交通运输工程学报

Influence of asphalt mixture volume indexes on asphalt pavement skid resistance performance

ZHOU Xing-lin, LIU Wan-kang, XIAO Wang-xin, RAN Mao-ping, HUANG Xiao-ming

Abstract: To study the relevance between asphalt pavement skid resistance performance and asphalt mixture volume indexes, and reveal the influence degrees of different volume indexes on the skid resistance performance, the density experiments of different AC-16 asphalt mixtures were conducted by vacuum method and plastic encapsulation method, and the volume indexes such as volumetric voidage (VV), void in mineral aggregate (VMA), void filled with asphalt (VFA) and void in coarse aggregate (VCA) were compared.Indoor polishing test and pendulum test on asphalt mixtures were conducted, asymptotic model was used to fit the skid resistance's decay trend, and the parameters such as the initial value, steady value and damping value of skid resistance were obtained.The function relationships between the volume indexes and the skid resistance performance were built, and the grey correlation degree ranks between the differentvolume indexes and the skid resistance performance were analyzed by grey correlation theory.Research result indicates that there are some differences between the influences of different volume indexes on the skid resistance performance.The skid resistance performance of asphalt mixture increases with the increase of VV and VMA, and the decrease of VFA and VCA.Grey correlation degree descending order is VV, VMA, VFA and VCA, which means that VV is the main influence factor of skid resistance performance, the influence of VMA on skid resistance performance is significant, however, the influence degrees of VFA and VCA are not obvious.In the design and construction process, the asphalt pavement skid resistance performance can be improved by controlling mixture voidage and adjusting the dense state and compact condition of mixture.More>

2017, 17(6): 1-9.

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Influence of air gap on dynamic response of LIM metro system

WEI Qing-chao, XIA Jing-hui, ZANG Chuan-zhen, HAO Min, LIANG Qing-huai

Abstract: Based on the theory of probability statistics and frequency domain analysis, the measured data of dynamic air gap between linear induction motor (LIM) and reaction plate (RP) during the train's running on Guangzhou Metro Line 4 were analyzed.Based on the vehicle-track vertical and lateral coupling dynamics model, the dynamic effect of vertical electromagnetic force influenced by the air gap on the vehicle and the track structure was studied and compared with the effect of track random irregularities on the dynamics properties of vehicle-track system.Research result shows that 92.2% of air gaps are within the standard range of 9-12 mm.The air gap obeys the normal distribution, the mean is 10.5 mm, and the standard deviation is 1 mm.The heightdifference between the upper surface of RP and the top of track is the determinant factor of peak air gap, so the most unfavorable position of air gap on the line can be determined by static air gap measurement.The frequency domain component of air gap is dominated by the spatial frequencies less than 0.1 m^-1, and the frequency peak of 0.2 m^-1 is found, which proves that a periodic component of about 5 mis in the air gap.The vertical electromagnetic force has little effect on the acceleration of vehicle.The vertical electromagnetic force can increase the displacement of track structure.When the track irregularity exists at the same time, the track displacement can reach up to 0.8 mm, and the maximum displacement of track slab can reach 1.0 mm.The track irregularity is the main cause of track structure's continuous vibration. The vertical electromagnetic force only results in larger accelerations at the moment beginning to act on the track structure. The maximum acceleration of track structure caused by the vertical electromagnetic force is greater than the maximum acceleration caused by the track irregularity.The coupling influence of track irregularity and vertical electromagnetic force on the track structure acceleration is far greater than single factor influence, the track acceleration can reach2 200 m·s^-2, and the track slab acceleration can reach 1 500 m·s^-2.The maximum effect of vertical electromagnetic force on the wheel/rail vertical force is less than 9 kN.Therefore, the dynamic and static detection methods can be used to measure the air gap.First, the general location of RP's over limit point is measured by the dynamic detection device on the train, then the artificial precision measurement is carried out.After maintenance, the dynamic detection is used again for air gap's qualification test.The method can quickly and accurately maintain the whole line's RP and reduce the influence of air gap on the track structure's vertical vibration.More>

2017, 17(6): 10-18.

