This study analyzed the spatial distribution characteristics of the foot-end trajectory of a robotic leg mechanism during different gait phases. Based on this analysis, a task space partition-based dimensional parameter optimization method was proposed. To further evaluate the spatial distribution of the high-performance transmission regions after optimization, a box-counting dimension and lacunarity were introduced as supplementary characterization indices. First, according to the functional requirements of different gait phases, the task space of the mechanism is partitioned into stance, mid-swing, and swing-transition regions. A unified kinematic model and singularity criterion are then established for the planar five-bar mechanism, and mechanism performance indices for different task regions are constructed based on the Jacobian matrix to characterize the force and velocity transmission capabilities of the mechanism, as well as its singularity margin. A genetic algorithm is used to perform dimensional synthesis optimization of the mechanism parameters. Furthermore, a task space transmission performance field is introduced, and the area ratio, box-counting dimension, and lacunarity of regions with high performance are used to characterize the spatial structure of high-performance transmission regions before and after optimization. Finally, a series of theoretical calculations and physical experiments are conducted to verify that the differential characteristics of the mechanism have a significant influence on both its static and dynamic performance. The experimental results show that the optimized mechanism achieves lower normalized objective values in all task regions and outperforms the reference mechanism in load capacity, static power consumption, positioning accuracy, and trajectory consistency. The maximum static load capacity reaches 1.29 times that of the reference mechanism, while the static power consumption is reduced to approximately one half of that of the reference mechanism.

The vibration control performance of powered wearable devices (PWDs) directly affects the health and comfort of the wearer. Effective vibration isolation technology has become a fundamental aspect of next-generation wearable device design. This study proposes a highly integrated nonlinear stiffness metastructure vibration isolator design for PWDs to address vibration isolation requirements in such scenarios. In this paper, we systematically analyze and experimentally verify the static characteristics of the proposed metastructure vibration isolator through numerical analysis, analytical model and experimental methods, and deeply discuss its dynamic transmissibility characteristics. Among them, we analytically derive and calculate the cantilever beam oscillator of the metastructure vibration isolator and verify the numerical results. Utilizing the mode superposition method, we examine the variations in vibration transmissibility under different operating conditions and geometric parameters. Experimental results are consistent with the numerical calculation results and demonstrate that the isolator exhibits excellent vibration attenuation within the vibration isolation frequency range of 53-61 Hz, achieving a minimum vibration transmissibility of -38 dB. The metastructure vibration isolation system presented in this study successfully achieves the anticipated vibration suppression performance, offering a novel approach to vibration isolation design for PWDs.

To address the shortcomings of traditional Genetic Algorithm (GA) in multi-agent path planning, such as prolonged planning time, slow convergence, and solution instability, this paper proposes an Asynchronous Genetic Algorithm (AGA) to solve multi-agent path planning problems effectively. To enhance the real-time performance and computational efficiency of Multi-Agent Systems (MAS) in path planning, the AGA incorporates an Equal-Size Clustering Algorithm (ESCA) based on the K-means clustering method. The ESCA divides the primary task evenly into a series of subtasks, thereby reducing the gene length in the subsequent GA process. The algorithm then employs GA to solve each subtask sequentially. To evaluate the effectiveness of the proposed method, a simulation program was designed to perform path planning for 100 trajectories, and the results were compared with those of State-Of-The-Art (SOTA) methods. The simulation results demonstrate that, although the solutions provided by AGA are suboptimal, it exhibits significant advantages in terms of execution speed and solution stability compared to other algorithms.

In this study, we present a small, integrated jumping-crawling robot capable of intermittent jumping and self-resetting. Compared to robots with a single mode of locomotion, this multi-modal robot exhibits enhanced obstacle-surmounting capabilities. To achieve this, the robot employs a novel combination of a jumping module and a crawling module. The jumping module features improved energy storage capacity and an active clutch. Within the constraints of structural robustness, the jumping module maximizes the explosive power of the linear spring by utilizing the mechanical advantage of a closed-loop mechanism and controls the energy flow of the jumping module through an active clutch mechanism. Furthermore, inspired by the limb movements of tortoises during crawling and self-righting, a single-degree-of-freedom spatial four-bar crawling mechanism was designed to enable crawling, steering, and resetting functions. To demonstrate its practicality, the integrated jumping-crawling robot was tested in a laboratory environment for functions such as jumping, crawling, self-resetting, and steering. Experimental results confirmed the feasibility of the proposed integrated jumping-crawling robot.

