基于CPG模型的仿生机器鱼运动控制

仿生机器鱼的研究已经成为一个富有挑战性的热点问题.为了控制机器鱼自身的运动和姿态,本文研究了胸鳍对机器鱼运动的影响,并且基于CPG模型,提出了一种运动控制方法.采用的控制模型由4个振荡器构成,可根据反馈的信息产生节律信号以控制机器鱼胸鳍和尾鳍的运动.根据CPG模型参数与反馈输入之间的关系,设计了机器鱼俯仰和转弯反馈控制方法,利用反馈的信息自主调节CPG参数,达到控制胸鳍运动模式的目的.仿真实验验证了控制模型和反馈策略的有效性.     

仿生机器鱼胸/尾鳍协同推进闭环深度控制

为改善机器鱼定深控制过程中的动态性能与稳态性能,根据深度误差的大小将定深控制过程分解为趋近阶段与巡游阶段,给出了一种基于中枢模式发生器（central pattern generator,CPG）与模糊控制相结合的闭环运动控制方法．为此,首先建立了以压力传感器信号为反馈输入,通过模糊控制器调节控制参数的CPG运动控制模型．在此基础上,针对误差较大的趋近阶段,采用胸/尾鳍协同方式,通过趋近模糊控制器改变摇翼关节的偏置量与幅值来使机器鱼快速到达期望深度;针对误差较小的巡游阶段,采用改变攻角方式,通过巡游模糊控制器改变胸鳍攻角来使机器鱼保持在期望深度．两阶段之间通过胸鳍CPG的启停实现切换．模糊控制器设计时利用了基于最小二乘法对实验数据拟合而得出的俯仰角变化率与控制参数的近似关系,提高了机器鱼趋向期望深度的速度并减小了在期望深度巡游时的稳态误差．仿真与实验结果验证了所提控制方法的有效性．     

作业型飞行机器人抓取后重心偏移的轨迹跟踪控制

作业型飞行机器人是指能够对环境施加主动影响的飞行机器人, 它通常由旋翼飞行器与机械臂组合而成. 本文针对作业型飞行机器人在动态飞行抓取后, 重心位置变化产生的系统控制难题, 设计了有效的跟踪控制策略. 首先, 在系统建模时引入重心偏移系统参数和重心偏移控制参数, 并考虑惯性张量不为常数, 提高了系统建模的精度. 然后, 在姿态解算时, 考虑重心偏移对系统性能的影响, 构建包含重心偏移系统参数的解算方法, 得到更高精度的期望翻滚角和期望俯仰角. 接着, 设计了基于滑模控制的重心偏移补偿位置控制器, 实现了有效的位置跟踪控制. 同时, 在姿态反演控制器的基础上, 加入自适应律估计重心偏移控制参数和变化的惯性张量, 再通过小脑神经网络逼近惯性张量的真实值, 提高姿态控制器的精度. 最后, 给出了所设计控制器的稳定性证明, 并在仿真环境下验证了所提出的方法的有效性和优越性.     

改进PID的无人机飞行姿态角控制消颤算法

无人机在整个纵平面飞行过程中,由于飞行姿态角的大幅度变化以及气流的作用,导致机身颤抖,影响飞行稳定性.提出一种基于PID变结构控制的无人机飞行姿态角控制消颤算法,首先进行了无人机飞行姿态角控制系统的被控对象参量分析,构建无人机在姿态角变化剧烈、大迎角飞行时的三通道模型,采用变结构控制方法进行控制器设计.结合小扰动原理和Lyapunov稳定性原理进行扰动抑制和稳定性证明,采用梯度算法调整权值进行飞行姿态角控制的消颤处理,采用自适应算法在线调整权值实现PID变结构控制改进.仿真结果表明:采用该算法进行无人机飞行姿态角控制和消颤处理,大幅度提高无人机飞行定姿的精度,横滚角、俯仰角和航向角的控制精度有较大提高,稳定性和收敛性较好,确保了无人机飞行稳定性.     

