Applied Mechanics and Materials Vols. 268-270

Abstract: The adaptive forced balancing (AFB) method was used to estimate and eliminate the rotor vibration with unknown amplitudes and frequencies in active magnetic bearing (AMB) feedback control systems. Firstly, the rotor vibration producing mechanisms of AMB were analyzed. Then, the AFB under the assumption of unknown rotational frequency and amplitude are designed. Finally the simulation results show that the AFB method proposed in this paper makes it possible to completely reject unknown sinusoidal disturbance in a closed loop control system

Abstract: A Cartesian impedance control for a 7-DOF space robotic arm (SRA) based on the feedback from a 6-dimensional force/torque sensor on its end effecter is presented in this paper. The unavoidable position error of SRA would generate large contact forces during the connection between SRA’s end effecter (EE) and grapple fixture (GF). To control the contact force we used 6D force feedback to modify the desired trajectory controlling a PID position inner loop to make the manipulator exert desired impedance dynamic properties on its end-effecter. After optimization of impedance parameters in Simulink, this control strategy has significantly improved the force control effect in EE/GF connection experiment. Kinematic solution of the 7-DOF redundant manipulator is also provided.

Abstract: The objective of this study is to design and optimize a vertically movable gate field effect transistor (VMGFET) - suitable for low-frequency, high-sensitivity applications - with an emphasis on modal analysis of the suspended gate structure, optimization of mesh density within the employed finite element analysis software, and optimization of the moveable gate dimensions given its relationship with fabrication complexity and the structure’s resonant frequencies. The methods of design, optimization, and analysis were carried out with COMSOL Multiphysics 4.2a under the assumption of no damping with free vibrations. The results indicate optimal dimensions of the suspended gate structure - given constraints on size, resonance, and fabrication complexity - which suggest a beam thickness of 3 µm and a beam width of 15 µm, yielding an upper limit of input force frequencies near 2 kHz.

Abstract: A new elastic element of fiber Bragg grating accelerometer which is four peripheral clamped trapezoidal beams is developed. On the basis of analyzing the mechanical condition of this elastic element, the theoretical model is obtained. Furthermore, the degree of strain uniformity of the beam will be discussed. The elastic element has nearly uniform stain near the fixed end , where can be as grating area. This kind of elastic element not only can be used with fiber Bragg grating accelero- meter, but also other types of sensors.

Abstract: A micro flowmeter was designed based on MEMS sensor and weak signal acquisition technique. The MEMS sensor adopted VO2 thermal resistor suspended structure, which has good heat isolation performance and high sensitivity. The flow channel was made up of SU-8 gum, and this technology is simple and suitable for batch production because of low cost. The following weak signal acquisition module used super low bias current operational amplifier, aided with Guard ring protection, and 24 bit high resolution ADC to realize high resolution, low noise data acquisition through reasonable layout and ground design. The experiment shows that the entire flowmeter has favorable linearity and sensitivity in the velocity range from 0 to 30mL/min at a certain suitable offset voltage. So it can satisfy the applications in the fields such as biochemical detection, medicine and so on.

Abstract: In this paper, a calibration method is proposed for fish-eye panoramic camera. We adopt the unifying spherical projection model to represent the optical nature of fisheye camera. Traditional corner detection works unreliably in highly distorted image. Therefore, edge-based corner detection is proposed based on Hough transform. The line segments within corner detection window and their intersection corner points are extracted accurately and reliably due to the robustness of Hough transform. We use the nonlinear optimization technique to estimate the camera parameters. Experimental results demonstrate the performance of our method.

Abstract: The flow distribution of fluidic gyroscope with three different cavities was researched when angular velocity ωi is input. Using Finite element method we calculated two-dimensional flow distribution of fluidic gyroscope with rectangular cavity and two streamlined cavity structures when ωi input. The results show that: with ωi increasing, the fluidic beam centers in three cavities have a more deviation on one side, while in two streamlined cavities it deviates obviously. When ωi is 10rad/s, velocity difference of two thermal wires in streamlined cavity 1 and cavity 2 increase 42.59% and 59.30% respectively compared with rectangular cavity, velocity and y-axial velocity of two thermal wires in streamlined cavity 1 are smaller than rectangular cavity but larger than streamlined cavity 2, but x-axial velocity of two thermal wires in streamlined cavity 1 are smaller than other two cavities, and so is ωi = 15rad/s. It also shows that velocity difference between two thermal wires in streamlined cavity 1 is larger than others, and temperature difference is larger, which can improve the resolution of fluidic gyroscope. This article has laid a theoretical foundation to further enhance performance of fluidic gyroscopes.

Abstract: The influence of thermal wires position on resolution of fluidic gyroscope with three different cavities was researched. Using Finite element method we calculated two-dimensional flow distribution of fluidic gyroscope with rectangular cavity and two streamlined cavities when the thermal wires are in different positions. As the results shown: define d is the distance between thermal wires and the nozzle along the fluidic beam propagation direction, when d ≥ 13mm, velocity 4SSUM in streamlined cavity 1 is bigger than velocity 2SSUM in streamlined cavity 2. When d >16mm, velocity SX of two streamlined cavities decrease faster than RX of rectangular cavity, which reduce the vortex phenomena in cavity. With the distance away from the center axis of cavity increases, the velocity gradient increases, and increasing the distance between two thermal wires within a certain range can increase velocity difference of two when angular velocity ωi inputs, temperature difference increases, so it increases the resolution of fluidic gyroscopes. This paper has an instructional role on structure optimization and performance improvement of fluidic gyroscopes.

Abstract: Electronic technology is widely applied in modern automobiles, making automobiles safer, more comfortable, economical and environment-friendly. With the development of automobile industry, electronic technology occupies an increasingly large portion within auto industry technology. To some extent, electronic technology gave rise to the revolution of environment-friendly automotive technology. This article expounds on principles of the automobile engine electronic control system as well as other applications of electronic technology to automobiles. Hopefully, readers could attain certain knowledge concerning the relationship between modern automobiles and electronic technology.

Abstract: Based on the widely used USB communication technology, when the speed requirement is not too high using USB controller chip with I2C bus develops USB interface, you can reduce the use of pin microcontroller ATmega8, simplify connection circuit. This article describes the design method of a Philips company with I2C interface USB interface chip PDIUSBD11, as well as the peripheral hardware circuit connection and USB HID class program design method. The test results show that can reliably achieve communication function between USB and computer, and has good application value.