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Geogrid dynamic characteristics of pile-net structure in low subgrade of high-speed railway

WEI Ping, WEI Jing, YANG Song-lin, CHEN Jian-feng, ZHANG Dong

Abstract: The dynamic finite element model of pile-net structure in low subgrade was built by ABAQUS software, its rationality was verified with real test data, the interaction mechanism among train dynamic load, geogrid, pile and soil was analyzed, and the rules of geogrid force and deformation under dynamic load were studied.Research result shows that along the longitudinal direction of railway and before train loading, the shape of geogrid's vertical deformation at pile top is like upside down U, and the vertical deformation is about 2.27 mm.The distribution shape of geogrid's pulling stress is like M at pile top and upside down V in the soil among piles.The increment of geogrid's vertical deformation is about 0.10 mm at pile top under train load, and the vertical deformation is bigger than the geogrid deformation in the soil among piles.The pulling stress increment decreases gradually from the edge of pile top, the center of pile top to the soilamong piles.The pulling stress increment of geogrid is bigger in the soil among four piles than between two piles.Along the transverse direction of railway and before train loading, the vertical deformation of geogrid is about 12.0 mm at subgrade center.Under train load, the vertical deformation of geogrid decreases gradually from the center to the slope toe of subgrade, and the increment is about 0.47 mm.At pile top and in the soil among piles, the global distribution rules of dynamic displacement and dynamic pulling stress of geogrid are similar and diminishing from the subgrade center to the slope toe.At the slope toe of subgrade, the dynamic pulling stress changes to negative value.The vertical deformation increment and the maximum dynamic pulling tress are bigger in the transverse direction of railway than in the longitudinal direction.More>

2017, 17(6): 19-27.

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Distribution and zoning of reinforcement loads for reinforced soil slopes

ZHANG Wan, XU Qiang, CHEN Jian-feng, XUE Jian-feng

Abstract: Based on the result of centrifuge model test, the finite element models of reinforced soil slopes with different slope heights and angles were established.The maximum reinforcement loads in the slopes were calculated by using the strength reduction method when the safety factor was 1.30.The influence of slope height and angle on reinforcement load distribution along the height was analyzed by normalizing reinforcement load and slope height.Furthermore, thedistribution and zoning of reinforcement loads were discussed by combining with the measured reinforcement loads of field reinforced soil slopes.Analysis result shows that the computed location and shape of slope sliding surface and the safety factor at slope failure are in agreement with the centrifuge model experiment results.The distribution of reinforcement load is little influenced by slope height, whereas greatly influenced by slope angle.With the increase of slope angle, the location of maximum reinforcement load transfers from the mid height to the bottom of slope.According to the total distribution of reinforcement loads, the sums of maximum loads in reinforcement layers within the top 1/3 and the bottom 2/3 of slope account for 1/4 and 3/4 of total reinforcement tensile force, respectively.The upper part of slope requires less reinforcement loads.If using one zone method that assumes a uniform reinforcement load distribution along slope height to distribute total reinforcement tensile force, the lower degree of safety of slope will decrease.The total reinforcement tensile force of reinforced soil slopes can be distributed into zones according to slope angle. When the slope angle is no more than 1.0∶1, the total reinforcement tensile force can be distributed into three zones with equal height. The reinforcement tensile force within the top, middle and bottom zones account for 1/3, 1/2 and 1/6 of total reinforcement tensile force, respectively.When the slope angle is in the range from1.0∶1 to 2.0∶1, its upper 1/3 of height is regarded as top zone, and the bottom 2/3 of height is regarded as bottom zone.The reinforcement tensile force within the top and bottom zones account for 1/5 and 4/5 of total reinforcement tensile force, respectively.When the slope angle is no less than 2.0∶1, it can be also divided equally into three zones.The reinforcement tensile forces within the top, middle and bottom zones account for 1/6, 1/3 and 1/2 of total reinforcement tensile force, respectively. More measured data can be collected to enrich the database of reinforcement loads, so that the zoning method of reinforcement tensile force according to slope angle for reinforced soil slopes can be further completed and validated.More>

2017, 17(6): 28-35.

