Volume 46,Issue 3,2023 Table of Contents

1 Modeling method and application of a novel helix deformation soft actuator

LI Jiaxing , TANG Xianzhi , CHEN Yuanjie , LUO Ji , JIANG Pei

2023, 46(3):1-9,102. DOI: 10.11835/j.issn.1000-582X.2021.18

[Abstract](493) [HTML](684) [PDF 7.73 M](793)

Abstract:
The soft actuator has great development potential in the fields of medical care, rescue, service, and manufacturing with the advantages of a high degree of flexibility and good adaptability. Currently, the deformation types of the soft actuator are mainly bending, expansion and contraction, which limits the greater flexibility of the soft actuator. To improve the operation of the soft actuator, a new type of soft actuator with helical deformation is proposed. The proposed soft actuator is driven by the pulling cable, and the helical deformation is generated by the scaffold so as to realize the controllable movement of the soft actuator end in three-dimensional space. Based on the kinematics theory of constant curvature continuous robot and the geometric relationship of helical deformation, a kinematic model for constant curvature helical deformation is developed to obtain the coordinate transformation matrix of the actuator end in the global coordinate. Simulation and experiments show that the model accuracy is greater than 98%. By presenting an accurate kinematics model for the helical deformation soft actuator, this study provides a theoretical model basis for the construction of the ultra-high flexibility gripper based on this actuator in the future.

2 Integrated optimization of the structure and control parameters of the battery swap robot lifting system

LIN Lihong , CUI Jiabin , HU Zengming , ZHANG Jinwen , LI Chengyuan

2023, 46(3):10-21. DOI: 10.11835/j.issn.1000-582X.2022.006

[Abstract](322) [HTML](450) [PDF 4.37 M](724)

Abstract:
To improve the battery life of the battery swap robot, an integrated optimization method of the battery swap robot lifting system structure and control parameters is proposed. Firstly, the preliminary parameter matching on the structure of the battery swap robot lifting system is performed. Secondly, a sliding mode variable structure controller is designed, and based on this, an energy consumption model is established for the lifting process of the lifting system. Then, an optimization model targeting the energy consumption of the lifting system and the steady-state error of angular displacement is established, and the multi-objective optimization algorithm is used to solve it to obtain the optimal combination of the structure and control parameters for the lifting energy consumption and angular displacement error. Finally, the reliability of the optimization results is verified through experiments. The optimization results show that the steady-state error is reduced by 53.68% and the energy consumption of the lifting system is reduced by 10.93% after the integrated optimization.

3 Lightweight design method of coaxial main reducerbased on graph theory

ZENG Li , HU Minghui , CHEN Guangyan

2023, 46(3):22-31. DOI: 10.11835/j.issn.1000-582X.2021.025

[Abstract](348) [HTML](623) [PDF 8.17 M](817)

Abstract:
Main reducer is an important component of helicopter drivetrain, and its quality has a crucial impact on the whole transmission. In this paper, taking coaxial counter rotating helicopter’s gearbox as objective, a design method of main reducer configuration based on graph theory is proposed. Firstly, connection laws, boundary conditions and gear units are obtained by review of existing literature of the reducer. Then, automatic generation of adjacency matrix corresponding to main reducer is realized before transforming adjacency matrix to model of graph theory. After setting up rules and screening schemes to yield feasible solution set of the reducer, an optimization procedure, which aims at screening gear weight of feasible solutions and obtaining the solution of the lightest gear weight, is built by SQP (sequential quadratic programming algorithm) method based on gear strength constraints. Finally, to verify the rationality of this method, the designing and screening processes of 3-stage main gearbox schemes of cylindrical gear configuration are listed.

