PATH PLANNING AND PATH TRACKING FOR AUTONOMOUS VEHICLE BASED ON MPC WITH ADAPTIVE DUAL-HORIZON-PARAMETERS

Yaohua Li,Jikang Fan,Yang Liu,Xiaoyu Wang 한국자동차공학회 2022 International journal of automotive technology Vol.23 No.5

According to the position relationship between the vehicle and the obstacle, a new obstacle avoidance path planner was designed to solve the limitation of traditional local obstacle avoidance path planner in excessive obstacle avoidance. In order to improve the control accuracy of the path tracking controller and ensure the stability of the vehicle, a comprehensive evaluation index of path tracking performance considering control accuracy and driving stability was established. The optimal prediction time domain and control time domain parameters at different vehicle speeds were obtained, and an adaptive dual time domain parameter path tracking controller was designed. Based on the joint-simulation platform, the integrated structure of the planning layer and the control layer was simulated and verified. Simulation results show that the new obstacle avoidance function can avoid excessive obstacle avoidance while ensuring real-time performance, and improve the driving stability of the vehicle. The adaptive time-domain parameter path tracking controller has better comprehensive control performance and can improve driving safety under extreme conditions. The integrated structure of local obstacle avoidance path planning and path tracking control are beneficial for the vehicle to plan and accurately track the local obstacle avoidance path in multiple static obstacle scenes.

DUAL-MOTOR FULL-WEIGHT ELECTRIC POWER STEERING SYSTEM FOR COMMERCIAL VEHICLE

Yaohua Li,Qianlong Feng,Yangsen Zhang,Youfei Nan 한국자동차공학회 2019 International journal of automotive technology Vol.20 No.3

In order to study the electric power steering system (EPS) which is suitable for the steering characteristics of commercial vehicles, the effect of weight on steering performance is analyzed, and a dual-motor full-weight EPS system is proposed. Firstly, the full-weight assist characteristics are studied, and two current distribution schemes and corresponding fault-tolerant control strategies are proposed according to the structural characteristics of dual-motor EPS system. By comparing with the traditional single-weight EPS system, it is proved that the full-weight EPS system improves the control stability and makes the driver get a better road feeling. Through the double line change test and step test, the effectiveness of the two current distribution schemes are verified, and it has better fault-tolerance performance. By comparison, the faulttolerance performance of scheme two is better than that of scheme one.

Study on Components Durability Test Conditions Based on Combined Clustering and Markov Chain Method

Li Yaohua,Liu Yang,Shao Pandeng,Li Zetian,Song Weiping 한국자동차공학회 2021 International journal of automotive technology Vol.22 No.3

The process of obtaining durability test conditions of bus components is complicated. A way to build components durability test conditions based on driving cycle is proposed. Pure electric urban bus driving cycle in Xi \'an based on running data is constructed based on combined clustering and Markov chain method, and simulation model of pure electric urban bus is built. The load conditions of the motor output shaft are obtained through simulation and calculation based on load torque applied on the motor shaft from simulation results based on actual drive cycle. The damage calculation method of motor output shaft under different load is constructed according to the liner fatigue cumulative damage theory and the material S-N curve. The four-peak-valley rain-flow counting method is used to calculate the damage of motor output shaft and the corresponding cycle life of motor shaft under different load conditions is determined. The motor speed condition and torque condition corresponding to driving cycle with the shortest life are selected as the motor output shaft durability testcondition.

Voltage Vector Selection Area of the Direct Torque Control for Permanent Magnet Synchronous Motor

Li, Yaohua,Ma, Jian,Yu, Qiang,Liu, Jingyu Journal of International Conference on Electrical 2012 Journal of international Conference on Electrical Vol.1 No.2

The control of stator flux, torque angle, excitation torque, reluctance torque and total torque of the direct torque control (DTC) for a permanent magnet synchronous motor (PMSM) are studied in this paper. Simplified expressions to represent the changes of these variables due to the application of a voltage vector are given. Finally, a voltage vector selection area and the implementation of a voltage vector selection strategy are proposed.

