Currently, robots are extensively utilized in industrial manufacturing. However, due to the influence of joint friction and other factors in the robot system, the robot trajectory tracking accuracy is difficult to meet the requirements of high-precision production. In this study, a friction compensation control algorithm in speed mode was proposed to mitigate the impact of non-linear friction factors in the mechanical structure and unmodelled disturbances on the robot’s operational stability and machining precision. The optimal excitation trajectory was designed by a combination of Fourier series and fifth-order polynomial. Dynamic parameters were then pre-identified by the least squares method and iteratively optimized through the Levenberg-Marquardt method to establish a more precise robot dynamic model. Subsequently, the Lyapunov method was adopted to design the trajectory tracking control algorithm, and the joint angles collected in the steepest discrete tracking differentiator were fed into the control algorithm to calculate the real-time compensation. The compensation value was then applied in the robot, which effectively achieving friction compensation. The proposed algorithm was validated by employing a six-degree-of-freedom serial robot as an experimental subject. The results demonstrate that the trajectory tracking error is reduced by approximately 35%, as comparing with that under the non-compensation conditions, which confirms the efficacy of the algorithm in the realm of robot friction compensation.

Collision detection technology can reduce the probability of equipment damage and personal injury and plays an important role in modern human-robot collaborative production. To realize the collision detection without external torque sensor, it is necessary to accurately estimate the external torque of industrial robots. However, the accuracy of external torque estimation can be affected by parameters identification error of dynamic model and measurement error of motor current. To solve these problems, this paper designed a disturbance Kalman filter external torque observer based on the disturbance principle. The observer takes the equivalent external torque of external collision as the disturbance term, defines the joint disturbance model, and introduces the generalized momentum of the robot to construct the state-space equation. Considering the parameters identification error of the dynamic model and the measurement error of the motor current, it carried out an iterative estimation based on Kalman filter algorithm to obtain the optimal external torque. In order to improve the sensitivity of collision detection, a time-varying symmetric threshold function which varies with joint velocity was proposed for collision detection. The proposed method can adjust the threshold according to the change of joint velocity to adapt to the observed values of external torques at different working speeds. Experimental results show that compared with the generalized momentum observer, the accuracy of external torque estimation of the proposed observer is improved by 52.03%. In order to verify the effectiveness of the proposed method, this paper used a 6-DOF series joint industrial robot to conduct collision detection experiments. The experimental results show that compared with the static threshold, the time-varying threshold method reduces the detection delay by 58.06%, which can improve the sensitivity of collision detection and is more conducive to the safe operation and collision protection of industrial robots.

Hydraulically-driven heavy-duty manipulator arms are widely used in construction and mining machinery, and there is an urgent need for its automatic control in the industry. However, the strong parametric uncertainties and difficult-to-model dynamics of the hydraulic system and other factors bring certain challenges to its automatic control. This paper studied the position tracking control problem of a class of heavy-duty hydraulic manipulator arm driven hydraulic cylinders by taking an anchor drilling truck as an example, and proposed a model feedforward compensation active disturbance rejection controller. To solve the control problems caused by nonlinear factors such as variable load, dead zone, parametric uncertainties and friction under heavy loads, the study adopted the control method of combining model feedforward and active disturbance rejection feedback, and established the mechanism model of the system by combining the mechanism dynamics model of the heavy-duty hydraulic manipulator arm and the model of proportional valve-controlled hydraulic cylinders. Then based on the mechanism model of the system, it constructed the feedforward compensation part of the controller, and designed an extended state observer to observe the unmodeled factors of the system in real time, and the active disturbance rejection controller was constituted together with the feedback adjustments based on the state error. The experimental studies were carried out on a real heavy-duty hydraulic manipulator arm, and the results show that the model feedforward compensation active disturbance rejection controller has smaller hysteresis and tracking error than PID controller, and the overall tracking accuracy is improved by 63.5% compared with that of PID controller. This indicates that the designed controller can overcome the adverse effects of the nonlinear factors of the hydraulic system very well, and it has a higher robustness than the PID controller. Therefore, the designed control method is more suitable for the position tracking control of this kind of heavy-duty hydraulic manipulator arm.