4 Analysis and optimization of the effective length of the slotting cutter for circular spline in double-circular-arc harmonic drive

WANG Shipu , SONG Chaosheng , LI Xinzi , SUN Jianquan , ZHU Caichao

2023, 46(3):32-44. DOI: 10.11835/j.issn.1000-582X.2022.003

[Abstract](290) [HTML](580) [PDF 5.63 M](799)

Abstract:
In order to predict and prolong the effective length of the slotting cutter of the double-circular-arc harmonic circular spline, several models are established: 1) the mathematical model of the circular spline tooth profile; 2) the mathematical simulation model of slotting the circular spline by the kinematic method; 3) the mathematical simulation model of grinding the slotting cutter by the tooth profile normal method, to obtain the equivalent tooth profile and the machining error and predict the effective length of the slotting cutter. Based on these models, the effective length of the slotting cutter is prolonged by optimizing the tooth profile of the grinding wheel and the tooth number of the slotting cutter. The results show that before optimization, the effective length of the slotting cutter with 55 teeth is 2.1 mm and the tooth profile error of the circular spline slotted by the 0-cross section slotting cutter is 2 μm. After optimizing the tooth profile of the grinding wheel, the maximum of the tooth profile error of the circular spline slotted by the 0-cross section slotting cutter is 0.14 μm. The effective length of the slotting cutter increases as the number of slotting cutter tooth increases 4.8% for 42 teeth, 52% for 55 teeth, and 81% for 68 teeth.

5 Non-contact detection and deviation evaluation method of small pitch roller profile

XU Hongwei , WEI Peitang , ZHOU Pengliang , DU Xuesong

2023, 46(3):45-57. DOI: 10.11835/j.issn.1000-582X.2022.007

[Abstract](339) [HTML](478) [PDF 11.03 M](638)

Abstract:
Planetary Roller Screw Mechanism (PRSM) is a new type of heavy duty precision transmission device, which can realize the transformation from rotating motion to linear motion and vise versa. The machining quality of the thread tooth directly determines its transmission accuracy and load-bearing performance. To address the problem of non-complete short arc detection and evaluation of PRSM roller tooth profile with small pitch, a roller tooth profile curve fitting method based on nonlinear interior point algorithm was proposed by using high-precision CMM for non-contact detection of roller axial section tooth profile, and the fitting accuracy of roller tooth profile curve was verified. The evaluation model and evaluation method of roller thread tooth profile deviation were established for the first time. The evaluation chart of roller tooth profile deviation based on the model was drawn, and the distribution of roller tooth profile deviation was analyzed and summarized. The proposed PRSM roller tooth profile detection and evaluation method with small pitch had a fitting accuracy of 1.5×10^-4. The fitting accuracy of tooth profile radius and tooth profile center z₀ coordinate could be controlled at 6 μm and 9.8 μm, respectively. It can quantitatively evaluate the shape accuracy and position accuracy of roller tooth profile, and has practical feasibility in engineering practice.

6 Influence of typical under-body structureon car crosswind stability and the mechanism

YUAN Zhiqun , JIN Chen , HU Yongzhu , LIU Yufeng , LIN Li , ZHANG Yi

2023, 46(3):58-70. DOI: 10.11835/j.issn.1000-582X.2023.03.006

[Abstract](306) [HTML](524) [PDF 23.06 M](619)

Abstract:
There are two typical design solutions in the car body design and layout: concave-convex under-body and smooth under-body. However, the effects of the under-body structure on the crosswind stability of the car is not clear, and clarifying the effects not only provides reference data for the design and layout of the bottom structure, but also is a key technical problem for the crosswind stability evaluation of car. Firstly, the numerical calculation model of typical bottom structure cars was established, and the influence laws of different side wind speeds on the aerodynamic force and aerodynamic moment of the cars were analyzed. Secondly, based on the coupling method of automobile aerodynamics and automobile system dynamics, the crosswind stability analysis and evaluation model of typical bottom structure cars was established, and the influence laws and mechanism of the under-body structure on the lateral motion, yawing motion and side-slip motion of the car were studied. The study shows that the concave-convex bottom structure causes an increase in aerodynamic lift force, pitch moment, drag, and side force, which not only intensifies the lateral motion and yaw motion of the cars under crosswind, but also increases the risk of cars skidding. The lower the tire-road friction coefficient, the greater the effect of the concave and convex bottom structure on the lateral motion and yaw motion, and the smaller the effect on the limit wind speed of lateral slipping.