Consumption patterns of the multicolored Asian ladybird Harmonia axyridis on the broad bean aphid Aphis craccivora

Liu Yaohua,Li Rui,Li Sheng-Cai 한국응용곤충학회 2022 Journal of Asia-Pacific Entomology Vol.25 No.1

The multicolored Asian ladybird Harmonia axyridis Pallas is often used as a biological control agent against Aphis craccivora Koch, a key pest aphid of broad bean. Understanding consumption characteristics of biological control agents is critical for developing effective biological control programs. Here, under laboratory conditions we studied consumption patterns of H. axyridis on A. craccivora including functional response and intraspecific competition. All larvae (1st-, 2nd-, 3rd-, 4th-instar) and adults (male and female) of H. axyridis exhibited a Type II functional response to A. craccivora. We found H. axyridis females were superior to individuals of other developmental stages, based on three key parameters in functional response model, i.e. attack rate (a = 90.0%), handling time (T h = 2.7 min), and consumption threshold (N max = 526.7 individuals). Results from our analysis of intraspecific competition showed that when attacking A. craccivora, 4th-instar larvae of H. axyridis suffered from the greatest intraspecific competition (coefficient of mutual interference, m = 0.48). Our results show that 4th-instar larvae and adults of H. axyridis are most effective in controlling A. craccivora, and proper density of H. axyridis released will reduce intraspecific competition. This analysis reveals both prey-predator and predatorpredator interactions, and highlights the value of biological control in reducing pesticide use and protecting ecological environments.

Reactive compensation of long primary HTS‑linear synchronous machines

Keyu Guo,Yaohua Li,Liming Shi,Yumei Du 전력전자학회 2022 JOURNAL OF POWER ELECTRONICS Vol.22 No.5

In propulsion systems requiring high speed and high acceleration, the long primary high-temperature superconducting linear synchronous machine (HTS-LSM) is a competitive candidate, since it can provide steady and high thrust. However, the armature windings on the long primary uncovered by a mover with HTS magnets can cause large flux leakage, which can lead to a high armature reaction voltage and a poor power factor. In this paper, to restrain the armature reaction voltage of the long primary HTS-LSM, compensation windings are proposed for installation on the primary. First, a mathematical model of a five-phase four-pole long primary HTS-LSM is established, and it is determined that the high armature reaction voltage is caused by the large self-inductance of uncovered armature windings. Then, compensation winding is applied in the armature winding to reduce the equivalent self-inductance. Four different compensation winding installation positions are studied and compared. To prevent the current in the compensation windings from affecting the function of the HTSracetrack magnet on the mover, a switch control strategy for the compensation windings is proposed. Finally, prototypes of armature windings with compensation windings are manufactured and the effectiveness of the compensation windings are validated and compared.

The Development of IGCT-based Large Capacity Three-Level Dual-PWM Converter

Lan Zhiming,Li Chongjian,Li Yaohua,Zhu Chunyi,Wang Chengsheng 전력전자학회 2011 ICPE(ISPE)논문집 Vol.2011 No.5

In media and high voltage large capacity converter systems the Integrated Gate Commutated Thyristor (IGCT) take the place of Gate Turn Off Thyristor (GTO) duo to its outstanding performance. And IGCT-based large capacity three-level converters are widely used in industrial motor-driving field. In this paper the development of a set of IGCT-based large capacity three-level dual-PWM converter is introduced. The converter includes PWM rectifier, DC capacitors, PWM inverter. The topology of the converter is given. The close-loop control strategy and SVPWM algorithm of PWM rectifier is presented in this paper. The control strategy and algorithm of the PWM inverter is also presented. The experiments were performed and the results show that the converter reaches the design requirement and has excellent performance.

Analytical loss model of series-resonant indirect-matrix-type power electronics transformers using MOSFETs

Hu, Yujie,Li, Zixin,Zhao, Cong,Li, Yaohua The Korean Institute of Power Electronics 2021 JOURNAL OF POWER ELECTRONICS Vol.21 No.11

A MOSFET-based series-resonant indirect-matrix-type power electronic transformer (PET) consists of line-frequency-switching folding-unfolding bridges and series-resonant dc-dc converters (SRCs), which is an attractive choice to achieve ac-ac conversion due to its high efficiency and high power density. However, the conduction losses, switching losses, and core losses in each of the high-frequency switching cycles T_s are different due to the pulsating dc voltage |ac|, which introduces difficulties in the calculation of losses. In addition, the small dc capacitors also participate in the resonance, and the resonant current shape deviates from a pure sine. Therefore, the conventional loss model is not suitable for PETs. In this paper, the time-domain analysis of SRC resonant current considering the dc capacitor is developed. Then, the analytical expression of the resonant current RMS value in grid cycle T_g is derived, which is more accurate in calculating conduction loss than the conventional model. In addition, it avoids the calculating losses in each T_s. Next, an analytical switching loss model is developed based on the curve fitting of the capacitance-voltage relationship. A simplified analytical core loss model is provided. Each part of the loss of the PET is verified by thermal simulations, and the total losses are verified by efficiency tests on an experiment prototype.

