Optimal Design for Flexible Passive Biped Walker Based on Chaotic Particle Swarm Optimization

Yao Wu,Daojin Yao,Xiaohui Xiao 대한전기학회 2018 Journal of Electrical Engineering & Technology Vol.13 No.6

Passive dynamic walking exhibits humanoid and energy efficient gaits. However, optimal design of passive walker at multi-variable level is not well studied yet. This paper presents a Chaotic Particle Swarm Optimization (CPSO) algorithm and applies it to the optimal design of flexible passive walker. Hip torsional stiffness and damping were incorporated into flexible biped walker, to imitate passive elastic mechanisms utilized in human locomotion. Hybrid dynamics were developed to model passive walking, and period-one gait was gained. The parameters global searching scopes were gained after investigating the influences of structural parameters on passive gait. CPSO were utilized to optimize the flexible passive walker. To improve the performance of PSO, multi-scroll Jerk chaotic system was used to generate pseudorandom sequences, and chaotic disturbance would be triggered if the swarm is trapped into local optimum. The effectiveness of CPSO is verified by comparisons with standard PSO and two typical chaotic PSO methods. Numerical simulations show that better fitness value of optimal design could be gained by CPSO presented. The proposed CPSO would be useful to design biped robot prototype.

Dynamic temperature gradient and unfalsified control approach for machine tool thermal error compensation

Xiao-dong Yao,Zheng-Chun Du,Guang-yan Ge,Jian-Guo Yang 대한기계학회 2020 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.34 No.1

In this work, a novel machine tool thermal error modeling method based on dynamic temperature gradient is proposed, and a thermal error compensation method based on unfalsified control is developed. The dynamic temperature gradient is used to optimize the locations of temperature measuring points on the machine tool. Real-time compensation for the thermal error can be achieved using the developed compensation method by establishing the correlations between dynamic temperature gradient and thermal error in the machine tool. Different from traditional model-based methods, the developed compensation approach does not rely on an accurate model of the thermal error but instead uses online input/output data to adaptively select the best controller at any moment, thereby improving thermal error prediction accuracy and robustness. The effectiveness of the developed thermal error compensation method is demonstrated on a turning center, where the spindle thermal error is compensated during the manufacturing of 120 inner bore parts and 120 shaft parts. After compensation using the proposed approach, thermal errors are reduced from 27 µm to 9 µm for the inner bore parts and from 31 µm to 11 µm for the shaft parts, respectively.

Management strategy for Spodoptera frugiperda (Lepidoptera:Noctuidae) in mountain maize planting areas in China

Yao Yao,He Yanyan,Zhang Lilan,Wang Kun,Li Bin,Du Guangzu,Zhu Chunyue,Yi Xiaocui,Liu Yiyi,Zi Shengjiang,Chen Bin,Xiao Guanli 한국응용곤충학회 2023 Journal of Asia-Pacific Entomology Vol.26 No.4

The fall armyworm, Spodoptera frugiperda (Lepidoptera: Noctuidae), is a major maize pest worldwide and has caused huge economic loss. To explore the control tactics of S. frugiperda in mountain maize planting fields, studies were performed in China from 2020 to 2021 for screening the S. frugiperda-resistant maize variety, seed coating agents, chemical insecticides, and biological agents. The results showed that 75 g/hm 2 Emamectin benzoate had better controlling efficacy (with a control efficacy of 91.05% at 1d) than other chemicals, so it was recommended in the high incidence period of pests. Compared with other seed coating treatments, 50% Lumi ngwei TM625FS (with a control efficacy of 76.19% at 10d) was the best seed coating against S. frugiperda. The biological control “Telenomus remus + Picromerus lewisi” and “T. remus + Eocanthecona furcellata” had good control efficacy on S. frugiperda with 76.01%, 64.10% at 20d, respectively. Additionally, there were lower numbers of S. frugiperda in maize variety GuiDan6, BaoYu9, and YanBaiYu8. In summary, this research rec ommended four effective pest management strategies (GuiDan6-resistant maize variety, 50% Lumingwei TM625FS-seed coating agents, 5% emamectin benzoate-chemical pesticide, and “T. remus + P. lewisi”-biological control) in mountain maize planting fields. The study provided effective control strategies for

The effects of ground compliance on flexible planar passive biped dynamic walking

Yao Wu,Daojin Yao,Xiaohui Xiao 대한기계학회 2018 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.32 No.4

Passive biped dynamic walking exhibits humanoid gait. Many efforts have been made to implement a flexible and anthropomorphic passive model. However, the couple of flexible passive walker on compliant ground has not been well studied yet. The objective of this paper was to develop multibody dynamics for flexible passive walker on compliant ground, in which the nonlinear spring-damper contact model was used both in normal and tangential directions to represent ground compliance. Inspired by elastic mechanisms in human locomotion, hip stiffness and damping were incorporated in the proposed flexible passive walker. Different from traditional impactmomentum method, one unified set of continuous dynamics based on continuous force method was developed to describe the entire passive walking gait on compliant ground, including the real double support phase. Through numerical simulations, stable period-one gait and double support phase were gained. After investigating the effects of contact parameters on step length, period and velocity, it was found that larger contact stiffness and smaller contact damping lead to a higher step velocity gait. The adjustment of hip stiffness could be used to improve the versatility of the flexible walker on varying compliant grounds.

