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Tribological behaviour of Cryogenically Treated WC-9Co Cemented Carbide

Materials Today: Proceedings 2018年第2期5卷 7797-7807页

作者： M. Padmakumar D. Dinakaran J. Guruprasath Dept. of Mechanical Engineering Hindustan University Chennai India Centre for Automation and Robotics Hindustan University Chennai India Quality analyst Kennametal India Ltd. Bangalore India

Tool life is one of the most critical parameters that have a significant impact on the overall cost of machining. Tungsten carbide is one of the most commonly used cutting tool material due to its superior mechanical properties. Processes like applying hard coatings and doping with alloying elements are being adopted by the cutting tool industries to improve the tool life of tungsten carbide. Heat treatment is one such traditional process that alters the metallurgical properties of steel and hence improves the performance. But there is no such simpler and cost effective technique for tungsten carbide as it is virtually unaffected by thermal treatments. In this research, commercially available tungsten carbide turning inserts with 9% cobalt content were subjected to deep cryogenic treatments to study the effect of cold treatment on such super hard tool material. Wear resistance of the treated inserts were compared against the untreated insert in cylindrical turning on cast iron and steel, the two most commonly used industrial materials. The result shows that the cryogenically treated inserts showed improved flank wear and nose wear resistance than the untreated inserts on both the materials. Metallurgical evaluation and hardness study revealed the microstructural changes in cobalt binder.

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Repetitive control design and implementation for periodic motion tracking in aerial robots

Repetitive control design and implementation for periodic mo...

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American Control Conference

作者： Xiang He Dejun Guo Kam K. Leang Design Automation Robotics and Control (DARC) Lab Univ. of Utah Robotics Center Dept. of Mechanical Engineering

ISBN: (纸本)9781509045839

This paper describes the design and implementation of a repetitive controller (RC) for tracking periodic trajectories in aerial robots, such as unmanned aerial vehicles (UAVs). The RC is ideally suited for situations where the robot is required to execute a defined flight pattern, over and over again in a periodic fashion. Applications include precision agriculture, and search and rescue, where the desired trajectory is often periodic in time and known a priori. Compared to iterative learning control (ILC), RC is a feedback-based approach which can be plugged into an existing feedback control loop to improve the tracking of period trajectories. Herein, a plug-in type RC is applied to a micro aerial robot, and a systematic approach is presented for designing the control system. The plug-in nature of the design also allows users to enable/disable the controller on the fly. The proposed RC is also compared to existing approaches, including no-reset ILC, which have recently been applied to control aerial robots. The effectiveness of the RC is demonstrated on a custom-designed experimental micro aerial robot. Tracking of circle, square, and figure-eight trajectories are shown in both simulations and experiments. In these cases, the RC reduces the average tracking error by over 58% compared to a well-tuned PID controller, and simulations that compare to no-reset ILC show that the performance of RC is less sensitive to changes in the reference trajectory.

关键词： Aerial robot Ritchey-Chretien telescope Unmanned Aerial Vehicle design control trajectory tracking International Labour Conference simulating Rescue Periodic Motion

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A unified angle control scheme for hypersonic vehicle based on disturbance rejection 21

A unified angle control scheme for hypersonic vehicle based ...

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21st AIAA International Space Planes and Hypersonics Technologies Conference, Hypersonics 2017

作者： Piao, Minnan Zhu, Kai Sun, Mingwei Chen, Zengqiang Dept. of Automation and Intelligent Science College of Computer and Control Engineering Nankai University Tianjin300350 China Tianjin Key Laboratory of Intelligent Robotics Tianjin300350 China Beijing Aerospace Technology Institute Beijing100074 China

