未知不平整地面上的双足步行稳定控制

 针对未知的不平整地面环境,提出了双足机器人稳定步行控制算法,该算法由步态规划和传感器反馈控制两部分组成.采用被动倒立摆模型设计双足机器人的步态,使得双足机器人能够自然、节能的稳定行走.实时反馈控制用来适应地面环境的凹凸不平以及处理外部环境的扰动.控制器包括上身姿态控制、期望ZMP控制以及非线性落地控制三部分.双足机器人机构柔性的存在对机器人稳定性以及控制效果造成很坏的影响,甚至使反馈控制造成负面的效果,因此柔性的影响也被考虑到步行控制器的设计当中.利用双足机器人不平地面上的步行实验验证所提出步行控制算法的有效性.     

Real-Time Planning of Humanoid Robot's Gait for Force-Controlled Manipulation

This paper proposes a new style of manipulation by a humanoid robot. Focusing on the task of pushing an object, the foot placement is planned in real time according to the result of manipulation of the object. By using the impedance control of the arms, the humanoid robot can stably push the object regardless of the mass of the object. If the object is heavy, the humanoid robot pushes it by walking slowly and vice versa. Also, for planning the gait in real time, we propose a new analytical method where a newly calculated trajectory of the robot motion is smoothly connected to the current one. The effectiveness of the proposed method is confirmed by simulation and experiment     

Real-Time Gait Planning for Pushing Motion of Humanoid Robot

This paper describes real-time gait planning for pushing motion of humanoid robots. This method deals with an object whose mass is not known. In order that a humanoid robot pushes an unknown object in both single support phase and double support phase, real-time gait planning for pushing the unknown object is proposed. Real-time gait planning consists of zero moment point (ZMP) modification and cycle time modification. ZMP modification is the method that modifies the influence of reaction force to ZMP. By cycle time modification, the period in double support phase is modified to avoid a robot tipping over. These modifications are calculated from reaction force on arms in every cycle. With these methods, trajectory planning for pushing an unknown object in both single support phase and double support phase is calculated. Even if parameters of an object and friction coefficient on the floor vary, the robot keeps on walking while pushing an object. The effectiveness of the proposed method is confirmed by a simulation and an experiment.     

Control of articulated robot arm with sensory feedback: laser beamtracking system

A method for the trajectory tracking control of an articulated robot arm using sensory feedback is presented. First, a general control algorithm for such a problem is presented. To implement sensory feedback effectively, the dynamics of a robot arm is described in the task coordinate system. Then the dynamics of the robot arm in the task coordinate system are linearized using nonlinear feedback. Because the linearization cannot be done completely because of variations and identification errors of the physical parameters of a robot arm, a robust controller is designed so that the effect of parameter variations and errors can be lessened. The control law is shown to be simplified by the use of high-gain feedback. The simplification can make the implementation of the control law very easy. The proposed algorithm is applied to the trajectory-tracking control of an articulated robot arm using a laser beam. The experiments show that the proposed algorithm works well for such a sensory feedback system     

小型仿人机器人的设计及步态规划

针对现有仿人形机器人造价高的缺点,设计一款低成本的小型双足机器人研究平台.根据人类步行过程及人体生理结构.依据模糊控制与专家控制相结合的理论提出一种简单的双足机器人模型.并根据仿生学原理确定机器人的自由度配置及各关节的比例尺寸.然后,利用目前通用的行为规划软件对双足机器人步态规划进行仿真.并在平坦地面上进行相应行走试验.实验证明.根据人行走模式对机器人进行步态规划的算法稳定可行.为机器人的教学和科研提供了良好的实验平台.     

Robust Iterative Learning Control Design: Application to a Robot Manipulator

This paper deals with robust iterative learning control design for uncertain single-input-single-output linear time-invariant systems. The design procedure is based upon solving the robust performance condition using the Youla parameterization and the mu-synthesis approach to obtain a feedback controller. Thereafter, a convergent iterative learning law is obtained by using the performance weighting function involved in the robust performance condition. Experimental results, on a CRS465 robot manipulator, are provided to illustrate the effectiveness of the proposed design method.     

