3-D Locomotion control for a biomimetic robot fish

This paper concerns with 3-D locomotion control methods for a biomimetic robot fish. The system architecture of the fish is firstly presented based on a physical model of carangiform fish. The robot fish has a flexible body, a rigid caudal fin and a pair of pectoral tins, driven by several servomotors. The motion control of the robot fish are then divided into speed control, orientation control, submerge control and transient motion control, corresponding algorithms are detailed respectively. Finally, experiments and analyses on a 4-link, radio-controlled robot fish prototype with 3-D locomotion show its good performance.     

Construction and locomotion analysis of modular robots with pneumatic-actuated and binary-controlled expandable cubes

This paper presents the construction and locomotion analysis of the modular robots composed of expandable cubes (E-Cubes). The kinematic properties and experiment research of the assembled modular robots are the main focus of the paper. The E-Cube consisted of only prismatic joints is a cubic module with three degrees of freedom corresponding to three mutually perpendicular directions. The modular robots are constructed by connecting the vertex or edge of the adjacent modules. In this paper, first, the modular robot system including the E-Cube hardware, connection method of modules and a potential binary control strategy is described. And then, the detailed kinematics, stability and motion simulations of three configurations assembled with four modules are analysed. After that, a set of experimental pneumatic-based robotic system is built. At last, the gait experiments of the configurations are carried out to testify the feasibility and validity of design and locomotion functions. The experiment results show the reliability of the mechanical, control and pneumatic systems and the programming and control efficiency of the binary control strategy. As extension, a modular robot with eight modules is assembled, and its different locomotion gaits are simulated accordingly.     

Robot fish with two-DOF pectoral fins and a wire-driven caudal fin

This paper presents a robot fish with a wire-driven caudal fin and a pair of pectoral fins. First, the design of the robot fish is presented. The caudal fin is driven through wire-driven mechanism. The pectoral fins can perform two degrees-of-freedom motions, i.e. flapping (roll) and feathering (pitch). The pectoral fins can move in labriform mode for propulsion, or for other purposes such as turning and diving. Second, the propulsion analysis models for caudal fin propulsion and pectoral fins propulsion are derived. Finally, three types of experiments are conducted. Experiment results show that the swimming speed of caudal fin propulsion and pectoral fin propulsion match the model predictions. Moreover, with the caudal fin propulsion alone, the robot fish can swim up to 0.66 BL/s (body length/second); with the pectoral fin propulsion alone, the robot fish can swim up to 0.26 BL/s. The pectoral fins can significantly improve the maneuverability of the robot fish. Without using the pectoral fins, the turning radius of the robot fish is 0.6 BL; with the pectoral fins, the turning radius is reduced to 0.25 BL.     

船舶零航速减摇鳍控制系统研究

船舶零航速减摇鳍是指在来流速度为0的流场中依靠鳍的主动摆动产生升力,以对抗海浪的作用力,从而减小系泊状态下船舶摇摆的减摇。设计了伺服控制系统,增加了升力限位环节。通过对有义波高分别为1,2m,浪向角均为90°海况下的仿真研究,减摇效果分别达到了78．30％和56．92％,优于减摇水仓减摇效果,证明所设计系统能够满足船舶零航速减摇的要求。     

事件反馈与状态反馈的混合模监控

在监控理论中 ,处理状态膨胀的标准方法之一是基于语言或谓词的模监控 .但文献中没有涉及同时基于语言与谓词的混合模监控 .本文研究混合模监控综合及其性质 .通过提出状态反馈与某一事件反馈的等价关系 ,给出了两者相连接的定义 ,进而得到了混合模监控器等价于子监控器与子控制器的连接 .并讨论了混合模监控器具有非阻塞性与无死锁性所满足的条件 ,即基于语言的闭环系统行为的封闭性与谓词的Σu-不变性 ,而其是无死锁的充要条件是子监控器与子控制器必须均是无死锁的并满足d-不变关系     

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.     

Optimal design and motion control of biomimetic robotic fish

This paper is concerned with the design, optimization, and motion control of a radiocontrolled, multi-link, free-swimming biomimetic robotic fish based on an optimized kinematic and dynamic model of fish swimming. The performance of the robotic fish is determined by both the fish＇s morphological characteristics and kinematic parameters. By applying ichthyologic theories of propulsion, a design framework that takes into consideration both mechatronic constraints in physical realization and feasibility of control methods is presented, under which a multiple linked robotic fish that integrates both the carangiform and anguilliform swimming modes can be easily developed. Taking account of both theoretic hydrodynamic issues and practical problems in engineering realization, the optimal link-lengthratios are numerically calculated by an improved constrained cyclic variable method, which are successfully applied to a series of real robotic fishes. The rhythmic movements of swimming are driven by a central pattern generator （CPG） based on nonlinear oscillations, and up-and-down motion by regulating the rotating angle of pectoral fins. The experimental results verify that the presented scheme and method are effective in design and implementation.     

