© 2018 IEEE. Measuring the interfacial stress between robots and objects is a prerequisite for robots to finish complicated works. In general, the interfacial stress is the 3-D interfacial stress which not only couple with the vertical normal interfacial stress but also the parallel shear interfacial stress. It is very important to develop a method to decouple the 3-D interfacial stress. This paper presents a measurement method that was able to decouple the measurement of the 3-D interfacial stress components. To implement the method, a 3-D interfacial stress sensor was fabricated based on graphene foams and superelastic materials. A high-resolution multichannel resistance measurement circuit was developed, and experiments were carried out with 3-D stress simulation equipment. The results showed that the sensor was capable of measuring z-direction normal stress at a range of 0-21 kPa with a sensitivity of 0.029 kPa -1 and x- A nd y-direction shear stresses at a range of 0-12.5 kPa with sensitivities of 0.020, 0.019, 0.018, and 0.019 kPa -1 , and the measurement circuit was capable of measuring a range of 100 Ω-100 M Ω with a resolution of 1%. This method can be utilized in robots to decouple the measurement of the 3-D interfacial stress components.
Yang Jiayi;Lu Xiaozhou;Li Xiaoping;Bao Weimin;Chen Renjie
IEEE Transactions on Electron Devices
© 2018 The Japan Society of Applied Physics High-performance InGaN-channel high-electron-mobility transistors (HEMTs) are fabricated and investigated in detail. The transconductance exhibits a high stability over a wide range of gate voltages, indicating excellent operation linearity. The relative saturation output current densities are 81 and 68% when the temperature increases to 400 and 500 K, respectively, with respect to the value of 1128.2 mA/mm at 300 K. In addition, the breakdown voltage reaches 187 V at 300 K, which is comparable to that of a GaN-channel HEMT. The presented results demonstrate the large potentials of the InGaN-channel HEMT in high-frequency power applications.
Zhang Yachao;Zhang Tao;Zhou Hong;Li Yao;Xu Shengrui;Zhang Jincheng;Hao Yue;Bao Weimin
Applied Physics Express
© 2018 Author(s).
In this paper, high performance InGaN double channel (DC) high electron mobility transistors (HEMTs) are proposed and systematically investigated. Due to the coordination of double InGaN channels, a large maximum drain current density and a distinct double-hump feature of the transconductance and frequency performance are achieved. More importantly, it is revealed that the coupling effect between the two InGaN channels is much stronger than that of the conventional GaN DC HEMTs. This characteristic leads to a remarkable enhancement in the gate voltage swing, indicating the excellent linearity of the InGaN DC HEMTs at both dc and rf conditions. Benefiting from the enhanced electron confinement in InGaN channels, the fabricated HEMTs show a low off state drain leakage current of 0.26 μA/mm and a high on/off current ratio (I
Zhang Yachao;Guo Rui;Liu Ge;Xu Shengrui;Zhang Jincheng;Hao Yue;Wang Zhizhe;Bao Weimin
Applied Physics Letters
© 2019 Chinese Physical Society and IOP Publishing Ltd.
Pulsed metal organic chemical vapor deposition was employed to grow nearly polarization matched InAlGaN/GaN heterostructures. A relatively low sheet carrier density of 1.8×1012 cm -2 , together with a high electron mobility of 1229.5 cm2/Vs, was obtained for the prepared heterostructures. The surface morphology of the heterostructures was also significantly improved, i.e., with a root mean square roughness of 0.29 nm in a 2 μm×2 μm scan area. In addition to the improved properties, the enhancement-mode metal-oxide-semiconductor high electron mobility transistors (MOSHEMTs) processed on the heterostructures not only exhibited a high threshold voltage (V
Zhang Ya-Chao;Guo Rui;Liu Ge;Zhang Jin-Cheng;Hao Yue;Wang Zhi-Zhe;Bao Wei-Min
Chinese Physics B
High quality InAlN/InGaN/InAlN/InGaN double channel heterostructures were proposed and grown by metal organic chemical vapor deposition. Benefiting from the adoption of the pulsed growth method and Two-Step AlN interlayer, the material quality and interface characteristics of the double channel heterostructures are satisfactory. The results of the temperature-dependent Hall effect measurement indicated that the transport properties of the double channel heterostructures were superior to those of the traditional single channel heterostructures in the whole test temperature range. Meanwhile, the sheet resistance of the double channel heterostructures reached 218.5 Ω/□ at 300 K, which is the record of InGaN-based heterostructures. The good transport properties of the InGaN double channel heterostructures are beneficial to improve the performance of the microwave power devices based on nitride semiconductors.