双足机器人RCG姿态控制算法的研究

稳定步行是仿人双足机器人开展实际作业的基础,也是研究的难点和热点.为了提高对仿人机器人步行失稳的响应速率和控制准确性,克服利用陀螺仪进行姿态测量及控制无法完整表述机器人运动状态,从而造成控制滞后的缺点.本文提出了RCG姿态控制算法,在以角速度和角度作为控制参量的模型基础上,引入机器人运动过程中的加速度作为姿态判断和调整的影响因子,实现对机器人行走过程的反馈控制,提高了双足机器人对失稳状态的响应速率和响应的准确性.通过对自主搭建的机器人样机进行测试,结果表明：当双足机器人步行失稳时,RCG姿态控制算法比以角速度和角度作为参量的控制算法能够更快速、准确的修正姿态偏差,保持姿态稳定.     

小型仿人机器人的设计及步态规划

针对现有仿人形机器人造价高的缺点,设计一款低成本的小型双足机器人研究平台。根据人类步行过程及人体生理结构．依据模糊控制与专家控制相结合的理论提出一种简单的双足机器人模型,并根据仿生学原理确定机器人的自由度配置及各关节的比例尺寸。然后,利用目前通用的行为规划软件对双足机器人步态规划进行仿真,并在平坦地面上进行相应行走试验。实验证明,根据人行走模式对机器人进行步态规划的算法稳定可行,为机器人的教学和科研提供了良好的实验平台。     

Use of Support Vector Regression in Stable Trajectory Generation for Walking Humanoid Robots

This paper concerns the use of support vector regression (SVR), which is based on the kernel method for learning from examples, in identification of walking robots. To handle complex dynamics in humanoid robot and realize stable walking, this paper develops and implements two types of reference natural motions for a humanoid, namely, walking trajectories on a flat floor and on an ascending slope. Next, SVR is applied to model stable walking motions by considering these actual motions. Three kinds of kernels, namely, linear, polynomial, and radial basis function (RBF), are considered, and the results from these kernels are compared and evaluated. The results show that the SVR approach works well, and SVR with the RBF kernel function provides the best performance. Plus, it can be effectively applied to model and control a practical biped walking robot.     

A Hybrid CPG–ZMP Controller for the Real-Time Balance of a Simulated Flexible Spine Humanoid Robot

Although a few researchers have started to realize the importance of a flexible spine in generating more natural-looking behaviors for humanoid robots, there has been no work on trying to make a full-body humanoid robot (that has a flexible spine) to maintain balance. The main reason for this is that it is very costly and difficult to develop and control this kind of robot. This paper serves two purposes. First, it proposes the use of a realistic 3-D robot simulator as a platform for costly flexible spine humanoid robotics research. Second, it presents a hybrid CPG-ZMP controller for the simulated robot. The biologically inspired CPG component of our controller allows the mechanical spine and feet to exhibit rhythmic motions using only two control parameters. Through monitoring the measured ZMP location, the engineering component modulates the neural activity of the CPG to allow the robot to maintain balance while it is standing and exhibiting motions on the sagittal and frontal planes in real time. The final postures of the simulated humanoid emerge automatically in real time through dynamic interactions between the neural networks, the robot itself, and its environment. Since experimental results have also demonstrated that our system is robust against disturbances from external pushing forces, our controller has the potential to be applicable to the next generation of humanoid robots.      

Reliable gait planning and control for miniaturized quadruped robot pet

This paper proposes a gait planning and control algorithm for the quadruped robot pet commercialized by Dasarobot, Korea. Reliable motion and online characteristics are the key requisites for the motion planning algorithm of a commercialized robot. At joint control level of the proposed gait control, sample-based interpolation makes joint trajectory tractable for small motor and controller of the miniaturized robot. Centroid body sway ensures walking stability to achieve reliability of the proposed gaits at the motion planning level. By using ground coordinates representation, it is possible to integrate several online gaits and realize a compact and efficient gait planning algorithm. Experimental results are presented to verify the proposed gait planning and control algorithm.     

