CI-CPG Based Locomotion Control Methods for Snake-like Robots

蛇具有细长无肢的身体、独特的半球形关节，使其可在神经系统控制下完成与环境相适应的多种节律运动。模仿蛇的运动机理和行为方式而设计的蛇形机器人克服了轮腿式机器人的缺点，增加了机器人的运动方式，扩大了机器人的应用范围。但应用传统的控制策略实现蛇形机器人运动控制遇到了很难克服的问题。随着社会经济与科技的发展，研究人员把从蛇运动神经系统研究中得到的启示应用到蛇形机器人上，希望不仅可以解决其运动控制问题，更能在构型、步态及控制机制上皆可展示蛇的特征。 生物学家已经证明动物的节律运动是其低级神经中枢的自激行为，是由中枢模式发生器(Central Pattern Generator，CPG)控制的。中枢模式发生器是一种能够在缺乏有规律的感知和中枢控制输入的情况下，产生有节奏模式输出的神经网络。 本文以国家自然科学基金课题《基于CPG的蛇形机器人控制方法研究》和国家“863”高技术计划资助项目《具有环境适应能力的蛇形机器人的研究》为依托，突破以相互抑制机理研究CPG的传统观点，首次创新性地提出应用循环抑制(Cyclic Inhibition, CI)机理来研究蛇形机器人的CPG建模与实现问题。本研究涵概了神经元模型的特性分析、蛇形机器人关节循环抑制CPG建模理论、蛇形机器人循环抑制CPG神经网络稳定性分析以及典型步态的生成方法、循环抑制CPG神经网络控制蛇形机器人蜿蜒运动参数设定策略、应用动力学仿真和实验对该CPG控制方法有效性的验证。 首先，本文介绍了两个用于CPG建模研究的蛇形机器人“勘查者”和“勘查者-I”。给出各自机械系统、控制系统的构成和动力学仿真平台。 其次，详细分析了神经元以及传统的相互抑制(Mutual Inhibition, MI)CPG的特性。从工程角度首次创新性地应用循环抑制建模理论构建了蛇形机器人CPG模型，并对其稳定性进行了深入的分析。首次证明持续型神经元构成的单向循环抑制(Unilateral Cyclic Inhibition, UCI) CPG是能产生振荡输出CPG中微分方程数量最少的，而且其产生振荡输出的机理完全不同于传统的相互抑制CPG。其不需要具备调整功能，只需要神经元之间强的单向循环抑制连接。 第三，首次应用单向激励连接循环抑制CPG构成蛇形机器人神经网络系统。分析了其稳定性，给出其产生振荡输出的条件。通过仿真和实验验证了循环抑制CPG神经网络实现典型步态(蜿蜒运动、伸缩运动和侧向运动)的有效性。首次应用双向循环抑制(Bidirectional Cyclic Inhibition, BCI)CPG神经网络在不同高级控制神经元命令激活下的输出实现蛇形机器人典型运动步态之间的转换。为蛇节律运动生成机制建模提供了新方法。 最后，从实时性、控制方便性等工程应用的角度，对单向循环抑制CPG神经网络实现蛇形机器人蜿蜒运动控制进行了深入的分析。给出了S-波形、幅值、运动速度和运动轨迹曲率的参数设定策略。该系统应用首CPG自激励权重调解成功解决了传统CPG控制系统中CPG的个数比蛇形机器人关节数多一个的问题，并用其实现了一种独特的转弯控制策略。 综上，为蛇形机器人运动控制提供了全新的方法

Simulation Study on Ｒising and Diving locomotion of underwater snake-like robot

根据水下环境特征,研究蛇形机器人在水中三维空间的运动步态。基于虚拟机器人实验平台(V-REP)动力学仿真软件搭建了具有垂直和水平关节的蛇形机器人模型,在蛇形曲线生成蜿蜒运动的基础上,采用逐节升降法实现了水中的上浮下潜运动步态。分析了蛇形机器人在水中运动过程中的位态、受力、关节力矩及运动效率的状况,为蛇形机器人水中运动的实用化提供数据参考,同时验证了逐节升降法实现蜿蜒下潜上浮的有效性

A Real-Time Analysis Method for Pulse Rate Variability Based on Improved Basic Scale Entropy

Base scale entropy analysis (BSEA) is a nonlinear method to analyze heart rate variability (HRV) signal. However, the time consumption of BSEA is too long, and it is unknown whether the BSEA is suitable for analyzing pulse rate variability (PRV) signal. Therefore, we proposed a method named sliding window iterative base scale entropy analysis (SWIBSEA) by combining BSEA and sliding window iterative theory. The blood pressure signals of healthy young and old subjects are chosen from the authoritative international database MIT/PhysioNet/Fantasia to generate PRV signals as the experimental data. Then, the BSEA and the SWIBSEA are used to analyze the experimental data; the results show that the SWIBSEA reduces the time consumption and the buffer cache space while it gets the same entropy as BSEA. Meanwhile, the changes of base scale entropy (BSE) for healthy young and old subjects are the same as that of HRV signal. Therefore, the SWIBSEA can be used for deriving some information from long-term and short-term PRV signals in real time, which has the potential for dynamic PRV signal analysis in some portable and wearable medical devices

