05 March 2023, Volume 59 Issue 5

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  • HU Yawen, JIANG Li, YANG Bin
    Journal of Mechanical Engineering. 2023, 59(5): 1-10. https://doi.org/10.3901/JME.2023.05.001
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    In recent years, the bidirectional bio-machine interface with the ability of neural control and sensory feedback has become the development trends of intelligent upper limb prosthesis. Most of the research focuses on the mechanism, sensor design and neural control of upper limb prosthesis, while less research on sensory feedback. The lack of reliable sensory feedback reduces the operational performance and limits the practical application of prosthetics. Firstly, the development status of bidirectional bio-machine interface of intelligent prosthesis is briefly summarized. Sensory feedback methods based on transcutaneous electrical nerve stimulation, vibration stimulation and pressure stimulation are introduced in detail. Sensory feedback strategies including sensory substitution, modality matched feedback and somatotopic matched feedback are also discussed. Based on the analysis, the naturalness of upper limb prosthetic sensory feedback and the multimodality of interactive information are prospected.
  • MA Jiliang, PENG Jun, GUO Yanjie, CHEN Xuefeng
    Journal of Mechanical Engineering. 2023, 59(5): 11-28. https://doi.org/10.3901/JME.2023.05.011
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    Wall climbing robot is an electromechanical system that can move on the surface of objects and complete operations with multiple degrees of freedom. It is especially suitable for performing special tasks, so it has a good application prospect and broad market demand. According to different adhesion mechanisms, wall climbing robots can be divided into negative pressure adsorption, electrostatic adhesion, gecko-like dry adhesion, bionic wet adhesion and so on. The research status of wall climbing robots at home and abroad is summarized from three aspects: adhesion mechanism, application scope and adhesion characteristics. In order to analyze and compare the load performance of different types of wall climbing robots, an analysis method of robot overall adhesion performance based on specific adhesion energy density is proposed, and a new material and structure design idea is proposed to solve the contradiction between large load and small volume. The application prospect of micro wall climbing robot in aero-engine fault detection is analyzed, and its development trends in the fields of intelligent materials, new driving, miniaturization and collaboration of adhesion mechanism are summarized.
  • QI Wenqian, SUN Shouqian, CHEN Chao, ZHANG Yebingqing, ZHAO Dongwei
    Journal of Mechanical Engineering. 2023, 59(5): 29-40. https://doi.org/10.3901/JME.2023.05.029
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    Currently, there is a lack of research on wearable devices that focus on assisting lower limbs to improve physical fitness training. The synergistic research of exoskeleton and virtual reality is an emerging direction in recent years. The exoskeleton system with multimodal information fusion can optimize the training effect and experience. Therefore, a multimodal interaction system of the lower limb exoskeleton for athletic training is developed. Which not only provides a wide variety of standardized training but also realizes a multisensory immersion experience. Firstly, a multi-degree-of-freedom step-by-step action planning method is designed to reproduce training actions based on lower limb movement action points. Second, a multimodal interaction system for the lower limb exoskeleton is proposed to realize the presentation and indication of normative movements in information space through a virtual reality athletic training simulator. The action data set and the lower limb exoskeleton robot are constructed to realize the assistance and correction of basic training in physical space. The system is based on a multimodal interaction execution strategy to give trainers visual, auditory, and tactile multisensory feedback in real-time to achieve an immersive experience that meets safety norms. Finally, the system is evaluated through two experiments on system functionality and user experience. The functional experiment proves that the system can improve the action accuracy rate by 27.62% on average compared with the original traditional training, and has certain generality. The experimental results of user experience show that the system’s function meets the design expectations, and the comfort compared to other indicators needs to be improved.
  • MO Xiaojuan, GE Wenjie, REN Yifei, ZHAO Donglai, WEI Dunwen
    Journal of Mechanical Engineering. 2023, 59(5): 41-52. https://doi.org/10.3901/JME.2023.05.041
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    A locust-inspired eight-bar jumping robot design method is proposed in order to mimic the straight-line trajectory of the tarsus end of locusts’ hindleg during take-off and jumping stability. The dimensional parameters are optimized based on beetle antennae search algorithm (BAS) and established kinematic model. The trajectory of the equal tarsus end of the optimized eight-bar jumping mechanism is very similar to the one of locusts, close to a straight line. The dynamic model of eight-bar jumping mechanism is established using lagrange equation, and the influence of the centroid location of equivalent body bar on the take-off performance is analyzed. It is found that increasing the mass of the equivalent tarsus bar is helpful to obtain better dynamic stability during take-off. Based on the results of kinematic and dynamic analysis result, a locust-inspired eight-bar jumping robot is designed and fabricated, and the high-speed camera is used to build an experimental platform to record its take-off process. It is verified that the mass of the equivalent tarsus bar has an effective adjustment effect on the dynamic stability of the take-off.
