The focus of this paper will be on the challenges and opportunities posed by use of wave active sensors for structural health monitoring of metamaterial as different from that of the metallic structures. Metamaterial exhibits application prospects in vibration control, wave manipulation and noise reduction due to their unique dynamic properties. Metamaterial has great potential in structural health monitoring and non-destructive testing. This paper presents modeling, analysis techniques and experiment of for Acoustic metamaterial Structure for knowing waves. For a unit cell of an infinite Acoustic metamaterial Structure, governing equations are derived using the extended Hamilton principle. The concepts of negative effective mass and how the spring-mass-damper subsystems create a stopband are explained in detail. Numerical simulations reveal that the actual working mechanism of the proposed acoustic metamaterial structure is based on the concept of conventional mechanical vibration absorbers. It uses the incoming wave in the structure to resonate the integrated mass-damper absorbers to vibrate in their optical mode at frequencies close to but above their local resonance frequencies to create shear forces and bending moments to straighten the panel and stop the wave propagation. And the stopband signal shows the structure characteristic. Moreover, It shows that metamaterial can be use in health monitoring and non-destructive testing.
Kinematics analysis of multi-joint robot play an important part in robotics research. Because of the non-uniqueness of its inverse solution, robot kinematics with more than 6 freedom degrees is still the focuses of the research. For the inverse kinematics problem, some optimization methods ,like neural network , are mostly used.These methods have many problems such as heavy calculation and low accuracy. In this paper, a new inverse kinematics algorithm based on geometric and analytical methods is proposed and verified by simulation. In this paper, the D-H model is established according to the robot structure and the structure parameters of the robot are determined. The positive and negative solutions of the robot are analyzed and calculated. Finally, MATLAB is used as the simulation tool to verify the correctness and accuracy of the results. It provides a new idea for the improvement, design and application of the robot with more than 6 axises.
A Buck-Boost converter with four fully synchronous transistors is proposed in this paper which achieves the output voltage lower or higher than the input voltage, in the un-isolated application. The control strategy and the working principle of circuit are discussed in this paper. Then, the implement of Buck-Boost converter with four fully synchronous transistors is expatiated, which is based on the LM5116. Furthermore, the design of key circuit parameter and the selection of power components are introduced. At last, the simulation and experimental results show the correction of the parameter designing.
Robot inverse kinematic problem is a widely studied problem. In this paper, we present a numerical method to solve robot inverse kinematic problem based on screw theory. In this method, we transform the inverse kinematic problem into optimization problem and a damping term is introduced. It combine the advantages of Newton method and gradient descent method improve the shortcomings of both methods. At last, we use this method to solve the inverse kinematics problem of JARI 6R serial industry robot and the calculation result is shown.