ISBN: (数字)9781624104633

ISBN: (纸本)9781624104633

Hypersonic vehicles are characterized with strong nonlinearities, coupling effects and uncertainties as well as fast time-varying parameters, which impose great difficulty to the attitude control. This study proposes a unified scheme for all the Euler angles, angle of attack, and sideslip angle. First, three controllers based on active disturbance rejection control (ADRC) are designed for the Euler angles respectively, in which the external disturbances and the internal uncertainties can be estimated by the extended state observer (ESO) and compensated in real time actively. Then the geometric relations among the angles with different time scales are utilized to transform the commands of α and β into the commands of the pitch angle and the yaw angle. Next the stability-margin tester method is employed to tune the controller parameters, which guarantees the stability and robustness of the control system. 1000 nonlinear six-degree-of-freedom Monte Carlo simulation results demonstrate the good tracking performance and the robustness of the proposed control method. © 2017, American Institute of Aeronautics and Astronautics Inc, AIAA. All rights reserved.

关键词： Hypersonic vehicles

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On active decoupling control for horizontal-lateral direction of hypersonic flight based on HIFOO 21

On active decoupling control for horizontal-lateral directio...

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21st AIAA International Space Planes and Hypersonics Technologies Conference, Hypersonics 2017

作者： Ma, Shunjian Zhu, Kai Sun, Mingwei Wang, Zenghui Chen, Zengqiang Dept. of Automation and Intelligent Science Nankai University College of Computer and Control Engineering Tianjin300350 China Beijing Aerospace Technology Institute Tianjin Key Laboratory of Intelligent Robotics Tianjin300350 China Beijing Aerospace Technology Institute Beijing100074 China Department of Electrical and Mining Engineering University of South Africa FL1710 South Africa

ISBN: (数字)9781624104633

ISBN: (纸本)9781624104633

Nowadays, hypersonic flight vehicles are widely studied. Since their high nonlinearity, strong coupling and uncertain factors, the conventional three-channel independent control design method is often unable to work well. In this paper, an active disturbance rejection controller (ADRC) is utilized to cancel internal uncertainties and exogenous disturbances for longitudinal dynamics. Then, the MIMO robust controller is obtained by choosing proper sensitivity functions and weighting functions to reduce horizontal-lateral direction coupling. The conventional H robust controllor is high-order, which is difficult for practitioners to implement. With frequency transformation, both ADRC for the longitudinal dynamics and MIMO robust controller for the horizontal-lateral dynamics are reformed into the static output feedback structure to reduce the high order of controller. Finally, all parameters in the controllers can be optimized by HIFOO (H-Infinity Fixed Order Optimization). The Winged-Cone, a 6-freedom NASA hypersonic vehicle model, is used as a benchmark, and Monte Carlo simulations demonstrate the effectiveness of the proposed method. © 2017, American Institute of Aeronautics and Astronautics Inc, AIAA. All rights reserved.

关键词： Controllers

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Transfer of Contact Skills to New Environmental Conditions

Transfer of Contact Skills to New Environmental Conditions

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IEEE-RAS International Conference on Humanoid Robots

作者： Aljaz Kramberger Andrej Gams Bojan Nemec Casper Schou Dimitrios Chrysostomou Ole Madsen Ales Ude Humanoid and Cognitive Robotics Lab Dept. of Automatics Biocybernetics and Robotics Jozef Stefan Institute Robotics & Automation Group Dept. of Mechanical and Manufacturing Engineering Aalborg University

ISBN: (纸本)9781509047192

Robots operating in contact with the environment should typically take into account the knowledge of both position/orientation trajectories as well as the accompanying force/torque profiles for successful execution. Pure position control is not appropriate because even small errors in the desired trajectory can cause significant forces at the contact points. In this paper we present a method that computes an appropriate control policy for a given condition of a contact task, with the peg-in-hole (PiH) assembly tasks as example use-cases. Our method is based on statistical generalization of successfully recorded executions at different values of the external condition. The major novelty of the method is that it provides not only generalized position and orientation trajectories, but a complete skill, consisting of desired position/orientation trajectories and the accompanying force/torque profiles. To improve the execution of the skill after generalization, we combine the proposed approach with an adaptation method to refine the newly generated movement. The versatility of the proposed approach was shown by applying it to firstly, two different types of robot arms: a humanoid 7-axis Kuka LWR-4 arm and a 6-axis industrial Universal robot UR5 arm and secondly, two different peg-in-hole problems: insertion of a square peg and insertion of a round peg.

