Aiming at the problems of resonant frequency drift and amplitude instability caused by dynamic load fluctuations during robotic ultrasonic machining, a frequency tracking and amplitude stabilization power supply system based on STM32 was designed and developed in this work. A compound frequency tracking strategy integrating "variable-step maximum current method for coarse tracking and phase difference method for fine locking" was proposed, and amplitude stabilization was achieved through current feedback. In terms of hardware, the system was constructed with a digital control circuit centered on the STM32F103, a power conversion circuit comprising a front-stage Buck voltage regulator and a rear-stage full-bridge inverter, and high-precision feedback sampling circuits. Experimental results indicated that the frequency tracking error of this system was less than 140 Hz under different static loads, the dynamic response time was less than 15 ms, and the amplitude fluctuation could be suppressed within ±5%. Comparative drilling experiments on Carbon Fiber Reinforced Polymer (CFRP) confirmed that after enabling the amplitude stabilization control, the quality of the hole exit morphology was significantly improved, with a notable reduction in burrs and fiber tear defects, and the cutting force became more stable. This research provides an effective solution for stabilizing ultrasonic energy output in dynamic robotic machining environments and possesses significant engineering application value.

To address the mismatch between pressure-bearing capacity and lightweight requirements in additively manufactured liquefied gas micro-propulsion tanks, this paper proposes a morphology-based lightweight design method constrained by mechanical performance. Using R134a (tetrafluoroethane) as the propellant and AlSi10Mg as the manufacturing material, a conformal tank system was designed, with the first-stage and second-stage tanks required to withstand pressures of 2 MPa and 1.6 MPa, respectively. High stress concentration and structural redundancy areas were identified using the von Mises equivalent stress method. Morphology optimization with variable thickness was performed with the objective of minimizing stress. The results indicate that with an optimized rib height of 1.6 mm, the maximum stress is 216 MPa, achieving a 37.07% reduction in mass and an 8.6% increase in propellant capacity. Fatigue and ultimate pressure tests were conducted, demonstrating that the tank's fatigue strength meets the 100-cycle requirement and the stages can withstand 2.1 MPa and 1.6 MPa respectively, satisfying the operational requirements for micro-nano satellites.

Polyimide (PI) light-trapping microstructures have shown great potential in improving the performance of optoelectronic devices. However, its high viscosity characteristic makes it difficult to achieve high-precision and large-area forming by traditional micro-nano fabrication techniques. Especially for the high aspect ratio light-trapping structure, the existing ultraviolet (UV) curing imprinting faces the key challenges of incomplete structure filling and insufficient morphology fidelity. Therefore, the study develops a simulation model incorporating two-phase flow of PI resin during imprint filling, revealing the influence of imprinting time, resin viscosity, and imprinting velocity on the filling completeness of microstructures. The experiments of UV curing imprinting replicated PI micro-pyramid array successfully with 500 μm height and 75° inclination angle. Through simulation guides optimization of imprinting parameters (imprinting temperature, imprinting force, and imprinting time), the large-area replication of PI micro-pyramid array achieves 96.2% structural height fidelity with inclination angle deviations below ± 1°. Optical performance testing indicates that the presence of the light-trapping microstructures reduces the surface reflectance of polyimide in the visible range from 7%-12% to 6%-10%. Furthermore, the reflectance can be lowered below 1% through the deposition of a coating on the surface of these light-trapping microstructures. The research not only overcomes the challenges in the fabrication of high-aspect-ratio PI microstructures but also provides a reliable and efficient method for the mass production of PI-based light-trapping structures. It offers new insights into the application of PI in advanced optoelectronic devices, promoting the development of high-performance and cost-effective photonic components.