Design of a snake-like robot and analysis of friction influence on its motion performance

为使蛇形机器人的结构和运动形式能够适应各种复杂环境,研究了蛇形机器人运动性能与环境的关系及其运动控制,设计了一种单被动轮为接触面的正交串联蛇形机器人,分析了蛇形曲线参数对其运动的影响,通过实验研究了摩擦系数对其运动步态的影响,得出了蛇形机器人的前行速率随蛇形曲线参数α的增大而增大,随摩擦系数μ的增大而减小的结论,以及蛇形曲线步态参数的调节策略

Output feedback control for a class of nonlinear systems with actuator degradation and sensor noise

This paper investigates the output feedback control problem of a class of nonlinear systems with sensor noise and actuator degradation. Firstly, by using the descriptor observer approach, the origin system is transformed into a descriptor system. On the basis of the descriptor system, a novel Proportional Derivative (PD) observer is developed to asymptotically estimate sensor noise and system state simultaneously. Then, by designing an adaptive law to estimate the effectiveness of actuator, an adaptive observer-based controller is constructed to ensure that system state can be regulated to the origin asymptotically. Finally, the design scheme is applied to address a flexible joint robot link problem

Simulation research on the serpentine locomotion performance of a snake-like robots

基于用V-REP仿真软件建立的蛇形机器人动力学模型,对蛇形机器人的蜿蜒运动性能进行了研究.首先通过蛇形曲线控制蛇形机器人实现蜿蜒运动,对关节角度和力矩情况进行了分析,其次通过变化蛇形曲线公式中的起始弯角、体内形成波个数、弧长变化率来观察分析这些参数对蛇形机器人蜿蜒运动性能的影响,最后研究分析了蛇形机器人蜿蜒运动的爬坡、转弯性能,得出了对实现蛇形机器人的实用化有理论、技术意义的结论

Recognition and representation of ball-passing motions for a middle size league soccer robot

为了使中型组足球机器人具有识别并模仿人的传球动作的能力，在研究人的传球行为的基础上，提出了一种使中型组足球机器人能够识别和再现人的传球动作的可行方法。该方法利用Kinect感应器获取人体的三维骨骼信息，从生成的人体骨骼模型中选取有效表征人体传球动作的特征变量，然后通过阈值法和帧差法判定特征变量的变化，实现对人的传球行为的识别，并以此获取传球动作的传球角度，使机器人再现人的传球动作。针对人机交互中的传球动作辨识与再现提出了一种实际可行的解决方案。试验表明，该方法能够辨别多个角度传球的动作，并能保持较高的识别率，从而验证了该方法的实用性和有效性

Effects of carbon dioxide on different PSK modulation formats of Optical Wireless Communications using USRP

This article explores the influence of the concentrated carbon dioxide (CO2) gas on the different Phase Shift Keying (PSK) modulations used for Optical Wireless Communication (OWC) links. In this work, the OWC consisted of a laser diode, a photodetector, and a transmission medium. The Universal Software Radio Peripheral (USRP) unit created and evaluated the PSK modulations. This unit modulated the laser diode on the transmitter side and demodulated the data which were received by the photodetector on the receiver side. The CO2gas was emitted as a consequence of sublimation of the solid carbon dioxide in hot water. The measurements were done in a closed box in laboratory. The CO2gas is a one element of smog which pollutes cities now and then. Our experimental results with CO2gas could help to choose a suitable modulation scheme for OWC which are installed in cities with smog-polluted atmospheric conditions

Simulation research on the serpentine locomotion performance of a snake-like robots

基于用V-REP仿真软件建立的蛇形机器人动力学模型,对蛇形机器人的蜿蜒运动性能进行了研究.首先通过蛇形曲线控制蛇形机器人实现蜿蜒运动,对关节角度和力矩情况进行了分析,其次通过变化蛇形曲线公式中的起始弯角、体内形成波个数、弧长变化率来观察分析这些参数对蛇形机器人蜿蜒运动性能的影响,最后研究分析了蛇形机器人蜿蜒运动的爬坡、转弯性能,得出了对实现蛇形机器人的实用化有理论、技术意义的结论

Serpentine locomotion of a snake-like robot controlled by musical theory

Based on the structure of both biological snakes and snake-like robots and their rhythmic locomotion, the musical theory is adopted as a control method to study on a snake-like robot. The relation between the rules and symbols of the musical theory and the control process of the snake-like robot is defined in this paper. Thus the data sequence of the relative angles in the serpentine locomotion is melodized. The gait score of the serpentine locomotion is utilized to control a snake-like robot named "Perambulator-I". Finally, the aspects of the future researches are discussed