Table of Content

25 October 2022, Volume 50 Issue 10

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Contents



2022, 50(10):  0-0. 

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Traffic & Transportation Engineering

Comparison of Data-Driven Human-Like Driving Models Under Different Behavior Model Frameworks



HUANG Ling, HUANG Zixu, WU Zerong, et al

2022, 50(10):  1-10.  doi:10.12141/j.issn.1000-565X.210783

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The traditional driving behavior model framework divides the driving behaviors into car-following and lane-changing, which are modeled separately. While the integrated driving behavior model framework believes that car-following and lane-changing are inseparable, so all driving behaviors are modeled as a whole. Based on these two behavioral model frameworks, this paper analyzed the performance of the data-driven human-like driving models. Firstly, it established integrated driving behavior model framework and car-following lane-changing combined model framework and then determined the input and output of the models according to the influencing factors in driving. Secondly, two combinations of car-following, lane-changing and intention recognition modules were proposed: discriminative combination and probability combination. Subsequently, the processing of the original data were carried out to build integrated driving behavior, car-following, lane-changing, and intention recognition datasets, which were used to train and calibrate the corresponding modules. Finally, the study compared the performance of the two combination models with the integrated driving behavior model in various aspects, including model accuracy, safety, robustness and migration. The results show that, when the model input and output, the parameter calibration process and the dataset are the same, the accuracy of the human-like driving model based on long short-term memory neural network (LSTM) is better than the model based on FNN. The mean square error of the model based on LSTM can reach 0.227 m², and the mean square error of the model based on FNN is 0.470 m². Within the LSTM-based model, the model using the car-following lane-changing combined model framework has better robustness and transferability than the model using the integrated driving behavior model framework. For the car-following lane-changing combined model, the mean square error of ±10% noise robustness can reach 1.383 m², and the mean square error of transferability can reach 0.462 m². For the integrated driving behavior model, the mean square error of ±10% noise robustness is 2.314 m², and the mean square error of transferability is 0.484 m².

Construction and Application of Cellular Automaton Model of Traffic Flow in Freeway Diverging and Merging Areas



QI Weiwei, MA Siwei, ZHOU Nanjie

2022, 50(10):  11-18.  doi:10.12141/j.issn.1000-565X.220008

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The operation and management optimization schemes of freeway always need to be formulated according to the traffic capacity of bottleneck sections. Due to the complexity of the traffic flow characteristics of the bottleneck sections of freeway, the current general calculation formulas of the traffic capacity are limited to many assumptions, and the accuracy is not high and the error is large. This paper attempted to construct a calculation method of traffic capacity in freeway bottleneck sections and verify it by actual measurement. Firstly, UAV technology and software Tracker were used for aerial video recording and dynamic identification and 680 groups of traffic flow data for car-following and lane-changing on freeway was obtained, including position, speed, acceleration, headway and other parameters. Then, the probability models and rule models of lane-changing considering driver characteristics were established according to the obtained traffic flow parameters, and the classical car-following model GHR was calibrated. Finally, a simulation application model of freeway traffic flow based on cellular automaton theory was constructed by the partitioning method, the acceleration requirements of following vehicles were characterized with GHR model, and the effectiveness of the model was verified by the indicators of vehicle lane-changing times and hourly traffic volume with error rates of 12.06% and 3.19%, respectively. The results show that this model can effectively calculate the capacity of freeway diverging and merging areas and design the road parameters such as the length of speed-change lane. In this case, a traffic flow simulation test was conducted on Cencun interchange sections of Guangzhou Northring Freeway, in which the road geometry characteristics, vehicle arrival conditions and traffic flow operation mechanism were simulated. The capacity of the diverging and merging areas is 5 456 and 5 253 pcu/h, respectively, and the optimization design values for the length of speed-change lanes in the diverging and merging areas are 125 and 200 m, respectively. The cellular automaton model of traffic flow constructed in this paper provides scientific basis for microscopic traffic flow simulation and road parameters design of freeway diverging and merging areas, and helps to improve the level of service and operational quality.