In order to further improve the transmission efficiency of the cycloidal pinwheel reducer, this study conducted in-depth research on the influence of the reducer transmission efficiency. It proposed a calculation model for the transmission efficiency of the cycloidal pinwheel reducer that takes into account changes in design parameters and working condition parameters and optimized the parameters. Firstly, considering the friction force and meshing backlash, the study established a multi-tooth load-bearing contact analysis model of the cycloid pinwheel transmission mechanism, and calculate the meshing force and load distribution pattern of the cycloid pinwheel gear. Then, considering the engagement loss, output loss, bearing loss, lubrication loss and sealing loss, this paper proposed a calculation model for the transmission efficiency of the cycloidal pinwheel reducer, and analyzed the influence of the design parameters and working condition parameters on the transmission efficiency of the cycloidal pinwheel reducer. Research shows that, taking frictional stress into account, rotation speed, load, pin tooth pin radius, pin tooth distribution circle radius, eccentricity, and pin tooth sleeve radius are the main parameters that affect transmission efficiency, followed by the number of pin teeth, pin distribution circle radius, pin radius and cycloid tooth width. Finally, the optimal parameter solution was obtained through a multi-objective optimization analysis of the design parameters with gear strength, gear width, tooth profile shape, inter-tooth clearance and load-bearing capacity as the parameter optimization range, and transmission efficiency and volume as the goals. And then a smaller volume and more efficient cycloidal pinwheel reducer was obtained.

Multi-object recognition and 6-DoF (degree of freedom) pose estimation are the key to achieve automatic sorting of robots in the state of unordered stacking of materials. In recent years, methods based on deep neural networks have received much attention in the multi-object recognition and 6-DoF pose estimation fields. Such methods rely on a large number of training samples, however, the collection and labeling of samples is time-consuming and laborious, which limits its application. In addition, when the imaging conditions are poor and the targets are occluded by each other, the existing pose estimation methods cannot guarantee the reliability of the results, resulting in grasping failures. To this end, this paper presented a method for target recognition, segmentation and pose estimation based on synthetic data samples. Firstly, multi-view RGB-D synthetic images of virtual scenes were generated using 3D graphics programming tools based on the 3D geometric models of the target objects, and then style transfer and noise enhancement was performed, respectively, on the generated RGB images and the depth images to improve their realism, so that they are suited for the detection in real scenes. Next, the YOLOv7-mask instance segmentation model was trained with synthetic datasets and tested by real data. The results demonstrate the effectiveness of the proposed method. Secondly, the ES6D model was utilized to estimate target poses based on the segmentation results, and an online posture evaluation method was proposed to automatically filter out severely distorted estimation results. Finally, a pose estimation correction strategy based on active vision technique was proposed to guide the robot arm to move to a new viewpoint for re-detection, which can effectively solve the problem of pose estimation deviation caused by occlusion. The above methods have been verified on a self-built 6-DoF industrial robot vision sorting system. The experimental results show that the proposed algorithm can well meet the requirements of recognition and 6-DoF posture estimation of common workpieces in complex environments.

Lightweight manufacturing is the only way to achieve the carbon peaking and carbon neutrality goals as soon as possible. Aluminum alloy with its low density, high specific strength, recyclability and other advantages such as high shaping, excellent corrosion resistance can be widely used in all walks of life. However, due to its special thermophysical properties and complex alloy chemical composition, welding defects such as pores and hot cracks are prone to occur during the welding process, its further development in the path of lightweight is limited. Combining the advantages of laser welding and arc welding, laser-arc hybrid welding has gradually become an important fusion welding process for efficient and high-quality welding of aluminum alloys with its large welding penetration, high welding efficiency and high welding quality. To grasp the current status of research on laser-arc hybrid welding of aluminum alloys, this paper analyzed for the first time the published academic papers in this field from 1995—2021 in the Web of science database through bibliometrics, and visualized the data with VOSviewer software. The results show that the welded joint, microstructure, heat-affected zone, mechanical properties, and laser-arc interaction for the research hotspots, so this paper summarized and analyzed the laser-arc hybrid welding of aluminum alloys from the above areas, and came up with the selection of the type of joints, the distribution of the microstructure, the enhancement of the mechanical properties, and the mechanism of interaction of the hybrid heat source in the laser-arc hybrid welding of aluminum alloys. It aims to provide reference for subsequent research laser-arc hybrid welding. Finally, based on the current research situation, this paper presented the challenges and the prospect of future work in this field.

