范围局限、感知精度不足、表征效果欠佳等突出问题,研究借鉴足式生物地形感知机理,充分利用足端与地形交替离散接触特性,创新提出基于足端位置的六足机器人漫游地形感知与表征方法。通过构建时变机体坐标系下足端位置解算模型,解决漫游地形无序足端序列坐标高效求取难题。基于足端序列的周期化处理与矢量化描述,建立基于周期足端位置状态的局部地形量化表征方法,间接构建时变机体位姿与局部地形间周期映射关系。系统分析相邻周期机体位姿间耦合约束与变换机制,建立基于机体位姿变换的全局形貌拓扑重构方法,以连续精准机体位姿作为参照实现周期映射局部地形的拓扑拼接。样机实验结果表明,基于足端位置的六足机器人地形感知与表征方法相比传统方法能够在无需增设外部观测传感器件条件下较为精准合理的量化表征不同特征局部地形,并实现漫游地形全局形貌的精准拓扑重构。     

不平整地面仿人机器人行走控制策略

针对仿人机器人行走于不平整地面会失稳倾倒的现象,提出基于Kane碰撞原理的在线调节控制算法。该调节算法可以实现快速的动力学解算,估算出仿人机器人遇到障碍时地面对腿部的冲击力大小,据此调节仿人机器人的腿部及躯干姿态参数,使机器人成功稳定行走过凸起或凹陷障碍。采用Matlab的Simulink工具,仿真验证了5杆仿人机器人模型基于Kane在线调节控制算法平稳行走过障碍的过程。     

拟人机器人运动学分析

由于拟人机器人自由度数目众多而且不存在一般工业机器人那样的固定基座,使用常规方法对其进行运动学分析并不是很合适。仿人机器人的13杆几何模型提出了一种新思路,即利用统一的模型对拟人机器人任何动作进行运动学的分析计算,并推导出了拟人机器人正、逆运动学的计算公式。最后利用3DS MAX3.0进行了动画仿真,验证了该方法和所推导公式的正确性。     

Optimum design method of multi-axis force sensor integrated in humanoid robot foot system

The multi-axis force sensor (MFS) has been extensively adopted in humanoid robot foot to obtain external forces/moments acted on the foot while in locomotion. The precision and comprehensive performances of MFS originally determined by its elastomer structure are significant essentially for humanoid robots to keep balance by detection of external forces/moments during walking motion. The reason for the transmission of coupling-error of structure is analyzed and then the optimum method for the function of objective-optimization of MFS compliance matrix, Finite Element Method (FEM), orthogonal design and range analysis method are all proposed synthetically. In addition, the comprehensive performances of MFS designed by the optimum method are analyzed and elaborated in a concrete design case. Finally, the main indexes of the MFS are verified experimentally through humanoid robot’s dynamic walking motion.     

Kinematics of wheeled mobile robots on uneven terrain

This paper deals with the kinematic analysis of a wheeled mobile robot (WMR) moving on uneven terrain. It is known in literature that a wheeled mobile robot, with a fixed length axle and wheels modeled as thin disk, will undergo slip when it negotiates an uneven terrain. To overcome slip, variable length axle (VLA) has been proposed in literature. In this paper, we model the wheels as a torus and propose the use of a passive joint allowing a lateral degree of freedom. Furthermore, we model the mobile robot, instantaneously, as a hybrid-parallel mechanism with the wheel–ground contact described by differential equations which take into account the geometry of the wheel, the ground and the non-holonomic constraints of no slip. We present an algorithm to solve the direct and inverse kinematics problem of the hybrid-parallel mechanism involving numerical solution of a system of differential-algebraic equations. Simulation results show that the three-wheeled WMR with torus shaped wheels and passive joints can negotiate uneven terrain without slipping. Our proposed approach presents an alternative to variable length axle approach.     

Vision guided dual arms robotic system with DSP and FPGA integrated system structure

Usually, a humanoid robot has two arms and stereo vision system to execute human daily actions. It has complicate mechanism and mechatronics control system structure. The hardware control structure should be planned ingeniously to execute the complicate computation of 3D image processing and manipulate a multi degree of freedom dual arms motion control, especially for mobile robot system. Here a 7 DOF dual arms robot with FPGA hardware control structure and a digital signal processor (DSP) based CMOS stereo vision system are designed and built in our lab. The intelligent fuzzy sliding mode control strategy is employed to establish the visual guided robotic motion control software. This low cost humanoid robotic system has compact control structure and mechanism integration for mobile application purpose. Object detecting and tracking schemes in 3D space were developed for locating the target position and then guided the robot arm to pick and place objects or track the specified moving target. Experimental results show that this delicate robotic system has basic humanoid function.     

