基于IPMC 驱动的自主微型机器鱼

本文从微小型鱼类的运动和受力分析入手,基于人工肌肉IPMC（离子聚合物金属复合材料）的特性, 进行微型机器鱼的结构和控制系统的设计．在此基础上实现仿小型鱼类的各种运动模式,然后,讨论了IPMC 驱动 器推进效率的优化．实验结果证明,基于IPMC 的厘米级机器鱼是可行的：通过改变控制信号的频率和占空比,实 现微型机器鱼的速度控制;通过控制胸鳍和尾鳍,实现上浮、下潜、转弯、巡游等运动模式．最后从尾鳍推进器的结 构角度分析了如何提高推进效率．     

基于CPG的沙漠蜘蛛机器人多模式运动控制方法

模仿具有多种运动模式的沙漠蜘蛛,设计了本体为双层六杆5R闭链机构的仿蜘蛛机器人,其中16个主动关节由直流伺服电机控制．提出了基于Hopf振荡器的中枢模式发生器（CPG）运动控制模型,用于实现仿蜘蛛机器人的翻滚、爬行、侧滚等多种运动模式以及步态切换．利用Matlab和ADAMS对仿蜘蛛机器人的多模式运动进行动力学仿真,结果表明机器人可实现连续平稳的翻滚、爬行、侧滚运动,验证了CPG仿生控制方法应用于闭链机器人多模式运动的可行性．     

Planning 3-D Collision-Free Dynamic Robotic Motion Through Iterative Reshaping

We propose a general and practical planning framework for generating 3-D collision-free motions that take complex robot dynamics into account. The framework consists of two stages that are applied iteratively. In the first stage, a collision-free path is obtained through efficient geometric and kinematic sampling-based motion planning. In the second stage, the path is transformed into dynamically executable robot trajectories by dedicated dynamic motion generators. In the proposed iterative method, those dynamic trajectories are sent back again to the first stage to check for collisions. Depending on the application, temporal or spatial reshaping methods are used to treat detected collisions. Temporal reshaping adjusts the velocity, whereas spatial reshaping deforms the path itself. We demonstrate the effectiveness of the proposed method through examples of a space manipulator with highly nonlinear dynamics and a humanoid robot executing dynamic manipulation and locomotion at the same time.      

Modeling and configuration-independent control of a self-mobile space manipulator

TheSelf-Mobile Space Manipulator (SM ²) is a 5-DOF, 1/3-scale, laboratory version of a robot designed to walk on the trusswork and other exterior surfaces of Space Station Freedom. It will be capable of routine tasks such as inspection, parts transportation and simple maintenance and repair. We have designed and built the robot and gravity compensation system to permit simulated zero-gravity experiments. The control ofSM ² is challenging because of significant structural flexibility, relatively high friction at the joints, positioning error amplified from joint errors due to the long reach, and high performance requirements for general 3-D locomotion. In this paper, we focus on the modeling of the robot system and the design of the control system based on the model. We address the kinematics and dynamic modeling of the 3-D motion ofSM ² and demonstrate the simulation and experimental modal analysis results. The robot dynamic characteristics vary significantly when the robot configuration changes. To consider this effect, we develop a control system that is composed of two basic parts, the model-based part and the servo part. The model-based loop can be updated based on the off-line dynamic model, and the servo control loop is updated by a gain schedule according to the off-line relationship between the closed-loop frequency and the modal frequency estimated from the off-line dynamic model. By taking dynamic variation into account in the controller, the control system is independent of the robot configuration, and the motion performance ofSM ² is greatly enhanced in implementation.     

仿生机器鱼俯仰与深度控制方法

提出一种基于重心改变法的仿生机器鱼俯仰姿态与深度控制方法, 用于实现机器鱼水中的浮潜运动. 该方法利用一种可调整位置的配重块结构, 改变机器鱼的重心位置, 进而实现机器鱼俯仰姿态的调节. 在对机器鱼内部配重块位置和机器鱼俯仰角的关系进行分析的基础上, 对一定速度下机器鱼的深度与俯仰角的关系进行建模, 提出由于尾部形变引起的俯仰姿态变化的补偿方法. 文中给出机器鱼原形样机的相关实验, 分析验证配重块位置变化和机器鱼重心及其姿态的调整, 深度控制等在多种情况下的结果.     