As one of the core components of electric vehicles, battery package has a critical impact on the overall performance of the electric vehicle. During the operation of electric vehicles, the battery package is constantly subjected to continuous impact from the road, causing fatigue damage to the battery package, which affects the safety of drivers and passengers as well as the performance of the whole vehicle. Taking battery package of electric vehicles as research object, this study established random vibration test method and calculation method for fatigue life of battery package. Firstly, it carried out frequency sweep analysis on Shaker table, fixture and battery package, and obtained the values of the acceleration sensors at shaker table surface, fixture unloaded end plate, and the connection end plate between battery package and fixture, which were consistent with the input frequency sweep acceleration values, verifying the effective transmission of the vibration signal and ensuring that the input vibration signal can be accurately transmitted to the battery package. After that, random vibration test of battery package was carried out. Cell performance testing, air tightness inspection, insulation resistance inspection, and resonance frequency inspection on the battery package were conducted and the damaged parts of battery package were obtained. The calculation method of battery pack fatigue damage was studied, and the battery box, battery module and battery pack were finely modeled. Based on the fine modeling, frequency response of battery package was analyzed. Based on the results of frequency response analysis and the random vibration load spectrum curve of the battery package obtained from the vehicle road spectrum acquisition test, and combined with the S-N curve of the battery pack material, random vibration fatigue life of battery package was analyzed under load spectrum by using Goodman fatigue life estimation method and Miner linear cumulative damage rule. The damage positions of battery package obtained from the test are in good agreement with the failure positions obtained from the analysis, which confirms the accuracy of the fatigue life calculation method proposed in this paper.

A compliant precision positioning platform is a core component of precision equipment. The high-speed and high-precision positioning operation requires the platform to possess high response speed and good regulation capabilities. Passive damping can effectively enhance the platform’s rapid response capabilities. To improve the rapid response capability of an XY compliant positioning platform with local resonance damping, this paper proposes an optimization design method that comprehensively enhances modal damping and natural frequency. In the investigation, firstly, based on elasticity theory and Castigliano’s second theorem, the platform stiffness is analytically modeled and synthesized, and the expression for the platform’s natural frequency is derived. Subsequently, aiming at the maximum control gain, a single-objective optimization function composed of natural frequency and the frequency response curve area of the resonant region is formulated, along with the mathematical expression for the platform optimization design problem and a ABAQUS-Python-Matlab joint optimization model. Then, to simplify the complexity of finite element calculations, an equivalent structure for the optimized platform based on the first-order fixed frequency equivalence is established. Moreover, simulation analysis of the optimized platform is conducted, and the optimization design results are compared and analyzed to verify the correctness of the natural frequency analytical expression. Finally, an experimental platform is constructed to perform static, dynamic and trajectory tracking experiments on the XY compliant platform with local resonance damping. The results demonstrate that the proposed comprehensive optimization method can increase the X-axis and Y-axis control bandwidths of the platform respectively by 7.42% and 24.70%, and effectively enhance the trajectory tracking performance of the system.

Aluminium-magnesium alloy is widely used in various fields due to its good material properties such as light weight and corrosion resistance. In view of the low efficiency of aluminum grinding alloy grinding wheel, the difficult surface quality and the surface adhesion of grinding wheel, this study proposed the use of abrasive belt grinding technology for the processing of aluminium-magnesium alloys. In order to study the law of grinding process of aluminium-magnesium alloy abrasive belt as well as the problem of adhesion characteristics easily produced in the grinding process, the study used 36, 60 two mesh alumina ceramic, silicon carbide, zirconium corundum abrasive belts to carry out experiments on aluminium-magnesium alloy grinding, and analyzed the material removal rate of aluminium-magnesium alloy, the noise of grinding, the energy consumption of grinding, and the rule of change of the abrasive belt material adherence rate under different grinding pressures and the rotational speed of abrasive belt. The results show that: under the same grinding parameters, zirconium corundum abrasive belt has the highest material removal rate and the lowest adhesion rate due to better abrasive toughness, impact resistance and sharpness, but the grinding noise and energy consumption are greater. So in aluminium-magnesium alloy abrasive belt grinding, zirconium corundum abrasive belts can be chosen to improve the grinding efficiency if the influence of noise and energy consumption is not considered. After the grinding pressure of three abrasive belts reaches 20 N, the adhesion rate of the abrasive belt reaches a stable formation stage, and the abrasive chips block the abrasive grain gap, which reduces the material removal efficiency. This conclusion can provide a reference for the selection of grinding pressure parameters for aluminium-magnesium alloy grinding belts. Within the range of process para-meters of 10~30 N and 1 500~3 500 r/min, the grinding pressure and the speed of abrasive belts have a great influence on the material removal rate and adhesion rate. However, the grinding belt speed has a greater effect on grinding noise, and the grinding pressure has a greater effect on grinding energy consumption. The conclusions of the study can provide certain reference for improving the efficiency and quality of aluminium-magnesium alloy belt grinding and reducing the grinding noise and energy consumption.