基于DSP的双足机器人运动控制系统设计

在仿人机器人研究领域,双足步行控制一直是其难点。主要介绍基于TI的DSP芯片TMS320F2812设计双足机器人的基本运动控制系统,围绕机器人腿部无刷直流电机的驱动进行优化设计。系统采用PWM进行电机调速,辅助以补偿参数,通过步态指令,验证电机运转的精确性、稳定性和系统的可操作性。电机调试为CCS仿真、步态规划和独立行走提供试验平台,使机器人能够实现步行功能。     

考虑关节角加速度约束的仿人机器人偏摆力矩控制方法

针对仿人机器人步行过程中存在的机器人关节角加速度约束影响控制性能的问题，提出一种考虑关节角加速度约束的仿人机器人偏摆力矩控制方法.该方法充分考虑了双臂在摆动过程中对偏摆力矩的影响，根据力矩平衡条件得到需要抵消的偏摆力矩的大小与方向，将偏摆力矩的控制问题转化为带约束条件的二次规划问题，并设计了一种在线变步长迭代算法计算得到优化后的双臂摆动轨迹.实验表明，该方法能有效抵消机器人步行中产生的偏摆力矩，避免控制过程中的"削峰"现象，有效提高机器人的步行稳定性.     

Robust PID control of fully-constrained cable driven parallel robots

In this paper dynamic analysis and robust PID control of fully-constrained cable driven parallel manipulators are studied in detail. Since in this class of manipulators cables should remain in tension for all maneuvers in their workspace, feedback control of such robots becomes more challenging than that of conventional parallel robots. In this paper, structured and unstructured uncertainties in dynamics of the robot are considered and a robust PID controller is proposed for the cable robot. To ensure that all cables remain in tension internal force concept is used in the proposed PID control algorithm. Then, robust stability of the closed-loop system with proposed control algorithm is analyzed through Lyapunov direct method and it is shown that by suitable selection of the PID controller gains, the closed-loop system would be robustly stable. Finally, the effectiveness of the proposed PID algorithm is examined through experiments on a planar cable driven robot and it is shown that the proposed control structure is able to provide suitable performance in practice.     

Genetic algorithm tuning of Lyapunov-based controllers: anapplication to a single-link flexible robot system

In this paper, a systematic controller design approach is proposed to guarantee both closed-loop stability and desired performance of the overall system by effectively combining genetic algorithms (GAs) with Lyapunov's direct-controller design method. The effectiveness of the approach is shown by using a simple and efficient decimal GA optimization procedure to tune and optimize the performance of a Lyapunov-based robust controller for a single-link flexible robot. The feedback gains of the controller are tuned by the GA optimization process to achieve good results for tip motion control of the single-link flexible robot based on some suitable fitness functions. The paper includes results of simulation experiments demonstrating the effectiveness of the proposed genetic algorithm approach     

Towards stable and efficient legged race-walking of an ePaddle-based robot

ePaddle mechanism is a novel hybrid locomotive mechanism designed for accessing terrestrial, aquatic and amphibious terrains with versatile locomotion gaits. Among those gaits, race-walking gait has a promised gait that is potential for achieving highly stable, and highly energetic efficient legged walking. This paper studies the motion planning method of this unique race-walking gait for an ePaddle-based quadruped robot. The standard gait sequence that consists of four phases is firstly presented. The selection of wheel-center trajectory for achieving the gait is then discussed based on kinematic models of the ePaddle module in these phases. Two motion planning methods are presented for an ePaddle-based quadruped robot to track planar path with the proposed race-walking gait. Stability and energetic performances of the proposed race-walking gait are discussed by evaluating duty factor of the ePaddle module, and by measuring stability margin and specific resistance of the robot. A set of simulations on tracking straight and circular paths verifies the idea of the race-walking gait as well as its stability and efficiency.     