  • ZHOU Jian, ZHENG Lianyu, FAN Wei, ZHANG Xuexin, CAO Yansheng
    Journal of Mechanical Engineering. 2023, 59(5): 53-66. https://doi.org/10.3901/JME.2023.05.053
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    Due to the geometric and non-geometric errors of the robot body structure, the actual trajectory of the robot has a big deviation from its nominal trajectory, which seriously limits the application of the robot in machining. Note that the positioning accuracy of the robot will be significantly deteriorated with the degradation of the working performance of the robot during the service time, in addition to the differential distribution of the positioning error levels in the workingspace of the robot. To cope with this problem, an adaptive online compensation method based on fixed-length memory window incremental learning is proposed to compensate the positioning errors of the industrial robot during long-term service. Firstly, the correlation between positioning errors and robot poses is quantitatively studied, and the workspace is divided into several pose blocks and a calibration sample library is created, thus an adaptive optimization mechanism of mapping model is established to address the problem of differential distribution of error levels in workingspace. Secondly, the incremental learning algorithm with fixed-length memory window is designed to overcome the catastrophic forgetting of neural network model and balance the accuracy and efficiency of establishing the mapping relationship between new and old robot pose data in online mode, solving the problem that robot performance degradation aggravates positioning errors and affects the applicability of pose mapping model. Finally, the proposed method is applied to long-term compensation case of Stäubli robot and UR robot, and experimental result shows the proposed method reduces the positioning error of the Stäubli robot from 0.85 mm to 0.13 mm and UR robot from 2.11 mm to 0.17 mm, respectively, outperforming similar methods.
  • LIU Dawei, LI Bingbing, FU Zhanglei, JIN Xin
    Journal of Mechanical Engineering. 2023, 59(5): 67-76. https://doi.org/10.3901/JME.2023.05.067
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    For the difficult manufacture of the core components and the unknown dynamic slip-limiting mechanism of the variable transmission ratio differential, a new type of variable transmission ratio differential based on non-circular face gear is presented, with the configuration principle and dynamic antiskid slip mechanism of the differential studied. The transmission principle of cylindrical gear and non-circular face gear is given to illustrating the the configuration principle of the new differential. For the condition that the vehicle is in trouble due to the skidding of the single-side drive wheel, the kinematics expression of the non-circular gear differential is obtained according to the mechanism rotation method. Based on the theory of advanced dynamics, the mechanics equilibrium equation of each component of non-circular face gear differential is constructed, with the vehicle traction force formula deduced. Then a dynamic model of horizontal movement of the vehicle driven by a non-circular face gear differential is established. The torque distribution of the differential on the two driving wheels, the change of dynamic traction force and the vehicle's escape behavior are studied by the method of test and simulation. The results show that the non-circular gear differential makes the slip wheel produce periodic inertia torque, which is beneficial to improve the maximum traction force of the vehicle and is the fundamental reason for the dynamic antiskid slip of the variable transmission ratio differential. Increasing the input speed of the differential not only could effectively improve the average speed of the vehicle out of distress but also increase the amplitude of the flexible impact on the vehicle. The research results provide a certain theoretical basis for the design of variable transmission ratio differential.
  • ZHAO Jing, ZHOU Zhenyong, ZHANG Ziqiang
    Journal of Mechanical Engineering. 2023, 59(5): 77-88. https://doi.org/10.3901/JME.2023.05.077
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    To solve all the inverse kinematics solutions of the redundant manipulators, a new self-motion manifolds calculation method is proposed to calculate the self-motion manifolds including all inverse kinematics solutions. This method is based on the artificial bee colony algorithm to complete the initial value search of each branch of self-motion manifolds, which solves the problem that the initial value of the branch is difficult to determine. Furthermore, a branch search strategy is proposed to realize the search of complete manifolds branches. On this basis, to improve the calculation efficiency of self-motion manifolds, the congruence and gradient of self-motion manifolds are defined, and the manifolds library is established. By indexing the self-motion manifolds in the manifolds library, the self-motion manifolds at any position in the workspace can be quickly calculated. The manifolds library is used to analyze the global performance of the manipulators, and the local optimal configurations on each branch are obtained. The local optimal configurations of each branch are used as the initial configuration for joint trajectory planning, and the global optimal joint trajectory planning for a given end trajectory is realized. The 4R manipulator and 7R manipulator verify the method's effectiveness. This method can also be used to calculate the self-motion manifolds of hyper-redundant manipulators, and it has good universality.