关键词： Trajectory Libraries Service robots Manipulators Robot kinematics Quaternions

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Particle swarm optimization based vector control of permanent magnet synchronous motor drive

Particle swarm optimization based vector control of permanen...

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IEEE NW Russia Young Researchers in Electrical and Electronic engineering Conference (EIConRusNW)

作者： Ahmed A. Zaki Diab S. A. Selim Basem E. Elnaghi Dept. of Electrical Engineering Minia University Minia Egypt Dept. of Robotics and Industrial Automation Saint-Petersburg Electrotechnical University Saint-Petersburg Russia Dept. of Electrical Engineering Suez Canal University Ismailia Egypt

ISBN: (纸本)9781509004461

In this paper, vector control scheme of a permanent magnet synchronous motor is proposed based on particle swarm optimization. Particle swarm optimization has been applied in order to reach the optimal gains of the speed controller of the a permanent magnet synchronous motor drive. The optimal gains of proportional-integral controller for speed is determined by using particle swarm optimization. Furthermore, a tuning method for proportional-integral controller is developed depending on the linearized model of the permanent magnet synchronous motor. The performance of the proposed control scheme with optimal gains has been verified through computer simulations. The results show that the robustness of the drive is satisfactory over a wide range of operating conditions. In addition, the performance of the drive system with these parameters is fast.

关键词： Torque Machine vector control Stators Particle swarm optimization Mathematical model Permanent magnet motors Optimization

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Improved performance of brushless direct current motor

Improved performance of brushless direct current motor

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IEEE NW Russia Young Researchers in Electrical and Electronic engineering Conference (EIConRusNW)

作者： S. A. Selim Ahmed A. Zaki Diab Basem E. Elnaghi Dept. of Robotics and Industrial Automation Saint-Petersburg Electrotechnical University Saint-Petersburg Russia Dept. of Electrical Engineering Minia University Minia Egypt Dept. of Electrical Engineering Suez Canal University Ismailia Egypt

ISBN: (纸本)9781509004461

This paper presents a method for improving the performance of brushless direct current motor drive. This method depends on the varying of switch-on angle of motor phase current. The phase current and torque for the proposed method are discussed. The operation of brushless direct current motor drive at different switch-on angle for the same speed is studied and discussed. The results of this study show that the improved performance characteristics of brushless direct current motor by advancing the switching-on angle, can successfully achieve high-speed and a noticeable reduction in torque ripple.

关键词： Torque Reluctance motors Switches Permanent magnet motors Rotors Brushless DC motors

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Adaptive repetitive visual-servo control of a low-flying unmanned aerial vehicle with an uncalibrated high-flying camera

Adaptive repetitive visual-servo control of a low-flying unm...

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IEEE/RSJ International Conference on Intelligent Robots and Systems

作者： Dejun Guo Woosoon Yim Kam K. Leang DARC (Design Automation Robotics & Control) Lab University of Utah Robotics Center Dept. of Mechanical Engineering University of Utah Salt Lake City 84112 United States Intelligent Structures & Control Laboratory Dept. of Mech. Engineering Univ. of Nevada - Las Vegas 89154 United States

ISBN: (纸本)9781509037636

This paper proposes a new adaptive repetitive visual-servo control system for a moving high-flying vehicle (HFV) with an uncalibrated camera to monitor, track, and precisely control the movements of a low-flying vehicle (LFV) or mobile ground robot. When deployed, a remote operator of the HFV defines the desired trajectory for the LFV in the HFV's camera frame (image frame). Due to the circulatory motion of the HFV, the resulting motion trajectory of the LFV in the image frame is periodic in time, thus an adaptive repetitive control system is exploited to improve the tracking precision from one operating period to the next. Not only is the adaptive control law able to deal with uncertainties in the camera's intrinsic and extrinsic parameters, but it can also tolerate uncertainties in the localization of the LFV. The design and stability analysis of the closed-loop control system is presented, where the Lyapunov approach is used to show stability. Simulations and experimental results are presented to demonstrate the effectiveness of the method for controlling the movement of a low-flying quadcopter vehicle. Results show good tracking performance for three simulated test cases, where the average maximum tracking error is reduced by approximately 75% compared to the performance of a standard adaptive visual-servo controller.