Vision-based 3-D trajectory tracking for unknown environments

This paper describes a vision-based system for 3-D localization of a mobile robot in a natural environment. The system includes a mountable head with three on-board charge-coupled device cameras that can be installed on the robot. The main emphasis of this paper is on the ability to estimate the motion of the robot independently from any prior scene knowledge, landmark, or extra sensory devices. Distinctive scene features are identified using a novel algorithm, and their 3-D locations are estimated with high accuracy by a stereo algorithm. Using new two-stage feature tracking and iterative motion estimation in a symbiotic manner, precise motion vectors are obtained. The 3-D positions of scene features and the robot are refined by a Kalman filtering approach with a complete error-propagation modeling scheme. Experimental results show that good tracking and localization can be achieved using the proposed vision system.     

Study on mobile mechanism of a climbing robot for stair cleaning: a translational locomotion mechanism and turning motion

In human living environments, it is often the case that the cleaning area is three-dimensional space such as a high-rise building. An autonomous cleaning robot is proposed so as to move on all floors including stairs in a building. When a robot cleans in three-dimensional space, it needs to turn for direction in addition to climb down stairs. The proposed robot selects movement using legs or wheels depending on stairs or flat surfaces. In this paper, a mobile mechanism and a control method are described for translational locomotion. The translational mechanism is based on using two-wheel-drive type omni-directional mobile mechanism. To recognize a stair using the position-sensitive detector, the robot shifts from translational locomotion to climbing down motion or edge-following motion. It is shown that the proposed robot turns to face a stair with the accuracy of 5°.     

Dynamic turning control of a quadruped locomotion robot using oscillators

We propose a dynamic turning control system for a quadruped robot that uses non-linear oscillators. It is composed of a spontaneous locomotion controller and voluntary motion controller. We verified the mechanical capabilities of the dynamic turning motion of the proposed control system through numerical simulations and hardware experiments. Various turning speeds and orientations made the motion of the robot asymmetrical in terms of the duty ratio, stride and center of pressure. The proposed controller actively and adaptively controlled redundant degrees of freedom to cancel out dynamic asymmetry, and established stable turning motion at various locomotion speeds and turning orientations.     

基于能量的蛇形机器人蜿蜒运动控制方法的仿真与实验研究

能量作为最基本的物理量之一, 联系着蛇形机器人蜿蜒运动的各个方面. 能量耗散描述了环境交互作用, 能量转换对应着运动的动力学过程, 能量平衡反映了蜿蜒运动的协调性. 提出一种基于能量的蛇形机器人蜿蜒运动控制方法-被动蜿蜒. 通过输出关节力矩控制机器人蜿蜒运动, 由机器人的能量状态调整力矩的大小. 仿真结果显示了被动蜿蜒控制下机器人的构形、角度、力矩、能量状态和转弯特性, 并对控制力矩进行了递归分析. 基于Optotrak运动测量系统构建了被动蜿蜒控制的模拟/物理混合实验系统. 进行了移动实验和拖动实验, 前者改变环境的摩擦特性,后者改变机器人的负载. 仿真和实验验证了蛇形机器人被动蜿蜒控制的有效性和适应性.     

An Optimal Control-Based Formulation to Determine Natural Locomotor Paths for Humanoid Robots

In this paper we explore the underlying principles of natural locomotion path generation of human beings. The knowledge of these principles is useful to implement biologically inspired path planning algorithms on a humanoid robot. By 'locomotion path' we denote the motion of the robot as a whole in the plane. The key to our approach is to formulate the path planning problem as an optimal control problem. We propose a single dynamic model valid for all situations, which includes both non-holonomic and holonomic modes of locomotion, as well as an appropriately designed unified objective function. The choice between holonomic and non-holonomic behavior is not accomplished by a switching model, but it appears in a smooth way, along with the optimal path, as a result of the optimization by efficient numerical techniques. The proposed model and objective function are successfully tested in six different locomotion scenarios. The resulting paths are implemented on the HRP-2 robot in the simulation environment OpenHRP as well as in the experiment on the real robot.     

