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The reliability of the Steam Generator is a key factor affecting the overall efficiency and safety of nuclear power plant reactors. Under the influence of nuclear radiation, remote control robots are currently used for Steam Generator heat transfer tubes inspection. In this paper, a new inspection robot is designed with better structure and higher working efficiency. Structural modeling and kinematic analysis are carried out. A modular control system is designed and applied for system integration. To verify the practicality of the robot, tube sheet motion experiments and performance analysis are undertaken. It results that the proposed inspection robot efficiently moves on the tube sheet and has excellent motion performance.

Soft modular robots have the advantages of both bionic continuum robots and modular self-reconfigurable robots. They have potential application for working in narrow space and uneven terrain. The outstanding abilities of the soft modular robots are infinite degrees of freedom and a changeable configuration. However, these advantages also incur difficulty in mathematical modeling and continuous motion control, especially for docking, which is the key to realizing a changeable configuration. Therefore, the development of a soft modular robot requires a modeling method to guide the module's motions accurately. In this paper, we design and manufacture a pneumatic soft modular robot with a novel connecting mechanism to achieve docking. A nonlinear dynamic model of our soft module is established. In particular, the analytic solutions of the module plane docking are presented. Based on the nonlinear dynamic modeling, three experiments are performed under different conditions. The experimental results pertaining to module plane bending agree with the theoretical values, which verify the accuracy of the modeling method. Moreover, fixed point docking and two modules docking experiments demonstrate the validity of the modeling method and the docking ability. The modeling method proposed in this paper can well guide the docking of soft modular robots.

Pneumatic muscles with similar characteristics to biological muscles have been widely used in robots, and thus are promising drivers for frog inspired robots. However, the application and nonlinearity of the pneumatic system limit the advance. On the basis of the swimming mechanism of the frog, a frog-inspired robot based on pneumatic muscles is developed. To realize the independent tasks by the robot, a pneumatic system with internal chambers, micro air pump, and valves is implemented. The micro pump is used to maintain the pressure difference between the source and exhaust chambers. The pneumatic muscles are controlled by high-speed switch valves which can reduce the robot cost, volume, and mass. A dynamic model of the pneumatic system is established for the simulation to estimate the system, including the chamber, muscle, and pneumatic circuit models. The robot design is verified by the robot swimming experiments and the dynamic model is verified through the experiments and simulations of the pneumatic system. The simulation results are compared to analyze the functions of the source pressure, internal volume of the muscle, and circuit flow rate which is proved the main factor that limits the response of muscle pressure. The proposed research provides the application of the pneumatic muscles in the frog inspired robot and the pneumatic model to study muscle controller.

To ensure applications requirements of rocket storage tank precision polishing, a 6-dof parallel collision detection mechanisms mounted on the end of rocket tank polishing robot used for heavy load condition is designed in this paper. Its each branch chain consists of spherical joint, revolute joint and prismatic joint, in which the prismatic joint is driven by the cylinder. The collision detection principle is to judge whether an external collision occurs by real-time detecting the changes of cylinder pressure and cylinder displacement. Besides, the kinematics of parallel mechanisms is analyzed and a numerical iteration algorithm for forward kinematics based-on our previous work is proposed here. The proposed algorithm can be not only used for 6-dof parallel mechanism but also for more or less than 6-dof ones in which Jacobian matrix is not square. Moreover, it is not sensitive to the iteration initial value. Then, a linear trajectory is simulated to verify the effectiveness of the proposed algorithm. Finally, the simulation results prove the accuracy of the proposed algorithm.

The most important feature of Modular Self-reconfigurable Robot (MSRR) is the adaption to complex environments and changeable tasks. A critical difficulty is that the operator should regulate a large number of control parameters of modules. In this paper, a novel locomotion control model based on chaotic Central Pattern Generator (CPG) is proposed. The chaotic CPG could produce various rhythm signals or chaotic signal only by changing one parameter. Utilizing this characteristic, a unified control model capable of switching variable locomotion patterns or generating chaotic motion for modular self-reconfigurable robot is presented. This model makes MSRR exhibit environmental adaptability. The efficiency of the control model is verified through simulation and experiment of UBot MSRR platform.