船载卫通天线配重最优化方法分析

船载卫星通信天线的配重在天线转动、跟踪目标卫星中发挥着平衡天线、稳定跟踪的重要作用。文中在介绍船载卫通天线驱动电机工作原理的基础上,结合天线所受的4个力矩,详细分析了天线配重与电流的关系,提出了一种根据天线动态情况下俯仰角与电流关系进行配重优化调整的方法。在此基础上,通过计算,对实际装备的配重进行调整,比较调整之前与调整之后的电流,很好地验证了方法的正确性,解决了卫通天线电流过大、配重过重的问题,对优化船载卫通天线设计和提高伺服系统稳定性具有重要的参考价值。     

基于四象限探测器的掩模版对准检测与控制

提出一种基于可编程控制器和四象限探测器的集成电路掩模版对准系统.该系统采用两个四象限探测器构成对准检测装置,实现对掩模版对准误差的实时检测.通过合理选择对准检测装置的安装位置与姿态,实现对准误差与掩模版运动之间的解耦.对准过程中,根据检测到的对准误差,由可编程控制器对传输机械手的位置和姿态进行调整,从而改变掩模版相对于对准检测装置的位置和姿态.对准控制采用阶梯步长逐步逼近算法,并且引入了机械手姿态调整后的补偿控制,以提高对准效率.实验结果表明,该检测与控制系统工作安全可靠,对准速度快,精度高.     

水下机器人跨越式顶球的方法及其仿真分析

本文提出了在水下机器人顶球比赛中的另一种顶球形式和实现的方法。该方法通过控制电机转速实现鱼的沉浮,通过重块与舵机的配合实现鱼的俯仰,通过电机实现鱼在水下的突然加速,从而实现鱼在水下的顶球和球在空中跨越动作的完成。该方法与以往的顶球方法相比,可以更大地提高比赛过程中的技巧性和观赏性。     

基于惯性姿态参量量化融合的机器腿仿生步态控制

为了提高机器腿仿生步态控制的稳定性,提出一种基于惯性姿态参量量化融合的机器腿仿生步态控制方法。构造机器腿仿生步态的运动学模型,进行机器腿仿生步态控制约束参量建模,采用陀螺仪和加速度计等位姿传感器进行姿态参量采集。采用扩展卡尔曼滤波方法进行机器腿的惯性姿态参量融合并输入到时控制执行器中。针对未知扰动对机器腿步态参量控制的误差,采用自回归更新方法进行姿态参量误差反馈修正,实现机器腿仿生步态稳定控制。仿真结果表明:提出的方法对机器腿仿生控制的稳定性较好,姿态参量的定位跟踪能力较强,提高机器腿步行的稳健性。     

飞行机械臂系统的接触力控制

针对飞行机械臂系统的接触力控制问题,本文首先从理论上证明了闭环无人机系统具有与弹簧-质量-阻尼系统一致的动态特性.基于飞行机械臂接触状态下力的分析,得到了无人机水平前向接触力与系统重力和俯仰角之间的动态关系,进而分析出接触力控制可以不使用力传感器来实现.根据阻抗控制思想,提出了飞行机械臂系统接触力控制方法,即通过同时控制位置偏差和对应姿态角度来实现接触力的控制.给出了单自由度飞行机械臂系统动力学模型,对应分析出系统的稳定性.开发了基于四旋翼飞行器的单自由度飞行机械臂系统,并进行了实际的飞行实验,验证了所提出接触力控制方法的有效性,同时也证实了所开发系统的可靠性.     

