To address the problem that pure rolling bevel gears are prone to angular velocity mutation, vibration, and noise excitation under the influence of mounting errors, a tooth surface design method with low sensitivity to mounting errors was proposed.

Firstly, based on the influence of installation errors on angular velocity, the transmission error curve was preset as a parabolic type. Secondly, the theoretical tooth surface of the pinion was modified using the preset transmission error curve to establish a mathematical model of the target tooth surface. Finally, a 3D solid model of the modified bevel gear was constructed, and tooth contact analysis was performed.

The results show that the derived transmission error curve is consistent with the preset curve, validating the effectiveness of the modification. The actual meshing points of the optimized tooth surface deviate from the edges, and the overall contact area centers on the tooth surface, effectively avoiding edge contact and stress concentration.

The pipe belt conveyors are crucial equipment for bulk material transportation with significant environmental advantages. This study is aimed to quantify the lateral bending stiffness of steel cord conveyor belts.

Based on the analysis of standard ISO 703:2017, the measurement and analysis method for the lateral bending stiffness was determined. Numerical model and 3D simulation model of the steel cord conveyor belt were established. Deformation data under different schemes was obtained using numerical analysis method and finite element method. Error analysis was conducted to demonstrate the validity of the models. Furthermore, a generalized deflection formula for the lateral bending stiffness was derived based on the functional dependence of the belt's troughability on elastic modulus, linear mass, and cross-sectional geometric parameters.

The results provide a new perspective for quantifying the lateral bending stiffness of pipe conveyor belts and offer a basis for their design and engineering practice.

For slotted disk magnetic couplers, the slotted conductor disk complicates the magnetic circuit during operation, increasing the difficulty of calculating electromagnetic torque. A reliable electromagnetic torque prediction model was established, and its torque characteristics were studied.

A 18-pole 16-slot disk magnetic coupler was studied. Firstly, via the equivalent magnetic circuit method, induced eddy currents from adjacent and self-magnetic circuits were introduced as a branch into a new model. Considering 3D end effects and combining Ampere's and Kirchhoff's laws, air gap flux and output torque expressions were derived. Secondly, the coupler was simulated and analyzed by the finite element simulation software, obtaining distributions of air gap magnetic field and eddy currents, and torque variations with air gap thickness and speed difference under adjacent eddy current influence. Finally, a test platform was established to verify theoretical and simulation results.

The results show that the results of theoretical calculation, finite element simulation and test are basically consistent. The proposed theoretical model has high accuracy, providing a reliable prediction model for studying the torque performance of such couplers.

The wave generator, as the driving component, has its profile curve directly affecting the deformation and stress distribution of the flexible wheel. To reduce the stress on the flexible wheel and improve its fatigue performance, a design method for a three-term cosine cam wave generator was proposed.

The profile curve of the three-term cosine wave generator was composed of a constant term, represented by the base circle radius, and three cosine terms superimposed. By using the curvature variation coefficient at the major axis, the correction factor at the minor axis, and the clearance of the flexible bearing as variable parameters, the influence of these parameters on the performance of the wave generator was analyzed, and the optimization of a specific harmonic reducer model was validated. Finite element analysis was performed on the flexible wheel structure after incorporating the new cam structure under expansion, no-load, and loading conditions, and comparisons were made with the pre-optimized structure to analyze the stress distribution on the flexible wheel.

The finite element results indicate that, compared to the traditional cosine wave generator, the flexible wheel under the three-term cosine wave generator exhibits superior stress performance under various working conditions and achieves longer fatigue life.

The industrial robot industry has put forward higher requirements for RV reducers, and the precision life reflects the ability of the reducer to maintain transmission accuracy, which is one of the most important design criteria and usage indicators. To improve the precision performance of precision reducers, it is crucial to evaluate their reliability. Therefore, the degradation characteristics of precision reducers were analyzed.

Taking the RV80E reducer as an example, a random degradation model based on Gamma process was proposed. Combined with the performance degradation data of the reducer transmission accuracy, the model parameters were estimated based on the matrix method and the maximum likelihood estimation method. A Gaussian process regression model optimized by genetic algorithm was established using vibration characteristic data to optimize the prediction of transmission accuracy.

