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In order to maintain robotic manipulators at a high level of performance, their controllers should be able to address nonlinearities in the closed-loop system, such as input nonlinearities. Meanwhile, computational efficiency is also required for real-time implementation. In this paper, an unknown input Bouc–Wen hysteresis control problem is investigated for robotic manipulators using adaptive control and a dynamical gain-based approach. The dynamics of hysteresis are modeled as an additional control unit in the closed-loop system and are integrated with the robotic manipulators. Two adaptive parameters are developed for improving the computational efficiency of the proposed control scheme, based on which the outputs of robotic manipulators are driven to track desired trajectories. Lyapunov theory is adopted to prove the effectiveness of the proposed method. Moreover, the tracking error is improved from ultimately bounded to asymptotic tracking compared to most of the existing results. This is of important significance to improve the control quality of robotic manipulators with unknown input Bouc–Wen hysteresis. Numerical examples including fixed-point and trajectory controls are provided to show the validity of our method.
Kan Xie; Yue Lai; Weijun Li. Computational Efficiency-Based Adaptive Tracking Control for Robotic Manipulators with Unknown Input Bouc–Wen Hysteresis. Sensors 2019, 19, 2776 .
AMA StyleKan Xie, Yue Lai, Weijun Li. Computational Efficiency-Based Adaptive Tracking Control for Robotic Manipulators with Unknown Input Bouc–Wen Hysteresis. Sensors. 2019; 19 (12):2776.
Chicago/Turabian StyleKan Xie; Yue Lai; Weijun Li. 2019. "Computational Efficiency-Based Adaptive Tracking Control for Robotic Manipulators with Unknown Input Bouc–Wen Hysteresis." Sensors 19, no. 12: 2776.
In this article, a novel inverted L‐shaped microstrip‐fed wideband circularly polarized (CP) modified square‐slot antenna is designed. By cutting a pair of triangle chamfers and introducing a pair of triangle patches at the square‐slot, the antenna achieves a wideband CP radiation. Moreover, CP performance of the antenna can also be remarkably enhanced by protruding an L‐shaped strip and embedding a tuning rectangle slot into the slot ground. The measured results demonstrate that the axial‐ratio bandwidth for AR < 3 is 75.1% (from 4.45 to 9.8 GHz) and the impedance bandwidth (|S11| < −10 dB) reaches 65.8% (from 4.95 to 9.8 GHz). In addition, surface current studies are performed to illustrate the operating mechanism of CP operation, and the antenna has bidirectional radiation characteristics with an average gain of ~4 dBic within the CP band.
Yuan Liu; Shu-Ting Cai; Xiao-Ming Xiong; Wei-Jun Li; Jian Yang. A novel wideband circularly polarized modified square‐slot antenna with loaded strips. International Journal of RF and Microwave Computer-Aided Engineering 2019, 29, e21873 .
AMA StyleYuan Liu, Shu-Ting Cai, Xiao-Ming Xiong, Wei-Jun Li, Jian Yang. A novel wideband circularly polarized modified square‐slot antenna with loaded strips. International Journal of RF and Microwave Computer-Aided Engineering. 2019; 29 (10):e21873.
Chicago/Turabian StyleYuan Liu; Shu-Ting Cai; Xiao-Ming Xiong; Wei-Jun Li; Jian Yang. 2019. "A novel wideband circularly polarized modified square‐slot antenna with loaded strips." International Journal of RF and Microwave Computer-Aided Engineering 29, no. 10: e21873.
This paper studies capacity allocation of an energy storage (ES) device which is shared by multiple homes in smart grid. Given a time-of-use (TOU) tariff, homes use the ES to shift loads from peak periods to off-peak periods, reducing electricity bills. In the proposed ES sharing model, the ES capacity has to be allocated to homes before the homes’ load data is completely known. To this end, an online ES capacity allocation algorithm is developed based on the online convex optimization framework. Under the online algorithm, the complex allocation problem can be solved round by round: at each round, the algorithm observes current system states and predicts a decision for the next round. The proposed algorithm is able to minimize homes’ costs by learning from home load data in a serial fashion. It is proven that the online algorithm can ensure zero average regret and long-term budget balance of homes. Further, a distributed implementation of the online algorithm is proposed based on alternating direction method of multipliers framework. In the distributed implementation, the one-round system problem is decomposed into multiple subproblems that can be solved by homes locally, so that an individual home does not need to send its private load data to any other. In simulation, actual home load data and a TOU tariff of the United States are used. Results show that the proposed online approach leads to the lowest home costs, compared to other benchmark approaches.
Kan Xie; Weifeng Zhong; Weijun Li; Yinhao Zhu. Distributed Capacity Allocation of Shared Energy Storage Using Online Convex Optimization. Energies 2019, 12, 1642 .
AMA StyleKan Xie, Weifeng Zhong, Weijun Li, Yinhao Zhu. Distributed Capacity Allocation of Shared Energy Storage Using Online Convex Optimization. Energies. 2019; 12 (9):1642.
Chicago/Turabian StyleKan Xie; Weifeng Zhong; Weijun Li; Yinhao Zhu. 2019. "Distributed Capacity Allocation of Shared Energy Storage Using Online Convex Optimization." Energies 12, no. 9: 1642.
Elliptic curve cryptography (ECC) is widely used in practical applications because ECC has far fewer bits for operands at the same level of security than other public-key cryptosystems such as RSA. The performance of an ECC processor is usually determined by modular multiplication (MM) and point multiplication (PM) operations. For recommended prime field, MM operation can consist of multiplication and fast reduction operations. In this paper, a 256-bit multiplication operation is implemented by a 129-bit (half-word) multiplier using Karatsuba–Ofman multiplication algorithm. The fast reduction is a modulo operation, which gets 512-bit input data from multiplication and outputs a 256-bit result ( 0 ≤ Z < p ) . We propose a two-stage fast reduction algorithm (TSFR) over SCA-256 prime field, which can obtain an intermediate result of 0 ≤ Z < 2 p instead of 0 ≤ Z < 14 p in traditional algorithm, avoiding a lot of repetitive subtraction operations. The PM operation is implemented in width nonadjacent form (NAF) algorithm and its operational schedules are improved to increase the parallelism of multiplication and fast reduction operations. Synthesized with a 0.13 μ m complementary metal oxide semiconductor (CMOS) standard cell library, the proposed processor costs an area of 280 k gates and PM operation takes 0.057 ms at the frequency of 250 MHz. The design is also implemented on Xilinx Virtex-6 platform, which consumes 27.655 k LUTs and takes 0.37 ms to perform one 256-bit PM operation, attaining six times speed-up over the state-of-the-art. The processor makes a tradeoff between area and performance, thus it is better than other methods.
Xianghong Hu; Xin Zheng; Shengshi Zhang; Weijun Li; Shuting Cai; XiaoMing Xiong. A High-Performance Elliptic Curve Cryptographic Processor of SM2 over GF(p). Electronics 2019, 8, 431 .
AMA StyleXianghong Hu, Xin Zheng, Shengshi Zhang, Weijun Li, Shuting Cai, XiaoMing Xiong. A High-Performance Elliptic Curve Cryptographic Processor of SM2 over GF(p). Electronics. 2019; 8 (4):431.
Chicago/Turabian StyleXianghong Hu; Xin Zheng; Shengshi Zhang; Weijun Li; Shuting Cai; XiaoMing Xiong. 2019. "A High-Performance Elliptic Curve Cryptographic Processor of SM2 over GF(p)." Electronics 8, no. 4: 431.