基于中枢模式发生器的仿人机器人步态规划

对Matsuoka振荡器进行了分析,根据仿人机器人步态规划的要求,选用Matsuoka振荡器构建了中枢模式发生器(CPG)网络;采用遗传算法(GA)来调整网络的参数,解决了关键的网络参数调整的问题;根据CPG网络的输出结果,控制仿人机器人的相应关节,实现了仿人机器人基本步态规划。通过ADAMS进行了仿真,结果表明,该控制策略具有较理想的效果,并且原理简单,易于实现。     

An Approach to Guidance Motion by Gait-Training Equipment in Semipassive Walking

Recently, population aging and declining birth rate have become very serious, and people who lack walking capability have truly increased in Japan. To address this issue, gait training has become a requirement for them. Although some training systems have been researched in the past, a training system that entails guidance of walking has not been researched well. This paper focuses on guidance of walking, and it is aimed to develop a training system that utilizes the activity and passivity of the trainee. In addition, rhythmic walking, which takes walking stability and trainee safety into account, is aimed for. In this paper, an improved electric wheelchair is used as gait-training equipment (GTE); then, the trainee is towed by the GTE, and walking is guided. In this paper, a targeted walking cycle is predefined, and the GTE must distinguish the cycle in order to guide walking. Therefore, this paper uses the center of gravity (COG) of the trainee as the index. Thus, the GTE tows the trainee when the swing leg moves more forward than the stance leg; then, rhythmic walking can be guided. In addition, this paper proposes a method to control the GTE by a proportional-differential controller based on virtual compliance that is composed of mass, spring, and damper. The gait training can be safely achieved by deciding the desired position and velocity of the GTE from the tow force through virtual compliance. In this paper, the validity of the proposed method is verified by numerical simulation and experiment. The validity of the proposed system is verified by using a four-link robot whose geometric expression is known as the trainee; then, the application of the proposed method will be extended to a human trainee by only adjusting the parameters.     

Prototype development and gait planning of biologically inspired multi-legged crablike robot

In order to investigate the walking gait of the legged robot with multiple redundant walking legs, the motion features of the biologic crab are studied. To study the motion property of multi-legged animals in depth, an event sequence analysis method is proposed, and employed to design the motion pattern of multi-legged robot. A low-consumption environmental self-adaptive bionic gait with its phase factor of 0.25 and duty factor of 0.454 is analyzed based on the analysis of pace order, gait parameters and single leg’s terminal trajectory on uneven terrain. According to the structures and motion patterns of biologic crab, a multi-legged crablike prototype with its experimental platform is developed. The contrast tests of environmental self-adaptive bionic gait and double tetrapod gait are experimented at the same velocity, and slope climbing tests are performed as well. The experimental results show that, although the double tetrapod gait enables four legs to support the robot’s body at any time, there exists halt or backward phenomena periodically. However, the robot using the new gait has lower gravity fluctuation in displacement and velocity without halt or backward problem, and the decreasing of motion speed leads to the increasing of the gravity fluctuation and the toe-force.     

Designing a robust adaptive dynamic controller for nonholonomic mobile robots under modeling uncertainty and disturbances

The main stream of researches on the mobile robot is planning motions of the mobile robot under nonholonomic constraints. Much has been written about the problem of motion planning under nonholonomic constraints using only a kinematic model of a mobile robot. Those methods, however, assume that there is some kind of a dynamic controller that can produce perfectly the same velocity that is necessary for the kinematic controller. Also there is little literature on the robustness of the controller when there are uncertainties or external disturbances in the dynamical model of a mobile robot. In this paper, we proposed a robust adaptive controller that can achieve perfect velocity tracking while considering not only a kinematic model but also a dynamic model of the mobile robot. The proposed controller can overcome uncertainties and external disturbances by robust adaptive technique. The stability of the dynamic system will be shown through the Lyapunov method.