Additive friction stir deposition (AFSD), in which molten metal materials are formed into free-form stacked structural parts according to the path design, may have a wide range of applications in high-efficiency mass production. In this study, experiments were conducted for the rotational speed in the AFSD parameters of 6061 aluminium alloy bars to investigate the effects of different rotational shear conditions and heat inputs on the properties of the deposited layer for diameter bars based on the analysis of the micro-morphology, micro-tissue composition, and mechanical properties. The width and thickness of each layer were constant, approximately 40 mm wide and 2.5 mm thick. The particle undulations on the surface of the deposited layer were positively correlated with the AFSD rotational speed. Continuous dynamic recrystallisation in the AFSD process can achieve more than 90% grain refinement. When the rotational speed increases, it causes localised significant orientation and secondary deformation within the recrystallised grains. The ultimate tensile strength of the deposited layer was positively correlated with the rotational speed, reaching a maximum of 211 MPa, and the elongation was negatively correlated with the rotational speed, with a maximum material elongation of 37%. The cross-section hardness of the deposited layer was negatively correlated with the number of thermal cycles, with the lowest hardness being about 45% of the base material and the highest hardness being about 80% of the base material.

The machining scheme selection (MSS) for features is to choose the optimal machining scheme for a feature before machining. To solve the issue of excessive human subjectivity in the traditional MSS, this paper proposes a simple and easy-to-use method based on process knowledge graph retrieval and through machining scheme similarity matching. First, process knowledge is extracted using natural language processing techniques, focusing on forming ternary groups such as part–feature, feature–attribute, and scheme–resource to construct a multi-level process knowledge graph. This graph is used to retrieve the available machining schemes for the features. Based on the part property, the feature basic information and manufacturing information are used to establish a feature information model and information coding dimensionality reduction. Then, considering the influence coefficient of the process parameter and the usage coefficient of the machining scheme, an improved cosine similarity formula is designed for MSS. According to the maximum similarity, the optimal machining scheme is matched to the feature. Finally, the effectiveness of this method is verified by selecting the machining schemes for six types of hole features on a typical shell part. The results demonstrate that the recommended schemes by the proposed method closely align with the existing mature schemes.

Current space engineering projects such as large space structure erection and spacecraft maintenance tasks require robots with space truss climbing capability. To adapt to the complex climbing environment, this paper developed a multi-branch reconfigurable robot suitable for space truss climbing by using a cellular space robot (CSR). In different climbing environments, the robot can switch between different motion modes by changing the modules’ states. Considering the kinematic modeling problem after module reconfiguration, this paper analyzes the kinematics of the CSR based on the screw theory and extends it to any multi-branch configuration. Meanwhile, for the problem that it is difficult to obtain the inverse kinematic analytical solution of the multi-branch robot climbing mode with planar continuous three-parallel joints, the kinematic analytical algorithm for different configurations is given by combining algebraic and geometric methods. Besides, a 3D truss climbing environment is built, and the kinematic characteristics of the robot joint drive force, working space, and motion energy consumption under different motion modes of the multi-branched robot are analyzed. The results indicate that the developed multi-branched robot has good 3D space truss climbing capability and provides a basis for selecting its working mode in orbit. This study can help to broaden the application field of CSRs in orbit.

In this paper, a kinematic separation calibration method of 6R series manipulator is proposed, and its absolute accuracy is improved by a binocular camera and standard sphere. First, a geometric error mapping model for the robotic arm was established, and the error parameters were divided into position parameters and attitude parameters for calibration purposes. Second, in the process of solving error parameters using numerical algorithms, it is easy to encounter matrix ill-conditioned problems. The spectral correction iteration method is introduced to improve the calculation accuracy. Third, three standard balls are installed at the end of the robotic arm as markers, and the center coordinates are measured using a binocular camera to obtain the actual end pose parameters. To verify the effectiveness of the proposed method, a simulation model verification was designed, and the results showed that the separation calibration method was the best. Finally, the IRB-1200 robot was successfully calibrated using the proposed method; the average robot position and angle error after calibration was significantly decreased. The position accuracy was improved by 66.9%, and the attitude accuracy was improved by 86.2%.