Biological synergies have emerged as a widely adopted paradigm for dexterous hand design, enabling human-like manipulation with a small number of actuators. Nonetheless, excessive coupling tends to diminish the dexterity of hands. This paper tackles the trade-off between actuation complexity and dexterity by proposing an anthropomorphic finger topology with 4 DoFs driven by 2 actuators, and by developing an adaptive, modular dexterous hand based on this finger topology. We explore the biological basis of hand synergies and human gesture analysis, translating joint-level coordination and structural attributes into a modular finger architecture. Leveraging these biomimetic mappings, we design a five-finger modular hand and establish its kinematic model to analyze adaptive grasping and in-hand manipulation. Finally, we construct a physical prototype and conduct preliminary experiments, which validate the effectiveness of the proposed design and analysis.

The use of tools is a distinctive characteristic of human intelligence. However, traditional mapping algorithms from human hand to robot hand are ineffective in tool grasping due to the specific functional areas of tools. In this paper, we propose a hybrid mapping algorithm based on task division to address this problem. Firstly, we establish a human hand kinematic model and experimentally observe the synergistic effects of hand postures during the grasping of 44 common tools. Based on the grasping gestures, tools are categorized into multiple types, each exhibiting similar synergistic effects. Subsequently, human fingers are divided into grasping fingers and functional fingers according to task requirements. Grasping fingers are further classified into important and non-important fingers based on their significance in grasping tasks. Important fingers undergo joint configuration using object-based mapping, while the joints of other fingers are determined through posture synergies. Functional fingers require precise contact with tool regions, and this process is achieved through direct Cartesian mapping. Finally, we conduct comparative experiments to evaluate our algorithm, and the results demonstrate that our mapping algorithm effectively adapts to tool grasping tasks.

The goal of the existing dexterous hands is to achieve multi-function, compact structure, and simple control, which makes it difficult to be installed and disassembled, and the application of fingers is limited. In order to realize the flexibility and convenience of dexterous hand application, this paper proposes the design and experiments of a modular dexterous hand based on human hand biology. Firstly, the movement characteristics of the human hand are combined with its biological tissue structure to analyze its movement laws. The synergy and independence of finger movements were summarized. Secondly, based on the biological proper-ties of the human hand, a design method for a modular dexterous hand is proposed. The flexion and extension (F /E) of the finger adopts the design method of compliance drive and flexible coupling, so that it can achieve great adaptability to the object. Combined with independent adduction and abduction (Ad/ Ab), the dexterity of the fingers is guaranteed. Finally, through the rapid combination of modular fingers, two-fingered hand, three-fingered hand, and humanoid hand were developed, and grasping and manipulation experiments were carried out to verify the feasibility of the design.

Hand synergy from neuroscience provides an effective tool for anthropomorphic hands to realize versatile grasping with simple planning and control. This article aims to extend the synergy-inspired design from anthropomorphic hands to general multifingered robot hands by reconstructing mechanically the crucial biomechanical characteristics of hand synergy. The synergy-inspired hands are not necessarily humanoid in morphology but perform primary functions like the human hand. At first, the biomechanics of hand synergy is investigated by combining human hand synergies with the anatomy of the musculoskeletal system. Three biomechanical characteristics of the human hand synergy are explored as a basis for the mechanical simplification of robot hands. Second, based on the three synergy characteristics, a design method of robotic hands is proposed. A three-fingered hand is designed, and some typical grasping and in-hand manipulation functions are analyzed. Finally, a prototype is developed, and experiments of grasping and in-hand manipulation are carried out to validate the effectiveness of the design method.

This paper addresses the generation mechanism and avoidance method of negative stiffness during in-Hand manipulation with underactuated compliant hands. Firstly, a planar hand with two three-jointed fingers manipulating a rectangular is set, and a quasi-static underactuated operation model is established. Secondly, based on this simulation model, we investigated the stiffness evolution during in-hand manipulation, and analyze the influence factors of system stiffness. Finally, a stiffness regulation method is developed to avoid negative stiffness during in-hand manipulation. The method is validated by simulation. The research results are beneficial to improve the performance of underactuated in-hand manipulation.

In order to study the effect of high strength steel laser welding line energy on the growth of HAZ austenite grain,the three-dimensional transient temperature field of laser welding was simulated by ANSYS finite element software,combined with the thermal cycling curve and the growth characteristic of HAZ austenitic grain,the kinetic equation parameters of HAZ austenite grain growth of high strength steel in laser welding were determined,and the effects of different line energy on the growth of HAZ austenite grain were analyzed,the theoretical calculation results are in good agreement with the experimental results.The results show that the phenomenon of HAZ austenitic grain growth is obvious when laser welding high strength steel.The energy of laser welding line has a direct effect on the growth of HAZ austenitic grain.In a certain range,with the increase of welding line energy,the austenitic grain growth is more significant,mainly due to the increase of welding line energy,the increase in welding heat input,HAZ peak temperature and grain coarsening temperature range duration is long.