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Mechanical characteristics of jointless bridge with wall-type integral abutment

ZHU Wei-qing, HENG Jiang-feng, LIU Yong-jian, WANG Wei-shan

Abstract: The spatial finite element model of jointless bridge with wall-type integral abutment was established under considering the abutment-soil interaction, and its accuracy was validated by using the measured data.The mechanical characteristics of main girder and abutment under different load cases were analyzed, and the effects of temperature, backfill compactness and bridge span on the mechanical characteristics were studied.Research result shows that, compared to the simply supported girder bridge with same span, the mid-span moment of worst stress condition's main girder of jointless bridge with wall-type integral abutment decreases by 20%-40%, and the sum of mid-span moment and girder-end moment decreases by 28%, which indicates that the distribution of internal force is more balance, and the structural integrity of longitudinal and transverse directions is more obvious.The top of abutment has larger moment and shear force, and the deformation of abutment is complex.The internal force and deformationof jointless bridge with wall-type integral abutment are sensitive to temperature actions.That gradient temperature rises and overall temperature decreases causes girder-end positive moment, and that gradient temperature decreases and overall temperature rises causes girder-end negative moment, so suitable load cases should be chosen for different members during design process.When the backfill compactness changes from loose to compact, the variations of main girder's end and mid-span moments are less than 5% when overall temperature rises or decreases, and the variation of abutment deformation is less than 9%, which indicates that backfill compactness has little effect on main girder moment and abutment deformation.When the bridge span changes from 6 mto 13 m, the top moment of abutment increases by 1.781 times, and the internal force of abutment increases rapidly.Therefore, it is suggested that the bridge span should not exceed10 mduring the design process of jointless bridge with wall-type integral abutment to control the concrete crack width of abutment under the serviceability limit state.More>

2017, 17(6): 36-45.

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Comparison of short fatigue crack behaviors for LZ50 axle steel under two loading frequencies

YANG Bing, LIAO Zhen, MA Bai-quan, WU Ya-yun, XIAO Shou-ne, YANG Guang-wu, ZHU Tao

Abstract: Under the loading frequencies of 180 and 15 Hz, short fatigue crack replica tests of six hourglass shaped specimens were carried out by using the high-frequency fatigue testing machine and the electrohydraulic servo fatigue testing machine, respectively.Test result shows that, at the microstructural short crack (MSC) stage, the growth of dominant short crack experiences two significant reduction processes.According to the two lowest growth rates, the statistical average crack sizes under the loading frequency of 180 Hz are 11.49 and 106.32μm, respectively, while the sizes under 15 Hz are 14.14 and 122.29μm, respectively.In consideration of the inevitable microstructural differences among the specimens, it is believed that the two main dominant crack growth rates decrease when the crack sizes are close to the average diameter 14.26μm of ferrite grains and to the average interval 111.53 μm of rich pearlite banded structures, respectively.At the physical short crack (PSC) stage, the growth rate of dominant short crack accelerates continuously with the increase of its size.The growth rate curves and density curves of dominant short crack under two loading frequencies overlap to a great extent and have the same change trends.In general, no significant differences exist.The growth rate of dominant short crack is slightly higher under low loading frequency than under high loading frequency at the MSC stage, but the difference is unobvious and less than a magnitude.The consumption life accounts for a smaller proportion of total life when the dominant crack breaks through the obstacles of microstructures, the fatigue life fractions are 0.027 and 0.525 under 15 Hz, respectively, and are0.071 and 0.688 under 180 Hz in the two significant reduction processes of dominant short crack growth.Based on 7 commonly used statistical distributions and comparative analysis, the distributions of size, fatigue life fraction and effective density of dominant short crack are determined, the size obeys the maximum distribution, and the fatigue life fraction and effective short crack density obey the minimum distribution.More>

2017, 17(6): 46-55.

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Calculation method of fuel consumption on CNG bus