四足机器人砂砾地面对角行走控制方法

为解决四足机器人在砂砾地面上对角行走容易失稳的问题,提高机器人对松软和凹凸不平地面的适应性,在位置控制的基础上提出了一种机身姿态角的调整策略,并在机器人对角行走的过程中采取了一种变阻抗参数的阻抗控制方法。最后在实际的砂砾地面进行了四足机器人对角行走实验,实验结果证明这种控制方法和调整策略对于四足机器人对角行走在砂砾地面上具有较好的控制效果。     

三自由度自适应抓持仿人手的设计研究

设计完成了用于仿人形机器人上的具有自动适应被抓持物体几何特征的三自由度仿人手。论文首先设计了具有自适应抓持能力的手指机构，进一步对该手指机构各关节之间的运动耦合关系进行了分析研究，并通过虚拟样机技术验证了所设计的仿人手机构传动系统的正确性和自适应抓持的可行性，最后提出了衡量仿人手抓持能力的指标，分析了所设计的仿人手的抓持能力。所有结果都表明手指机构是合理实用的，所设计完成的仿人手达到了设计要求。     

翻滚式探测机器人设计及运动仿真

针对探测机器人对未知环境探测时易发生倾覆而丧失运动能力的情况,结合探测机器人运行过程中车载仪器需维持一定的姿态角的功能要求,提出了一种翻滚式探测机器人结构.该机器人由八个驱动轮、两个侧向支撑架以及平衡架组成:八个驱动轮保证机器人发生倾覆后仍有四个驱动轮与地面接触,从而不丧失运动能力;侧向支撑架可使机器人发生侧倾后与地面保持较大的倾角,待稳定后借助驱动力恢复至正常姿态,从而恢复运动能力;平衡架可保证车载仪器的横滚角和俯仰角在探测机器人发生倾覆和侧倾时基本不变.针对探测机器人的上述功能,运用ADAMS进行运动仿真,以验证各部件功能的可实现性.仿真结果表明,翻滚式机器人各部件实现了设计功能.     

面向不平地面的双足欠驱动步行稳定控制

为实现双足机器人在不平地面上的欠驱动步行,提出一种基于质心运动状态的稳定步行控制策略.考虑地面柔性,使用柔性接触模型描述"机器人足部地面"柔性接触,并通过解耦建模的方式建立了"机器人地面"前向与侧向耦合动力学模型.根据人类变速步行特征,提出基于机器人质心速度控制的步行控制策略,将三维步行解耦为前向和侧向的主从控制,通过...     

Posture optimization for a humanoid robot using a simple genetic algorithm

This study proposes a method of real-time posture optimization of humanoid robots using a genetic algorithm and neural network. Here, the motion of a humanoid robot pushing an object is considered. When the robot starts pushing the object, the palms of its hands and the soles of its feet are assumed to be fixed on the object and on the ground, respectively, and they sense the reaction force from those surfaces. The reaction force results in changes of torques in the joints. This study determines an optimized posture using a genetic algorithm such that either the torques are evenly distributed over all joints or the torque of the weakest joint is rapidly reduced. Several different optimized postures are then generated by varying the reaction forces at the palms and the soles. The data is used as training patterns for a multilayer perceptron neural network with a back-propagation learning algorithm. Using the trained neural network, the humanoid robot can find the optimal posture for different reaction forces in real time. Several simulations were conducted to confirm the effectiveness of the proposed method. The simulation results showed that the proposed method can be used for real-time posture optimization of humanoid robots.     

Experimental Characterization of Operation of a Waist-Trunk System with Parallel Manipulators

An extensive research activity has been focused on the upper and lower limbs of humanoid robots. However, due to mechanical design difficulties and complex control of multi-body system, the torso of humanoid robot is somehow a neglected or simplified design part. In this paper, operation performance of a new waist-trunk system as torso for humanoid robots is presented through results of lab experimental tests. The proposed waist-trunk system is composed of two 3 DOFs (degrees of freedom) parallel manipulators, which are connected in a serial chain architecture. A prototype is built by using two prototypes of CaPaMan (Cassino Parallel Manipulator), which are convenient stiff architectures with easy-operation characteristics. Experimental tests are carried out with the aims to imitate lateral-bending and transverse-rotation movements of human torso. Operation performances like displacements, accelerations, and actuation torque are measured for a performance evaluation and design characterization of the used manipulator solution imitating human torso. Experimental test results are illustrated and discussed to show the practical operation feasibility of the proposed architecture and the operation characteristics of the built prototype.     