Braking Collision Avoidance System for Vehicles Driving on Superhighway Based on Co-simulation



HE Yongming, FENG Jia, QUAN Cong, et al

2022, 50(10):  19-28.  doi:10.12141/j.issn.1000-565X.210703

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To solve the safety problem of collision between a high-speed intelligent vehicle and a low-speed vehicle on the superhighway, the vehicle braking collision avoidance system was studied by using the method of co-simulation. CarSim was used to establish the vehicle dynamics model and set the front vehicle parameters, road parameters and sensor parameters, and the control model based on vehicle distance and speed was established in MATLAB/Simulink. The signal connection is established through the input and output parameter interface module of CarSim software. When the speed of the front car is 100, 120 and 140 km/h, and the speed of an intelligent vehicle is 140, 160 and 180 km/h, respectively, the control model sends the braking deceleration signal to the intelligent vehicle through the real-time distance and speed collected by the sensor and establishes the emergency braking collision avoidance strategy for the vehicle on the superhighway. The results show that when the road adhesion coefficient is 0.60 and the car is braked on the flat straight section of the superhighway, the optimal wheel cylinder pressure is 7 MPa, and at this time, the braking distance of the car is 170.3 m at a speed of 160 km/h. The front car travels at a speed of 100, 120 and 140 km/h, and the smart car brakes at 140, 160 and 180 km/h, respectively, to the same speed as the car in front, requiring relative distances of 10.8, 10.7 and 10.5 m, respectively. When the road adhesion coefficient is 0.60, the vehicle speed of the front vehicle is 100, 120 and 140 km/h, respectively. When the initial cylinder pressure is 1 MPa and the intelligent vehicle braking decelerates to the same speed as the front vehicle, the distance between the front suspension of an intelligent vehicle and the rear suspension of the vehicle in front is 3.1, 3.5, and 3.8 m, respectively. When the initial cylinder pressure is 3 MPa and the intelligent vehicle braking decelerates to the same speed as the front vehicle, the distance between the front suspension of an intelligent vehicle and the rear suspension of the vehicle in front is 7.0, 7.3, and 7.7 m, respectively. Through the CarSim/Simulink co-simulation platform of vehicle emergency braking and collision avoidance control, the validity and accuracy of superhighway braking and collision avoidance model are verified, which can improve the safety of superhighway driving.

Interval Optimization Model of Signal Control at Intersection Based on Possibility Degree



CHEN Xiaohong, HU Fang

2022, 50(10):  29-40.  doi:10.12141/j.issn.1000-565X.210405

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In order to meet the traffic demand and improve the effective of the traffic signal control under uncertain condition, this paper initially proposed a new signal timing interval optimization model of traffic signal control based on the interval optimization theory. Firstly, the traffic flow interval in rush hour was determined by 5 min acquisition section and used as the input parameters of traffic control system. Secondly, the interval-valued nonlinear optimization model of signal timing was constructed by taking the average vehicle control delay interval as the objective function.Thirdly, taking the intersection service level as the performance objective, this model was transformed by using the interval possibility degree model and solved by using genetic algorithm. Finally, the three-phase and two-phase intersections in rush hour in Beijing were simulated by using VISSIM simulation software. The results show that the method is feasible and effective, and is obviously superior to Webster scheme, robust optimization method and measured data at three-phase intersection with large fluctuation of traffic flow. The vehicle average delay decreases by 26.57% and capacity increases 7.07% compared with the measured data. At the two-phase intersections with relatively stable traffic volume, the interval optimization method is feasible and can achieve the expected control effect, but it is weaker than other schemes. Furthermore, the signal timing interval optimization model was used by the eight intersections in rush hour in Beijing with VISSIM simulation software and analyzed by the fluctuation trend of the saturation and the average delay of the 5 min acquisition section.The analysis show that the interval optimization model can achieve the expected control effect for each intersection during peak hours, and is more suitable for intersections with large traffic flow fluctuations, and the performance of the control scheme is more stable.