YAN Sheng-yu, XIAO Run-mou, LI Teng-fei, DENG Qun

Abstract: The test parameters of fuel consumption of CNG bus were analyzed, and the suitable installation location of CNG flowmeter was determinated.Based on a fixed pressure range of CNG at installation location, the influence of driving energy saving technology level and passenger number was considered, and a calculation method of CNG mass flow was put forward.Field test was carried out to verify the nonlinear relationship among the mass flow, temperature and pressure of CNG, in addition, the relationship among the mass flow, the ambient temperature and the outlet pressure of cylinder.Based on the operational test, the difference of CNG mass flows before and after correction was analyzed, and the feasibility of testing method was verified.Research result shows that because of the limit of tested CNG pressure, the unique position ofCNG flowmeter is fixed between the outlet of pressure reducing valve and hypobaric gas filter, and CNG pressure decompresses to 0.80-0.95 MPa by pressure reducing valve.In the process of modifying operation test result, the driving energy saving technology level has greatest impact on the final test result of CNG mass flow, and the maximum tolerance may reach 4%.87.6% of the relative values for the driving factor are between 0.9 and 1.1, which reflects lower dispersion.When the rising speed of ambient temperature is between 4.0 ℃ ·h^-1 and 4.3 ℃ ·h^-1, the variance ratio of CNG temperature ranges from-0.61 ℃·h^-1 to 0.61 ℃·h^-1, which verifies that the CNG temperature is insensitive to the ambient temperature.Precisely speaking, there is no necessary connection between CNG pressure and cylinder outlet pressure, and the decrease of cylinder outlet pressure does not interfere with CNG mass flow.Under the CNG pressure of0.80-0.95 MPa, the CNG equivalent density at the testing position is stable at 6.1 kg·m^-3.After continuous testing about 30 km, the deviations are less than 5% between the test result and computation result of CNG mass flow.After modifying CNG mass flow, the variations of CNG mass flows of 3 buses are 1.88%, -4.04% and 1.71%, respectively, so CNG mass flow can be used to accurately compute CNG consumption.More>

2017, 17(6): 56-63.

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Optimization of tram operation network based on considering traffic demand characteristics

LI Yan-hui, CHEN Kuan-min, MA Jing, LI Yan, WANG Yu-ping

Abstract: In order to improve the scientificity and operation efficiency of tram network planning, the characteristics and indicators of tram operation network were studied, and the operation network searching method based on the characteristics of passenger flow demand was established.The separation characteristics of tram network and operation was considered, and the passenger flow demand-operation benefit was used to establish the node-edge network.Based on the section passenger flow volume, the initial selection threshhold was determined by Chebyshev law.The optimal operating beneficial model of time benefit-ticket price-operation cost was established bycomputing importance degrees and node-passerger volume matrix.The tram operation network was selected, and the overall scale of operation network was controlled by the genetic algorithm.Based on the tram network planning project in Xixian New Area, 14 operation lines were selected, the optimization of tram operation newtork was simulated by MATLAB softwore.Analysis result shows that the optimization operation line length of the tram is between 24-25 km, and the total scale of operation network is 339.5 km.The final operational network is well matched with the optimization benefit, the distribution of section passenger flow, the layout of tram network, the characteristics of passenger demand and the important distribution points of passenger flow, and most of the lines' lengths are less than 30 km, which meets the general tram operation network requirements.The optimization method takes into account many practical factors in the planning and operation of tram.Through the integration and quantification of searching process, the optimization result and the demand characteristics are more consistent.More>

2017, 17(6): 64-75.

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Weibull dependence stochastic traffic assignment model considering risk prone drivers

YU Li-jun, TAN Jin-zhou

Abstract: A Weibull dependence stochastic traffic assignment (Weibull-DSA) model considering risk prone drivers was established. The Weibull marginal survival function of perceived equivalent route disutility was analyzed.It was assumed that travelers always chose the routes with the minimized expected perceived equivalent route disutility to reach their destinations.Thejoint survival function of perceived equivalent route disutility was constructed by using Copula method, and the route choice probability was predicted.An iterative solution algorithm was designed for the model, and the theoretical analysis and numerical verification of the model were carried out.Risk coefficient obtained from the traffic survey in Guangzhou was analyzed.The route choice probabilities, road section traffic volumes, saturation degrees and total travel times were calculated by using Weibull-DSA model, classic Logit stochastic user equilibrium (LogitSUE) model and Weibit stochastic user equilibrium (Weibit-SUE) model under the assumption of risk prone and risk neutral drivers, respectively.Calculation result shows that as the risk coefficient becomes smaller, the total travel times of traffic system for all three kinds of traffic assignment models become larger.Under the risk neutral condition, the maximum differences among the route choice probabilities of all alternative routes connecting each OD pair are 0.17, 0.33, 0.34, respectively calculated by using Weibull-DSA model, Logit-SUE and Weibit-SUE model.Similarly, under the risk prone condition, the maximum differences calculated by the three models are 0.20, 0.36 and 0.41, respectively.Therefore, the maximum difference of different route choice probabilities calculated by Weibull-DSA model is obviously less than the maximum differences obtained by two classical models.Compared with the risk neutral situation, the risk coefficient increases the maximum difference of the route choice probabilities of all alternative routes connecting each OD pair.For either risk prone or risk neutral drivers, the saturation degrees of each road section calculated by Logit-SUE and Weibit-SUE models are all less than 0.9, whereas the saturation degrees obtained by Weibull-DSA model are more than 0.9.Unlike the calculation results of classical models, the maximum difference of route choice probabilities obtained by Weibull-DSA model is smaller, some routes get more traffic volumes, which makes the saturation degrees of road sections with the smallest capacity in the route are greater than 0.9.This feature gives a new explanation for the congestion phenomenon at some bottlenecks in the urban road network.More>

2017, 17(6): 76-85.