Characterization of quercetin and its glycoside derivatives in Malus germplasm

Lei Zhang,Qipeng Xu,Yaohua You,Weifeng Chen,Zhengcao Xiao,Pengmin Li,Fengwang Ma 한국원예학회 2018 Horticulture, Environment, and Biotechnology Vol.59 No.6

Quercetin and its glycoside derivatives were identifi ed and quantifi ed using high-performance liquid chromatograph (HPLC)and liquid chromatograph/mass spectrometer/mass spectrometer (LC/MS/MS) in the leaves, flowers, and fruits of 22 Malusgenotypes. In all genotypes, small amounts of quercetin aglycone were present, with water-soluble glycoside forms were themost abundant in diff erent Malus plant tissues, including quercetin-3-galactoside, quercetin-3-rutinoside, quercetin-3-glucoside,quercetin-3-xyloside, quercetin-3-arabinoside, and quercetin-3-rhamnoside. Among these six quercetin glycosides,quercetin-3-galactoside was the common form in Malus plants, except in the leaves and flowers of M. ceracifolia and M. magdeburgensis , and in the fruits of M. micromalus ‘Haihong Fruit’, where there was a higher concentration of quercetin-3-glucoside. Among the diff erent tissues tested, leaves contained the highest concentration of quercetin and its glycosides,while fruits contained the lowest concentrations of these compounds. Among the genotypes we analyzed, no specifi c genotypeconsistently contained the highest concentration of quercetin and its glycoside derivatives. M. domestica ‘Honeycrisp’had the highest total compound concentration (approximately 1600 mg kg −1 ), whereas M. hupehensis contained the lowestin its fruits. In contrast, the concentration of total quercetin and its glycosides was more than 5000 mg kg −1 in the leaves ofeight genotypes and greater than 2500 mg kg −1 in the flowers of seven species. In general, the concentration of quercetinand its glycoside derivatives depended on the species and tissue type. These results may provide useful information for theevaluation and selection of edible Malus fruits and the materials for quercetin glycoside extraction.

Characterization of Phenolic Compounds and Active Anthocyanin Degradation in Crabapple (Malus orientalis) Flowers

Rana Naveed Ur Rehman,Yaohua You,Chengquan Yang,Abdul Rehman Khan,Pengmin Li,Fengwang Ma 한국원예학회 2017 Horticulture, Environment, and Biotechnology Vol.58 No.4

The red coloration of young crabapple (Malus orientalis) flowers results from their high cellular concentrationof anthocyanins. As the petals grow larger, the color fades, which is commonly regarded as being caused by floraltissue expansion diluting the anthocyanin levels in larger cells. We hypothesized that the anthocyanins are degradeddue to hydrogen peroxide (H2O2) and that the concentrations of each phenolic intermediate depends on the physiologicalgrowth of flower petals. A high-performance liquid chromatography (HPLC) analysis was performed to characterizethe identities and concentrations of the diverse array of phenolics present during different growth stages in the crabappleflowers. The concentrations of gallic acid, caffeic acid, syringic acid, chlorogenic acid, phloridzin, procyanidin B1,procyanidin B2, and catechin significantly increased throughout development, while epicatechin and cyanidin-3-galactosidelevels declined. Most flavonols (quercetin-3-xyloside, quercetin-3-rhaminose, quercetin-3-glucoside, and quercetin-3-arabinoside)increased until the fourth stage, after which they declined suddenly. Likewise, cyanidin-3-galactoside degraded sharplyat stage III, exhibiting reciprocal relationship with H2O2 concentration. Our results suggest that the concentrations ofphenolic compounds are congruent with their functional activities in floral tissues, and that their systematicfluctuation mainly depends on environmental cues and physiological imbalances, not merely petal expansion. Theresults of this study will be useful for better understanding the physiological changes in phenolic content andanthocyanin degradation that occur during flower development.