Rapid mold manufacturing can be used to print wax molds for investment casting, shorten the production cycle and improve the production efficiency. However, in the actual forming process, due to the uneven temperature distribution in different positions of the workpiece, the internal stress will be different, which may result in warping deformation, and then have a significant impact on the forming quality of the workpiece. Moreover, due to the constraints of forming parameters such as 3D printing speed and deposition layers’ number, it is difficult to reduce the degree of warping deformation of the workpiece and improve the forming efficiency simultaneously. To solve this problem, this paper establishes a mathematical model for the warping deformation of formed parts, and combines experimental design and mathematical calculation methods to explore the influence mechanism of printing speed on the degree of warping deformation and printing efficiency of casting wax direct writing. Experimental results show that, at a certain printing speed, the warpage value decreases with the increase of the number of deposition layers, while gradually increases with the continuous increase of printing speed; and that the higher the printing speed, the closer the printing time of different samples is to a certain stable value, which means that the impact of printing speed on the forming efficiency decreases with the increase of printing speed. In addition, by assigning weight coefficients respectively to the forming warping deformation and the printing efficiency, a continuous function model for the optimal printing speed of surface contours is established, and the effectiveness of the model is verified. The results show that the continuous function model of optimal printing speed based on the warping deformation of casting wax can simultaneously reduce the warping deformation and improve the printing efficiency.

The large-size thin-walled shell has large size and mass, and is easy to deform with strict assembly accuracy requirement. In order to meet the high-precision requirement of spacecraft shell docking assembly, it is necessary to actively predict and control the shell assembly deviation. In this paper, a large thin-walled shell is taken as the research object. Based on the small displacement spinor method, the key characteristic errors of cabin are characterized, the geometric error spinor expression of the cabin and the constraint relationship between the spinor parameters are obtained. Then, the cumulative paths of parallel and series assembly chains considering the key feature errors of the shell are established, the assembly deviation of the cabin is characterized based on the Jacobian spinor theory, and an assembly deviation transfer model of the cabin based on the improved Jacobian spinor is obtained. Moreover, the Monte Carlo simulation method is used to numerically simulate the shell assembly step difference qualification rate of the improved Jacobian-Torsor model, with the results being compared with the simulation analysis results. Based on which, a calculation method for quantifying the contributions of various errors is proposed. Finally, by taking the minimum total processing cost as the optimization objective, and the variation relationship of various errors as well as the requirements of assembly order difference as the constraint conditions, an optimal allocation strategy for cabin tolerance considering the error contribution is proposed. The success rate of cabin assembly and the qualified rate of assembly order difference before and after the optimization are then compared, finding that the proposed method increases the qualified rate from the original 88.12% to 99.56%. The research method proposed in this paper provides theoretical reference for designers to carry out active tolerance design.

In the service process of self-lubricating joint bearings, the wear of the liner leads to the gap between the inner and outer rings of the self-lubricating joint bearings. The existence of the clearance of the self-lubricating remote pair accelerates the collision between the inner and outer rings and further wear of the liner, which has a great impact on the dynamic characteristics of the self-lubricating joint bearings. In addition, the wear of the liner will also lead to the deterioration of the nonlinear characteristics of each component and reduce the stability of self-lubricating joint bearings. In order to study the effects of the wear of the self-lubricating liner on the dynamic response of the self-lubricating joint bearing, this study established the kinematic subvector model of self-lubricating joint bearing with clearance. Firstly, it modeled the collision force at the gap between the inner and outer rings by modifying the Lankarani-Nikravesh (L-N) normal contact force model and improving the Coulomb friction force model. Then, based on Newton’s second law, it established the rigid-flexible coupling dynamic equation with gap. Finally, it analyzed the dynamic characteristics of the drive system of the self-lubricating knuckle bearing with clearance under different wear amount and friction factor. And it also analyzed the nonlinear characteristics of the self-lubricating knuckle bearing by using phase diagram and Poincare mapping diagram. The results show that the dynamic behavior of the inner and outer rings of the self-lubricating joint bearing exhibits nonlinear characteristics with the increase of the wear amount of the fabric liner. When the wear amount is certain, the stability of the system is improved with the increase of the friction factor of the liner, and the occurrence of chaos is suppressed.