Jumping robots can be widely applied in archeology, interstellar probe, antiterrorism, and resource exploration. This article adopts the frog as the bionic object and briefly analyzes biological features and jumping movements in a complete jumping sequence of the frog. Then an equivalent six-bar mechanism model depicting frog jumping movement is built up, and the optimizing simulation of the six-bar mechanism model is performed. On the basis of the optimized results, the robot is designed and prototype is manufactured. An adaptive cascade controller is proposed to control the robot. Proportional–integral–derivative parameters of the controller are tuned online using radial basis function neural network to deal with nonlinearities of the robot. Jumping experiment demonstrates the jumping capacity of the robot and the ability of the proposed controller in tracking the desired trajectories.

Background Although Pneumatic Artificial Muscle (PAM) has a promising future in rehabilitation robots, it's difficult to realize accurate position control due to its highly nonlinear properties. Objective This paper deals with position control of PAM. Methods To describe the hysteresis inside PAM, a polynomial based phenomenological function is developed. Based on the phenomenological model for PAM and analysis of pressure dynamics within PAM, an adaptive cascade controller is proposed. Both outer loop and inner loop employ BP Neural Network tuned PID algorithm. The outer loop is to handle high nonlinearities and unmodeled dynamics of PAM, while the inner loop is responsible for nonlinearities caused by pressure dynamics. Results Experimental results show high tracking accuracy as compared with a convention PID controller. Conclusion The proposed controller is effective in improving performance of PAM and will be implemented in a rehabilitation robot.

Pneumatic Muscle Actuator (PMA) has a broad application prospect in soft robotics. However, PMA has highly nonlinear and hysteretic properties among force, displacement, and pressure, which lead to difficulty in accurate position control. A phenomenological model is developed to portray the hysteretic behavior of PMA. This phenomenological model consists of linear component and hysteretic component force. The latter component is described by Duhem model. An experimental apparatus is built up and sets of experimental data are acquired. Based on the experimental data, parameters of the model are identified. Validation of the model is performed. Then a novel cascade position PID controller is devised for a 1-DOF manipulator actuated by PMA. The outer loop of the controller is to cope with position control whilst the inner loop deals with pressure dynamics within PMA. To enhance the adaptability of the PID algorithm to the high nonlinearities of the manipulator, PID parameters are tuned online using RBF Neural Network. Experiments are performed and comparison between position response of RBF Neural Network based PID controller and that of classic PID controller demonstrates the effectiveness of the novel adaptive controller on the manipulator.

In this paper, a dynamic equivalent test platform for large-mass spacecraft docking in thermal vacuum has been successfully developed. An equivalent-mass docking test principle for reducing the size of the test platform has been introduced. In addition, by adopting a flywheel to simulate part equivalent mass of docking test, the scheme of making a more compact test platform has been realized. Furthermore, the identification of the friction force in the platform to guarantee the equivalent velocity of docking test has been demonstrated. At last, the performance of the test platform has been evaluated through both the docking simulation with software and the docking test on the platform. The results of comparison between the docking simulations and the experimental tests proved the effectiveness of the equivalent-mass docking test principle and also indicated that the docking test platform developed in this work has the ability to simulate the docking process precisely.

Estimate of the hydrodynamic force exerting on the frog is a key factor in design of mechanical structure and control system. To research propulsion generation mechanism during frog swimming, computational fluid dynamics–based method was performed. From the propulsive force results, drag and lift components of hydrodynamic forces were decomposed in terms of the palm motion. The thrust in the aquatic swimming trial turned to involve the lift propulsion, while drag component contributed almost the whole thrust in the terrestrial swimming trial. The hydrodynamic results were analyzed and compared to reveal the propulsion generation mechanism. The lift thrust characterized a U-shaped vortex ring around the palm to symbolize the lift mechanism.

Study on frog swimming mechanism is an interesting topic, and a frog inspired robot has been designed with the pneumatic muscles as the driver. To improve the design and trajectory planning, the optimization of the robot was studied in this paper. For the robot structure, the limb size was optimized in ADAMS and joint parameters of the bionic robot are optimized by particle swarm optimization (PSO) method. Meanwhile, the trajectory during propulsive phase is also optimized in Matlab. Simulations in ADAMS verified the feasibility of the proposed optimization for the frog inspired robot.

