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101.
《中国航空学报》2016,(5):1455-1468
Chinese Chang'e lunar exploration project aims to collect and return subsurface lunar soil samples at a minimum penetration depth of 2 m in 2017. However, in contrast to those on the Earth, automated drilling and sampling missions on the Moon raise the risk of burning bits.Test-beds are required for testing the thermal properties of drill tools in a lunar environment. In this paper, a novel temperature measuring method based on thermocouples and a slip ring was proposed. Furthermore, a data acquisition system for a drilling process was designed. A vacuous,cryogenic, and anhydrous soil environment simulating the lunar surface was established. A drilling test-bed that can reach a depth of 2.2 m was developed. A control strategy based on online monitoring signals was proposed to improve the drilling performance. Vacuum and non-vacuum experiments were performed to test the temperature rising effect on drill tools. When compared with the non-vacuum experiment, the vacuum temperature rise resulted in a 12 °C increase. These experimental results provide significant support for Chinese lunar exploration missions. 相似文献
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采用Ti Al N涂层硬质合金麻花钻对钛合金(TC4)进行钻削试验,研究了切削用量对轴向力、加工孔壁表面粗糙度和切屑形态的影响。结果表明:轴向力随着进给量的增加而增加,轴向力随着转速的增加而减小。运用指数公式模型对轴向力实验结果进行回归分析,得到轴向力与转速以及进给量之间的关系式,并对该方程进行了检验验证误差均小于7%;随着进给量的增加断屑能力逐渐增加,切屑长度逐渐变短。在低转速和进给量为50 mm/min时切屑形态为短螺旋形切屑,此时排屑和孔壁粗糙度均为最佳。 相似文献
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This article investigates virtual reality (VR)-based teleoperation with robustness against modeling errors. VR technology is an effective way to overcome the large time delay during space robot teleoperation. However, it depends highly on the accuracy of model. Model errors between the virtual and real environment exist inevitably. The existing way to deal with the problem is by means of either model matching or robot compliance control. As distinct from the existing methods, this article tries to combine model matching and robot compliance control. On one hand, the status of the virtual robot is corrected by using the position sensor data from robot joints before and during teleoperation, and the pose of the virtually manipulated object is obtained with visual recognition technology. On the other hand, compliance control algorithms of impedance control based on joint torque sensors and hybrid position/force control based on a wrist sensor have been executed in order to eliminate the small sustaining model errors. A VR-based teleoperation system of satellite on-orbit self-serving is built up. In order to verify the proposed method, an experiment deploying the solar panel troubled by malfunction is carried out through teleoperation. It shows that the large model errors are removed with the model matching method and the adopted compliance control is robust against the remaining small model errors. 相似文献
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《中国航空学报》2020,33(5):1494-1504
Adapter ring is a commonly used component in non-cooperative satellites, which has high strength and is suitable to be recognized and grasped by the space manipulator. During proximity operations, this circle feature may be occluded by the robot arm or limited field of view. Moreover, the captured images may be underexposed when there is not enough illumination. To address these problems, this paper presents a structured light vision system with three line lasers and a monocular camera. The lasers project lines onto the surface of the satellite, and six break points are formed along both sides of the adapter ring. A closed-form solution for real-time pose estimation is given using these break points. Then, a virtual structured light platform is constructed to simulate synthetic images of the target satellite. Compared with the predefined camera parameters and relative positions, the proposed method is demonstrated to be more effective, especially at a close distance. Besides, a physical space verification system is set up to prove the effectiveness and robustness of our method under different light conditions. Experimental results indicate that it is a practical and effective method for the pose measurement of on-orbit tasks. 相似文献
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Space robotics is regarded as one of the most impressing approaches for space debris removal missions. Due to the residual momentum of debris, it is essential to stabilize the base rapidly after capture. This paper presents a novel control strategy for stabilization of a space robot in postcapture considering actuator failures and bounded torques. In the control strategy, the motion of the manipulator is not regarded as a disturbance to the base; in contrast, it is utilized to compensate for the limitation of the control torques by means of an inverse dynamical model of the system. Different scenarios where actuators are external mechanisms or momentum exchange devices have been carried out, and for actuator failures, both single- and two-actuator failures have been considered. Regarding to the performance of actuators, control torques are bounded. In cases that either single or two actuators have failed, the base can be stabilized kinematically when actuators are external mechanisms, but can only be stabilized dynamically when only momentum exchange devices are used. Finally, a space robot with a seven-degree-of-freedom manipulator in postcapture is studied to verify the validity and feasibility of the proposed control scheme. Simulation results show that the whole system can be stabilized rapidly. 相似文献