Wearing ankle prosthesis is an important means for patients with below-knee amputations to restore walking ability. The lower limb prostheses are divided into passive prostheses and power prostheses according to whether it can actively output torque. Power prostheses are further divided into active prostheses and active-passive hybrid prostheses. Passive ankle prostheses cannot provide active torque and have limited application scenarios. Powered ankle prostheses can output active torque, but it has the problem of incompatibility between low passive friction and high active transmission ratio. To improve the performance and adaptability of ankle prosthesis, this research proposed a new configuration of active-passive hybrid ankle prosthesis based on the principle of electro-hydraulic actuation from the perspective of practical application. Firstly, based on the analysis of the angle and torque of the human ankle joint, it designed the driving system of the ankle prosthesis and proposed the overall design scheme of the active-passive hybrid ankle prosthesis. Then, the mathematical model of the prosthesis system was established, the rationality of the prosthesis system was verified by the simulation analysis of the hydraulic system of the prosthesis, and the principle prototype of the prosthesis was developed. Finally, the performance of the prosthesis was verified by bench test and human walking experiment. The test results show that the maximum active output torque of the prosthetic ankle joint is 28 N·m when the walking speed is 1.0 m/s (close to the average walking speed of adults). The research results show that the active-passive hybrid ankle prosthesis proposed in this research can realize the active assist function in the human walking process, and can better fit the human ankle movement posture, enhance the wearing adaptability, and further reduce the volume and mass of the prosthetic. The work in this research provides a design idea and reference for the research of dynamic lower limb prosthesis.

In order to study the effect of tooth back meshing on the nonlinear dynamic response of the gear system more deeply, a method of analyzing the coupling of tooth transient contact and system dynamics considering the tooth back meshing is proposed. First, the differences in dynamic model and the phase relationship between tooth back meshing and normal meshing are analyzed by studying the mechanism of tooth back meshing. Next, a dynamic model of the gear system considering tooth back meshing is established. Then, a closed-loop “excitation-response-feedback” coupled method is proposed by combining with the dynamic loaded tooth contact analysis (DLTCA). The proposed method can not only can consider the inverse effect of dynamic displacement on the dynamic contact state of the tooth surface, but also can factor in the tooth backlash, flank errors and modification, thus helping obtain more actual dynamic mesh stiffness and system response. The results show that the tooth back meshing mainly affects the nonlinear vibration responses in the speed-down process, while the effect on the speed-up process is not obvious; that increasing the tooth clearance may increase the main resonance speed range of the gear system, while the sensitivity of system vibration to the change of tooth clearance may decrease; that the tooth clearance with small value mainly affects the system nonlinear vibration through the tooth back meshing; and that considering the tooth back meshing may not only change the chaotic rotational speeds, but also change the chaotic state at the same rotational speed. This research provides some theoretical guidance for the nonlinear dynamic control of gear system.

In order to effectively calculate the fatigue life of rubber vibration isolator under random vibration loads, a rubber vibration isolator for air conditioning compressor of an electric vehicle was taken as the research object, and the road spectrum acquisition of rubber vibration isolator was carried out, by which the acceleration signals versus time of rubber vibration isolator were obtained. Then, Fourier transform was used to transform the acceleration signals into the acceleration power spectral density as load input, and a random vibration test of rubber vibration isolator for compressor was carried out under variable temperature and constant humidity conditions, with the cracking of main spring of rubber vibration isolator being observed. Moreover, a finite element model of rubber vibration isolator was established, with its validity being verified by static characteristic tests as the relative error between simulation value and test value is within ±5%. In addition, frequency response of rubber vibration isolator under unit load was analyzed by ABAQUS, that is, extracting and importing stress response PSD of rubber element into Fe-safe, and using acceleration PSD as load input to calculate the fatigue life. The calculated results were compared with the random vibration test results, finding that the predicted life is consistent with test data, with a relative error of only 2.5%, and that fatigue danger position of rubber vibration isolator unit can be effectively predicted. Finally, the structure of rubber vibration isolator was improved, through which the fatigue life of rubber vibration isolator is 2.8 times that before the improvement, meaning that the fatigue life design requirements are successfully met. This study helps to shorten the design cycle of rubber vibration isolator and reduce the cost of sample test.