变质心自主水下航行器定深控制研究

对变质心自主水下航行器（AUV）定深控制问题进行了研究。建立了相应的纵平面的变质心AUV的运动数学模型。在此基础上,基于滑模控制理论设计了变质心控制系统,控制质量块的偏移运动,进而控制AUV定深运动。仿真结果表明：该控制器可满足AUV定深控制的需要,使定深误差趋近于零,并对建模误差具有一定的鲁棒性。     

Adaptive Jacobian vision based control for robots with uncertain depth information

This paper presents a simple vision based setpoint controller with adaptation to uncertainty in depth information. Depth uncertainty plays a special role in vision based control as it appears nonlinearly in the overall Jacobian matrix and hence cannot be adapted together with other uncertain kinematic parameters. We propose a novel parameter update law to update the uncertain parameters of the depth. It is proved that system stability can be guaranteed for the vision regulation task in presence of uncertainties in depth information, robot kinematics and dynamics. Simulation results are presented to illustrate the performance of the proposed controller.     

带未知干扰的模块化航天器系统相对轨道的队形控制

基于多智能体系统一致性理论,在有向拓扑结构中对模块化航天器相对轨道的队形控制问题进行研究.考虑与状态相关的未知外部干扰,在存在模块质量不确定性的情形下,基于自适应增益技术,设计仅依赖模块自身及其邻近模块信息的分布式控制算法,并通过Lyapunov稳定性方法证明闭环系统是渐近稳定的.最后在Matlab/Simulink中对6个模块组成的模块化航天器系统的队形进行仿真分析,仿真结果表明所设计的控制律是有效且可行的.     

Neurobiology suggests the design of modular architectures for neural control

The existence of modular structures in the biological world strongly suggests that the training of this kind of structure is actually feasible. It is a key indication for the development of neural network applications, especially in the field of robotics. Indeed, a single network can only efficiently treat problems with few independent variables; the combination of several networks is necessary to address more complex tasks. We investigate learning techniques and show that using a particular form of architecture can ease the training of a modular structure: a bi-directional structure that allows combining several neural networks. The approach is illustrated with Kohonen's self-organizing maps for a robotic visual servoing task.     

Models,feedback control,and open problems of 3D bipedal robotic walking

The fields of control and robotics are working toward the development of bipedal robots that can realize walking motions with the stability and agility of a human being. Dynamic models for bipeds are hybrid in nature. They contain both continuous and discrete elements, with switching events that are governed by a combination of unilateral constraints and impulse-like forces that occur at foot touchdown. Control laws for these machines must be hybrid as well. The goals of this paper are fourfold: highlight certain properties of the models which greatly influence the control law design; overview the literature; present two control design approaches in depth; and indicate some of the many open problems.     

Bio-harmonized control experiments of a carangiform robotic fish underwater vehicle

This paper presents experimental implementation and comparison of three different control schemes of a bio-inspired robotic fish underwater vehicle. The dynamics model is obtained by unifying conventional rigid body dynamics and bio-fluid dynamics of a carangiform fish swimming given by Lighthill’s(LH) slender body theory. It proposes an inclusive mathematical design for better control and energy efficient path travel for the robotic fish. The system is modeled as an two-link robot manipulator (caudal tail) with a mobile base (head). This forward thrust drives the robotic fish head represented by a combined non-linear equation of motion in earth fixed frame. We develop and compare the dynamic motion closed loop control strategy of the bio-harmonized robotic fish based on three different non-linear control schemes using CTM (Computed Torque Method), FF (Feed-Forward) controllers both with dynamic PD compensation and finally a proposed combination of CTM with FF. An inverse dynamic control method based on non-linear state function model including hydrodynamics is proposed to improve tracking performance. CTM control generates a feedback loop for linearization and decoupling robot dynamic model with a shorter response time, while a dynamic PD compensation in the FF path is employed by FF scheme through the desired trajectories. FF model-based strategy results in an improved tracking and shorter route to travel between two points. Overall results indicate that performances of the proposed control schemes based on the inverse dynamic model are comparable and useful for robotic fish motion tracking in fluid environment.     