7 Influence of different parts of the claw alternator on aerodynamic noise

HUANG Taiming , LI Weiping , JI Nianzhou , GUAN Chenglin , YUE Wanhao

2023, 46(3):71-83. DOI: 10.11835/j.issn.1000-582X.2021.024

[Abstract](290) [HTML](831) [PDF 18.90 M](619)

Abstract:
In order to understand the effects of different parts on the aerodynamic noise of the claw alternator for vehicle at high rotational speeds, the aerodynamic noise characteristics of the claw alternator were studied by numerical simulation. The no-load acoustic power level experiments of the claw alternator for vehicle were carried out to verify the accuracy of the numerical simulation. The noise sources of each order were determined by removing front fan or rear fan, or claw, and replacing claw with cylinder envelope. The contribution levels of front and rear fans and claw to noises at different orders were clarified. The results show that dipole was the main noise source at high rotational speed. The front fan mainly influenced the aerodynamic noise at 8th, 10th, 12th and 16th order. When the front fan was removed, the aerodynamic noise at 12th and 16th order was reduced by 6.54 dB(A) and 9.04 dB(A), respectively. The rear fan mainly affected the aerodynamic noise at 6th, 8th and 10th order. When the rear fan was removed, the aerodynamic noise at 6th, 8th and 10th order was reduced by 11.75 dB(A), 2.42 dB(A) and 7.38 dB(A), respectively. With or without claw had slight influence on the aerodynamic noise, but when the cylinder envelope was used to replace the claw, the flow field was affected, causing a certain change of the noise at the 8th order and also verifying that the front and rear fans were main sources of the aerodynamic noise.

8 A linear fatigue life prediction model based on dynamic residual S-N curve

ZHANG Tuo , LIU Kun , HE Aiming , SUN Yizhong , SHI Wankai

2023, 46(3):84-93. DOI: 10.11835/j.issn.1000-582X.2021.22

[Abstract](344) [HTML](743) [PDF 5.08 M](827)

Abstract:
In order to estimate the fatigue life of structures under variable amplitude loading, based on the dynamic residual S-N curve, the cumulative fatigue damage of materials under loading was quantified combined with the degradation law of materials, and a linear fatigue damage prediction model under variable amplitude loading was proposed. According to the fatigue life test data of hot-rolled 16Mn steel and 20Cr2Ni4A standard cylindrical gear under multistage load, the fatigue life prediction accuracy of the proposed model was verified. The results show that the prediction results of the linear fatigue life prediction model based on strength degradation is closer to the experimental results than those of the traditional Miner’s rule and material memory degradation accumulation model, showing higher prediction accuracy.

9 A fast life prediction method for hard metals under multiaxial high-cycle fatigue loading

LIU Tianqi , ZHANG Guangxin , ZHANG Tian , LIU Hao , QI Xinxin , SHI Xinhong

2023, 46(3):94-102. DOI: 10.11835/j.issn.1000-582X.2021.262

[Abstract](254) [HTML](506) [PDF 3.06 M](825)

Abstract:
According to the study of multiaxial fatigue life of 30CrMnSiA steel, the concept of equivalent S-N curve is proposed based on the uniaxial tension-compression and pure torsion S-N curves in this paper. Based on the equivalent S-N curves, an empirical formula is established to predict the multiaxial fatigue life of hard metal materials. The empirical formula is verified by predicting the fatigue life of various hard metal materials in the literature. Results show that more than 94.0% of the data points are in the ±3 times fatigue life scatter band, and more than 81.8% of the data points are in the ±2 times fatigue life scatter band.