Climate warming and the increased demand in air travels motivate the aviation industry to urgently produce technological innovations. One of the most promising innovations is based on the smoothly continuous morphing leading-edge concept. This study proposes a two-step process for the design of a morphing leading-edge, including the optimization of the outer variable-thickness composite compliant skin and the optimization of the inner kinematic mechanism. For the compliant skin design, an optimization of the variable thickness composite skin is proposed based on a laminate continuity model, with laminate continuity constraint and other manufacturing constraints. The laminate continuity model utilizes a guiding sequence and a ply-drop sequence to describe the overall stacking sequence of plies in different thickness regions of the complaint skin. For the inner kinematic mechanism design, a coupled four-bar linkage system is proposed and optimized to produce specific trajectories at the actuation points on the stringer hats of the compliant skin, which ensures that the compliant skin can be deflected into the aerodynamically optimal profile. Finally, a morphing leading-edge is manufactured and tested. Experimental results are compared with numerical predictions, confirming the feasibility of the morphing leading-edge concept and the overall proposed design approach.

The strength and endurance of human limbs can be enhanced through equipping exoskeletons or other types of wearable devices. However, long-time use of such devices may cause musculoskeletal disorders (MSDs) or potential injuries due to external shocks and vibrations. Consequently, preventing potential risks and enhancing comfortability are crucial to the design of exoskeleton. This research introduces a novel hybrid rigid-soft knee joint exoskeleton, which is well flexible and supported by two curved beams. This design is friendly and comfortable for wearers. The stiffness of the curved beam is meticulously calibrated to match the natural need of the knee joint, which provides appropriate support under vibration and impact. We employ the analytical modeling, finite element method (FEM), numerical analysis, and experimental approaches to analyze the static and dynamic properties of the knee exoskeleton system. The results confirm that the exoskeleton system exhibits reduced vibration transmissibility in low-frequency environments, and present a new methodology for the design and mechanical analysis of exoskeleton systems.

Locusts keep their bodies moving in a straight line during the takeoff and maintain the body stable during the whole jumping with small pitching motions, ensuring both kinematic and dynamic stability to reach their intended destinations. Inspired by locusts’ jumping performance, the Stephenson II six-bar jumping mechanism is adopted to mimic the kinematic stability of locusts’ takeoff and a dynamic model is developed to analyze the impacts of the torsional spring location, the spring stiffness, and the location of the equivalent body bar centroid on the jumping performance. Furthermore, a revised eight-bar jumping mechanism is proposed to solve the difficulty in realizing dynamic stability using the six-bar mechanism, as the moments of momentum of each component around the overall centroid are positive and contribute together to the counterclockwise rotation of the jumping. The dynamic modeling shows that the mass of the equivalent tarsus bar plays an important role in realizing the dynamic stability for the eight-bar jumping mechanism. Finally, two kinds of jumping robots are designed, fabricated and tested with jumping performance recorded by high-speed cameras, which validates the impacts of the mass of the equivalent tarsus bar on the jumping stability in the eight-bar jumping mechanism.

When optimizing the fiber orientation of multilayer composite laminates, with the increasing number of layers, the number of design variables increases sharply, resulting in a large amount of computational cost. To address this challenge, this paper proposes a novel discrete fiber angle optimization method based on the Archimedean spiral function and applies it to a collaborative design framework of topology and fiber orientation. The proposed method uses the normal distribution function as the angle selection function in every layer. To prevent convergence issues in optimizing the fiber angle, a new candidate angle weighting formula is proposed. Further, a discrete fiber angle parameterization method based on the Archimedean spiral function for the thickness direction of laminates is presented, which requires only one variable to represent the fiber angle of any two layers in the element. To circumvent the issue of local optima and expand the design space, a collaborative optimization strategy is employed to improve the discrete fiber angle optimization results. Finally, the numerical examples indicate that in comparison to conventional approaches, the correlation of the proposed method with initial values is significantly reduced (σ2=0.00188). Under identical initial conditions, this method can improve the structural stiffness by over 20% at maximum.

