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Gao F.,Shanghai JiaoTong University | Qi C.,Shanghai JiaoTong University | Ren A.,Institute of Aerospace System Engineering Shanghai | Zhao X.,Shanghai JiaoTong University | And 15 more authors.
Science China Technological Sciences | Year: 2016

In the one-gravity environment on the ground, the simulation of the contact process of two flying objects in the zero-gravity environment of space has been a challenging issue since humans first explored space by flying objects. Hardware-in-the-loop (HIL) simulation is an important and effective method to test the usability, reliability, and safety of real docking mechanisms in space. There are four main issues for HIL simulation systems: Design of simulators capable of high frequency response, high motion precision, high velocity, and rapid acceleration; compensation for simulation distortion; design of a control model for the HIL simulation process; and experimental verification. Here, we propose a novel HIL simulator system with a 6-DOF 3-3 perpendicular parallel mechanism and a 3-DOF 3-PRS parallel mechanism; discover the principle of simulation distortion; present distortion compensation models for the force measurement system, dynamic response, and structural dynamics of the simulator; and provide a control model for the HIL simulation process. Two kinds of experiments were performed on the passive-undamped elastic rod and the docking mechanisms to test their performances and to verify the effectiveness and usability of the HIL simulator. The HIL simulation system proposed in this paper is useful for developing space docking, berthing, refueling, repairing, upgrading, transporting, and rescuing technologies. © 2016 Science China Press and Springer-Verlag Berlin Heidelberg


Qi C.,Shanghai JiaoTong University | Gao F.,Shanghai JiaoTong University | Zhao X.,Shanghai JiaoTong University | Ren A.,Institute of Aerospace System Engineering Shanghai | And 4 more authors.
Mechatronics | Year: 2016

The hardware-in-the-loop (HIL) simulator is an important equipment to test the performance of the docking mechanisms (DMs) in the docking process of two spacecrafts on the ground. However, the design and control of the HIL simulator is very challenging due to the simulation divergence caused by the time delay. The phase lead is a common approach to compensate the time delay. In this study, it is found that the simulation is still divergent using the traditional phase lead compensation approach when the contact frequency increases to a threshold value depending on the HIL simulator. In practice, because the experimental contact frequency is time-varying and unknown, traditional phase lead compensation approach could make the system instable and divergent. The Smith predictor based delay compensation is proposed in this study. It integrates the Smith predictor and the phase lead compensation. The contact model of the DMs is not required. The simulation system is stable and convergent when the contact frequency increases and satisfies the stability condition. The HIL simulation with a little convergence is better than the divergent simulation because the previous one can be considered to have some simulation error while the latter one could destroy the hardware. The phase and stability analyses are given to prove the simulation convergence and the closed-loop stability. Simulations and experiments are used to verify the effectiveness of the proposed compensation approach. © 2016 Elsevier Ltd. All rights reserved.


Qi C.,Shanghai JiaoTong University | Zhao X.,Shanghai JiaoTong University | Gao F.,Shanghai JiaoTong University | Ren A.,Institute of Aerospace System Engineering Shanghai | Hu Y.,Shanghai JiaoTong University
Acta Astronautica | Year: 2016

The hardware-in-the-loop (HIL) contact simulation for flying objects in space is challenging due to the divergence caused by the time delay. In this study, a divergence compensation approach is proposed for the stiffness-varying discrete contact. The dynamic response delay of the motion simulator and the force measurement delay are considered. For the force measurement delay, a phase lead based force compensation approach is used. For the dynamic response delay of the motion simulator, a response error based force compensation approach is used, where the compensation force is obtained from the real-time identified contact stiffness and real-time measured position response error. The dynamic response model of the motion simulator is not required. The simulations and experiments show that the simulation divergence can be compensated effectively and satisfactorily by using the proposed approach. © 2016 IAA.


Qi C.,Shanghai JiaoTong University | Gao F.,Shanghai JiaoTong University | Zhao X.,Shanghai JiaoTong University | Ren A.,Institute of Aerospace System Engineering Shanghai | Qian W.,Shanghai JiaoTong University
Chinese Control Conference, CCC | Year: 2016

The hardware-in-the-loop (HIL) simulation is an attractive and effective approach to simulate the contact dynamics of flying objects in space. However, the HIL contact simulation is very difficult due to the simulation divergence caused by the time delay existing in the HIL simulation closed-loop system. In this study, the static delay of the force measurement system is compensated by the phase lead. The dynamic delay of the motion simulator is compensated by the response error based force compensation. Simulations and experiments show that the proposed approach can effectively compensate the simulation divergence and guarantee the reproduction fidelity of the contact process in space. © 2016 TCCT.


