The end-effector is a key device for direct contact and operation between the operator and the workpiece, and its mechanical structure will directly affect the quality of the machine and expand its application. The theoretical research and technical implementation of the end-effector for compliance control are facing a lot of urgent challenges to be solved, therefore, the research results of active compliance control of robot end-effectors have a very broad application prospect. This paper describes the design and research results of different end-effectors under impedance-based control, hybrid force/position control, and intelligent flexible control methods, respectively. Under each control method, the structural characteristics and the optimized control scheme under different drives are introduced. Finally, key techniques for achieving compliance control are derived by summarizing, which broadens the engineering applications and provides methods and ideas for future research.

With space technology development, the spatial robotic arm plays an increasingly important role in space activities. Spatial robotic arms can effectively replace humans to complete in-orbit service tasks. The trajectory planning is the basis of robotic arm motion. Its merit has an essential impact on the quality of the completed operation. The research on spatial robotic arm trajectory planning has not yet formed a broad framework categorization, so it is necessary to analyze and deeply summarize the existing research systematically. This paper introduces the current situation of space obstacle avoidance trajectory planning and motion trajectory planning. It discusses the basic principle and practical application of the spatial robotic arm trajectory planning method. The future development trend has also been prospected.

The modular robot is becoming a prevalent research object in robots because of its unique configuration advantages and performance characteristics. It is possible to form robot configurations with different functions by reconfiguring functional modules. This paper focuses on studying the modular robot’s configuration design and self-reconfiguration process and hopes to realize the industrial application of the modular self-reconfiguration robot to a certain extent. We design robotic configurations with different DOF based on the cellular module of the hexahedron and perform the kinematic analysis of the structure. An innovative design of a modular reconfiguration platform for conformational reorganization is presented, and the collaborative path planning between different modules in the reconfiguration platform is investigated. We propose an optimized ant colony algorithm for reconfiguration path planning and verify the superiority and rationality of this algorithm compared with the traditional ant colony algorithm for platform path planning through simulation experiments.

Background: With the rapid development of spatial technology and mankind's continuous exploration of the space domain, expandable space trusses play an important role in the construction of space station piggyback platforms. Therefore, the study of the in-orbit assembly strategy for space trusses has become increasingly important in recent years. The spatial truss assembly strategy proposed in this paper is fast and effective, and it is applied for the construction of future large-scale space facilities effectively. Objective: The four-prismatic truss periodic module is taken as the research object, and the assembly process of the truss and the assembly behaviors of the spatial cellular robot serving for on-orbit assembly are expressed. Methods: The article uses a reinforcement learning algorithm to study the coupling of truss assembly sequence and robot action sequence, then uses a q-learning algorithm to plan the strategy of the truss cycle module. Results: The robot is trained through the greedy strategy and avoids the failure problem caused by assembly uncertainty. The simulation experiment proves that the Q-learning algorithm of reinforcement learning used for planning the on-orbit assembly sequence of the truss periodic module structures is feasible, and the optimal assembly sequence with the least number of assembly steps obtained by this strategy. Conclusion: In order to address the on-orbit assembly issues of large spatial truss structures in the space environment, we trained the robots through greedy strategy to prevent failure due to the uncertainty conditions both in the strategy analysis and in the simulation study.Finally, the Q-learning algorithm in reinforcement learning is used to plan the on-orbit assembly sequence in the truss cycle module, which can obtain the optimal assembly sequence in the minimum number of assembly steps.

Background: With the improvement of living standards and the acceleration of the pace of modern life, people pay more and more attention to health. All kinds of ball games are deeply loved by people. Most people like to go to all kinds of equipment halls for all kinds of sports. However, at present, there are few types of service machines, and there is still a lot of room for development. With the development of ball games, small simple serve machine, as important equipment for modern entertainment and sports, has research projects in various countries and occupies a large market share. Objective: The purpose of this study is to synthesize the existing pitching mechanism, summarize and analyze the advantages and disadvantages of various pitching mechanisms from a large number of documents and patents, and solve some problems with the existing pitching machine. Methods: This paper summarizes various patents and the latest research progress on ball-pitching machines. From the mechanical structure of the pitching machine to the functions it can realize, the advantages and disadvantages of the serving machine are analyzed. Results: By summarizing the characteristics of a large number of pitching mechanisms, this paper analyzes some problems existing in the pitching machine and looks forward to the research and design of the pitching machine. Conclusion: Combined with relevant mechanical technology, this paper refers to the patents related to various ball automatic mechanical pitching devices and draws valuable conclusions through the summary and comparison of these patents.

Background: The high-speed motorized spindle system is the main component and the most significant heat source of high precision CNC machine tools in mechanical processing. Plenty of research shows that 60%~80% of the machining accuracy error comes from the thermal deformation of each part in automated manufacturing. Therefore, it is urgent to study the control method of thermal error for motorized spindle systems. Objective: Some valuable conclusions are drawn through the introduction and discussion of thermal error control methods for motorized spindles in recent years, and we prospect the future research and development of thermal error control methods for motorized spindles Methods: The patents and papers on the control methods of thermal error for motorized spindles are studied. The advantages and disadvantages of thermal error control methods and their research status are summarized. Results: With the urging of social as an essential part of CNC machine tools, we cannot ignore the thermal error of high-speed motorized spindles. To improve the machining accuracy, increase efficiency and prolong life, etc., all need a motorized spindle with excellent thermal dynamic performance. Conclusion: : We analyze the structural characteristics and the primary heat sources of high-speed motorized spindles, review a mass of patents and papers related to the motorized spindle thermal error control methods for investigation. By comparing these papers, some valuable conclusions are drawn to predict the future research and development of thermal error control methods for the motorized spindle.