关键词： low frequency vibration vehicle Cameras tracking accuracy Repetitive Servo control Closed loop control systems Self tuning control systems visual tracking drone honey bees Unmanned Aerial Vehicle Frame

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Multi-stage feature learning based object recognition and 3D pose estimation with kinect 6

Multi-stage feature learning based object recognition and 3D...

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6th International Conference on Information Science and Technology, ICIST 2016

作者： Zeng, Wei Liang, Guoyuan Guangdong, Can Wang Wu, Xinyu Guangdong Provincial Key Lab of Robotics and Intelligent System Shenzhen Institutes of Advanced Technology Chinese Academy of Sciences Shenzhen China Key Laboratory of Human-Machine-Intelligence Synergic Systems Shenzhen Institutes of Advanced Technology Chinese Academy of Sciences Shenzhen China Shenzhen College of Advanced Technology University of Chinese Academy of Sciences Shenzhen China Dept. Mechanical and Automation Engineering Chinese University of Hong Kong Shenzhen China

ISBN: (纸本)9781509012206

Impressive achievements have been achieved over the years in object recognition and 3D pose estimation while detecting objects and estimating their 3D poses reliably is still a very challenging problem, especially for texture-less objects in heavily cluttered scenes. In this paper, we introduce an improved approach based on multi-stage feature learning to identify object as well as their 3D orientation efficiently. Our approach is motivated by visual neuroscience models. Currently similar architectures have been successfully applied to pedestrian detection, traffic recognition, face representation, etc. We compute the feature descriptors by multi-stage convolutional neural networks (CNNs) which could map the object identity and 3D poses to the Euclidean distance space by evaluating the similarity between descriptors. By contrast with classical approaches, our method relies on fast and approximate Nearest Neighbor (NN) matching to solve the large scale problems instead of one classifier per object or multi-class classifiers whose complexity grows rapidly with the number of objects. The experiments of detecting poorly-textured objects in cluttered scenarios have been carried out to verify the effectiveness and efficacy of the proposed approach. © 2016 IEEE.

关键词： Object recognition

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Inverse kinematics of redundant serial manipulators using interval method in handling uncertainties 15

Inverse kinematics of redundant serial manipulators using in...

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2015 Conference on Advances In robotics, AIR 2015

作者： Kumar, Virendra Sen, Soumen Shome, S.N. Roy, S.S. Robotics and Automation Div. CSIR - Central Mechanical Engineering Research Inst. Durgapur713209 India Mechanical Engineering Dept. National Institute of Technology Durgapur713209 India

ISBN: (纸本)9781450333566

The paper presents an application of Interval method to solve the inverse kinematics of a serially connected redundant manipulator, aiming its use in design optimization of manipulators. The article attempts to solve inverse kinematics, when the lengths of the links of the manipulator are not precisely known. The sources of uncertainties include manufacturing tolerances, approximations for complex link geometries, inaccuracies in joint angle measurements etc. The inverse kinematics is intended to produce solutions for joint variables in interval of tolerances for specified end effector accuracy range. The redundancy resolution is cast as an optimization problem with arm isotropy as performance metric. In solving for the inverse kinematics, two stage interval optimization method is implemented, where, in the first stage, bisection technique is applied and in the second stage interval discrete random variable method is used. As exemplar problem solving, two cases, namely a planar3-degrees-of-freedom and a spatial 5-degrees-of-freedom serial link manipulators are considered. © 2015 ACM.

关键词： Redundant manipulators

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