  • XIANG Hongbiao, YANG Dahu, YANG Lu, WANG Shoujun, ZHANG Mian, HUANG Xian, HUO Wenxing
    Journal of Mechanical Engineering. 2023, 59(5): 89-99. https://doi.org/10.3901/JME.2023.05.089
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    The miniature swimmer made of magnetic elastic material can achieve continuous deformation through the external uniform magnetic field to complete the swimming action. Despite visual feedback improving path tracking accuracy, visual closed-loop robot control is prone to recognition errors and tracking failures under complex backgrounds. Aiming at the above problems, firstly, the obstacle information in complex environments is obtained, and the improved RRT* algorithm (IIC-RRT*) is proposed for path planning. In addition, YOLOv5 based on circular smooth label (CSL-YOLOv5) recognition and tracking algorithm is used to update the central position and rotation angle of miniature swimmers in real time under complex conditions. Using this method, the miniature swimmer is controlled via dual closed loop servos with position and angle against a complex obstacle background. According to the experimental results, the proposed path planning algorithm improves the efficiency and smoothness of the path generation process, while the recognition and tracking algorithm improves the recognition stability and accuracy of the miniature swimmer. This work may provide an innovative idea for the precision control of the magnetic miniature swimmer under complex backgrounds.
  • WANG Rugui, DONG Yichen, CHEN Huiqing
    Journal of Mechanical Engineering. 2023, 59(5): 100-111. https://doi.org/10.3901/JME.2023.05.100
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    According to the working principle of the metamorphic industrial robot, its working trajectory model is established. And based on this model, a time optimization trajectory planning method of the metamorphic industrial robot is proposed. This method focuses on the transformation process of robot configuration and transforms the trajectory planning problem into an internal and external nested optimization problem for analysis. The design variables, objective function and constraints of the optimization problem are presented respectively, and the mathematical model of the time optimization trajectory planning problem of the metamorphic industrial robot is obtained. The proposed method is used to study the trajectory planning of the metamorphic palletizing robot developed by our research group. According to its working trajectory model, the mathematical model of the optimization design problem is established. After presenting the calculation method for coefficients of the joint angle interpolation functions, the optimization problem is solved by nested PSO algorithm, and the optimized joint angle functions and theoretical working trajectory are calculated. Compared with the actual working track gained by the experiment, the feasibility of the proposed method is verified. This work provides a reference for the research of motion planning of metamorphic robots.
  • SUN Peng, DAI Xianyong, LI Yanbiao, YANG Kui
    Journal of Mechanical Engineering. 2023, 59(5): 112-120. https://doi.org/10.3901/JME.2023.05.112
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    Aiming at the problem that the theoretical analysis of spherical 3-RRP parallel mechanism is insufficient, resulting in unclear kinematics and dynamic characteristics, the specific structure of the mechanism is designed, and the kinematic characteristics of transfer and constraint and driving torque characteristics are analysed. According to the Panda-Kahan theory about inversed position solution, the distribution of flexible and reachable orientation space are clarified. Based on the reciprocal product of screw vector, the transfer and constraint energy efficiency coefficients of joints are established. On this basis, the multi-parameter plane model technology is applied to further reveal the coupling relationship among parameter scale, orientation space and performance index. Thereby,the parameter value is determined, and the range of high-quality orientation space and the distribution trend of performance index are illustrated. Based on the principle of virtual work, the dynamic model is derived, and the driving torque characteristic is qualitatively analysed. The results show that the wrist mechanism takes into account the characteristics of compact structure, large posture space, complete constraint performance, excellent transfer performance, and high load-weight ratio, which is in line with the functional characteristics of human wrist.
  • SU Jinzhan, LI Xudong, YIN Xunmin, JIA Haitao, GUO Fang
    Journal of Mechanical Engineering. 2023, 59(5): 121-129. https://doi.org/10.3901/JME.2023.05.121
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    In order to reduce the vibration excitation caused by the fluctuation of loaded transmission error, an optimization design of linear triangular end relief of double helical gears based on form grinding is proposed. According to the ISO definition of triangular end relief, the helix angle of starting line of modification at the tooth top and tooth root on the rotating projection plane is calculated, the modification curve is designed as linear, and the tooth surface equation of triangular end relief is determined by giving the maximum modification amount. Based on tooth contact analysis(TCA) and loaded tooth contact analysis(LTCA), the loaded transmission error of double helical gears under working load is calculated. The optimization objective was to minimize the fluctuation of the loaded transmission error, and triangular end relief parameters are optimized by genetic algorithm. The objective function is established to minimize the sum of squares of normal deviation of the modified target tooth surface. The helix angle, modulus and pressure angle are taken as design variables, and the tooth top and tooth root modification regions are approximated by genetic algorithm respectively, so as to realize the form grinding of triangular end relief. The results show that the fluctuation of loaded transmission error can be reduced to 36.65% by linear triangular end relief of double helical gears. The theoretical error of form grinding with three-section grinding wheel is controlled within 1 μm, and high accuracy is obtained. The test results of pinion for the double helical gears are controlled within grade 4 accuracy, and the contact patterns rolling test of gear pair is also performed, which verify the effectiveness of the proposed method.