The results show that the prediction accuracy based on Gaussian process regression model is significantly better than that of the traditional regression model. The posterior distribution parameters of the random degradation model are updated by using the algorithm to predict the results, which can effectively evaluate the reliability of the accuracy life of RV reducer and lay the foundation for further reliability optimization design of accuracy life.

To solve the problems of fixed damping force and poor pseudo-humanity of traditional lower limb prosthetic knee joints, a magnetorheological damper was designed to meet the vibration reduction requirements of the lower limb prosthetic knee joint.

Through theoretical calculation, the maximum damping forces required for the knee joint swing phase during flat walking and flat running were obtained, which were 179.6 N and 1 377 N respectively. In order to adapt to the motion state of the lower limb prosthesis, a vibration absorber was designed to meet the damping force required by the knee joint swing phase. Through numerical simulation and test research, the influence of external disturbed magnetic field and temperature rise effect on the dynamics characteristics of magnetorheological damper were analyzed. The test of influence of external disturbance magnetic field and temperature rise effect on the dynamics characteristic of the lower limb prosthetic knee joint was conducted by using the lower limb prosthetic knee joint simulator.

The results show that the output damping force of the magnetorheological damper increases with the increasing magnetic flux density of the external disturbed magnetic field. Under the same conditions, the output damping force of the magnetorheological damper decreases with the rising temperature of the magnetorheological fluid. In the early stage of knee joint swing and the first half of its middle stage, with the increase of the magnetic flux density of external disturbed magnetic field, the hysteresis of knee joint movement increases, and the angle error increases. When the magnetic flux density of external disturbed magnetic field is 10, 20 and 30 mT respectively, the maximum bending angle of the lower limb prosthetic knee joint is 59.0°, 57.8° and 55.7° respectively, and the maximum angle error reaches 3.0°, 6.8° and 11.9° respectively. As the rise of the temperature of the magnetorheological fluid, the hysteresis of knee joint movement increases, and the angle error increases. When the temperature of the damper rises to 30, 35 and 40 ℃ respectively, the maximum bending angle of the lower limb prosthetic knee joint is 57.1°, 54.0° and 49.8° respectively, and the maximum angle error reaches 1.9°, 5.1° and 9.8° respectively. These conclusions provide a basis for the design and optimization of the lower limb prosthetic knee joint based on the magnetorheological damper.

Existing research on flexible hinges corresponds to complex expressions for flexibility and rotational accuracy calculations. To address this issue, a new type of catenary flexure hinge was designed, and a method for establishing the hinge’s compliance and rotational accuracy model by approximating arc segments with straight-line segments was proposed.

Firstly, by defining the flexure hinge as a series combination of tapered and expanded sections, the curve in the tapered segment was divided into several arc segments, and the curve segments were approximated with straight segments. Based on the Castigliano’s second theorem, a method by calculating the flexibility of the tapered section and then establishing the hinge flexibility and rotational accuracy model through matrix operations was established. Secondly, using specific examples, the derived formula, literature formulas, and the finite element method were employed for calculations. When the curve segment was finely divided, the calculation results align well, thereby verifying the formula’s correctness. Thirdly, the influence of structural parameters on the flexibility, rotation accuracy, and flexibility-accuracy ratio of catenary flexure hinges was analyzed. Finally, the bending flexibility and flexibility-accuracy ratio of the catenary, conic, and their hybrid hinges were analyzed with the same structural parameters.

The results show that a single parameter has a negative correlation with flexibility and rotation accuracy of the catenary hinge, and reducing the minimum thickness is the best way to improve flexibility. Under the same structural parameters, the flexibility and flexibility-accuracy ratio of the catenary hinge is between parabolic and circular shapes. Choosing a hybrid hinge with a section of high flexibility for the tapered section and a section of low flexibility for the expanded section allows for a balance between flexibility and motion accuracy.The greater the difference in flexibility, the better the flexibility-accuracy ratio.

In response to the visualization requirements of the models and analysis results necessary for the development of simulation analysis software for spiral bevel gear transmission systems, based on the structural characteristics of the bevel gear transmission system, the topological structure of the transmission system and the complete expression of the interrelationships among components were achieved by applying graph theory and object-oriented data structures.

