A time varying washout approach for flight simulation hexapod motion system

mechanical arm is an essential replaced tool in the operations under heavy, dangerous and harsh environment (such as nuclear radiation, toxic and hazardous, etc.), but also a key technical equipment in the development of the country. Mechanical arm motion system is a very complex time-varying, strong coupling, highly nonlinear system. This paper presents a model of the robot visual tracking. Through the computer vision track the mechanical arm motion process to make the mechanical arm movement to become more intelligent, more environmentally friendly. Experiments show that the method can complete the mechanical arm intelligent trajectory tracking, and the tracking effect is better. 1 Introduction

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Development of Multi-Axis Crank Linkage Motion System for Synchronized Flight Simulation with VR Immersion

Applied Sciences ◽

10.3390/app11083596 ◽

2021 ◽

Vol 11 (8) ◽

pp. 3596

Author(s):

Cheng-Tang Pan ◽

Pei-Yuan Sun ◽

Hao-Jan Li ◽

Cheng-Hsuan Hsieh ◽

Zheng-Yu Hoe ◽

...

Keyword(s):

Degrees Of Freedom ◽

Spatial Information ◽

Angular Displacement ◽

Control Unit ◽

Flight Simulation ◽

Servo Motor ◽

Linkage Mechanism ◽

Motion Platform ◽

Motion System ◽

Control Automation

This paper developed a rotatable multi-axis motion platform combined with virtual reality (VR) immersion for flight simulation purposes. The system could simulate the state of the flight operation. The platform was mainly comprised of three crank linkage mechanisms to replace an expensive six degrees of freedom (DoF) Stewart platform. Then, an independent subsystem which could rotate ±180° was installed at the center of the platform. Therefore, this platform exhibited 4-DoF movement, such as heave, roll, pitch, and yaw. In the servo motor control unit, Visual Studio C# was applied as the software to establish a motion control system to interact with the motion controller and four sets of servo motors. Ethernet Control Automation Technology (EtherCAT) was utilized to communicate the commands and orders between a PC and each servo motor. The optimum controller parameters of this system were obtained using Simulink simulation and verified by experiment. The multiple sets of servo motors and crank linkage mechanisms were synchronized with flight VR imagery. For VR imagery, the software Unity was used to design the flying digital content. The controller was used to transmit the platform’s spatial information to meet the direction of the pilot commands and to compensate the direction of the deviation in spatial coordinates. To achieve synchronized response and motion with respect to the three crank linkage mechanism platform and VR imagery on the tester’s goggle view, the relation of the spatial coordinate of VR imagery and three crank linkage mechanisms was transformed to angular displacement, speed and acceleration which were used to command the motor drive system. As soon as the position of the VR imagery changed, the computer instantly synchronized the VR imagery information to the multi-axis platform and performed multi-axis dynamic motion synchronously according to its commanded information. The testers can thus immerse in the VR image environment by watching the VR content, and obtain a flying experience.

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An online identification approach for a nonlinear ship motion model based on a receding horizon

Transactions of the Institute of Measurement and Control ◽

10.1177/01423312211019654 ◽

2021 ◽

pp. 014233122110196

Author(s):

Jian Zheng ◽

Ming Yan ◽

Yun Li ◽

Changhai Huang ◽

Yiping Ma ◽

...

Keyword(s):

Real Time ◽

Time Window ◽

Control Object ◽

Ship Motion ◽

Identification Algorithm ◽

Time Varying ◽

Ocean Engineering ◽

Online Identification ◽

Motion System ◽

Window Method

The ship motion system is a nonlinear control object, and its system parameters exhibit time-varying characteristics with the ship motion state, which increases the difficulty of control. Therefore, parameter identification has an important significance for the stability of ship motion control. Aiming at the real-time identification problem of the nonlinear and time-varying ship motion system during movement, this paper reconstructs the ship motion system with the propeller speed and rudder angle as control variables and designs an online identification algorithm with the sliding time window method based on the extended Kalman filter algorithm. In addition, to solve the problem of noise in ship motion data collected in real-time, a real-time wavelet filter is developed to perform online preprocessing of the input data of the identification algorithm. The applicability of the method is further demonstrated via a model-scale Korea Research Institute of Ships and Ocean Engineering container ship free-running experiments in a basin.

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