  • WANG Peng, YANG Ce, GUO Zhuo, LIN Jiachun, SHI Zhaoyao
    Journal of Mechanical Engineering. 2023, 59(5): 130-141. https://doi.org/10.3901/JME.2023.05.130
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    Speed-increasing gears are key parts of many gear transmission systems, for instance, wind turbine gearboxes. Due to the friction force between contacting gear tooth surfaces, the meshing characteristics between speed-increasing and -reducing gear pairs are different, therefore, the knowledge and experience of the former cannot be directly applied to the latter. Based on the most widely used involute spur gears, employing the bending strength calculation standards and Abaqus software, the tooth bending stress under speed-increasing and -reducing cases are analyzed and compared. The comparison shows that, with the same transmission power, the maximum speed-increasing bending stress of the gear will decrease for the dedendum area, and increase for the addendum area by 27.8%, compared with the speed-reducing case. On the contrary, the bending stress of pinion will increase for the dedendum and decrease for the addendum. This work will help to develop a new approach for the design and modification of speed-increasing gears.
  • LI Zhaotong, YANG Yuwei, LI Bin, ZHAO Lei, LIU Liang, MA Yue, LIU Qi
    Journal of Mechanical Engineering. 2023, 59(5): 142-155. https://doi.org/10.3901/JME.2023.05.142
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    Aiming at the biomechanical characteristics of swing phase and weight-bearing phase of human gait cycle, a new prototype of human-machine parallel research is put forward, which integrates the metamorphic bionic knee exoskeleton robot and the equivalent lower limbs of the motion associate human body with "J" trajectory characteristics is innovatively proposed. On the basis of in-depth analysis of the working mechanism of metamorphic motion weight-bearing biomimetic, a method of dimensional synthesis based on multi-body kinematics is proposed systematically. Firstly, the method builds the human-machine parallel kinematics model based on multi-body kinematics systematically. Secondly, aiming at the effective geometric inclusion of the exoskeleton for the slip of its wearing position and the individual differences of lower limbs, a new kinematics comprehensive performance evaluation index, bionic dexterity and inclusiveness is proposed. Thirdly, the dimensional synthesis based on multi-body kinematics is reduced to a class of multi-objective optimization problems. Finally, considering the gait differences of different groups, the compressed particle swarm algorithm is used to carry out in-depth dimensional synthesis based on multi-body kinematics numerical simulation of the knee joint exoskeleton system. Through comparison of simulation data with the parameter sensitivity analysis, the comprehensive performance of metamorphic biomimetic kinematics of the exoskeleton robot and the rationality and effectiveness of the method are proved, and the theoretical basis for the subsequent research on the effectiveness of prototype weight-bearing is provided.
  • WU Hongyu, NIU Wendong, ZHANG Yuling, WANG Shuxin, YAN Shaoze
    Journal of Mechanical Engineering. 2023, 59(5): 156-166. https://doi.org/10.3901/JME.2023.05.156
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    As a promising autonomous observation platform for ocean phenomenon, underwater glider can achieve space motion by adjusting its net buoyancy and attitude. Because of the driving mode with relatively low energy consumption, underwater glider is suitable for long-term ocean exploration missions. For the multi-point exploration missions of underwater glider, this paper proposes a path planning method to minimize the glider energy consumption. First, the dynamic model of underwater glider is established, and the energy consumption model of the glider motion in a single profile is further deduced. Based on the simulation results, the polynomial fitting method is used for determining the approximate functional expressions among the glider energy consumption, voyage range, control parameter values and targeted diving depth. Under the specific motion path, the relationship between the glider energy consumption and the motion profile number is studied. Further, the path planning of multi-point exploration missions is regarded as a traveling salesman problem (TSP), and a genetic algorithm-based method is proposed to solve the above path planning problem. The numerical example illustrates that the proposed path planning method can effectively reduce the energy consumption of underwater glider when carrying out the multi-point exploration mission.