六圆锥轮式月球车运动控制系统的设计研究

六圆锥轮式月球车是一种混合适应型移动机器人车,具有地形适应能力优越,越障能力强的特点。针对该款月球车,本文提出并设计了一套基于TCP/IP通讯,具有一定自主能力的遥操作运动控制系统。遥操作计算机提供月球车路径规划服务,监控月球车运行。基于实时Linux和PC104总线计算机的车载计算机运动控制系统,解析遥操作运动指令,驱动控制月球车运动。运动控制系统在六圆锥轮式月球车样机上调试,模拟现场运行验证了所设计的运动控制系统是可行的。     

Robust adaptive tracking control of robotic systems with uncertainties

To deal with the uncertainty factors of robotic systems, a robust adaptive tracking controller is proposed. The knowledge of the uncertainty factors is assumed to be unidentified; the proposed controller can guarantee robustness to parametric and dynamics uncertainties and can also reject any bounded, immeasurable disturbances entering the system. The stability of the proposed controller is proven by the Lyapunov method. The proposed controller can easily be implemented and the stability of the closed system can be ensured; the tracking error and adaptation parameter error are uniformly ultimately bounded （UUB）. Finally, some simulation examples are utilized to illustrate the control performance.     

Fractional-order sliding mode load following control via disturbance observer for modular high-temperature gas-cooled reactor system with disturbances

Load-following control of the modular high-temperature gas-cooled reactor (MHTGR) system is one of the essential control problems in practical applications. In this paper, a fractional-order sliding mode control strategy via a disturbance observer (FOSMCS-DO) is presented for load following of the MHTGR system with model uncertainties and external disturbances. First of all, the mathematical model of the MHTGR system is constructed by taking neutronics and thermodynamics as well as disturbances into account. Then, based on the MHTGR model, a DO is designed to estimate the lumped disturbances that are composed of model uncertainties, external disturbances, and unmeasured states. Meanwhile, by adopting the Lyapunov stability theory, a FOSMCS is developed to guarantee all the signals of the closed-loop load-following control system tend to be stable, where in the control framework, the adverse effects of the lumped disturbances are alleviated by means of the feedforward compensation and the DO. This implies that the proposed overall control strategy possesses strong robustness against model uncertainties and external disturbances. Finally, comparative simulation results with some existing control approaches are provided to illustrate the superiority of the proposed control strategy.     

Discrete-time modeling and control of robotic manipulators

A general approach is presented to derive discrete-time models of robotic manipulators. Such models are obtained by applying numerical discretization techniques directly to the problem of the minimization of the Lagrange action functional. Although these models are in implicit form, they own a dynamic structure that allows us to design discrete-time feedback linearizing control laws. The proposed models and control algorithms are validated by simulation with reference to a three link robot.     

Adaptive learning tracking control of robotic manipulators with uncertainties

An adaptive learning tracking control scheme is developed for robotic manipulators by a synthesis of adaptive control and learning control approaches. The proposed controller possesses both adaptive and learning properties and thereby is able to handle robotic systems with both time-varying periodic uncertainties and time invariant parameters. Theoretical proofs are established to show that proposed controllers ensure asymptotical tracking performance. The effectiveness of the proposed approaches is validated through extensive numerical simulation results.     

Experimental implementation of distributed flocking algorithm for multiple robotic fish

This paper presents the experimental implementation of a flocking algorithm for multiple robotic fish governed by extended second-order unicycles. Combing consensus protocols with attraction/repulsion functions, a flocking algorithm is proposed to make the agents asymptotically converge to swim with consistent velocities and approach the equilibrium distances to their neighbors. The LaSalle–Krasovskii invariance principle is applied to verify the stability of the system. Besides numerical simulations, platform simulations involving robotic fish kinematic constraint and control mechanism are shown. An experiment with three robotic fish is implemented to illustrate the effectiveness of the proposed flocking algorithm in the presence of external disturbance and boundary collision.     

Stability of hybrid position and force control for robotic manipulator with kinematics and dynamics uncertainties

Most research so far on hybrid position and force control laws of robotic manipulator has assumed that knowledge of kinematics is known exactly. In the presence of modeling errors, it is unknown whether the stability of the constrained robot system can still be ensured. In this paper, stability and setpoint control problems of constrained robot with kinematics and dynamics uncertainties are formulated and solved. We shall show that the manipulator end-effector's motion is asymptotically stable even in the presence of such uncertainties.