10 Robust control strategy for dynamic lateral obstacle avoidance of intelligent vehicle considering parameter perturbation

NIE Zhigen , SHEN Ao , WANG Wanqiong , WANG Chao

2023, 46(3):103-117. DOI: 10.11835/j.issn.1000-582X.2022.001

[Abstract](282) [HTML](610) [PDF 11.55 M](558)

Abstract:
The dynamic change of velocity and acceleration of obstacle vehicle under the actual dynamic traffic environmental can cause the unsmooth change of the real-time reference trajectory of lateral obstacle for intelligent vehicle. To overcome the poor control effect of the controller caused by the unsmooth trajectory, parameter perturbation and signal disturb, the robust control strategy for dynamic lateral obstacle avoidance of intelligent vehicles considering parameter perturbation was presented. The strategy includes dynamic trajectory planning and dynamic trajectory tracking. In the dynamic trajectory planning, according to dynamic change of acceleration and velocity of obstacle vehicle, the dynamic trajectory planning algorithm based on obstacle avoidance limit position was proposed to plan real-time reference trajectory which can ensure lateral safety of obstacle avoidance for intelligent vehicles. In the dynamic trajectory tracking, with consideration of the perturbation of mass, moment of inertia and front and rear lateral stiffness parameters, a robust controller considering parameter perturbation was designed to accurately track real-time reference trajectory of lateral obstacle avoidance. Finally, the proposed dynamic lateral obstacle avoidance control strategy was validated by combining Matlab/Simulink with Trucksim. The simulation results indicate that according to the real-time change of acceleration and speed of obstacle vehicle, the real-time safety reference trajectory of lateral obstacle avoidance can be achieved in the dynamic trajectory planning. The real-time reference trajectory of lateral obstacle avoidance can be smoothly,stably and well tracked in the dynamic trajectory tracking. Therefore, the proposed control strategy realizes the dynamic lateral obstacle avoidance of intelligent vehicles while ensuring the vehicle yaw stability during the whole process of obstacle avoidance.

11 Identification of road friction coefficient based on Elman neural network

WU Wenguang , ZHANG Fanhao , XU Menglong

2023, 46(3):118-128. DOI: 10.11835/j.issn.1000-582X.2021.023

[Abstract](330) [HTML](419) [PDF 8.54 M](894)

Abstract:
Accurate and efficient identification of road adhesion coefficient provides important input parameters for active safety system. In this paper, an identification method of road friction coefficient based on Elman neural network was proposed. Through Carsim/Simulink co-simulation, 63 driving conditions and 20 important dynamics responses of a vehicle were obtained. The identification model of road friction coefficient based on Elman neural network was constructed. The road surface with friction coefficient from 0.2 to 0.9 was identified. The average absolute percentage error was 4.92% and the accuracy was 91.22%. Compared with traditional BP neural network method, this method reduced the average absolute percentage error of road friction coefficient by 2.24% and improved the accuracy by 9.82%. Vehicle experiments on wet and dry asphalt pavement verified the effectiveness and feasibility of the proposed method.

12 A packed malware variants detection method based on weighted dynamic behaviour feature clustering

CHEN Cen , LI Nuannuan , CAI Junfei , GUO Zhimin , LYU Zhuo

2023, 46(3):129-136. DOI: 10.11835/j.issn.1000-582X.2023.03.012

[Abstract](307) [HTML](608) [PDF 2.41 M](700)

Abstract:
In order to avoid malware detection, attackers often use packing techniques to encrypt or compress malware binaries, which makes it difficult for security analysts and malware detectors based on traditional static analysis to use reverse tools, such as disassembly tools, to statically analyze malware before it runs. Currently, to detect packed malware, dynamic analysis methods are mainly used. However, due to the limitation of the types of packing tools and packed samples, as well as the confusion noise caused by malware packers, traditional machine learning based detection methods have insufficient accuracy. In this paper, to filter the packing behavior, the system call behavior features of packed malware are extracted and analyzed, and then sensitive behaviors are identified and filtered out. Next, the feature dimensions of system call behaviours are reduced by weighting to improve the contribution of each feature. Finally, these behaviours are analyzed by using density-based clustering, realizing the detection of unknown variants of packed malware and the update of the detection model. The experimental results show that the proposed packed malware variants detection method based on weighted clustering of sensitive behavior features achieves 3.9 % false alter rate and significantly reduces the false alter rate compared with that of some other machine learning-based detection methods.

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