Yachao Zhang;Zhizhe Wang;Shengrui Xu;Dazheng Chen;为民 包;金风 张;进成 张;跃 郝
Applied Physics Letters
Based on sliding mode control, this paper presents a novel differential geometric guidance law for a homing missile against maneuvering targets. The three-dimensional guidance problem is reduced to two-dimensions by an engagement plane rotation reference frame. In the design of guidance law, two well-constructed mild sliding manifolds are introduced to decrease control efforts. Moreover, target maneuver is treated as a disturbance with known upper bound and no algorithm is required to estimate the maneuver. Simulation results illustrate that the mild sliding manifolds can be fast arrived at in finite time and the proposed differential geometric guidance law yields better performance by contrast with other existing guidance laws.
Jingshuai Huang;Hongbo Zhang;Wei Lv;Guojian Tang;为民 包
The solar vector is one of the most important parameters for attitude control of nanosatellites. This attitude control must be achieved without the sensors adding significantly to its size or mass. This paper presents a photodiode-based miniature sun sensor, which consists of two triangular pyramidal sensor unit structures, with each unit comprising three micro-silicon photodiodes. The two sensor units are installed on the diagonal of the nanosatellite to form a complete sun sensor capable of achieving a full-field range of solar vector measurements. In this paper, the mathematical model of the short-circuit currents of the silicon photodiodes as a function of the solar vector coordinates is deduced. A sensor sample was built and installed on a nanosatellite model, and the temperature compensation coefficient of the silicon photodiodes was obtained experimentally. The dynamic characteristic, linearity, hysteresis and repeatability of the component were measured. The sun sensor introduced in this paper can be placed on any satellite platform to allow a full range solar vector measurement, and this would result in an increase of only 1.86 g and 0.9 cm3 of the satellite's mass and volume, respectively.
Xiaozhou Lü;Yebo Tao;楷 谢;松林 王;小平 李;为民 包;人杰 陈
Measurement Science and Technology
Mathematic model of the pulse phase estimation problem was addressed, and the effective weighted nonlinear least-square (WNLS) estimator was presented. The weighting matrix of the WNLS estimator was derived by adopting statistical properties of epoch folding noises. The performance of the proposed technique was compared with the Cramér-Rao lower bound (CRLB). The results of numerical simulations and real data experiments indicate that the proposed estimator is asymptotically unbiased and efficient, its asymptotical performance outperforms the nonlinear least square (NLS) estimator and is comparable with the maximum-likelihood (ML) estimator as the observation time increases. As for the experiment of real Crab pulsar data, the position error of the WNLS method is about 400 m less than that of the NLS method when the observation time is 80 s.
Haifeng Sun;为民 包;Haiyan Fang;小平 李
Huazhong Keji Daxue Xuebao (Ziran Kexue Ban)/Journal of Huazhong University of Science and Technology (Natural Science Edition)
A novel guidance algorithm using feedback linearization and sliding mode control is proposed to realize high precisionguidance and maneuvering flight for hypersonic vehicle in dive phase. First, the longitudinal ellipse trajectory which can satisfy both the terminal impact point and angle constraints is designed, and the lateral maneuver trajectory is also generated to improve the penetration capability. Second, it introduces feedback linearization to decouple the original motion equations into linear guidance subsystems in longitudinal and lateral channel. With the linear equations, the tracker is designed with the help of sliding mode control, and the practical tracking guidance law can also be obtained by substituting the tracker into the original system. In addition, the stability of the guidance system is proven using the Lyapunovtheorem. This tracking guidance is independent of the relative motion information and relative equation, while only the current motion states are needed. Besides, the results of CAV-H vehicle guidance test show that maneuvering flight and high precision guidance can be realized with the novel proposed algorithm, and the robustness is also validated through different guidance missions and Monte Carlo simulation.
Luhua Liu;Jianwen Zhu;Guojian Tang;为民 包
Aerospace Science and Technology
Three-dimensional (3D) nonlinear diving guidance strategy considering the coupling between longitudinal and lateral motions for hypersonic vehicle is investigated in this paper. It constructs the complete nonlinear coupling motion equation without any approximations based on diving relative motion relationship directly, and converts it into linear state space equation with the same relative degree by feedback linearization. With the linear equation, slide mode control with strong robustness is employed to design the guidance law, and 3D diving guidance law which can satisfy terminal impact point and falling angle constraints with high precision is obtained by substituting the previous control law into the origin nonlinear guidance system. Besides, regarding lateral overload as the standard, hybrid control strategy which can take full advantage of the excellent characters of both bank-to-turn (BTT) and skid-to-turn (STT) controls is designed to improve the guidance accuracy further. Finally, the results of CAV-H vehicle guidance test show that the algorithm can realize high accuracy guidance even if serious motion coupling exists, and has strong robustness to the path disturbances and navigation errors as well.
Jian Wen Zhu;Lu Hua Liu;Guo Jian Tang;为民 包
Science China Technological Sciences