In order to improve the performance of the battery box of electric vehicles and strengthen the safety and reliability of each component, the acceleration response of the battery modules at different positions inside the box was investigated with the battery box body of an electric vehicle, finding that the calculation results of the power spectral density curves of the three groups of battery modules in the z direction are in good agreement with the test results. Then, by considering the dimensional parameters, such as the top cover of the box, the front end parts of the box, the rear end parts of the box, the middle parts of the box, the module fixing brackets and the reinforcement parts, a response surface proxy model, which describes the relationship between the dimensional parameters of the battery box’s main parts and the intrinsic frequency, deformation as well as vibration response, was established, and the random vibration and the mechanical shock of the box were calculated, with the results verifying the correctness of the model. Based on the Box-Behnken response surface method for designing tests, several combinations of tests with six design variables and three levels were obtained, and the corresponding test design matrices were obtained. A polynomial response surface approximation model was fitted using multiple regression analysis, and the model was iterated and optimized using a multi-objective genetic algorithm to obtain the optimal dimensional parameters of the battery box. Experimental results show that, as compared with the original model, the first-order intrinsic frequency in the optimized case increases by 29.12%, the deformation reduces by 29.39%, and the vibration response reduces by 40.31%, which means a successful lightweighting. The modelling and analyzing methods in this paper can be used to calculate the influence of the battery box components on the overall structure of the battery box, improve the performance of the battery box through optimized design, and strengthen the safety and reliability of each component.

The mining and loading operations are the central link in the open-pit coal mining process, and its energy consumption accounts more than half of the total energy consumption of open-pit coal mining and loading, which determines the mining efficiency and equipment energy consumption. Traditional open-pit coal mining and loading operations are completed by manually operating mining electric shovels, and the process is of low excavation full-bucket rate and high energy consumption. To further reduce the energy consumption and meet the requirements of unmanned and intelligent electric shovels, this paper deals with the optimal excavation trajectory of mining electric shovels. In the research, firstly, a kinematic analysis was conducted on the working device, and the relationship between the pose space and joint space of the working device was revealed through kinematic forward and inverse solutions. Secondly, a dynamic analysis was conducted on the working device of the mining electric shovel. Based on the static analysis of the working device during the excavation process, as well as the analysis of dynamic excavation resistance and material gravity, the Lagrange dynamic equation of the working device was constructed. Then, based on the particle swarm optimization algorithm and the optimization design model of trajectory planning, the optimal excavation trajectory for excavation energy consumption per unit material volume was obtained. Moreover, the effects of material pile surface characteristics, operating parameters and fitting functions on the energy consumption and operation stability of the working device were analyzed, and an excavation trajectory planning strategy that balances energy conservation and stability was proposed. Finally, an experimental study was conducted on the optimal excavation trajectory planning. The results show that the proposed excavation trajectory planning method based on the optimal energy consumption per unit material volume can ensure the efficiency and energy-saving requirement during the excavation with mining electric shovel.

In view of the lack of effective treatment for neurogenic and myogenic bladder, a new solution, namely an artificial bladder detrusor system, was proposed from an engineering perspective. Based on the shape memory effect of shape memory alloy (SMA) springs, a system structure consisting of a wireless power transfer module, a control module, a feedback module and an executive module was designed to realize the assisted urination in accordance with human urodynamics. A finite element model of human bladder was established, and the storage process as well as the assisted urination process of the human bladder was simulated and analyzed. Based on the simulation results and the mathematical model of SMA springs, the structural parameters of SMA spring actuator were optimized. Then, the temperature-free height equation of SMA springs was derived according to experimental data. Furthermore, by combining with the thermodynamic formula and the spring mathematical model, the system control equation was derived, and an open-loop control strategy of the system was proposed on this basis. Finally, based on the feedback module of the system, a proportional integral differential (PID) closed-loop control strategy was designed, and a simulation experiment platform was constructed to study the urine flow rate characteristics of the system. The results indicate that the principle of the system is feasible, and that the assisted urination process is continuously controllable. Under different urine volumes, the two control strategies can both achieve assisted urination in accordance with human urodynamic principles. This research can provide guidance for the design of clinically applicable artificial bladder detrusor system and also offer a reference for the design of other implantable devices using SMA springs as actuators.