Most of the upper limb exoskeletons proposed in the literature are designed for rehabilitation, however, there are few developments for activities assistance of daily living. This paper presents a wearable upper limb exoskeleton for activities assistance of daily living with the feature of mobility. It provides five degrees-of-freedom (DOF) for each arm, where 3 DOF and 2 DOF are given to the shoulder and elbow, respectively. And it allows the wearer to keep freedom and mobility as usual after wearing the device. To conquer the strength-to-weight limitations of exoskeleton mobility, we introduced gravity balance method to reduce energy consumption and proposed a novel cable-driven joint mechanism to reduce its total weight to 4.2 kg. In order to verify the plausibility of joints design and its performance on motion assistance, joints tracking test and motion assistance test were carried out, respectively. Their results support that the proposed exoskeleton is feasible and efficacious.

This paper describes a cellular robot(C-Balls) consisting of soft spherical modules with on-board actuation, power, computation and wireless control system. The robot modules maintain connection and realize relative movement by utilizing magnetic force and friction force between driving units inside the soft modules. Preliminary tests of locomotion and deformation of the robot are proposed. The rolling experiment displays the mobility of the robot of two spherical modules. The deforming experiments indicate that the robot with five spherical modules deforms from linear to circular configuration successfully. Further more, a climbing experiment is conducted, which shows the robot can climb on various surfaces including soft materials.

We propose an indirect stiffness estimation method of flexible joint based on system function approximation in this paper. At first, an alternative system function is constructed. Then a system function estimation method based on saturation function is introduced to estimate its output. Taking the estimated system function as prior model, the least square method is finally introduced to identify the joint stiffness. Meanwhile, another system estimation method based on RBF neural network is also introduced to verify the efficiency of the former one. There are two advantages of the new proposed stiffness estimation method. Firstly, it is more robust to environmental noise, since no basic version or filter version of angle acceleration is maintained in the estimation process. Secondly, it's easy to apply because only measurements of joint angle on motor side, joint velocity on motor side and joint angle on link side is needed.

Self-reconfiguration of Modular Self-Reconfigurable (MSR) robots is a fundamental primitive that can be used as part of higher-lever functionality. The biological principle of self-organizing and growth in both animals and plants is learned to solve the automatic planning of configuration and control methods. A bioinspired approach is proposed for distributed self-reconfiguration. This method aims at utilizing the self-organization and pattern emergence of the MSR robotic system, which is made of large quantity of modules to promote the system to reconfigure in the direction of adapting to environments and tasks. This mechanism is hybrid by combining Lindenmayer systems (L-systems) and Cellular Automata (CA). L-systems are introduced for defining global structure and providing topological description. Cellular Automata (CA) handle motion planning of distributed modules. This method is absolutely distributed and convergent to self-adaptive structures with desired organizing principles. The convergence of proposed method is verified through simulations and experiments on UBot robots.

This paper presents a mechanical model of jumping robot based on the biological mechanism analysis of frog. By biological observation and kinematic analysis the frog jump is divided into take-off phase, aerial phase and landing phase. We find the similar trajectories of hindlimb joints during jump, the important effect of foot during take-off and the role of forelimb in supporting the body. Based on the observation, the frog jump is simplified and a mechanical model is put forward. The robot leg is represented by a 4-bar spring/linkage mechanism model, which has three Degrees of Freedom (DOF) at hip joint and one DOF (passive) at tarsometatarsal joint on the foot. The shoulder and elbow joints each has one DOF for the balancing function of arm. The ground reaction force of the model is analyzed and compared with that of frog during take-off. The results show that the model has the same advantages of low likelihood of premature lift-off and high efficiency as the frog. Analysis results and the model can be employed to develop and control a robot capable of mimicking the jumping behavior of frog.

