Quantitative Assessment of Dynamic Stability Characteristics for Jet Transport in Sudden Plunging Motion

The main objective of this article is to present a training program of loss control prevention for the airlines to enhance aviation safety and operational efficiency. The assessments of dynamic stability characteristics based on the approaches of oscillatory motion and eigenvalue motion modes for jet transport aircraft response to sudden plunging motions are demonstrated in this article. A twin-jet transport aircraft encountering severe clear-air turbulence in transonic flight during the descending phase will be examined as the study case. The flight results in sudden plunging motions with abrupt changes in attitude and gravitational acceleration (i.e. the normal load factor). Development of the required thrust and aerodynamic models with the flight data mining and the fuzzy-logic modeling techniques will be presented. The oscillatory derivatives extracted from these aerodynamic models are then used in the study of variations in stability characteristics during the sudden plunging motion. The fuzzy-logic aerodynamic models are utilized to estimate the nonlinear unsteady aerodynamics while performing numerical integration of flight dynamic equations. The eigenvalues of all motion modes are obtained during time integration. The present quantitative assessment method is an innovation to examine possible mitigation concepts of accident prevention and promote the understanding of aerodynamic responses of the jet transport aircraft.

Kinematic analysis and simulation of 6-DOF vehicle driving simulator

In order to reasonably design the six degrees of freedom turntable (hereinafter referred to as the transfer table), based on the structure size and motion index parameters of the turntable, The motion mechanics calculation model was established to simulate and analyze the mechanical variation curve of singing platform under different motion modes. The analysis shows that when the upper platform load and the component mass are 3000 kg, the maximum action force of the rotating platform support moving cylinder is 1376.4 kg.

Design and Analysis of the Rolling and Jumping Compound Motion Robot

Complex and unknown areas in deep space exploration present major challenges to the motion ability of current space robots. Different from the traditional single-mode motion space robot, a compound motion robot with flexible movement and strong obstacle surmounting ability is proposed. Through the highly integrated structure design, the lightweight robot has the ability of rolling and jumping, and the kinematic characteristics of the robot under two motion modes are analyzed. This work provides a reference for the design of deep space exploration equipment with high motion capability in the future.

Information system for remote monitoring the vehicle operational efficiency

The article describes the information system for remote monitoring and control of vehicle technical condition and motion modes with the use of modern telematics technologies. There are 17 morphological features in the system, which determine the level of telematic support of the main functional elements of the system to obtain information about vehicle technical condition and motion modes in the appropriate infrastructural conditions. The information model of the system for monitoring of parameters of vehicle technical condition, motion modes and infrastructural characteristics was built. This model is implemented in the information and software complex for remote monitoring of vehicle operational efficiency. The results of experimental studies of freight vehicle operational efficiency on a given route with use of the developed information and software complex are presented. The results show significant influence of the vehicle technical speed and average coolant temperature of its engine on operational efficiency indicators such as fuel consumption, carbon dioxide, nitrogen oxides and particulate matter emissions on the route characterized by different road height profiles.

Modeling the vehicle operational efficiency in the "Vehicle - Infrastructure” system

The article is devoted to the study of vehicle operational efficiency in certain infrastructural environment conditions. The vehicle operational efficiency is evaluated according to dynamic, economic and environmental criteria using a mathematical model of the "Vehicle-Infrastructure" system. The mathematical model describes the main processes in the studied system: the conversion of input energy into mechanical energy of propulsion system, mechanical energy transmission to the vehicle wheels, the conversion of wheels rotation into vehicle translational motion, change of vehicle motion modes and directions according to a given motion law in certain infrastructural environment conditions. The presented structure of the mathematical model contains generalized dependences between the main parameters of the system processes and feedbacks implementing the target functions of thermal control of individual propulsion subsystems and vehicle modes to achieve the desired values of energy consumption and emissions per transport work unit. The results of vehicle operational efficiency evaluation using verified model in the implementation of individual algorithms for thermal development control of propulsion subsystems (engine and catalytic converter) in the heating mode are given.