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DEA model of land use and traffic coordination for regulatory detailed planning unit with preference constraints

YUAN Zhen-zhou, YAN Xin-xin, ZHANG Ye, WANG Jia-dong

Abstract: To quantitatively evaluate the coordination degree of traffic and land use in urban regulatory detailed planning stage, the mutual mechanism of land use and traffic coordination for urban regulatory detailed planning unit was analyzed.It was pointed out that the traditional data envelopment analysis (DEA) makes an undifferentiated treatment between input indexes and output indexes, which was not consistent with actual situation.In view of the characteristics of regulatory detailed planning unit and actual control demand, the index system of land use and traffic coordination was established. According to the constraint cone theory based on mathematical programming, using the aid of analytic hierarchy process (AHP), the constraint cone model responsing land index and traffic index preferences was constructed.The objective analysis of data envelopment evaluation was combined with the subjective judgment of analytichierarchy process.The mutual coordination degree of land use and traffic system in the cases of input and output was determined by using membership degree function.Therefore, the mutual coordination effects of the different planning schemes for the traffic and land use of regulatory detailed planning unit were quantitatively evaluated.Based on the No.3 management unit of Nanhu in Handan City, 22 external traffic zones and 68 internal traffic zones were set up.4 types of land use indicators and 9 types of urban traffic indicators were predicted.The preference constraints of the input index and output index of proposed model were calculated.Analysis result shows that the proposed model overcomes the limitation of too dependent on subjective intention in AHP, and makes up for the deficiency of ignoring the decision preference in DEA.The deviation between the results of land use and traffic coordination analysis and the actual situation reduces.The mutual coordination degrees of 6 blocks calculated by the original model are all more than 0.80, all of which are coordinated.After improvement, the mutual coordination degrees of 4 blocks are 0.32-0.57, all of which are incongruous.The mutual coordination degrees of the other 2 blocks are over 0.80, which is more consistent with the actual situation.More>

2017, 17(6): 86-96.

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Optimization of express distribution by cooperatively using private trucks and buses

HE Yun-zhu, YANG Zhong-zhen

Abstract: For dealing with the demand of large quantity, small parcel, high batch frequency, and high timeliness of urban express distribution, the distribution mode by cooperatively using buses and private trucks was proposed, and an optimization model aimed at minimizing the total cost of express distribution was built.The transport network of expresses based on cooperatively using private trucks and buses was optimized by determining distribution batches, departure time and distribution routes.Ant colony algorithm was designed for solving model.The schemes of collaborative distribution and sparate distribution only using trucks were solved and compared for97 demand sites based on the road network and public transit network in Dalian.Analysis result shows that, in collaborative distribution mode, the total cost decreases by 9.5%, the driving distance of trucks decreases by 12.6%, the CO₂ emission decreases from 0.159 tto 0.139 t, the demand sites of unpunctual distribution decreases by 26.2%, and the total delay decreases by57.7%.In additional, the applicative range of unit time penalty cost of collaborative distribution is 0.2-0.4 yuan·min^-1, and the optimal unit distribution cost of buses is 1.5 yuan· (t·km) ^-1.In conclusion, the collaborative distribution can provide better service than truck distributionbecause of lower distribution cost, higher punctuality and less environmental load in certain extent.More>

2017, 17(6): 97-103.