一种新型爬壁机器人机构及运动学研究

提出了一种新型爬壁机器人机构,介绍了机构的构型及结构特点,推导了运动学正、逆解方程式,规划了直线行走、平面旋转及交叉面跨越三种运动模式．机构构型及运动模式的分析表明,该机构具有体积小、运动特性较好的特点．仿真结果证明,该机器人在运动过程中所需吸附力矩较小且占据的空间较少．     

Control of snake robots with switching constraints: trajectory tracking with moving obstacle

We propose control of a snake robot that can switch lifting parts dynamically according to kinematics. Snakes lift parts of their body and dynamically switch lifting parts during locomotion: e.g. sinus-lifting and sidewinding motions. These characteristic types of snake locomotion are used for rapid and efficient movement across a sandy surface. However, optimal motion of a robot would not necessarily be the same as that of a real snake as the features of a robot’s body are different from those of a real snake. We derived a mathematical model and designed a controller for the three-dimensional motion of a snake robot on a two-dimensional plane. Our aim was to accomplish effective locomotion by selecting parts of the body to be lifted and parts to remain in contact with the ground. We derived the kinematic model with switching constraints by introducing a discrete mode number. Next, we proposed a control strategy for trajectory tracking with switching constraints to decrease cost function, and to satisfy the conditions of static stability. In this paper, we introduced a cost function related to avoidance of the singularity and the moving obstacle. Simulations and experiments demonstrated the effectiveness of the proposed controller and switching constraints.     

An approach to analyzing biped locomotion dynamics and designing robot locomotion controls

An approach to analyzing biped locomotion problems is presented. This approach applies the principles of Lagrangian dynamics to derive the equations of motion of locomotion gaits, state-variable techniques to analyze locomotion dynamics, and multivariable feedback to design locomotion controls. A robot model which has no knee joints or feet and is constrained to motion in the sagittal plane is chosen as a sufficiently simple model of a biped to illustrate the approach. A goal of the analysis is the design of a locomotion control for the robot which produces a walking gait having a velocity and stride length similar to those of a human walking gait. The principle feature of the approach is a much deeper understanding of the dynamics of biped locomotion than previous approaches have provided.     

3-D Snake Robot Motion: Nonsmooth Modeling, Simulations, and Experiments

A nonsmooth (hybrid) 3-D mathematical model of a snake robot (without wheels) is developed and experimentally validated in this paper. The model is based on the framework of nonsmooth dynamics and convex analysis that allows us to easily and systematically incorporate unilateral contact forces (i.e., between the snake robot and the ground surface) and friction forces based on Coulomb's law of dry friction. Conventional numerical solvers cannot be employed directly due to set-valued force laws and possible instantaneous velocity changes. Therefore, we show how to implement the model for numerical treatment with a numerical integrator called the time-stepping method. This method helps to avoid explicit changes between equations during simulation even though the system is hybrid. Simulation results for the serpentine motion pattern lateral undulation and sidewinding are presented. In addition, experiments are performed with the snake robot ldquoAikordquo for locomotion by lateral undulation and sidewinding, both with isotropic friction. For these cases, back-to-back comparisons between numerical results and experimental results are given.     

Discretization and fitting of nominal data for autonomous robots

This paper presents methodologies to discretize nominal robot paths extracted from 3-D CAD drawings. Behind robot path discretization is the ability to have a robot adjusting the traversed paths so that the contact between robot tool and work-piece is properly maintained. In addition, a hybrid force/motion control system based on Fuzzy-PI control is proposed to adjust robot paths with external sensory feedback. All these capabilities allow to facilitate the robot programming process and to increase the robot’s autonomy.     