Mathematical Modeling and Dynamic Analysis of a Compact Vectored Thruster

In this paper, a compact vectored thruster based on a composite gear train is proposed. First, the space transformation between different coordinate systems is carried out, and the mathematical model of the vectored thruster is established, according to classical navigation mechanics theory. Then, the swing and roll motion analysis of the composite gear train is implemented, and the motion relationship of the whole thruster structure is analyzed systematically. Moreover, SolidWorks and MATLAB software are used for simulation to verify the accuracy of the mathematical model. In addition, the trajectories of the propeller shaft under different motion modes are analyzed and compared. Finally, the dynamic analysis of the vectored thruster is carried out, and the change trend of the scaling factors of the vector thrust components with the swing angle δ and the roll angle χ is studied, and comparison with the scaling factors of the vectored water jet propeller presented in other literature is taken into account. To endow the thruster with superior maneuverability, the fairwater structure of the vectored thruster is optimized, and the lateral vector component of the optimized vectored thruster is greatly increased.

Design and Kinematic Analysis of a 4-SPS/U-based Four-level Rigid Trunk Mechanism

A 4-SPS/U four-level rigid trunk mechanism, with SPS as the driving branch and U as the middle constrained driven branch, is innovatively proposed in this paper. It can improve the flexibility of hexapod mobile robots in posture adjustment in various motion modes such as walking, water propulsion, climbing, and rolling. Firstly, the screw theory is adopted to calculate the degree of freedom of the 4-SPS/U four-level rigid trunk mechanism. Secondly, a combination of closed vector method and decoupling method of eigenstructure assignment has been applied to constructing the inverse kinematics solution, and deriving the velocity and acceleration models as well as analyzing the high posture flexibility in workspace of the trunk mechanism. Thirdly, theoretical simulation data diagram of the movement branch chain displacement, end height, speed and acceleration of the trunk mechanism are calculated through theoretical numerical examples, and the excellent motion characteristics of the 4-SPS/U type four-level rigid trunk mechanism are analyzed. Finally, a quantitative comparison was made between the theoretical simulation data and the experimental data of the experimental prototype. The error rates of the variation curves of the displacement length, height, velocity and acceleration of the driving branch chain were 0.8%, 0.2%, 0.5% and 0.9%, which verified the correctness and reliability of the theoretical derivation.

The investigation on flight quality of tilt-rotor aircraft

Purpose This paper aims to present an investigation on flight quality analysis and design of tilt-rotor aircraft combined with corresponding flight quality specifications. Design/methodology/approach From the perspective of modal characteristics of tilt-rotor aircraft, it focuses on the analysis of the change rules of the longitudinal short-term motion mode, lateral roll convergence mode, spiral mode and Dutch roll mode. Then, the flight quality design research is carried out using the explicit model tracking control method. The quantitative relationship between flight quality requirements and explicit model is established. Accordingly, the closed-loop flight quality of XV-15 tilt-rotor aircraft is evaluated. Findings The stability of spiral mode is the result of the interaction of various aerodynamic derivatives and spiral instability occurs in helicopter mode. The other motion modes are stable in full flight mode and meet the requirements of level 1 specified in ADS-33E-PRF and MIL-F-8785C flight quality specifications. There is a quantitative relationship between flight quality requirements and explicit model, and the flight quality of tilt-rotor aircraft is improved through the explicit model tracking control method. Practical implications The presented analysis results showed the influence of motion modes and flight quality and the effectiveness of explicit model tracking control method in flight quality improvement, which could be considered as new information for further flight quality design of tilt-rotor aircraft. Originality/value The originality of the paper lies in the proposed design and analysis method of the flight quality of tilt-rotor aircraft from the direction of the influence of its aerodynamic derivatives and motion modes.

Structure Synthesis and Reconfiguration Analysis of Variable-DOF Single-Loop Mechanisms With Prismatic Joints Using Dual Quaternions

This paper deals with the structure synthesis and reconfiguration analysis of variable-DOF (variable degree-of-freedom) single-loop mechanisms with prismatic joints based on a unified tool - the dual quaternion. According to motion polynomials over dual quaternions, an algebraic method is presented to synthesize variable-DOF single-loop 5R2P mechanisms (R and P denote revolute and prismatic joints respectively), which are composed of the Bennett and RPRP mechanisms. Using this approach, variable-DOF single-loop RRPRPRR and RRPRRPR mechanisms are constructed by joints obtained from the factorization of motion polynomials. Then reconfiguration analysis of these variable-DOF single-loop mechanisms is performed in light of the kinematic mapping and the prime decomposition. The results show that the variable-DOF 5R2P mechanisms have a 1-DOF spatial 5P2P motion mode and a 2-DOF Bennett-RPRP motion mode. Furthermore, the variable-DOF 5R2P mechanisms have two transition configurations, from which the mechanisms can switch among their two motion modes.