To overcome the issue of poor absolute positioning accuracy owing to the low stiffness of serial robot arms, this study proposed a new dual-arm robot (DAR) through the optimisation of the configuration of traditional robots. The DAR adopts a novel kinematic structure comprising a pair of 3-degree of freedom (DOF) robots: the workpiece and tool arms. A kinematic modelling method based on a closed-loop virtual kinematic chain was proposed to solve the problem of synchronous control of both arms via one controller. The workspace of the DAR was calculated, and the singularity was analysed. Furthermore, the stiffness was evaluated through finite element analysis. The results demonstrate that the DAR exhibits significantly higher stiffness, thus enabling considerably better positioning accuracy. To verify the superiority of the proposed DAR, a machining platform was developed based on the DAR for grinding and polishing an aero-engine blade. Compared to a traditional serial 6-DOF robot, the proposed DAR significantly improved the contour accuracy, with a surface roughness Ra 0.3 v.s. 0.4 $\mu $ m. Furthermore, the profile deviation of the blade body and edge were $+$ 0.05 mm, -0.07 mm v.s. $+$ 0.075 mm, -0.07 mm, and $+$ 0.05 mm, -0.03 mm v.s. $+$ 0.05 mm, -0.05 mm, respectively. Note to Practitioners —This study aimed to enhance the machining accuracy of industrial robotic machining. A novel dual-arm robot with superior stiffness was designed and compared with a conventional serial 6-DOF robot. A prototyping DAR was developed as the foundation for a grinding platform’s subsequent design and construction. The platform was utilised in aero-engine blade grinding and polishing. The contour accuracy of the processed blade drastically improved compared with that of the traditional serial 6-DOF robot system. Experiments verified the proposed robot’s feasibility and superiority in improving the robotic machining accuracy. Furthermore, the proposed DAR exhibited good potential for application in other robotic machining scenarios, such as assembly, carving, etc.

Due to their superior machining quality, efficiency, and availability, five-axis machine tools are important for the manufacturing of complicated parts of freeform surfaces. In this study, a new type of the five-axis machine tool was designed that is composed of four rotary axes as well as one translational axis. Given the structure of the proposed machine tool, an inverse kinematics analysis was conducted analytically, and a set of methods was then proposed to address the issues in the kinematic analysis, e.g., the singularity and multi-solution problems. Compared with traditional five-axis machine tools, which are typically composed of three linear axes and two rotary axes, the proposed machine tool exhibited better kinematic performance with machining parts with hub features, such as impellers, which was validated by simulations and real cuttings.

The smoothing of linear toolpaths plays is critical in improving machining quality and efficiency in five-axis CNC machining. Existing corner-smoothing methods often overlook the impact of spline curvature fluctuations, which may lead to acceleration variations, hindering surface quality improvements. The paper presents a five-axis toolpath corner-smoothing method based on the space of master–slave movement (SMM), aiming to minimize curvature fluctuations in five-axis machining and improve surface quality. The concept of movement space in master–slave cooperative motion is introduced, where the tool tip position and tool orientation are decoupled into a main motion trajectory and two master–slave movement space trajectories. By deriving the curvature monotony conditions of a dual Bézier spline, a G2-continuous tool tip corner-smoothing curve with minimal curvature fluctuations is constructed in real-time. Subsequently, using the SMM and the asymmetric dual Bézier spline, a high-order continuous synchronization relationship between the tool tip position and tool orientation is established. Simulation tests and machining experiments show that with our smoothing algorithm, maximum acceleration values for each axis were reduced by 21.05%, while jerk was lowered by 22.31%. These results indicate that trajectory smoothing significantly reduces mechanical vibrations and improves surface quality.

The scroll disc is a critical functional component of the scroll compression mechanism, and its machining precision and quality directly impact the performance and longevity of the compressor. Current machining methods for scroll profiles face challenges in simultaneously achieving wide applicability, high precision, and high efficiency. This paper addresses issues related to unsmooth toolpaths of machine tool axes and high acceleration in the rotary axis during redundant degrees of freedom scroll profile machining. This paper proposes a toolpath optimization method for redundant axes, with optimization objectives focused on reducing the counts of directional changes in the linear axes and smoothing the trajectories of all axes. Experimental results demonstrate that the proposed method offers higher machining efficiency compared to traditional polar coordinate machining.