Numerical Study on Influence of Attached Rigid Splitter Plate on Vortex-Induced Vibration of Cylinder



DAI Shaoshi, ZHANG Xuyang, ZHAI Tianlei, et al

2022, 50(10):  41-50.  doi:10.12141/j.issn.1000-565X.210688

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Cylindrical structures exist widely in nature and engineering. The problem of suppression of vortex-induced vibration of cylindrical structures caused by viscous flow separation has received close attention in past decades. Splitter plate is commonly used as a passive control device due to its effective suppression of vortex shedding, but it is worth of further research about its influence on the VIV of circular cylinder and internal mechanism of VIV suppression. Herein, combining with lift oscillator model and Detached Eddy Simulation turbulence model (DES) and adapting asynchronous iterative algorithm, numerical computation of strong coupling resolved method were carried out by using SIMPLE algorithm and Newmark-\beta method to solve the discrete fluid and structural equations. The accuracy of the strong coupling algorithm based on Detached Eddy Simulation was verified, and then the effect of suppression of splitter plate (L/D=\mathrm{0.5}) on a cylinder with single degree of freedom vibration was studied when the range of reduced velocity was . Moreover, the suppression effect of the splitter plate on the wake mode, responses of fluid force and vibration, and frequency characteristics of vibrating cylinder was analyzed. The critical velocity was obtained. The numerical results show that the vibration can be well suppressed when .The maximum vibration amplitude decreases about 69%, lock-in region of frequency becomes narrow and the vortex shedding frequency decreases obviously. The maximum fluid parameters C_{\mathrm{D},\mathrm{m}\mathrm{e}\mathrm{a}\mathrm{n}},C_{\mathrm{D},\mathrm{r}\mathrm{m}\mathrm{s}}and C_{\mathrm{L},\mathrm{r}\mathrm{m}\mathrm{s}}, acting on the cylinder, decrease about 40%, 90% and 52% respectively. For cylinder attached a splitter plate, galloping phenomenon occurs as U^{\mathrm{*}}>\mathrm{10}. The vibration amplitude of the cylinder keeps increasing. With the continuous increase of U^{\mathrm{*}}, the separating shear layer reattaches to the splitter plate again, and the cylinder absorbs energy from the flow, which was far greater than the energy consumed by structural damping. The amplitude conti-nues to increase and exceeded that of the smooth cylinder, so the vibration of the cylinder is more severe and vibration of cylinder cannot be suppressed by splitter plate in this region.

Electronics, Communication & Automation Technology

Deep Feature Domain Motion Estimation and Multi-Layer Multi-Hypothesis Motion Compensation Net for Video Compression Codec



YANG Chunling, LÜ Zeyu

2022, 50(10):  51-61.  doi:10.12141/j.issn.1000-565X.220221

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Traditional video compression coding methods are widely used. In order to further improve the compression performance, research on deep learning-based video compression coding methods has received increasing attention. Existing deep learning video compression coding methods realize motion compensation based on optical flow, which will produce artifacts during the optical flow alignment process, reducing the accuracy of prediction. This paper proposed a motion estimation idea in the deep feature domain, and designed a corresponding neural network to extract motion information in the deep feature domain. On this basis, it proposed a multi-layer multi-hypothesis prediction motion compensation network. By using the multi-hypothesis prediction module in the deep feature domain, the shallow feature domain and the pixel domain, the accuracy of motion compensation was improved, thereby improving the overall rate-distortion performance. Simulation results show that the inter-frame prediction results of the algorithm in the paper mitigate artifacts and the visual effect is significantly better than optical flow alignment. At the same time, the proposed algorithm achieves better rate-distortion performance compared with traditional H.264 and H.265 methods and single-frame reference methods DVC and DVCpro based on deep learning. Compared with the DCVC method at the forefront of research, the algorithm reduces the coding time by approximately 26.8% while the rate distortion performance is similar. Taking the H.264 encoding result as the benchmark, under the condition of the same bit rate, the decoding quality was improved by 3.73 dB, 4.76 dB and 2.65 dB on HEVC test sequences ClassB, ClassD and ClassE. The simulation experiment results show that, when compressing and coding video sequences, the algorithm proposed in the paper can improve the accuracy of motion compensation prediction frames, reduce the prediction error, shortens the residual signal compression coding code stream and improve the overall rate distortion performance.