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Impact of public transport fare on travel mode structure of commuting corridor

YAO En-jian, ZHANG Qian, ZHANG Rui

Abstract: Traffic mode choice models for commuting corridor were established, and the impact of public transport fare on the travel mode structure of commuting corridor was analyzed.Considering the multiple end access modes of public transport, the travel mode choice NL models containing combined travel mode were proposed respectively for commuters with or without cars.The commuting corridor along Subway Line 5 in Beijing was taken as an example, and the precisions of NL models were examined with actual data.On the basis of the consideration of public transport capacity constraint, the travel mode share rate and public transport load factors with different single traffic mode fares and combined fares were analyzed by using NL models, the rationalities of travel mode structure under different fares were evaluated according to capacityutilization rate and service level of public transport.Analysis result shows that the fare adjustment policy in Beijing can improve the capacity utilization rate of bus, but the effect on load factors of subway is limited.When the bus fares are 0.01-0.06 yuan·km^-1, or the subway fares are 0.32-0.42 yuan·km^-1 in the commuting corridor, the average peak hour load factors of bus are 60%-65%, and the peak hour load factors of Subway Line 5 in Beijing are 86%-100%, which shows that while the capacity utilization rate of public transport is kept in a certain level, the service level of public transport is improved, the share rate of car remains the status quo, and car trip volumes don't increase greatly.When the constraints of bus fare and subway fare are satisfied in the commuting corridor, the average peak hour load factors of bus are 58%-80%, the peak hour load factors of Subway Line 5 in Beijing are 86%-100%, and the growth rate of share rate of car is less than 5%.The fare adjustment can improve the travel mode structure of commuting corridor.More>

2017, 17(6): 104-114.

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Integrated scheduling of handling operation between train and vessel in container terminal under uncertain factor

CHANG Yi-mei, ZHU Xiao-ning

Abstract: To improve the efficiency of container terminals, an integrated scheduling model of handling operations between trains and vessels was established. Loading and unloading synchronization, as well as some practical constraints, such as quay crane (QC) interference, gantry crane (GC) interference, QC safety distance, GC safety distance and so on, were considered.Some uncertain factors during production scheduling, such as the change of QC speed and inner truck (IT) speed and so on, were also considered.In order to solve the model, an improved multi-layer genetic algorithm (MLGA) was developed.To determine the value of random variable, Monte Carlo method was introduced into the traditional genetic algorithm.To balance the allocation of containers among ITs, a balanced operator was introduced into traditional genetic algorithm.The feasibility and effectiveness of the proposed model and algorithm were verified by using computational experiments, and a comparison experiment wascarried out between the improved MLGAs with and without balanced operator.Analysis result indicates that the makespan of handling operation with balanced operator is 7 437.8 sand 760.3 s less than that without balanced operator.Meanwhile 50 FEU containers are evenly allocated to 5 ITs in the experiment with balanced operator, while in the experiment without balanced operator, they are unevenly assigned to ITs.Fixing the number of GCs and QCs, and changing the number of ITs, when the number of containers is 80, 90, and 100 FEU, respectively, the best equipment proportions are 3 GCs, 10 ITs and 4 QCs by comparing the makespans and marginal benefit values in each group of experiments.The efficiency of handling operations between trains and vessels in container terminals is enhanced by using improved MLGA, and the improved MLGA can be an effective approach to solve the integrated scheduling problem of container handling operation.More>

2017, 17(6): 115-124.

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Trajectory tracking control of underactuated ship based on adaptive iterative sliding mode

SHEN Zhi-peng, DAI Chang-sheng, ZHANG Ning

Abstract: Aiming at the trajectory tracking control problem of underactuated ship, the unknown parameters and external disturbances of ship system were considered, and a control method with reinforcement learning based on neural network adaptive iterative sliding mode was put forward.The nonlinear iterative sliding mode functions were constructed based on the horizontal and vertical deviations of tracking trajectory, and the neural network iterative sliding mode controllers of diesel engine speed and rudder angle were designed, respectively.According to the real-time measurement values of diesel engine speed and rudder angle, the reinforcement learning signals reflecting the chattering states of control quantities were calculated, and the neural networks' constructions and parameters were optimized online to restrain control the chattering states and enhance the control system's adaptability.The mathematical model of 5446 TEU container ship was established, and the trajectory tracking controls of circular and sinusoidal trajectories werecarried out, respectively.Simulation result shows that when the circular trajectory is tracked under the disturbances of wind and sea wave, the tracking time of target trajectory is about 250 s with the proposed control strategy, and the tracking speed is about 1 time higher than the value with iterative sliding mode control strategy.The maximum tracking yaw distance is 250 m, and the error reduces by about 30%.The control rudder angle is basically stable after 400 s, and its chattering amplitude is about 2°.The chattering amplitudes of rudder angle and diesel engine speed reduce by more than 50%.The control parameters of diesel engine speed and rudder angle are adaptively adjusted between 38-45 and 3.3-3.9, respectively.When the sinusoidal trajectory is tracked, the proposed control strategy is compared with the fuzzy iterative sliding mode control strategy, and the average vertical tracking error is less than 20 mand reduces by more than 50%.The average chattering amplitude of rudder angle is less than 10°and reduces by more than 60%.The control parameters of diesel engine speed and rudder angle are adaptively adjusted between5.7-5.8 and 0.8-2.5, respectively.More>

2017, 17(6): 125-134.