专题报道：机器鱼水球赛技巧与技术——基于角度和加速度传感器的仿生机器鱼自我定位技术研究

本文分析角度传感器和加速度传感器的技术特点,总结欧拉角法、方向余弦法,四元数法三种常用坐标换算方法,对机器鱼实现自我定位、获得自身位置信息（游速,游向、游动距离、深度等）和姿态信息（鱼头仰角、鱼体转角等）的可行性进行论证,研究了在机器鱼水球比赛环境中,传感器的安装、校准、数据计算以及信息记录的     

Maneuverability modeling and trajectory tracking for fish robot

This study develops a 6-DOF mathematical model for a robotic fish that considers surge, sway, heave, roll, pitch, and yaw. The model considers the conditions of a fish swimming in ocean current perturbations similar to the ocean current perturbations of the slender-body autonomous underwater vehicles. For swimming and turning behaviors, a nonlinear, dynamic, carangiform locomotion model is derived by using a planar four-link model. A 2-DOF barycenter mechanism is proposed to provide body stabilization and to serve as an actuating device for active control design. A barycenter control scheme is developed to change the center of gravity of the robot fish body by moving balancing masses along two axes. The projected torque on x and y axes propel pitch and roll angles to the desired settings. A Stabilizing controller, fish-tail mechanism, rigid body dynamics, and kinematics are incorporated to enable the fish robot to move in three dimensional space. Simulation results have demonstrated maneuverability and control system performance of the developed controller which is proposed to conduct path tracking of the robot fish as it swims under current perturbations.     

Development of a biomimetic robotic fish and its control algorithm

This paper is concerned with the design of a robotic fish and its motion control algorithms. A radio-controlled, four-link biomimetic robotic fish is developed using a flexible posterior body and an oscillating foil as a propeller. The swimming speed of the robotic fish is adjusted by modulating joint's oscillating frequency, and its orientation is tuned by different joint's deflections. Since the motion control of a robotic fish involves both hydrodynamics of the fluid environment and dynamics of the robot, it is very difficult to establish a precise mathematical model employing purely analytical methods. Therefore, the fish's motion control task is decomposed into two control systems. The online speed control implements a hybrid control strategy and a proportional-integral-derivative (PID) control algorithm. The orientation control system is based on a fuzzy logic controller. In our experiments, a point-to-point (PTP) control algorithm is implemented and an overhead vision system is adopted to provide real-time visual feedback. The experimental results confirm the effectiveness of the proposed algorithms.     

Locomotion Control of a Hydraulically Actuated Hexapod Robot by Robust Adaptive Fuzzy Control with Self-Tuned Adaptation Gain and Dead Zone Fuzzy Pre-compensation

Hydraulically actuated robotic mechanisms are becoming popular for field robotic applications for their compact design and large output power. However, they exhibit nonlinearity, parameter variation and flattery delay in the response. This flattery delay, which often causes poor trajectory tracking performance of the robot, is possibly caused by the dead zone of the proportional electromagnetic control valves and the delay associated with oil flow. In this investigation, we have proposed a trajectory tracking control system for hydraulically actuated robotic mechanism that diminishes the flattery delay in the output response. The proposed controller consists of a robust adaptive fuzzy controller with self-tuned adaptation gain in the feedback loop to cope with the parameter variation and disturbances and a one-step-ahead fuzzy controller in the feed-forward loop for hydraulic dead zone pre-compensation. The adaptation law of the feedback controller has been designed by Lyapunov synthesis method and its adaptation rate is varied by fuzzy self-tuning. The variable adaptation rate helps to improve the tracking performance without sacrificing the stability. The proposed control technique has been applied for locomotion control of a hydraulically actuated hexapod robot under independent joint control framework. For tracking performance of the proposed controller has also been compared with classical PID controller, LQG state feedback controller and static fuzzy controller. The experimental results exhibit a very accurate foot trajectory tracking with very small tracking error with the proposed controller.     