采用三种不同的激光焊接顺序对镀锌钢板进行焊接,使用ANSYS软件对激光焊接温度场和残余应力场进行有限元分析,运用盲孔法测量焊后焊件的残余应力的分布情况,其结果和模拟结果相吻合.结果表明,不同的焊接顺序主要影响纵向焊接残余应力分布,对横向残余应力影响可忽略不计.焊缝区纵向残余应力在热输入段中点达到最大值,随着垂直于焊缝距离的增加焊接纵向残余应力逐渐减小,并最终趋于稳定.除了单焊道之外,受二次加热的影响,纵向焊接残余应力减小,最大减少量达15％,横向焊接残余应力变化很小,但存在正负波动现象,这主要是由焊接过程中温度分布不均匀和焊缝及近焊缝区的横向收缩引起的.

Alumina engineering ceramics has high strength ,hardness,and good wear resistance ,but its machining performance is poor.Laser assisted machining is one of the effective processing methods for this kind of high hardness materials .The influences under differential processing parameters such as laser power ,spindle speed,feed rate,etc to the CBN tool wears were studied dur-ing laser assisted machining alumina engineering ceramics .The results indicated that the wears are mainly found on the rake and flank face of CBN tool which were caused by abrasive and adhesive wearing .Also, through the experiment found that the tool wears were reduced significantly during laser-assisted machining compared to the traditional turning .

Laser-assisted machining (LAM), defined as a hot machining process, combines laser technology with traditional machining method for improving material removal rates. It can reduce the cutting force and improve the processing efficiency of hard-to-wear materials, especially engineering ceramics. To enhance the processing precision of alumina ceramic turning, this article presents the results of an experimental study of a two-step laser-assisted turning process including laser-induced thermal cracking and turning. This study investigates the distribution of microcracks for different process parameters. Comparing with the results, it is observed that the mechanism of crack formation and crack types are different. The cracks are caused by thermal stress and mechanical stress, separately. Based on uniform design, a back propagation neural network model is developed to map the complex nonlinear relationship between process parameters and processing requirements. The results show that the model is an effective tool for predicting the integrity of the machined ceramic surface.

激光辅助加热切削是解决陶瓷类硬脆材料难加工问题的有效方法。为研究工艺参数的选取对脉冲激光辅助切削陶瓷加工效果的影响,建立了脉冲激光加热辅助切削Al2O3陶瓷传热模型,求解不同参数组合下工件温度场分布。根据Al2O3陶瓷温度在1000K以上时的软化层尺寸选取理论上合适的切削用量;采用激光参数和切削用量开展切削试验,统计试验切除率,检测加工表面粗糙度和表面形貌,探讨试验切除率与加工表面粗糙度之间的关系,结果发现采用温度场模拟获取的工艺参数能够获得较高的加工质量和切除效率。研究表明通过模拟温度场分布从而选取切削工艺参数,能有效保证脉冲激光辅助加热切削陶瓷类硬质脆性材料的工艺要求。

Aimming at the problems of heterogeneous convex ear produced on hot rolled and pickled steel plate for compressor upper shell in drawing forming, the primary and secondary factors affecting the formation of convex ear were obtained by orthogonal experiment. And trimming edge line was solved by using the reverse numerical simulation method combined the theory of the plastic forming and finite element method. The shape of the best blank was gained. For the convex ear defect caused by the anisotropic coefficient in the thickness direction, the test sample was extracted by using symmetrical Latin square method and then the response surface model(RSM) was gotten based on the sample point and the target value, which can accurately predict the convex ear value according to different anisotropic coefficients in the thickness direction.

论述了我国经济发展新形势下企业对工科高层次人才的迫切需求和现阶段人才培养质量存在的主要问题对国内外工科大学生实践教学培养模式进行了对比,分析了存在差距的主要原因.结合我国大学生创新训练实践所积累的经验,提出了改革和完善工科大学生实践教学培养模式,政府及相关部门应重点做好的几项工作.

Dissimilar metal plates welding between galvanized steel and carbon steel was investigated experimentally.The fiber laser and equipped robot were used in the experiment.The microstructure and mechanical properties of joints were analyzed.Based on the experiment,the influence of parameters variation such as laser beam power,welding speed and defocusing distance on the width and depth of welding seam was studied.The experimental results indicate that the width and depth of welding seam are inclined to be higher with the increase of laser beam power and the decrease of welding speed,and the surface hardness in the welded joint and heat affected zone are higher than that of base materials,and the tensile strength of the welded joint is reasonable equal to that of the carbon steel under the experimental condition.It is advisible that laser beam center offset a bit to the carbon steel side so as to prevent the uncoinciding between the centerline of joint and butt caused by the material physical properties difference,and to keep the continuity of strength and performance in the joint during the laser welding dissimilar materials between galvanized steel and carbon steel.