The generation method of regularized point sets on the geometric surfaces of key heterogeneous components in the transmission system was investigated, and the precise construction and rapid assembly of the geometric models of bevel gears, transmission shafts, and bearings were accomplished using the open-source 3D computer graphics tool VTK. On this basis, the mapping between the geometric model of the transmission system and the mechanical model of loading contact analysis was established, and the visualization methods for the analysis results such as system deformation under loading and tooth surface meshing state were studied. Finally, the visualization effects of modeling and simulation analysis results of the bevel gear transmission system were verified through examples.

Research has shown that the comprehensive application of graph theory and object-oriented data structures can achieve a complete expression of the topological configuration and geometric correlation properties of bevel gear transmission systems. By applying the parameter expression modeling, sweep modeling, and triangulation modeling methods of the VTK library, accurate modeling of heterogeneous components can be achieved. Based on this, a mapping between the system geometry model and the mechanical analysis model can be established to complete the loading contact analysis of the bevel gear transmission system, and visualize the analysis results. The above research results provide technical support for the development of modeling and simulation analysis software for bevel gear transmission systems.

In order to improve the torque to volume ratio of magnetorheological （MR） brakes, a MR brake with internal and external fluid flow channels was developed.

Firstly, the structure and working principle of the MR brake with internal and external fluid flow channels were introduced, and the mathematical model of the braking torque was established based on Bingham constitutive model. Secondly, in order to obtain the optimal structure size of the MR brake, structural optimization design was carried out based on the non-dominated sorting genetic algorithm (NSGA-Ⅱ). Finally, the prototype of MR brake was fabricated, the torque performance test system was built, and the braking performance test was conducted for the MR brake.

There are both internal and external fluid flow channels in the MR brake. Six effective damping gaps are obtained by reasonable setting of magnetic conductive and magnetic isolating materials in the MR brake, so that it can produce excellent torque performance under the premise of the same size. The theoretical calculation results show that the braking torque and the adjustable range after optimization are increased by 30.23% and 16.58% respectively compared with those before optimization. Test results show that at the applied current of 2.0 A, the maximum braking torque is 44.28 N·m, and the dynamic adjustable range is 17.8. The relative errors of the braking torque and the dynamic adjustable range between the test values and the theoretical calculation values are 6.5% and 16.1% respectively, which verifies the rationality of the design.

In order to increase the depth of planting seedlings and reduce the width of transplanting holes, so as to improve the uprightness of rice pot seedlings after transplanting, the comprehensive design and test research of the transplanting mechanism based on the belt-shaped transplanting trajectory were carried out.

Firstly, a belt-shaped transplanting trajectory that can reduce the width of the hole was proposed, and the posture analysis of 10 key posture points on the transplanting trajectory was conducted according to the parameters of the transplanting mechanism and the requirements of motion design. Secondly, the seven-tooth non-circular gear planetary gear train transplanting mechanism was simplified into a planar 2R open chain mechanism, and a mechanism mathematical model based on the belt-shaped transplanting trajectory was constructed using the multi-position motion synthesis theory. Then, the objective function of the minimum change of the length of the planet carrier was established, and the App Design module of Matlab software was used to develop the multi-position motion comprehensive solution software for the rice pot seedling transplanting mechanism based on the genetic algorithm, and the optimal solution set of the key parameters of the transplanting mechanism was obtained. Finally, a simulation on the kinematic characteristics of the transplanting mechanism was carried out using Adams software, and a test prototype was fabricated to conduct the test research on field transplanting.

The simulation results show that the transplanting mechanism has the characteristic of quick return, and all the parameters and kinematic characteristics of the mechanism meet the design requirements, where the planting depth and transplanting hole width are 22.19 mm and 9.78 mm, respectively, which represent increases of 41.9% and decreases of 27.9% respectively compared to the corresponding value in relevant literature. The results of field test show that the average planting depth of rice pot seedlings is 22.84 mm, the average hole width is 10.37 mm, the excellent rate of verticality is 93.3%, and the transplanting effect is satisfactory.