The slender truss boom is a key working component of the crane with truss boom, and unloading rebound impact is an important working condition that threatens the safety of slender truss boom crane. To address the dynamic behavior of slender truss booms under unloading impact, this paper used rigid flexible coupling multi-body simulation method and crane unloading impact experimental method to explore the variation law of dynamic stress under unloading rebound conditions of the truss boom, and the unloading impact dynamic load coefficient was calculated based on the dynamic stress of the truss boom. A refined simulation model of a boom tower crane equipped with slender truss booms was established using a rigid flexible coupling method, which includes load model and structural dynamic characteristic model. It analyzed the dynamic stress changes caused by the rebound vibration of the truss boom, and the distribution law of peak dynamic stress during unloading rebound of truss booms was discovered. According to the lifting performance table of cranes with different boom lengths, the relationship between the elevation stress relationship curve and the lifting performance curve was studied, and the sudden unloading condition of the crane corresponding to the maximum stress in the middle of the boom occurred was found. Based on the simulated results of crane unloading impact, a crane unloading impact experiment method based on simulation prediction was established. The sudden unloading impact experiment of the series of boom tower cranes was carried out. The error between the experimental and simulated values of the truss boom dynamic stress is less than 13%, proving that refined model simulation is an effective tool for solving the unloading impact dynamic response of truss boom. Through model simulation, the unloading impact dynamic load coefficient of the slender truss boom under critical situations was further predicted. It finds that there are defects in the relevant regulations on unloading impact dynamic load coefficient in the current crane design specifications. The impact of the truss boom slenderness ratio on the unloading impact dynamic load coefficient was explored, providing a basis for the optimization design of key crane structures.

The level set method uses a zero level set of the implicit level set function to describe the structure boundary in topology optimization problems. Since it can conveniently express structural topological changes and keep the structure boundary clear and smooth, the level set method has quickly become one of the important methods in the field of topology optimization. However, due to the discontinuity of topological changes during the optimization process, the level set method is prone to facing problems such as numerical instability and initial design dependence. In recent years, the level set band method has been proposed to effectively improve this phenomenon and has become an important means to improve the topological expression ability of the level set methods. This paper introduced the level set band into the parameterized level set-based topology optimization methods, and studied its application in compliant mechanism optimization design problems. The level set band method introduces a level set band area near the zero level set of the level set function. The level set function interpolation can be used to obtain the material density continuously distributed in the [0,1] interval within the bandwidth range. During the optimization process, the material density within the bandwidth range can gradually converge to a 0-1 distribution by gradually reducing the of the level set bandwidth. This method combines the advantages of the variable density method to maintain continuous material density changes during the optimization process, which can improve the stability of the parameterized level set method, obtain better objective function values, and effectively evaluate the initial design dependence of the level set method. This paper verified the effectiveness of the proposed method by studying various compliant mechanism optimization examples from the aspects of different initial designs, irregular design domain, geometric nonlinearity, etc. The optimization results show that the proposed method has good applicability for complex design problems in practical engineering.

Aiming at the durability problem of electromagnets for proportional valves of construction machinery, in order to improve the resistance of electromagnets to thermal failure under random load conditions, a parametric redesign model of proportional electromagnets was proposed based on multi-physical field coupling theory and robust optimization theory. By taking a proportional electromagnet with basin-type suction structure as the research object, the effectiveness of the proposed parametric model was verified through steady-state electromagnetic test and temperature distribution test. Under the premise of ensuring the accuracy of electromagnetic calculation, the parameters such as magnetic conductivity and heat transfer with fuzzy magnitude in the system were calibrated. With the main structural parameters of electromagnet and coil as control factors, and with the random error of wire diameter of coil enameled co-pper wire caused by the uncertainty of production process as noise factor, orthogonal tests were designed based on Taguchi method, and the evaluation function of the thermal robustness redesign of multi-factor weighted proportional electromagnet was defined. Then, with the thermal load of the proportional electromagnet obtained in the field test of the excavator as the response calculation heat source, the redesign of the key structural parameters with the minimum system response variation under noise disturbance was carried out, under the constraint of allowable temperature rise that does not cause the coil insulation failure. The results show that the coil length and the number of turns are the main factors affecting the thermal robustness of the electromagnet, and that the coil window shape determined by the winding process determines the magnetic permeability and heat transfer capability of the system. The thermal robustness redesign method of proportional electromagnet proposed in this paper is of engineering reference value for the custo-mized design of electromechanical products under magneto-thermal coupling.