Open-loop Velocity Control of Concrete Floor Finishing Robots

The twin trowel concrete floor finishing robot consists of a pair of trowels, each of which rotates four plastering blades, and does not have any mechanism like wheels for its locomotion. However, while leveling the concrete floor, it can move in any direction with the unbalanced friction forces occurring between the trowels and the floor, which are controlled by adjusting the posture of the trowels. For the motion control of the robot, this paper discusses the following: First, the typical velocity feedback control method is not dependable because of the difficulties of measuring the robot velocity; secondly, the friction force, which drives the robot, is modeled when the robot is in translation motion; thirdly, the friction force decreases as the robot velocity increases, thus resulting in a saturated velocity dependent on the posture of the trowel; finally, the saturated velocity enables us to control the motion of the robot only by adjusting the posture of trowels without any feedback about the robot velocity.     

Generation of bipedal walking through interactions among the robot dynamics,the oscillator dynamics,and the environment: Stability characteristics of a five-link planar biped robot

We previously developed a locomotion control system for a biped robot using nonlinear oscillators and verified the performance of this system in order to establish adaptive walking through the interactions among the robot dynamics, the oscillator dynamics, and the environment. In order to clarify these mechanisms, we investigate the stability characteristics of walking using a five-link planar biped robot with a torso and knee joints that has an internal oscillator with a stable limit cycle to generate the joint motions. Herein we conduct numerical simulations and a stability analysis, where we analytically obtain approximate periodic solutions and examine local stability using a Poincaré map. These analyses reveal (1) stability characteristics due to locomotion speed, torso, and knee motion, (2) stability improvement due to the modulation of oscillator states based on phase resetting using foot-contact information, and (3) the optimal parameter in the oscillator dynamics for adequately exploiting the interactions among the robot dynamics, the oscillator dynamics, and the environment in order to increase walking stability. The results of the present study demonstrate the advantage and usefulness of locomotion control using oscillators through mutual interactions.     

Intelligent robots as artificial living creatures

This article introduces a multi locomotion robot, MLR III, which has multiple locomotion types, i.e., not only brachiating but also walking. Conventionally we have studied dexterous locomotion robots and their controller design. One is a simplified two-link robot, Brachiator II. This is an example of an underactuated system in which a robot mechanism has more degrees of freedom than actuators. The desired motions are encoded as the output of a target dynamical system inspired by the pendulum-link motion of an apes brachiation. The other is a monkey-type robot, Brachiator III. Brachiator III achieves a dexterous motion using redundant degrees of freedom. The motion is generated in an empirical learning process on an intelligent structure, on which the learning algorithm coordinates some primitive motions to generate the desired motion. MLR III is an extended locomotion robot that has multiple types of locomotions: brachiation, bipedal walking, and quadrupedal walking, similar to a monkey or gorilla. This article introduces the mechanism and controller design for brachiating motion.This work was presented, in part, at the 8th International Symposium on Artificial Life and Robitics, Oita, Japan, January 24–26, 2003     

动物运动指令的中枢模式发生器对机器人运动控制的启示

动物运动指令的中枢模式发生器（central pattern generator, CPG）在动物的节律运动中发挥着重要的作用,对机器人的仿生控制方法研究具有借鉴意义.首先介绍了CPG的神经环路和控制机制,然后分析了组成CPG的非线性振荡器的典型数学模型,接着介绍了利用CPG进行机器人运动控制在国内外的发展现状,最后展望了其应用前景.     

仿壁虎机器人足端工作空间分析及其实现协调运动的步态规划

基于对壁虎爬行运动的研究,提出一种四足仿壁虎爬壁机器人.对其机械结构、运动学、足端工作空间和越障能力进行了分析,规划了两种爬行步态,并针对实验中出现的过驱动问题进行了分析,设计了一种多关节协调控制算法.实验结果表明,使用该控制算法的机器人运动是协调稳定的,验证了分析结果的正确性和控制算法的有效性.