A Fast Teaching Method of Robot Based on Position Tracker



SHI Buhai, OU Huahai, GUO Qingda

2022, 50(10):  62-69.  doi:10.12141/j.issn.1000-565X.220003

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In order to avoid the problems of delay, low control accuracy, and difficult operation in the drag teaching of medium and large manipulators, the study proposed a fast teaching system for robots based on position tracker. Firstly, the position tracker receiver was fixed at the end of the manipulator, and the relationship between their coordinate systems was analyzed. Secondly, the study deduced the transformation relationship between the robot base coordinate system and the position tracker transmitter coordinate system, and the position relationship between the robot end coordinate system and the position tracker receiver coordinate system. A solution method based on quaternion was proposed to carry out transformation relationship between the transmitter coordinate system and the robot base coordinate system. Finally, the position tracker receiver can be used as a teaching pen for robot dragging teaching when the calibration work is done. Accodring to the transformation relationship between the robot base coordinate system and the position tracker receiver, teaching work and getting waypoint information can be completed easily and quickly by converting the pose of the receiver to the pose of the robot base coordinate system without dragging. In addition, the position tracker receiver is lighter and smaller than robot end. Using the position tracker receiver for drag teaching is more convenient and efficient than manually dragging the robot in some scenarios that require drag teaching in a small area. A fast teaching system with the Elephant E series industrial robot and the trakStar position tracker of Ascension in US was built to carry out the error experiment and the trajectory teaching experiment in spraying application. The experimental results show that the absolute of the rotation angle error of the robot end pose calculated by the position tracker’s pose is no more than 0.8°, and the absolute of the translation error is less than 2.5 mm, which can meet the actual control requirements.

Legitimate Eavesdropping Scheme for Suspicious Relay Communication Networks



WU Haowei, HUANG Fengjiao, YAN Lian, et al

2022, 50(10):  70-79.  doi:10.12141/j.issn.1000-565X.210506

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In order to improve the legal eavesdropping performance against the suspicious relay networks and enhance the monitoring ability of the legal monitoring center in communication networks, the study proposed an eavesdropping-then-jamming scheme (EJS), a two-slot continuous eavesdropping scheme (CES) and a jamming-then-eavesdropping scheme (JES) for a legal interception model consisting of suspicious nodes with a single antenna and legitimate listeners with multiple antennas, and derived the closed-form expressions, including the outage probabi-lity of suspicious communications, the non-outage probability of eavesdropping and the average eavesdropping rate of each scheme. In particular, for EJS and JES schemes, the optimization problem of maximizing the average eavesdropping rate was solved, and the approximate optimal solution expression of the transmitting signal-to-noise ratio (SNR) of the legitimate monitor with a single antenna was given. By integrating the advantages of the previous three schemes, the optimal-eavesdropping-mode selection scheme (OEMS) based on maximizing the non-outage probabi-lity of eavesdropping was designed in the scenario where part or all of the links between the legitimate surveillance and the suspicious nodes are available. Specifically, by comparing the non-outage probability of eavesdropping of the above three schemes, the scheme corresponding to the highest value was selected as the eavesdropping means. Simulation results show that when the legitimate monitor is closer to the suspicious relay, compared with the EJS, CES has higher non-outage probability of eavesdropping and JES has higher eavesdropping rate in low SNR areas. The proposed OEMS can achieve the optimal secrecy performance and has better adaptability for more scenes. Compared to the legitimate monitor with single antenna, the legitimate monitor with double antennas has more advantages as following: in order to achieve continuous monitoring, the transmitting power of interference signal can be reduced by about 15 dB; and the average eavesdropping rate of EJS scheme and JES scheme can be increased about 0.8 bits/(s·Hz) in low SNR region. Therefore, increasing the antenna number of legitimate monitor can not only save the power cost, but also enhance the monitoring ability.

