Applied Mechanics and Materials Vol. 709

Abstract: Dragonflies possess one of the most maneuverable flights among various insects. As the bionic Micro Air vehicles (MAVs) with the flight capabilities like dragonflies have been widely applied, detailed studies of dragonfly flight become critical and necessary for improvement and accomplishment of MAVs design. The phase relation between the forewings and hindwings is the most distinct feature of dragonfly flight and it plays an important role in the aerodynamic performance. In this paper, both tethered and quasi-free flapping flight of the dragonfly Pantala flavescens was filmed using a high-speed camera in indoor laboratory. Dragonflies tend to flap in-phase when an additional force is expected, while out-of-phase flapping is conducive to the stability and control of flight. In the takeoff maneuver, the large-and small-amplitude wingbeat alternated. Dragonflies obtain a high acceleration rapidly by the suddenly enlarged wingbeat amplitude which increases by 42%, and maintain the velocity and make ready for following acceleration by the small-amplitude but high-frequency wingbeat with amplitude decreases by 51% and frequency increases by 30% relatively.

Abstract: This paper performed the longitudinal nonlinear PID Controller parameter optimization of general aircraft autopilot based on the longitudinal channel model and genetic algorithm. Proportion, integration and differential gain of nonlinear PID Controller is nonlinear function of controlling error. The objection function involves time integration of error’s absolute value, output of controller and system overshoot. The longitudinal controlling rate optimization of general aircraft autopilot is realized by minimizing the objection function value. Simulation results show that controller designed by the present method is better than traditional PID controller.

Abstract: A new approach is designed to the guidance of rocket-propelled missile with multiple object constraints. It allows the rocket-propelled missile to reach its target with a close to zero falling angle at a least time-of-flight (TOF). Instead of deriving the optimum guidance law by a series of linear quadratic optimization methods which results in guidance laws being complex, the new guidance law adopts a mixed framework composed of a modified PN guidance command and a TOF guidance command. The modified PN guidance is designed based on measured state information including missile position, flight-path angle and acceleration, which yields zero-miss-distance and zero-falling-angle. The TOF guidance command is determined in quadratic multinomial with respect to TOF error that is estimated with missile velocity reduction due to aerodynamic drag. Simulation results are presented to show that the proposed guidance law performs favorably in multiple object constraints.

Abstract: A rigid-elastic coupling multi-body dynamic model of an in-wheel motor vehicle with double pivot suspension was established. The steering effort performance is analyzed. Results showed an excessive steering force of the vehicle with double pivot suspension. By optimizing the suspension parameters using response surface surrogate model and genetic algorithm, the characteristic of steering effort was improved.

Abstract: In order to obtain the ideal steering performance, an active rear wheel steering (ARS) controller, based on the variable transmission ratio control strategy, is developed in this paper. ARS controller using sliding mode technique is designed to follow the desired yaw rate which is calculated by the ideal variable transmission ratio. Simulation result shows that, the proposed control strategy both obtains desired steering performance and provides the obvious benefits for the human driver.

Abstract: Vehicle robot drivers are widely used in automotive tests especial for some tests on automotive chassis dynamometer. However, China has less technology accumulations than west developed countries in the field of research and development of robot driver. In order to promote the developments of the domestic robot driver technology, a vehicle robot driver based on servo motor control was developed for automobile chassis dynamometer test, its system composition, functional features, and key technologies in developing process were expounded specifically in this paper.

Abstract: By analyzing the dynamic model of working mechanism for excavator, motion status of working mechanism during digging process was researched. The tests under two kinds of commonly operating conditions for the motion of excavator were carried out by method of ultrasonic distance measuring. The results show that the motion law of working mechanism under two kinds of operating conditions was basically similar, and digging process presented periodicity clearly. Each excavating period included four stages which were bucket excavating, boom lifting, medium dumping, and working mechanism returning respectively. One-arm excavating and two-arm linkage excavating was main operating method for excavator. The purpose of three-arm linkage excavating was to adjust excavating posture, therefore, which often happened in a short time during an excavating period, and appeared relatively few during digging process.

Abstract: Chain type coal-fired hot blast furnace boiler has a strong coupling, large delay, large inertia characteristics. Control effect of control method of mathematic modeling method and the classical routine of it is very difficult to produce the ideal. The predictive control theory combined with neural network theory. Through the model correction and rolling optimization control method of the system is good to overcome the effects of model error and time-varying process. The experimental results showed that neural network predictive control system is improved effectively the static precision and dynamic characteristic. It has better practicability of boiler temperature of this kind of large time delay system.

Abstract: Regenerative brakes offer the opportunity to improve a vehicle’s braking performance in emergency situation. This study investigates slip ratio emulation on a test bench to enable these issues to be studied in a lab. Compared with vehicle drive cycle emulation on a test bench, the slip ratio emulation on a test bench requires higher bandwidth because of the higher dynamic requirement of slip control than that of vehicle energy management. Toward this end, a feedforward compensation method that could also prevent the amplification of the noise from the sensor is designed for this based on a linearized wheel slip equation. The results of simulations and tests indicate that the proposed slip-ratio emulation method can emulate the dynamic variation of the slip rate effectively.

Abstract: In view of the working principle and characteristics of the CVT with electronic control and a motor as actuator (EM-CVT), a economical car performance is studied by means of combination of simulation calculation and prototyping test. EM-CVT mathematic model is established and embedded into the simulation software Cruise to finish the whole vehicle modeling. The performance comparison between vehicle with EM-CVT and automatic transmission is presented after simulation based on the experiment data on the EM-CVT prototype under UDC, which indicates that the vehicle fuel consumption with EM-CVT is reduced distinctly with the same power performance.