The variable camber trailing edge enables the aircraft to maintain the best aerodynamic performance throughout the flight envelope, so as to achieve the ultimate goal of reducing aircraft fuel consumption and air pollutant emissions. It is one of the important characteristics and development direction of the new generation civil aircraft. In order to solve the contradiction between the high load-bearing and the large deformation of the variable camber trailing edge of large aircraft, a structure scheme for variable camber trailing edge based on multi-block rotation was proposed. A parametric optimization method was established for smooth and continuous deformation of multi-block rotating mechanism. The multi-block rotating structure and driving system of variable camber trailing edge were designed, and the deformation function of the variable camber trailing edge demonstrator was preliminarily verified by ground test. The result shows that variable camber wing trailing edge designed by using the present optimization method of multi-block rotating mechanism can realize smooth and continuous morphing. The actual deformation range of the demonstration is 3.9 degrees up to 12.5 degrees down, and the error with the design target is 16.7%. It provides a design reference for solving the engineering application problem of variable camber structure for large aircraft.

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.

Most of the existing propulsion systems that can rotate around the rotation axis and change the pitch angle of the propeller are applied to helicopters and ships. Their structure or weight cannot meet the requirements of lightweight and high bearing performance for near-space aircraft. To improve the adaptation range of near-space aircraft, this paper proposes a new variable-pitch vector mechanism for propellers based on a sine mechanism. The mechanism can adjust the blade angle of the propeller to produce unbalanced thrust. Firstly, the structural design and optimization of the variable-pitch mechanism are carried out, and the transmission system is designed according to its kinematics and statics. Secondly, the parts with high stress in the mechanism are analyzed using ANSYS. Finally, the principle prototype design and experiment are carried out. The experimental results show that the pitch-change mechanism designed in this paper can be matched with a pair of propellers of 6 m in diameter. When the propeller is running on the ground at 200 rpm, the pitch variation error is less than 0.5°, and the weight of the mechanism is only 18.78 kg.

Larger deformation and higher bearing capacity is a worthwhile goal for designing the compliant mechanism. By virtue of the anisotropy, variable stiffness and superior designability, fiber reinforced composite material is effective way to solve the contradictory problem. There are several reports to design compliant mechanism with composites and improve its performances. But adding directly stress constraints in topology optimization process is very complex and difficult to establish the explicit expression of stress constraints for compliant mechanism with composites. This paper investigated the topology optimization and performance prediction of compliant mechanism with composites by neural network. Topology configurations, output displacements and maximal stress in matrix materials of compliant mechanism under different fiber laying angles were firstly implemented. Subsequently, neutral network models were built to predict the output displacement and maximal stress. Examples of compliant inverter and gripper were used to verify the proposed method.

This study investigates and designs a novel stacked hinge with low stiffness, large rotation angle, high strength, and length-adaptive functionality. Firstly, based on the large deformation theory of cantilever beams and relevant theories of leaf springs, a stiffness theoretical model for stacked flexure hinges is established. Subsequently, the stiffness theoretical model is further modified by considering the frictional force, aiming to reduce errors. Secondly, a stiffness-testing experimental platform for this flexure hinge is designed to verify the correctness of the theoretical model. Finally, the stacked flexure hinge is applied to the trailing-edge mechanism of a variable camber wing, achieving a deformation target of 15° downward bending of the wing and demonstrating good shape retention, thereby proving the feasibility of the application.

As an important part of the wing, the skin deformation accuracy directly affect the aerodynamic performance of the aircraft in different environments. Based on the idea of easy processing and easy deformation, a method for designing variable section thickness skin for trailing edge of variable camber wings is proposed. In this paper, firstly, the thickness and length of each segment of 3~8 segments of trailing edge skin are optimized. Then the deformation results of different segments of skin are compared and analyzed. Finally, the correctness of the design results and the effectiveness of the method are verified by using stacked skin experiment.

Animal joint motion is a combination of rotation and translational motion, which brings high stability, high energy utilization, and other advantages. At present, the hinge joint is widely used in the legged robot. The simple motion characteristic of the hinge joint rotating around the fixed axis limits the improvement of the robot's motion performance. In this paper, by imitating the knee joint of a kangaroo, we propose a new bionic geared five-bar knee joint mechanism to improve the energy utilization rate of the legged robot and reduce the required driving power. Firstly, based on image processing technology, the trajectory curve of the instantaneous center of rotation (ICR) of the kangaroo knee joint was quickly obtained. Then, the bionic knee joint was designed by the single-degree-of-freedom geared five-bar mechanism and the parameters for each part of the mechanism were optimized. Finally, based on the inverted pendulum model and the Newton-Euler recursive method, the dynamics model of the single leg of the robot in the landing stage was established, and the influence of the designed bionic knee joint and hinge joint on the robot's motion performance was compared and analyzed. The proposed bionic geared five-bar knee joint mechanism can more closely track the given trajectory of the total center of mass motion, has abundant motion characteristics, and can effectively reduce the power demand and energy consumption of the robot knee actuators under the high-speed running and jumping gait.