Bioinspired Tough and Strong Hierarchical Fibers with Controlled Structure

Yao Xiao,Dong Chen 한국고분자학회 2022 한국고분자학회 학술대회 연구논문 초록집 Vol.47 No.1

Relationship Between the SER Treatment Period and Prognosis of Patients with Small Cell Lung Cancer

Xiao, Xiao-Guang,Wang, Shu-Jing,Hu, Li-Ya,Chu, Qian,Wei, Yao,Li, Yang,Mei, Qi,Chen, Yuan Asian Pacific Journal of Cancer Prevention 2014 Asian Pacific journal of cancer prevention Vol.15 No.15

Purpose: To explore the relationship between SER (time between the start of any treatment and the end of radiation therapy) and the survival of patients with limited-stage small cell lung cancer. Materials and Methods: Between 2008 and 2013, 135 cases of limited-stage small cell lung cancer (LS-SCLC) treated with consecutively curative chemoradiotherapy were included in this retrospective analysis. In terms of SER, patients were divided into early radiotherapy group (SER<30 days, n=76) and late radiotherapy group ($SER{\geq}30$ days, n=59) with a cut-off of SER 30 days. Outcomes of the two groups were compared for overall survival. Results: For all analyzable patients, median follow-up time was 23.8 months and median overall survival time was 16.8 months. Although there was no significant differences in distant metastasis free survival between the two groups, patients in early radiotherapy group had a significantly better PFS (p=0.003) and OS (p=0.000). Conclusions: A short SER may be a good prognostic factor for LD-SCLC patients treated with concurrent chemoradiotherapy.

Study on Two-Phase Flow with High Accuracy Phase- Field Spectral Element Model

Yao Xiao,Liangqi Zhang,Xiaoshuang Wang,Hao Li,Yisong Jin,Yong Liu,Zhong Zeng 한국전산유체공학회 2022 한국전산유체공학회 학술대회논문집 Vol.2022 No.10

Evolution of the porosity and characterization of alumina matrix proppants from bauxite, ball clay and natural manganese ore

Xiao Yao,Xue Ma,Meiping Li 한양대학교 세라믹연구소 2010 Journal of Ceramic Processing Research Vol.11 No.3

A series of alumina matrix proppants based on the composition of bauxite and ball clay were studied. In order to improve the sinterability and mechanical properties, natural manganese ore (NMO) was used as a doping additive. The phase formation was estimated by XRD, the crush strength under 52 MPa closing pressure was measured, and as well the densification process was evaluated by the apparent density, real density, pore size distribution and microstructure. The results show that NMO doping leads to achieving a good crush strength in a wide temperature range of 1150-1350 oC. Open porosity decreased significantly at a high temperature of 1350 oC by doping with NMO, whereas closed porosity increases because of the existence of a considerable Fe2O3 content and excessive grain growth. The proppant obtained with a high crush strength and low apparent density, prepared by doping with 5 wt.% NMO and sintering at 1350 oC is beneficial to its utilization in the petroleum or gas industries.

Batch sequential adaptive designs for global optimization

Xiao Yao,Ning Jianhui,Xiong Zikang,Qin Hong 한국통계학회 2022 Journal of the Korean Statistical Society Vol.51 No.3

Efficient global optimization (EGO) is one of the most popular sequential adaptive design (SAD) methods for expensive black-box optimization problems. A well-recognized weakness of the original EGO in complex computer experiments is that it is serial, and hence the modern parallel computing techniques cannot be utilized to speed up the running of simulator experiments. For those multiple points EGO methods, the heavy computation and points clustering are the obstacles. In this work, a novel batch SAD method, named “Accelerated EGO”, is forwarded by using a refined sampling/importance resampling (SIR) method to search the points with large expected improvement (EI) values. The computation burden of the new method is much lighter, and the points clustering is also avoided. The efficiency of the proposed batch SAD is validated by nine classic test functions with dimension from 2 to 12. The empirical results show that the proposed algorithm indeed can parallelize original EGO, and gain much improvement compared against the other parallel EGO algorithm especially under high-dimensional case. Additionally, the new method is applied to the hyper-parameter tuning of support vector machine (SVM) and XGBoost models in machine learning. Accelerated EGO obtains comparable cross validation accuracy with other methods and the CPU time can be reduced a lot due to the parallel computation and sampling method.

Optimal Design for Flexible Passive Biped Walker Based on Chaotic Particle Swarm Optimization

Wu, Yao,Yao, Daojin,Xiao, Xiaohui The Korean Institute of Electrical Engineers 2018 Journal of Electrical Engineering & Technology Vol.13 No.6

Passive dynamic walking exhibits humanoid and energy efficient gaits. However, optimal design of passive walker at multi-variable level is not well studied yet. This paper presents a Chaotic Particle Swarm Optimization (CPSO) algorithm and applies it to the optimal design of flexible passive walker. Hip torsional stiffness and damping were incorporated into flexible biped walker, to imitate passive elastic mechanisms utilized in human locomotion. Hybrid dynamics were developed to model passive walking, and period-one gait was gained. The parameters global searching scopes were gained after investigating the influences of structural parameters on passive gait. CPSO were utilized to optimize the flexible passive walker. To improve the performance of PSO, multi-scroll Jerk chaotic system was used to generate pseudorandom sequences, and chaotic disturbance would be triggered if the swarm is trapped into local optimum. The effectiveness of CPSO is verified by comparisons with standard PSO and two typical chaotic PSO methods. Numerical simulations show that better fitness value of optimal design could be gained by CPSO presented. The proposed CPSO would be useful to design biped robot prototype.