  • ZHANG Peng, ZHU Changsheng
    Journal of Mechanical Engineering. 2023, 59(5): 167-179. https://doi.org/10.3901/JME.2023.05.167
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    Different from the base translational motion, the base swing motion not only generates additional load in a rotor system, but also changes its damping and stiffness, thereby affecting its stability. Taking the flexible rotor system supported by active magnetic bearings as an example, the stability of the rotor system under the base swing motion was studied. The dynamic model was firstly established by the finite element method. Then the stability of the rotor system under constant swing base motion was derived with Routh-Hurwitz and analyzed using the root locus. After that, based on Floquet theory, the influence of sinusoidal swing base motion on the system stability was studied, and the stability boundary was obtained, which was verified by the response of the rotor system. Finally, the effect of the PID controller parameters on the system stability under the base swing motion was studied. For the sinusoidal swing motion condition, the phase compensator was proposed to compensate the system stability. The results show that the system stability is related to the motion amplitude under the constant swing base motion, and related to both the amplitude and frequency under the sinusoidal swing motion. Reasonable selecting the parameters of the PID controller will improve the system stability. The phase compensator has a good effect on the system stability under the sinusoidal base swing motion.
  • ZHANG Xufei, LIU Xinchao, MA Jie, ZHANG Fengyang, QUAN Long
    Journal of Mechanical Engineering. 2023, 59(5): 180-191. https://doi.org/10.3901/JME.2023.05.180
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    In view of the serious output vibration harmonic distortion caused by the nonlinear stiffness of the low-frequency electromagnetic standard vibrator, the acceleration distortions are analyzed firstly based on the power series equivalent principle of nonlinear characteristics. Then, in order to overcome the low efficiency and poor accuracy of the traditional uniform sampling method for the vibrator inverse model identifying samples, a nearest neighbor uniform design input-output sample extraction method is proposed. The uniform design method selects a small sample data set from the traditional sampling points, and then adds other sample points that cannot be accurately identified to the data set according to the nearest neighbor method to form the optimal training sample set. Further, the neural network inverse model of the vibrator to be controlled is identified, and the harmonic distortion open-loop control system is constructed after it is connected in series with the original vibrator model. Finally, within the whole working frequency band, the simulation and experimental analysis show that the neural network control method can control the vibration acceleration distortion with different displacement amplitudes within 2% of the standard requirements, and the proposed sample optimization neural network control method with nearest neighbor uniform design has better harmonic distortion suppression effect.
  • WANG Min, LIAO Songquan, SUN Yi, DING Jiheng, PU Huayan, LUO Jun, LIU Qingyu
    Journal of Mechanical Engineering. 2023, 59(5): 192-201. https://doi.org/10.3901/JME.2023.05.192
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    The high-precision payloads carried by on-orbit satellites are extremely sensitive to the environmental micro-vibration, which puts forward higher requirements for the performance of vibration isolators. In order to improve the vibration isolation performance, the traditional two-parameter passive vibration isolator usually adopts the method of adding constant damping for energy dissipation, but there is an inherent contradiction between the suppression of resonance peaks and the rapid attenuation of vibration at high frequency. To solve this problem, a four-parameter vibration isolator with damping varying with frequency is proposed. The theoretical model of the system transmissibility and equivalent damping are established by normalization method, and the vibration isolation performance is compared with the two-parameter and three-parameter vibration isolators. Based on the theory of frequency-dependent equivalent damping, a specific four-parameter vibration isolator with friction damping generated by piezoelectric ceramics actuator is designed, the fusion problem of nonlinear friction damping is considered, and the influence of the intermediate equivalent mass on its frequency-dependent characteristics of damping is analyzed. Finally, the frequency-dependent damping characteristics and vibration isolation performance were verified by simulation and experiment. The results showed that: in the time domain, the isolation ratio of the four-parameter vibration isolator for random signals reaches 91.1%; in the frequency domain, the peak value of the four-parameter vibration isolator at the natural frequency is 5.46 dB higher than the system with small and fixed damping, and the rapid attenuation of vibration is maintained in the high frequency range, which exhibits the frequency-dependent damping characteristics of large damping at low frequency and small damping at high frequency. Both the simulation and experimental results show that the isolator can well overcome the contradiction of vibration isolation performance between the high-frequency and low-frequency existing in passive vibration isolators.
  • HU Yinlong, XU Jin, CHENG Changjun, ZHOU Hui, CAI Xuhao
    Journal of Mechanical Engineering. 2023, 59(5): 202-211. https://doi.org/10.3901/JME.2023.05.202
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    Mechatronic inerter is a new type of inerter device that utilizes circuit networks to achieve high-order mechanical impedances with performance and space advantages. Due to the limited nacelle space of offshore wind turbines, the influence of mechatronic inerter located in a floating platform on the mechanical loads of barge-type offshore wind turbines is studied. According to the characteristics of the DC motor, the torque output of the motor shaft has a linear relationship with the current in the motor circuit. Therefore, for the established mechatronic inerter, focuses on the effects of all circuit networks consisting of a single resistor, capacitor, and inductor on the vibration reduction performance of floating wind turbines. In order to reduce the complexity of the optimization process, a three-degree-of-freedom (3DOF) barge-type offshore wind turbine model is first established, and then the H2 norm of the input and output transfer functions including the circuit network model is optimized to obtain the optimal parameters of the circuit network. Finally, the optimization results are simulated based on the USA National Renewable Energy Laboratory 5 MW baseline wind turbine model. The simulation results show that the established mechatronic inerter tuned mass damper(MITMD) system can effectively reduce the structural load of the wind turbine system if the working stroke of the device is not considered. Compared with the case where the vibration device in the nacelle, the MITMD system in the platform established can reduce the load on the tower base and the tower top at the same time. The control effect of MITMD comes at the expense of motion displacement, therefore, in practical applications, it is necessary to compromise between the vibration reduction effect and the working stroke of the device.