Combination of back propagation(BP)neural network and particle swarm optimization(PSO) algorithms is used to optimize process variables during the laser cladding.BP neural network model is developed to express the relationship between the clad process variables and the clad parameters(the width,height of clad bead),and the samples obtained in experiments are used to train network model to form the perfect map relation between input and output.Then,PSO algorithm is used to grabble the suitable values of the process variables.The experimental clad parameters with the process variable values calculated by this optimization method are coincident well with the expected ones.It is verified experimentally that combination of BP neural network and PSO algorithms can help to obtain the expected laser clad quality.

Considering current main problem in laser heating-assisted turning engineering ceramics,several factors affecting the machining quality and accuracy were theoretically analysed.Based on lots of experiments about laser heating-assisted turning Al2O3,curves of different parameters affecting the turning surface integrity,such as cutting depth,axial feed velocity,spindle rotating speed and laser power were plotted.The optimum turning parameter ranges were presented according to the investigation,which are benificial to the engineers' selecting machining parameters to improve the machining accuracy and surface quality.

Laser transformation hardening of ductile cast iron QT600-3 was investigated experimentally.In the experiment,a CO2 laser unit was used.The experimental results show that great amounts of acicular martensite are obtained in the zone hardened with a fairly large laser beam diameter and consequentially low power density on the sample surface,under a lower scanning velocity of laser beam.The hardness of the hardened surface reaches up to 60 HRC,which is about 2.4 times as high as that of matrix.In addition,the microhardness of surface improves with increase of laser power and decrease of laser scanning velocity.The depth of hardened layer is up to 0.95 mm,and it decreases with increase of laser scanning velocity and increases a little with increase of laser power.

针对目前采用激光加热辅助车削加工工程陶瓷方面存在的缺陷及这些缺陷引起的表面质量问题,对影响工程陶瓷加工质量和精度的各个因素进行了综合的理论分析研究。以Al2O3工程陶瓷为例,进行了大量的试验及数据处理,绘制了切削深度、轴向进给速度、机床转速和激光功率等工艺参数对加工结果的影响曲线,分析出了采用激光加热辅助车削加工Al2O3工程陶瓷的最优参数范围。分析结果能够使工程技术人员对Al2O3工程陶瓷的加工性能有更深层次的认识,便于在加工过程中合理地选择相关参数,有效提高工件的加工精度和表面质量。

Iron-based alloy coating was prepared by laser cladding on surface of nodular cast iron QT600-3.Microstructure,microhardness of the coating and distribution of element Fe and Cr at interface between the coating and substrate were examined by means of optical microscope,SEM,XRD and hardness test.The results show that the microstructure of the laser clad coating consisted of cellular crystal layer and dendrite layer is homogeneous and free of pore.The inter-diffusion of elements Fe and Cr in the coating and substrate near interface is detected,indicating that metallurgically bonding forms between the coating and the substrate.The hardness of the coating increases 2.6 times compared with that of substrate due to dispersion hardening of carbides in the coating.

Formation procedure of cross-sectional clad profile in laser cladding is investigated theoretically and experimentally.Based on the law of conservation of mass and that of balance of energy,a melt pool can be defined as a quasi-steady system.It is indicated that the cross-sectional clad profile is derived from the points at the back part of the boundary between the liquid,gas and solid,and these points' heights are equal to those of the counterpoints at the cross-sectional clad profile.Based on the above analysis,the model of a cross-sectional clad profile in single-pass coaxial laser cladding is presented.A 500 W CO2 laser is used in the experiment.The experimental result agrees well with the calculated cross-sectional profile.

The polarization of the laser beam output from the PHC-1 500 laser unit was experimentally verified.The Al2O3 ceramics surface reflectivity to line polarized CO2 laser beam of both parallel and perpendicular to incidence plane at different incidental angles were measured.Based on the above data,Al2O3 ceramics' refractive index,Brewster angle and absorption coefficients were obtained.The experimentally-obtained absorption coefficients were in good agreement with the ones calculated by means of Fresnel formula.The experimental results have indicated that the Al2O3 ceramics surface absorption coefficient to line polarized CO2 laser beam,which is parallel to incidence plane,increases from about 75% at zero incidental angle to 95% at Brewster incidental angle.These results have provided the experimental and theoretical basis for the design of the laser beam transportation road with higher energy utilization and the accurate calculation of temperature field during laser-assisted machining of Al2O3 ceramics.