Study on Third-Order Wide Band Miniaturized Element Frequency Selective Surface with an Ultra Wide Stopband



ZHENG Guangming, ZHANG Yandong, LONG Yifei

2022, 50(10):  80-86.  doi:10.12141/j.issn.1000-565X.210774

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In view of the problems of large area, narrow bandwidth, low stopband rejection and narrow stopband of frequency selective surface unit, this paper proposed a novel third-order ultra wide stopband miniaturized frequency selective surface element based on three symmetrical interdigital microstrip metal layer, square metal layer coupled loop and four dielectric layer. The symmetrical interdigital structures is equivalent to capacitance, the square coupling rings is equivalent to inductor, and the dielectric layer is equivalent to short lines. The hybrid parameter equivalent circuit with lumped and distributed parameters was obtained. According to the circuit theory, the frequency response characteristics of the third-order Chebyshev band pass filter and the frequency characteristics of the ultra wide band stopband were calculated. The third-order frequency selective surface was designed by combining the circuit theory calculation with the electromagnetic simulation software HFSS. The results of the theoretical calculation are in agreement with those of the electromagnetic simulation software HFSS, and has a frequency response characteristic curve of third-order band-pass filter and ultra wide stopband. The size of the ultra wide stopband mi-niaturized frequency selective surface element is 6 mm×6 mm, and the thickness is 7 mm. A 41×41 third-order wide band miniaturized element frequency selective surface was machined and tested. The measured center frequency is 2.48 GHz, the relative bandwidth is 11.2%, the in-band insertion loss is less than 0.5 dB, the return loss is greater than 18 dB, the stopband exceeds 55 GHz, and the rejection in the stopband is greater than 25 dB in the frequency range from 2.8 GHz to 55 GHz. It has good frequency stability in the angle of incidence from 0° to 70°. The experimental results are in good agreement with the simulation results, indicating that the design method and the structure of the three-order frequency selective surface adopted in this paper are correct.

Measurement Method of Radial Double-Layer Dielectric Thickness of Cylindrical Cavity



ZHANG Shue, LAI Shuai, ZAHNG Jingxi

2022, 50(10):  87-93.  doi:10.12141/j.issn.1000-565X.210510

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Accurate measurement of steam humidity is of great significance for maintaining the stability of steam turbine. The measurement of steam humidity is affected by the thickness of the water film. To solve the problem of measuring the thickness of water film on the inner wall of cylindrical cavity, this paper proposed a new method for measuring the thickness of dielectric film on the inner wall of cylindrical cavity based on the principle that the resonant frequency of a dielectric loaded cylindrical cavity varies with the thickness of dielectric film. The characteristic equation of cylindrical waveguide filled with double-layer dielectric was derived according to Maxwell’s equations and boundary conditions of dielectric loaded cylindrical waveguide. Under the given dielectric film thickness, the relationship between the phase constant of propagation mode and the working frequency of waveguide was given according to the characteristic equation. Based on the derived characteristic equation, the study established the model of relationship between the thickness of dielectric film on the inner wall of cylindrical cavity and the value of resonance frequency. The resonant frequencies corresponding to different media and different thicknesses were obtained by numerical solution with MATLAB software. Under the same parameters as those set by numerical solution, the resonant frequencies corresponding to the cylindrical cavity loaded with double-layer media were simulated and analyzed by HFSS software. Comparing the simulation data with the theoretical calculation data, the results show that with the increase of the dielectric film thickness, both of them show a parallel downward trend, and the resonance frequency offset is linearly related to the dielectric film thickness, which verifies the feasibility of this method. There is no limit to the thickness of dielectric film measured by this method (within radius), and this method is universal. A network analyzer was used to carry out related experiments, and a practical measurement system was built. When the thickness of the medium is within 100 μm, every 10 μm interval, the interval of the measured medium thickness value is about 6.8 μm ~ 7.1 μm, and the relative measurement error does not exceed 24.6%. The result of comparison between theoretical data and experimental data shows that the data measured by this method is more accurate.