  • ZHOU Yicong, LIN Qiyin, WANG Chen, HUANG Weixuan, ZHANG Guoyue, HOU Qiao, HONG Jun
    Journal of Mechanical Engineering. 2023, 59(5): 212-222. https://doi.org/10.3901/JME.2023.05.212
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    The uniformity of the stress distribution is an important indicator of the assembly accuracy and assembly performance stability of precision electromechanical products, and uniform stress distribution is one of the goals pursued in the current assembly process of precision electromechanical products. Shape design is an important way to improve the contact stress distribution at the assembly interface. In view of the problems that the initial parameters are difficult to determine in the current stress distribution-based active design method of the interface shape, and that the relevant parameters have a large impact on the calculation efficiency and numerical stability of the optimization process, an adaptive parameter calculation method is proposed to adjust the optimization parameters based on the information of the uniformity of contact stress distribution during the optimization process. Then, a typical single bolted joint structure is used as the design object to carry out the interface shape design, and the results of the adaptive parameter design method and the fixed parameter design method are compared and analyzed after the active design of the assembly interface shape respectively. Results show that the problem of determining the initial parameters in the stress distribution-based active design method of interface shape can be well solved, and the improvement of the optimization effect, the calculation efficiency and the numerical calculation stability of the optimization process can be achieved simultaneously.
  • ZHANG Yongfei, LU Wenqi, YANG Liangliang, WU Wenjun, ZHU Qixin
    Journal of Mechanical Engineering. 2023, 59(5): 223-234. https://doi.org/10.3901/JME.2023.05.223
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    The special process of the knitting circular knitting machine requires its drive motor to have large starting and loading capacity and high steady-state operation accuracy. Synchronous reluctance motor is an ideal motor for knitting circular knitting machines. However, the sensorless control of the existing synchronous reluctance motor has the problem of low rotor position estimation accuracy. In this regard, a synchronous reluctance motor sensorless vector control system based on full-speed domain hybrid control is proposed. The pulsed high-frequency current injection method is used at zero speed and low speed, and an appropriate amplitude is injected into the d-axis of the estimated coordinate system. Use the high-frequency voltage signal to estimate the q-axis to estimate the rotor position; use the model reference adaptive method at medium and high speeds to estimate the rotor position by establishing a mathematical model and performing stability analysis on it; in order to achieve zero To switch between high-speed and low-speed to medium-high speed, an improved transition zone fusion observation scheme is proposed, and a sinusoidal saturation function is used to replace the traditional linear switching function for position fusion. In order to verify the effectiveness of the program, a platform was built for testing. The results show that the program has strong load capacity during the startup process, smooth and stable switching process, and small fluctuation during steady-state operation. It is a sensorless vector control method that is more suitable for large circular knitting motors.
  • WANG Yaliang, GAO Kanghong, FAN Xinyu, JIN Shousong
    Journal of Mechanical Engineering. 2023, 59(5): 235-246. https://doi.org/10.3901/JME.2023.05.235
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    According to the uncertainty of manufacturing system and the integration optimization problem of workshop layout and scheduling, the integrated optimization of workshop layout and scheduling under uncertain environment is studied, which realized the efficient and orderly operation of manufacturing system by coupling the uncertain factors in shop floor scheduling. The uncertain factors including the workpiece requirements, processing time and equipment failures are selected, which affecting the integrated optimization of layout and scheduling. An uncertainty-oriented workshop layout scheduling integration optimization model is constructed, which taking the minimum total cost, total completion time and maximum robust indexes in the manufacturing process as the optimization objectives. An algorithm called NSGA-III with improved selection operator (NSGA-III-ISO) is designed, which could enhance the global search capability and stability of the algorithm. At the same time, PBI distance is introduced and the method of determining a minimum is improved. The effectiveness of NSGA-III-ISO is verified by DTLZ series test functions and numerical examples. Finally, the integrated model and the improved algorithm are applied to a workshop layout scheduling engineering example, and the results further verified the validity and feasibility of the model and algorithm.