Muscular rigidity and atrophy caused by long-term underactivity usually lead to foot drop, strephenopodia, foot extorsion or some other complications for the lower limb movement disorders or lower limb surgery sufferers. The ankle-foot orthosis can help patients conduct the right ankle motion mode training, inhibit spasm and prevent ankle complications. In this paper, a quasi-passive 3 DOFs ankle-foot wearable orthosis was designed on the basis of kinematics and dynamics analysis of the ankle joint. Ankle joint trajectory and dynamic characteristics similar to those of natural gait can be obtained by the combination of passive energy storage and additional power complement. In terms of function, the orthosis has shock absorption and low energy consumption. Given its excellent characteristics of comfortableness, lightweight, and anthropomorphic construction, the orthosis can be used in medical institutions for rehabilitation training or as a daily-walking auxiliary equipment for surgery sufferers.

This paper presents a jumping four-bar mechanism using pneumatic muscle actuators. The mechanism has three joints and each one is powered by one artificial muscle; jumping and restoring action is achieved by muscle contracting force and spring respectively. Kinematic analysis is performed in landing and airborne phase respectively. Vertical jumping simulation is performed according to the prototype parameters and results demonstrate the kinematic analysis and show the torques supplied by muscles can meet the jumping requirement.

Comparing with the local algorithm in stereo matching, the global algorithm can get highly quality disparity space image (DSI) usually. The graph cuts algorithm, as the traditional global matching method, can get the highly quality DSI with long computation time, so the graph cuts algorithm is difficult to used in real-time matching applications. In this paper, a new method is proposed to accelerate the matching speed. Firstly, the segments of the image are calculated using the Gaussians pyramid (DoGs) computing method, secondly calculate the disparity range of two corresponding image segments in image pair using the color feature, and every segment pair is matched based on graph cuts algorithm according to the offset of disparity range in parallel time, finally all the segments are assembled into a whole disparity image. The experimental results show that the matching speed is accelerated greatly with a high disparity image quality.

A novel admittance haptic device which has low inertia and high speed to guarantee the high force bandwidth for the haptic interaction system is presented. Friction wheel is used to implement a rapid adjustment of the velocity loop. According to the admittance character of the haptic interface, PI velocity feedback control is utilized in the haptic interaction system. By introducing the virtual coupling into the system, Llewellyn's stability criteria in circuit theory is used to derive the constraint conditions to guarantee the system's absolute stability. Furthermore the parameters of the virtual coupling are optimized oriented to high transparency of the system. Man-machine haptic interaction system is established with the novel admittance interface. The experimental results indicate that optimized virtual coupling guarantees the large range stability, as well as improving the transparency effectively.

A new type of reconfigurable modular robot is developed. This robot has some characteristics: realize modularization in the structure, the electrical, the drive, the kinematics and dynamic performance; It can construct the work topology rapidly according to the actual need and complete tasks in real time. The control method of reconfigurable modular robot is researched according to these characteristics. Taking the single module as the Agent model, the intelligent control system of the robot is established, and the control algorithm of the robot is researched emphatically to prove its astringency . Finally the analyses of the simulation experiment are made.

Mechanism analysis of frog swimming is an interesting subject in the field of biofluid mechanics and bionics. Computing the hydrodynamic forces acting on a frog is difficult due to its characteristics of explosive propulsion and large range of joint motion. To analyze the flow around the body and vortices in the wake, in this paper, the method based on Computational Fluid Dynamics (CFD) was utilized to solve the velocity and pressure distributions in the flow field and on the frog. The hydrodynamic problem during the propulsive phase of a frog, Xenopus laevis, was calculated using the CFD software FLUENT. A self-propulsion simulation was performed which computed the body velocity from the joint trajectory input and CFD solved the hydrodynamic forces, and visual CFD results of the hydrodynamic forces and flow field structures were obtained.

Developed the foot mechanism, which is one of the key parts of three-limb permanent magnetic adsorption robot HIT-RMT. With this foot mechanism, the limbs of the robot can be transformed into adsorption feet to walk when needed, as well as operators to carry out assignments. Three-dimension force/moment sensor has been employed in the design of the foot, which is used to detect force information between the robot and the walking surface or operating objects. One permanent magnetic adsorption mechanism has been designed, and with it, the robot is easy to realize the adsorption and departure with the working surface with comparatively small energy consuming and ensured safety.