Chaotic Communication System of Noise Reduction Improved Multiple User Multiple Ary Correlated Delay Shift Keying



HE Lifang, WANG Lei, ZHANG Tianqi

2022, 50(10):  94-105.  doi:10.12141/j.issn.1000-565X.210755

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In view of the poor transmission efficiency of Correlation Delay Shift Keying (CDSK) system, this study proposed a noise reduction improved multiple user multiple ary correlated delay shift keying (NR-I-MUMA-CDSK) based on Schmidt Orthogonalization Chaotic communication system. The system uses Schmidt orthogonalisation to generate N different sets of orthogonal chaotic sequences at the transmitter side, and then copies the generated sequences P times. It also employed multiple ary information mapping and multi-carrier technology, enabling each user to carry K bits of data. It also designed to transmit N sets of user information on a single carrier wave by superimposing N different orthogonal chaotic signal carriers. The transmission rate and energy efficiency of the system were improved. The receiver uses the moving average filter to process the signal, reducing the noise variance from N_{\mathrm{0}}/\mathrm{2} to N_{\mathrm{0}}/\mathrm{2}P. This reduces noise interference, which in turn reduces the system bit error rate(BER). The theoretical formula derivation and simulation analysis of the system in Additive White Gaussian Noise (AWGN) and Rayleigh fading channel were carried out respectively. The results show that, compared with CDSK, the system improves the information transmission rate and energy efficiency. The information transfer rate increases with N and K, and the average bit energy decreases by nearly 100% with K. The effects of different parameters on the system BER were verified by simulation. The results show that the system BER is inversely proportional to P and the binary number M, directly proportional to N and R, and consistent with the deduction of theoretical formulas under both channels. The effects of path number L and path gain on the bit error rate were verified by simulation in Rayleigh fading channel. Compared with many chaotic communication systems, the system BER is greatly reduced, and the system BER decreases with the increase of M, which proves that the system has good theoretical value and practical engineering significance.

Vibration Testing of Poppet Valve Based on Virtual Binocular Vision



LI Beibei, WEI Lingxing, LIU Xiumei, et al

2022, 50(10):  106-113.  doi:10.12141/j.issn.1000-565X.220287

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The vibration of the spool caused by the change of the medium flow near the spool of the hydraulic valve has an important influence on the stability and service life of the poppet valve. In order to investigate the three-dimensional vibration characteristics of the poppet valve, this paper proposed a visual experiment method based on virtual binocular vision, and obtained the image sequence of the valve core vibration. The spatial coordinate value of the geometric vertex of the spool was obtained by fitting the outline of the spool, which improves the measurement accuracy of the spool position. By analyzing the vibration characteristics of the valve core under different inlet and outlet pressures, spring stiffness, and other conditions, it is shown that the spatial range and impact degree of the valve core vibration are closely related to the operating conditions of the hydraulic system and the valve core structure. When the inlet pressure increases from 3.2 MPa to 4.4 MPa, the vibration of the valve core gradually intensifies, and the dispersion increases; when the precompression amount increases from 14 mm to 17 mm, the valve core vibration tends to be stable and the dispersion decreases. In addition, with the increase of the spring stiffness and the valve core half cone angle, the dispersion of the valve core vibration also shows a trend of decreasing firstly and then increasing, and its minimum values appear when the spring stiffness is 2 N/mm and the valve core half cone angle is 30°. In the projection of the spool vibration along the axial, front, and side directions, the waveform factor of the side radial vibration is larger than that of the front radial, while the waveform factor of the axial vibration is the smallest. The variation trend of the waveform factor is consistent with the variation trend of the dispersion. The dispersion of the valve core vibration is positively correlated with the waveform factor, and the waveform factor is the smallest when the valve core half cone angle is 30° and the spring stiffness is 2 N/mm. The research results can provide theoretical support for the structural design of the hydraulic valve with the poppet valve structure, thereby improving the stability of the hydraulic system and reducing the damage to the hydraulic valve caused by vibration.