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Integrated control strategy of articulated heavy vehicle based on timely mode switching under medium/high speed conditions

NIE Zhi-gen, WANG Wan-qiong, WANG Chao, ZONG Zhang-fu

Abstract: Under the medium/high speed conditions, the simplified model of articulated heavy vehicle with five degrees of freedom was established, and the integrated control strategy based on timely mode switching was proposed based on the active steering control system of trailer and differential braking control system.According to different medium/high speed conditions, the control modes of integrated control strategy were timely switched to achieve the precision control of articulated heavy vehicle.The optimizing functions corresponding to the control modes were designed to optimize the weight coefficients of control modes by the genetic particle swarm optimization algorithm.According to the optimal weight coefficients, the multiple single controlstrategies in integrated control strategy were fused and coordinated to achieve the optimal control of articulated heavy vehicle under various modes.The simulation results of multiple control strategies of articulated heavy vehicles were analyzed, and the hardware-in-the-loop test bench was constructed to verify the control effect of integrated control strategy.Research result indicates that the control effect of integrated control strategy is similar to the effect of active steering control strategy of trailer and better than the effect of differential braking control strategy under the normal working condition, and better than the effects of active steering control strategy of trailer and differential braking control strategy under the limit working condition.The maximum slip angle of tractor, the maximum yaw velocity of trailer and the maximum slip angle of trailer are improved by 27.46%, 53.19% and 91.60%, respectively, and the maximum hitch angle is improved by 29.07%, so the integrated control strategy can improve the yaw and jackknife stability of articulated heavy vehicle under the medium/high speed normal conditions.The maximum path deviation of trailer rear is improved by 95.48%, so the integrated control strategy can enormously promote the path following ability of articulated heavy vehicle under the medium/high speed normal conditions.The maximum roll angle of tractor, the maximum roll angle of trailer and the maximum lateral acceleration of trailer are improved by 11.15%, 10.34%and 4.08%, respectively, so the integrated control strategy can improve the roll stability of articulated heavy vehicle under the medium/high speed normal conditions.The integrated control strategy can avoid vehicle rollover under the limit working condition and control the roll angles of tractor and trailer in the stable range of about 25°.More>

2017, 17(6): 135-149.

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Mode transition coordination control of hybrid electric bus based on multiple controllers

TIAN Xiang, HE Ren

Abstract: The switching process from pure electric driving mode to engine driving mode of parallel hybrid electric bus was analyzed, the basic idea of switching system was considered, and the mode transition coordination control strategy of hybrid electric bus based on multiple controllers was proposed.The driving mode transition was divided into three phases in terms of clutch states.According to the vehicle operating status, fuzzy-PI controller and sliding mode controller were constructed to coordinate the engine and driving electric motor in the phases.The shock degree was used as quantitative index to assess the quality of mode transition.The simulation model of parallel hybrid electric bus was built in MATLAB/Simulink/Stateflow platform.The vehicle experiment platform was constructed, and the coordinated control effect was analyzed.Simulation result shows that when the coordinated control strategy is not adopted, the friction torque of clutch in slipping stage generates a reverse impact of 189 N·m due to the large speed difference between the two sides of clutch, which results in the sharp decline of vehicle velocity and the maximum reverse shock degree of 41.2 m·s^-3.When the coordinatedcontrol strategy is used, the variation of shock degree is -3-4 m·s^-3 in entire mode transition.So the output stability of power transmission system is assured, and the impact caused by the switching of driving mode is restrained effectively.In an entire driving mode transition, the experiment result is basically consistent with the simulation result, the error of vehicle velocity is less than 5%, and the variation of shock degree is-5-7 m·s^-3, so the strategy is feasible and effective.More>

2017, 17(6): 150-158.

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