Qi C.,Shanghai JiaoTong University | Zhao X.,Shanghai JiaoTong University | Gao F.,Shanghai JiaoTong University | Ren A.,Institute of Aerospace System Engineering Shanghai | Sun Q.,Shanghai JiaoTong University
Acta Astronautica | Year: 2016

The hardware-in-The-loop (HIL) contact simulator is to simulate the contact process of two flying objects in space. The contact stiffness and damping are important parameters used for the process monitoring, compliant contact control and force compensation control. In this study, a contact stiffness and damping identification approach is proposed for the HIL contact simulation with the force measurement delay. The actual relative position of two flying objects can be accurately measured. However, the force measurement delay needs to be compensated because it will lead to incorrect stiffness and damping identification. Here, the phase lead compensation is used to reconstruct the actual contact force from the delayed force measurement. From the force and position data, the contact stiffness and damping are identified in real time using the recursive least squares (RLS) method. The simulations and experiments are used to verify that the proposed stiffness and damping identification approach is effective. © 2016 IAA. Published by Elsevier Ltd. All rights reserved.


Chen W.,Shanghai JiaoTong University | Gao F.,Shanghai JiaoTong University | Meng X.,Shanghai JiaoTong University | Chen B.,Shanghai JiaoTong University | Ren A.,Institute of Aerospace System Engineering Shanghai
Ocean Engineering | Year: 2016

Energy resources of offshore wind and ocean wave are abundant, clean and renewable. Various technologies have been developed to utilize the two kinds of energy separately. We present a high-power integrated generation unit for offshore wind power and ocean wave energy (W2P). The unit includes that: (1) The wind wheel with retractable blades and the 3-DOF (degrees of freedom) mechanism with the hemispherical oscillating body are used to collect the irregular wind and wave power, respectively; (2) The energy conversion devices (ECDs) are utilized to convert mechanical energy from both the wind wheel and the 3-DOF mechanism into hydraulic energy; (3) The hydraulic energy is used to drive the hydraulic motors and electrical generators to produce electricity. Some analyses and experiments have been conducted to obtain the performance of the key components of the unit. Based on the layout method, the single row wind-wave power plant is established. © 2016 Elsevier Ltd


Wang C.,Chinese University of Hong Kong | Chen Y.,Chinese University of Hong Kong | Chen M.,Institute of Aerospace System Engineering Shanghai | Han L.,Institute of Aerospace System Engineering Shanghai | And 4 more authors.
2013 IEEE International Conference on Robotics and Biomimetics, ROBIO 2013 | Year: 2013

This paper proposed a biologically inpired handrail climbing robot 'MonkeyBot' that could provide inspection and maintenance for the space station. Space debris is the biggest hazards for space station from the outer space. When a threat from orbital derbis is idenfitied a bit late, the station will be potentially damaged by the debris. MomkeyBot is designed to meet this challenge, especially for some key components or areas on the space station. MonkeyBot is a redundancy robot with four limbs, which not only has multi climbing strategies and gaits to achieve a full coverage of the space module, but also it has dexterous capability for on-orbit servicing with each limb. This paper will focus on the geometry design, mathematical modeling, workspace and dexterity analysis and climbing strategies and climbing gaits evaluation. The analysis result shows that the maneuverability surpasses the state of art space station exterior robot. © 2013 IEEE.


Qiao B.,Nanjing University of Aeronautics and Astronautics | Liu Z.,Nanjing University of Aeronautics and Astronautics | Hu B.,Institute of Aerospace System Engineering Shanghai | Chen M.,Institute of Aerospace System Engineering Shanghai
Transactions of Nanjing University of Aeronautics and Astronautics | Year: 2014

The tracking of orientation and angular velocity is a primary attitude control task for an on-orbit spacecraft. The problem for a rigid spacecraft tracking a desired angular velocity profile is addressed using an adaptive feedback control. An angular velocity feedback tracking algorithm is firstly developed based on the precisely known attitude dynamics of the spacecraft, and the global tracking of the control algorithm is proved based on the Lyapunov analysis. An adaptation mechanism is then designed to deal with the dynamic uncertainties of the spacecraft. Such an adaptation mechanism enables the controller to track any desired angular velocity trajectories even in the presence of uncertain inertia parameters, although it does not guarantee the inertia tensor being precisely identified. To verify the effectiveness of the proposed adaptive control policy, computer simulations on dynamic equations of a spacecraft are conducted and their results are discussed.


Qiao B.,Nanjing University of Aeronautics and Astronautics | Tang S.,Institute of Aerospace System Engineering Shanghai | Ma K.,Nanjing University of Aeronautics and Astronautics | Liu Z.,Nanjing University of Aeronautics and Astronautics
Acta Astronautica | Year: 2013

The capacity to acquire the relative position and attitude information between the chaser and the target satellites in real time is one of the necessary prerequisites for the successful implementation of autonomous rendezvous and docking. This paper addresses a vision based relative position and attitude estimation algorithm for the final phase of spacecraft rendezvous and docking. By assuming that the images of feature points on the target satellite lie within the convex regions, the estimation of the relative position and attitude is converted into solving a convex optimization problem in which the dual quaternion method is employed to represent the rotational and translational transformation between the chaser body frame and the target body frame. Due to the point-to-region correspondence instead of the point-to-point correspondence is used, the proposed estimation algorithm shows good performance in robustness which is verified through computer simulations. © 2013 IAA.

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