Quasi-Static Contact Characteristics of Double Gearboxes with Coupling Misalignment



GONG Jingyi, YANG Long, LIU Geng, et al

2022, 50(10):  114-123.  doi:10.12141/j.issn.1000-565X.220130

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Due to its vibration reduction and error compensation capabilities, diaphragm couplings are widely used in marine multi-gearbox systems. However, due to the existence of factors such as installation error, system load deformation and asymmetric elastic support, the coupling will inevitably produce misalignment and affect the operation of the gear system. This paper proposesed a calculation method for the quasi-static contact characteristics of the gear pair considering the diaphragm coupling misalignment. By combining the coupling misalignment model, the meshing misalignment model, the system static equilibrium equation and the tooth surface load contact analysis model (LTCA) to construct an iterative calculation process, the contact characteristics analysis of the gear pair under the non-ideal meshing condition caused by the coupling misalignment was realized. Taking the double-gearbox transmission system in the multi-gearbox transmission system of ships as the research object, the influence of coupling misalignment and load torque on the meshing characteristics of the double-helical gear pair was studied. The research results show that the misalignment of the coupling on the double-helical gear near the coupling has a greater impact so that the tooth surface load is asymmetrically distributed, the tooth surface appears disengaged area, away from the coupling gear is not affected by it. As the amount of misalignment increases, the amount of meshing misalignment increases, the gear pair disengagement area increases, the actual contact line length becomes smaller, and the gear pair meshing stiffness decreases. At light loads, the gear pair contact state is more sensitive to coupling misalignment. The tooth surface will produce a large disengagement area and the mesh stiffness curve changes significantly. With the increase of torque, the tooth surface reaches the complete contact state. With the increase of torque, the tooth surface reaches a complete contact state, and there is no disengagement area on the tooth surface. However, due to the misalignment force of the coupling, the meshing misalignment between the left and right tooth surfaces of the double-helical gear pair is asymmetric, so the tooth surface presents the phenomenon of partial load.

Kinematic Characteristics and Dynamic Analysis of Recirculating Planetary Roller Screw Mechanism



QIAO Guan, LIAO Rong, JIANG Guangjun, et al

2022, 50(10):  124-131.  doi:10.12141/j.issn.1000-565X.220120

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The recirculating planetary roller screw mechanism is a transmission mechanism that is engaged by the screw or nut thread and multiple circular groove rollers. This study theoretically analyzed the working principle and motion relationship of the recirculating planetary roller screw mechanism, and established the 3D model of the recirculating planetary roller screw mechanism. The 3D model was imported into the multi-rigid-body dynamics simulation software ADAMS, and the reasonable connection relationship of virtual prototype was set. The dynamics analysis was carried out and related parameters such as angular speed, velocity, force and torque were extracted. The results show that the simulated value of roller angular speed is 28.28 rad/s, the angular speed of roller is -5.20 rad/s, the nut movement velocity is 1.98 mm/s, and the nut displacement is 2 mm. The above values were compared with their corresponding theoretical values, and the error was found to be less than 5%, thus verified the correctness of the simulation results. The contact force of the roller contacting with the screw and the nut respectively presents sine curve characteristics in the nut threadless area.When the load is 5, 10 and 15 kN, the maximum peak of the collision force between the same roller and convex platform of cam ring under different loads are 113.92, 32.31 and 54.08 N, respectively. Besides, the fluctuation range of the maximum peak of the collision force between diffe-rent rollers and convex platform of cam ring under the same load is similar to the above values, thus the collision force between the roller and convex platform of cam ring peak value is not affected by the load size. The collision torque between the roller and the carrier increases under higher load; the angular speed of the roller begins to change in the nut threadless area during the operation of the recirculating planetary roller screw mechanism, and the maximum sudden change occurs at the contact between the roller and the convex platform of cam ring. This study has certain reference significance for optimizing the overall performance of the recirculating planetary roller screw mechanism.