应用欧拉角表达步行机器人系统的机械模型

步行机器人作为一种载运工具适应地况能力强,结构复杂,运动控制难。实现类人型机器人动态行走,必须对机器人进行动力学建模、步态设计和稳定姿态控制算法设计。其中,数学模型的建立一直是一个机构学难题, 在类人型机器人研究中起着重要作用。讨论了应用欧拉方程建立步行系统的机械模型,提出了一些简化条件,然后用欧拉方程表达了构件的旋转和线运动及关节处的力矩模型,并在此基础上研究了定常步行时简化步行机器人的运动方程式,为进一步研究定常步行机器人甚至变步长机器人的运动学提供了又一理论工具。     

Fabrication of four-point biped robot foot module based on contact-resistance force sensor and its evaluation

This paper presents the design of robot foot module of four-point biped walking robot and its fabrication. The foot module has four sensor units based on contact-resistance force sensor. The thin-film-type force sensor is fabricated by coating resistive ink on thin polyimide film using silk screening technique. The simple structure is devised and fabricated to assemble the thin force sensor rigidly. The unit force sensor module is evaluated by the calibration setup to obtain the characteristics of repeatability and hysteresis. The sensor module presents hysteresis error of about 5% and repeatability error of about 0.37%. The calculated zero moment point (ZMP) of the foot module is also compared with the measured position using static load of 50 N. The maximum location error of ZMP is less than 10%. The robot foot module shows the possibility of applying it to humanoid walking.     

多移动机器人协同模式及其倾翻稳定性研究

针对山地果园单个移动机器人爬坡能力不足及稳定性差等问题,提出了一种多移动机器人协同操作的方法。在原有六足机器人结构的基础上增加了用于多机协同操作的连接件,得到了用于多机协同操作的机器人单体。将3个六足机器人单体通过协同操作得到了3种典型协同模式：串行模式、并行模式、三角模式。最后采用稳定锥法对足式移动机器人系统的单体模式及3种典型协同模式在6种典型地形情况下的静态、动态稳定性分别进行了分析。理论分析及仿真实验结果表明：3种典型协同模式间可进行两两切换;在6种典型地形情况下,通过多机协同操作及协同模式切换的方式可提高足式机器人系统的稳定性。     

并联六轮腿机器人机身平稳性控制方法研究

轮腿式机器人在非结构化路面运动时,机身平稳性控制对于提高运动平稳性、降低系统能耗、提高定位与建图精度等具有重要意义。针对并联式六轮腿机器人在通过不规则地形时足端悬空、姿态倾斜、机身晃动等问题,提出一种融合足端力控制器、姿态控制器及重心高度控制器的机身平稳性控制框架。其中,足端力控制器通过阻抗控制算法抑制机器人足端受力因地形变化带来的突变扰动;机身姿态控制器对机身倾斜角进行解耦,并控制各腿的长度补偿机身的偏移量;重心高度控制器根据各腿的伸长量自适应地调节机身高度,保证腿部执行机构具有足够的运动空间。针对三种控制器相互耦合、对外部扰动抑制效果不佳等问题,利用串级控制的思想将三种控制目标统一为力跟踪控制,降低机身振荡的风险。在并联式六轮腿机器人上进行了实验验证,结果表明所提出的控制算法框架能有效抑制外部地形扰动,当机器人以大约0.6 m/s的速度前进时,机身的俯仰角及横滚角保持在-0.7°~0.7°范围内,足端接触力维持在期望力附近,且机身重心高度随地面起伏自适应地调整,确保了机器人的运动平稳性。     

姿态传感器在仿人机器人足部感知系统中的应用

仿人机器人要实现在复杂环境下稳定行走,仅仅依靠地面反力信息是远不能满足应用要求的,此时足部姿态信息显得更为重要。为实现仿人机器人的稳定行走,自主开发了基于姿态传感器的足部感知系统,利用姿态传感器(ADIS16355)与TMS320F2811实现对姿态信息的实时高速采集与处理。实验证明姿态传感器在仿人机器人足部感知系统中的可行性。     

A dynamic model of humanoid robots using the analytical method

This paper presents a new approach to analyzing dynamic models of humanoid robots. This new approach is divided into an unconstrained system that applies the principle of Lagrangian dynamics and a constrained system that applies Gauss’ principle. Constrained motion is important in the design and analysis of humanoid robots. In this paper, the central issue in the determination of the constrained system is considered to be the determination of this constraint factor. Using the fundamental equation described by the proposed approach, the constraint equation can easily be generated. Based upon the fundamental equation, the dynamic model of the humanoid robot is explained as divided by the sagittal and frontal planes. The suggested approach simplifies designing dynamic models of humanoid robots which will obey the constrained system whether or not they are constrained, holonomic, or open chain.