  • NI Lin, JIA Yunan, WANG Sen, LIU Nana
    Journal of Mechanical Engineering. 2023, 59(5): 247-258. https://doi.org/10.3901/JME.2023.05.247
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    Product recycling is an important part of green manufacturing system. The recycling of waste household appliances occupies a large component of it. In the recycling of waste household appliances, the recycling mode that e-commerce platform connects professional recyclers with recycling users has become a new development direction. Inevitably, there are complex conflicts of interest between the two groups, which hinder the development of the recycling industry. Based on this, the complex interest distribution and investment decisions of recyclers and e-commerce platforms in collaborative recycling business are studied. An evolutionary game model is constructed to analyze the evolutionary stability equilibrium state and evolutionary stability path when both groups “increase investment”. Combined with numerical analysis, the influence of various influencing factors on the evolutionary results of the model is studied. The study show that: the e-commerce platform and recycler both choose the ideal state of “increasing investment” as the premise of ESS evolutionary stability strategy, and there is a sub-optimal situation. The function between investment cost and additional recovery amount is a key factor, when this factor presents a certain functional relationship, there i no suboptimal situation. The platform sets reasonable commission rates for recyclers to facilitate cooperation. It is better to improve the investment utilization rate of cooperation between both parties in exchange for more recycling quantity than to increase the recycling price to attract more consumers to participate in recycling.
  • ZHANG Mengqi, GOU Bin, DENG Yu, DUAN Wenjun, MO Jiliang, ZHOU Zhongrong
    Journal of Mechanical Engineering. 2023, 59(5): 259-270. https://doi.org/10.3901/JME.2023.05.259
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    The tunnel boring machine (TBM) is one of the key equipment used in long tunnel construction, which plays an important role in Sichuan-Tibet railway and other major national strategic projects. However, TBM still suffers some problems in hard rock stratum, such as large thrust, slow tunneling speed and serious cutter wear, which need to be solved urgently. The feasibility of controlling the cutter-rock contact based on the cutter surface structure design is discussed, and a spiral-grooved disc cutter is designed. The rock cutting efficiency of the new cutter under different penetration depth and rock types is studied by using linear rock cutting experiments, and the rock breaking mechanism is explained by using the particle flow discrete element numerical simulation. The results show that the spiral grooves on the surface of the cutter can reduce the cutting force, but has only minor effect on the total volume of rock fragments, so it can significantly reduce the work done by the cutter, and improve the energy utilization efficiency of rock cutting process. The reason is that the spiral groove optimizes the rock stress distribution so the rock under a groove is broken by tensile stress, i.e., rock fragments are formed by the interpenetration of cracks, which reduced the number of rock powder, alleviate the excessive degree of broken rock, and finally the cutting load and energy consumption are reduced.
  • YUAN Hao, ZHAO Ximei
    Journal of Mechanical Engineering. 2023, 59(5): 271-279. https://doi.org/10.3901/JME.2023.05.271
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    To solve the problem of synchronous feed in dual axis direct drive platform servo system, a novel synchronous control scheme combining cross-coupled iterative learning controller and adaptive jerk controller is proposed. Firstly, the synchronous error model is established. Cross-coupled controller is used to solve the coupled problem of the two axes. Adaptive PD-type learning law is designed to reduce synchronous error so that coordinated synchronization is implemented. The model feedforward control is used to compensate for parametric uncertainties to speed up the response. Adaptive jerk controller is adopted to suppress the uncertainties such as external disturbance and friction in the system, which can guarantee the asymptotic tracking control. The jerk is integrated to form the feedback control law, which ensures the stability and continuity of control signal. Adaptive update law of robust gain is designed to converge exponentially, which can weaken the effect of measurement noise and enhance the robustness of the system. The experimental results indicate that the control method can enhance the synchronous control performance of the system significantly. The control precision of the dual axis direct drive platform servo system is also improved.