Research on Teleoperation and End Force Feedback System of Soft Actuator



ZHOU Junjie, ZHANG Lingyu, YU Yang, et al

2022, 50(10):  132-139.  doi:10.12141/j.issn.1000-565X.220164

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The soft actuators are flexible in nature, and as an end-effector, it can realize functions that are difficult to be achieved by the traditional rigid actuator, such as flexible grasping and flexible motion. Moreover, it is friendly to human body and has a high degree of security in human-machine interaction. This paper presented a teleoperation and end force feedback system of soft actuator. Its control was studied based on kinematic model and force feedback method. The bending model, elongation model and force feedback model were established, and the control method and control flow were presented. Through a pair of handles, the operator realized the remote control of the soft actuator located in another physical space, which can not only control the soft actuator to bend in any direction, but also control its elongation with the same curvature. The soft actuator is composed of three bellows uniformly arranged in the circumferential direction, and the force feedback effect of the end is realized by the pneumatic components inside the handle. The pair of handle is a new type of main hand structure, including handle A and handle B, which control bending and elongation of soft mechanical arm respectively. Handle B has a certain force sense of presence. The proposed system was experimentally verified, and the functions of the soft manipulator were proved in the bending, elongation and force feedback stages, and the skin model was equipped to verify the functions of the soft actuator as the end-effector in the ultrasonic detection scene. The experimental data show that the pressure at the ends of soft actuator is 7 N, force feedback control loop time is around 1 s. The system established in this paper, on the one hand, plays the flexibility of the soft actuator, on the other hand, it also increases the function of remote control, and has a powerful sense of presence, which can be widely used in telemedicine, massage and other fields in the future.

Terminal Force Soft Sensing of Hydraulic Manipulator Based on Joint Torque Compensation



LI Gang, LI Feng, DING Ruqi, et al

2022, 50(10):  140-152.  doi:10.12141/j.issn.1000-565X.220274

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To meet the requirements of the high-precision operation of the hydraulic manipulator in a complex environment, it is necessary to equip it with an accurate force measurement system. Due to the large and complex end-effector contact force against the working environment, the force sensor is vulnerable to damage. Therefore, focu-sing on the accurate measurements of the terminal force with force sensorless, this paper proposed a force soft-sensing method of hydraulic manipulator based on joint torque compensation, taking 3-D of hydraulic manipulator as the research object. A finite Fourier series model was used to design the excitation trajectory, and the recursive least squares method was used to identify the dynamics parameters of the manipulator. The nonlinear friction torque model was used to replace the Coulomb viscous friction model to improve the precision of manipulator dynamics model. A neural network joint torque compensation model was established to reduce the influence of uncertain factors on the precision of the dynamics model. The AMESim/Simulink co-simulation model was built to design the triangular trajectory of the hydraulic manipulator end-effector, which verified the high accuracy of the dynamic model proposed in this research. A constant force load of 500 N and a variable force load of 0~500 N were applied to the horizontal and vertical direction of the end-effector respectively. Under the constant force load, the soft sen-sing accuracy of the end force in the horizontal and vertical directions is 4.84% and 2.79%, respectively. Under the variable force load, the accuracy of the soft sensor can reach 5.73% in the horizontal direction and 4.81% in the vertical direction. By comparing the end force soft sensor accuracy with that before optimization, it is verified that the force soft-sensing model of hydraulic manipulator based on joint torque compensation can effectively improve the accuracy of end-effector contact force.