Gradient-free optimization methods can result in significant computational costs when solving complex structural design problems for composite materials. To this end, this article presents a machine learning-based co-optimization method for composite material structure and fiber orientation. In this approach, DNN are utilized as surrogate models for the optimization problem. Equilibrium optimizer is employed to find real-time optimal solution of the DNN. Subsequently, elite samples are generated based on this optimal solution and used to update the DNN until convergence is achieved. During the post-processing stage, B-spline functions are applied to smooth the density and fiber orientation of the optimized results.

A seamless deformation structure that changes the curvature of the main airfoil has a positive effect on improving the aerodynamic performance of long-range aircraft and reducing noise. Aiming at the problems of obvious wrinkles and heavy weight of rigid mechanism driven skin, this paper describes a compliant mechanisms-based leading-edge of morphing wing with a seamless deformation structure. In order to avoid the wrinkling of the wing skin, the driving points and the driving forces on the deformed skin were designed. In addition, the leading-edge flexible rib designed by the topology optimization method of flexible mechanism can make the wing leading-edge deflect downward by 17°. Finally, a set of experimental prototypes and experimental platforms were manufactured for the wing load-bearing deformation experiment. Experiment shown that the aerodynamic performance of the variable camber morphing wing was improved and can resist aerodynamic loads well.

Thermal radiation and vacuum lead to the deformation of bearing cylinder with carbon fiber composites which generates the defocus phenomenon for space optical camera. As heavier weight and higher complexity of the rigid focusing mechanism for the space optical camera, a novel compliant focusing mechanism with lighter weight and simple structure was designed and tested in this paper. In order to achieve stroke range and ensure image quality for the compliant focusing mechanism, micro driving displacement from the piezoelectric ceramics was amplified by two-stage flexible hinge lever-type mechanism. Taking the size parameters of the flexure hinges and beams as the design variables, an optimization model of the compliant focusing mechanism was established in which minimizing weight was considered as objection function under the stroke requirements. Consequently, optimal structure parameters of the compliant focusing mechanisms under different input forces can be obtained under the allowable stress and lighter weight. The effectiveness of the proposed compliant focusing mechanism was verified by the simulations and experiments. The results show that the compliant focusing mechanism can achieve a stroke of 2 mm for the focal plane assembly. The proposed method provided a new idea to design the focusing mechanism with lighter weight, simpler structure and higher reliability.

Equivalent single-layer theory is widely used in the analysis of fiber-reinforced composite laminate structures, but this theory cannot accurately evaluate the stress and deformation of thick plates. In order to improve the accuracy of the structural optimization design of composite laminate, we propose a topology optimization method of composite laminate based on the layerwise theory. Firstly, the displacement field model of laminates is given by using layerwise theory. Then, with the goal of maximizing stiffness and flexibility, topology optimization equations for composite laminates are established. The structural optimization problem of straight/curved fiber-reinforced composite laminates under different conditions is studied. Finally, several simulation cases are designed to evaluate the accuracy of the layerwise theory and the performance of the proposed topology optimization method. The results show that the calculation accuracy is much higher when using the layerwise theory for structural deformation analysis and optimization than that of the classical laminate theory.

以生物肌肉肌腱为灵感,基于变胞机构思想设计了一种多构态仿生弹性驱动器,其中驱动元件和弹性元件通过变构态行星差速齿轮机构实现高效耦合.根据机器人关节不同运动相差异化功率需求,控制弹性驱动器构态的切换,实现输出功率调制和能量调节,从而提高机器人系统的运动性能和能量效率.在此基础上,设计了基于多构态仿生弹性驱动的单足跳跃机器人并验证不同驱动模式情况下的跳跃性能.实验结果表明,与传统齿轮减速驱动器相比,多构态仿生弹性驱动器有效提高瞬时输出功率,使单足跳跃机器人跳跃高度提高了 6.8％.跳跃机器人落地过程中弹性元件压缩吸收动能,减小碰撞冲击的同时提高了能量利用率,证明了多构态仿生弹性驱动器在输入能量耦合和在动态输出功率调制方面的可行性.