  • YAN Zheng, WANG Lixin, DONG Shiyun, YAN Shixing
    Journal of Mechanical Engineering. 2023, 59(5): 280-290. https://doi.org/10.3901/JME.2023.05.280
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    At present, obvious difference in maneuverability exists between the micro biomimetic flying aerocraft and its biomimetic prototype in the landing/take-off process, which reduces the safety of its operation process and the universality of its application scope. Accurate characterization of contact force of biomimetic prototype in the landing/take-off process without interference is a necessary prerequisite to solve this problem. A micro-Newton scale contact force measurement system for small flying insects during landing/take-off was designed. The carbon fiber spring T300 was selected as the sensing device of contact force and calibrated to obtain the mathematical equation involved contact force-deflection-contact point position (goodness of fit R2=0.979). A high frame camera was selected to record the image information of small flying insects during landing on and take-off from the carbon fiber spring. Taking the fly (Musca domestica) as the small flying insect, the operation debugging of the contact force measurement system was conducted. The image analysis and processing program based on the Matlab software was used to accurately obtain the deflection of carbon fiber spring and the position of landing/take-off contact point. According to the mathematical equation, the contact force was calculated and corrected to eliminate the influence of carbon fiber spring’s gravity. Result shows that the contact force of flies during landing/take-off process ranges from 0.121 mN to 0.772 mN, which is about 0.71 to 4.53 times of their body weight (17.38 mg). Four the designed contact force measurement system, its resolution is 0.001 mN and its accuracy is improved by four aspects: simulation/actual calibration, accurate acquisition of deflection, contact force correction and no interference in landing/take-off process. Our result provides a reference technology/method for the quantitative and accurate characterization of the biomimetic prototype’s movement behavior for developing micro flying aerocraft.
  • FU Yanshu, LU Cong, YE Xiaojun, XIAO Xianfeng, CHENG Manping, SONG Lijun
    Journal of Mechanical Engineering. 2023, 59(5): 291-306. https://doi.org/10.3901/JME.2023.05.291
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    As the basic unit of laser material interaction, the molten pool experiences transient and localized heat and mass transfer, which have a great influence on the formation of microstructure and macro-defects. Understanding the flow behavior mechanisms of the molten pool and adopting certain control strategies are the keys to obtain high-quality laser material processing parts. With the continuous development of test equipment and technology, experimental study of flow behaviors is moving in the direction of depth and refinement, and up to now, certain achievements have been made. The development and applications of experimental research methods are introduced, and the research progresses of molten pool flow behaviors during laser welding and laser additive manufacturing are summarized. Firstly, the driving forces in the molten pool and their main influencing factors are presented. After that, progresses of visual experimental research on molten pool flow using direct and indirect methods are reviewed and discussed, and the current main control strategies of molten pool flow are summarized. Finally, the further research on the flow behavior mechanism of the molten pool and more efficient strategies of molten pool flow control are prospected.
  • ZHANG Yuan, XU Nianwei, BAO Yan, DONG Zhigang, HAN Song, GUO Dongming, KANG Renke
    Journal of Mechanical Engineering. 2023, 59(5): 307-316. https://doi.org/10.3901/JME.2023.05.307
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    Axial ultrasonic assisted face grinding is widely used in difficult-to-machine material machining and the surface topography and roughness, which have significant influence on friction and fatigue properties. Ultrasonic vibration amplitude has a considerable influence on axial ultrasonic assisted facing grinding surface topography and roughness. In present surface topography and roughness prediction models, the influence of load on vibration amplitude has not been considered, so an axial ultrasonic assisted face grinding metal surface topography and roughness prediction model considering the variation of amplitude is proposed. A model of grinding wheel end face is built according to the wheel size and granularity. Three dimensional grinding trajectory is described mathematically. The three dimensional surface topography data and roughness of machined surface are calculated. On this basis, variation of surface roughness with ultrasonic vibration amplitude is investigated. Consequently, a concept of amplitude attenuation topography mapping coefficient is processed, and its calibration method is also given. Further, the amplitude with loaded could be calculated via the amplitude attenuation topography mapping coefficient. With the amplitude with loaded, the surface topography and roughness are gained with the axial ultrasonic assisted face grinding metal surface topography and roughness prediction model. Finally, accuracy of the prediction model is verified via axial ultrasonic assisted face grinding experiments.
  • JIANG Chen, GAO Rui, ZHENG Zexi
    Journal of Mechanical Engineering. 2023, 59(5): 317-324. https://doi.org/10.3901/JME.2023.05.317
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    To meet the demand for ultra-precision manufacturing of the cleavage cavity surface of GaAs based semiconductor lasers, the molecular dynamics simulation and experimental investigation of mechanical cleavage of GaAs are carried out. First, molecular dynamics simulations of scratching on GaAs are conducted to investigate the influence of crystal anisotropy on the surface and subsurface deformation mechanism. Then, a series of verification experiments are carried out. The cleavage plane morphologies are also analyzed. Compared with the [100] direction, the maximum damage width, scratching width and subsurface depth of [110] direction is decreased 5.23 %, 3.98 %, 2.61 % respectively. as the scratching depth increased. A better scratching quality of the GaAs surface can be obtained in the scratches along the [110] direction. In addition, the maximum damage width, scratching width and subsurface depth is increased as the scratching depth increased. The surface and subsurface morphology of GaAs is not significantly affected by scratching speed. The experimental results are in good agreement with the simulation results. For GaAs, the [110] direction is the best cleavage direction.