Observer-Based Adaptive Controller Design of Flexible Manipulators Using Time-Delay Neuro-Fuzzy Networks

In this paper, a dynamical time-delay neuro-fuzzy controller is proposed for the adaptive control of a flexible manipulator. It is assumed that the robotic manipulator has only joint angle position measurements. A linear observer is used to estimate the robot joint angle velocity. For a perfect tracking control of the robot, the output redefinition approach is used in the adaptive controller design using time-delay neuro-fuzzy networks. The time-delay neuro-fuzzy networks with the rule representation of the TSK type fuzzy system have better learning ability for complex dynamics as compared with existing neural networks. The novel control structure and learning algorithm are given, and a simulation for the trajectory tracking of a flexible manipulator illustrates the control performance of the proposed control approach.     

Dynamic modeling of a CPG-governed multijoint robotic fish

This paper is devoted to the formulation of a dynamic model of a serially connected multijoint robotic fish with a pair of wing-like pectoral fins, in which the whole robot is treated as a moving multilink rigid body in fluids. Considering that the thrust of fish mainly results from the force of trailing vortex, added lateral pressure, and leading edge suction force, the dynamic equations of the swimming fish have been derived by summing up the longitudinal force, lateral force, and yaw moment on each propulsive component in the context of Lagrangian mechanics. Along with the bio-inspired central pattern generators (CPGs) as the locomotor controller, the overall dynamic propulsive characteristics of the swimming robot are then estimated in a mathematical environment (i.e. Mathematica). Finally, simulations and experiments are carried out to validate the effectiveness of the built dynamic model. Results demonstrate that the CPG-coupled dynamic model provides a fairly good guide to seeking pragmatic backward swimming patterns for a carangiform robotic fish.     

机器海豚多模态游动CPG控制

受自然界海豚超凡的水中游动技能启发,机器海豚在军事和民用上具有潜在的广泛应用前景,因此受到研究人员的极大关注. 然而,要实现机器海豚在水中自如地机动游动,必须为机器海豚设计一个具有丰富游动技能的多模态控制器. 为此,通过振荡器建模与分析、中枢模式发生器（Central pattern generation,CPG）与机器海豚关节配对、CPG单元间耦合等环节建立了机器海豚的链式弱耦合CPG运动控制模型,提出一种基于CPG激发产生多模态振荡波形控制机器海豚运动的方法. 详细阐述了机器海豚样机研制、控制器设计、运动控制实现与实验测试等内容. 向前直游、转弯、浮潜等游动实验结果验证了所提出的机器海豚CPG运动控制方法的有效性和实用性.     

A method for determination of optimal gaits with application to a snake-like serial-link structure

In this paper, we present a method of determining optimal gaits for shape actuated locomotion systems. This method is the synthesis of techniques for computing reduced equations for robotic locomotion systems and a numerical optimal control strategy. Symmetry reduction processes induce a form of locomotion system dynamics that reveals a cyclic-like coupling between group, shape, and momenta coordinates. This form allows one to focus on designing gaits, abandoning concern over shape dynamics. Using this vantage point we indicate how a numerical optimal control method based on Gaussian quadrature may be acclimatized to periodicity, thus providing optimal gaits. The method is demonstrated by means of its application to a snake-like serial-link structure or snake robot. This application provides scientific merit to hypotheses concerning observed locomotion phenomena amongst animals employing undulatory propulsive mechanisms.     

考虑剩余浮力影响的欠驱动水下机器人深度控制

为了实现水下机器人带有剩余浮力影响的欠驱动深度控制, 将垂直面控制划分为定速航行控制和深度控制. 采用成熟的S 面速度控制器保证速度控制稳定, 着重解决深度控制问题. 引入虚拟控制量, 使剩余浮力影响下的深度偏差映射为目标纵倾角, 通过设计俯仰控制器实现对目标纵倾角的跟踪. 稳定性分析表明, 所研究的欠驱动深度控制是稳定的, 且对于参数估计的偏差不敏感. 仿真实验结果表明, 所提出的方法能够抵抗剩余浮力的影响, 深度控制准确, 并具有良好的鲁棒性.