It is well known that the friction force can lead to the analysis complexity of the contact constraint model. Based on Coulomb’s frictional model and unilateral constraint model, non-rigid bodies’ compliant dynamic model was established. Considering the whole motion of the assembly system and elastic contact deformation caused by assembly forces, the nearly rigid contact analysis is proposed. Jamming and wedging must be avoided for successful robot assembly operation. Based on the compliant dynamic model the conditions for jamming and wedging are provided in the formulations of the constrained dynamic system of peg-in-hole insertion.

The melting of the material is regarded as the moving boundary problem of the heat conduction equation. In this paper, the method of fundamental solution is extended into this kind of problem. The temperature function was expressed as a linear combination of fundamental solutions which satisfied the governing equation and the initial condition. The coefficients were gained by use of boundary condition. When the metal wire was melting, process of the moving boundary was gained through the conversation of energy and the Prediction-Correlation Method. A example was given. The numerical solutions agree well with the exact solutions. In another example, numerical solutions of the temperature distribution of the metal wire were obtained while one end was heated and melting.

The manufacturers nowadays are forced to respond very quickly to changes in the market conditions. To adopt flexible mixed model assembly lines (MMAL) is a preferred way for manufacturers to improve competitiveness. Managing a mixed model assembly line involves two problems: assigning assembly tasks to stations (balancing problem) and determining the sequence of products at each station (sequencing problem). In order to solve both balancing and sequencing problem in MMAL simultaneously, an integrated mathematical model based on mixed integer programming (MIP) is developed to describe the problem. In the model, general type precedence relations and task duplications are considered. Due to the NP-hardness of the balancing and sequencing problem of MMAL, GA is designed to search the optimal solution. The efficiency of the GA is demonstrated by a case study.

Due to bad welds including small button, weld expulsion, and weld whisker etc., it is studied that the effect of constant and variable electrode force with servo gun on the weld quality of high strength steels with different thickness and materials. The results show that the electrode force plays an important role in resistance spot welding of AHSS as well as that of mild steels. Under the same welding current and time, better welds with higher tensile shear strength and larger nugget size can be obtained by optimizing electrode force curve using servo gun. The solutions could supply reference to study the prospect of servo gun in the joining of high strength steels.

A mixed-model assembly line (MMAL) is a type of production system that is capable of producing different models of a common base product simultaneously. Mixed-model assembly line level scheduling problem (MMALSP) is a challenge for Just-in-time (JIT) production systems. In the paper, a mixed-model assembly line level scheduling model is proposed which considers multiple objectives simultaneously. The considered objectives include the variation in parts consumption considering the batch part supply, inventory cost and maximum transportation load. An approach based on genetic algorithm is proposed to solve the multiple objectives problem. In order to translate individuals in the GA population into candidate scheduling schemes a delivery scheduling algorithm (DSA) is proposed. In addition, dimensionless processing technique is employed in the design of the fitness function in order to comprehensively evaluate different individual considering three objectives simultaneously. The approach’s performance is validated through comprehensive experiment.