Aiming at the demand of variable configuration and reconfigurable antenna technology for space equipment such as satellites, a frequency reconfigurable antenna manufacturing method based on laser Selective Melting (SLM) NiTi shape memory alloy is proposed. Firstly, the SLM process is studied by experiments, and the electromagnetic properties of NiTi alloy with defects are analyzed. The shape memory effect and the functional characteristics of superelasticity are revealed. On this basis, a frequency reconfigurable satellite antenna based on NiTi shape memory alloy is developed. S11 measurement and microwave darkroom gain test show that the antenna is tunable in the 7.7-12.6 GHz band, with a maximum gain of 6.2 dBi and a reflection loss of less than −10 dB.

Carbon Fiber Reinforced Polymer (CFRP) and aluminum stacked are widely used in aircraft assemble thanks to the high strength-to-weight ratio. Riveting is an important joining technique of stacked structure and requires drilling and countersinking. Robotic machining systems are gradually used in the machining of holes due to their high flexibility. However, weakly rigid stacked structure and low-stiffness industrial robot system bring about complex and diverse countersinking depth errors, which significantly affects the fatigue life of components. In this paper, the influence mechanism of ultrasonic energy on the accuracy of robotic countersinking of stacked structure is investigated. Firstly, a workpiece deformation model is established with the thin-walled plate deformation theory, defined as static error. Then, the vibration of the industrial robot is calculated from the acceleration with the frequency domain integration, defined as dynamic error. The suppression of ultrasonic energy on the two kinds of errors were elucidated, respectively. Base on this, a depth compensation model of robotic ultrasonic countersinking is established. Finally, the feasibility of the accuracy compensation is experimentally verified, and the countersinking depth error can be controlled within ±0.09 mm.

Due to the unique configuration of the stealth satellite, the spatial utilization of the carrying space is very low. The need of research on on-orbit assembly technology for stealth satellites is urgent. Based on the parameters and design requirements of in-orbit assembly for stealth satellites, the on-orbit assembly interface between stealth satellite modules is designed. In a microgravity environment where loads are not easily dissipated, excessive contact forces for on-orbit assembly affect the attitude stability of the spacecraft with the on-orbit assembly platform. Based on the geometric shapes of the components in contact during the assembly process, classify contact phases and calculate the Hertz contact force. Three feed paths are set, then the trend of the contact force magnitude and the location where the maximum contact force occurs for three paths are analyzed. The contact force experiment is carried out and results are compared with analyzed results. The correctness of the trend of the magnitude of the contact forces, the maximum contact forces and the location where the maximum contact forces occurs are verified.

To mitigate the high drilling temperatures and extensive machining damage associated with CFRP/titanium alloy laminated materials, a new robotic high and low frequency compound vibration-assisted drilling method has been developed. To assess the effectiveness of this process, a comparative experimental study was performed, comparing four machining techniques: conventional robot drilling, robotic high-frequency vibration drilling, robotic low-frequency vibration drilling, and robotic high and low frequency compound vibration-assisted drilling. The study evaluated drilling force, titanium alloy cutting temperature, titanium alloy chip morphology, the quality of CFRP holes, and the quality of Ti holes walls. The experimental results show that among the four processing methods, the high and low frequency compound vibration-assisted drilling by the robot can effectively reduce the axial force during drilling; the high and low frequency compound vibration-assisted drilling by the robot significantly reduces the cutting temperature of titanium alloy, with a maximum reduction of 31.25% compared to conventional robot drilling; the titanium alloy chips produced by the robot's high and low frequency compound vibrationassisted drilling are fan-shaped and the smallest in size; the high and low frequency compound vibration-assisted drilling by the robot significantly improves the CFRP hole edge damage and hole wall quality at low feed rates; the high and low frequency compound vibrationassisted drilling by the robot can significantly improves the quality of titanium alloy hole walls at low feed rates. Moreover, this improvement remains evident as the feed rate increases.

Aiming at the problems of low efficiency and serious tool wear in the drilling large hole for aviation large and complex carbon fiber reinforced polymer (CFRP)/titanium alloy (TC4) laminated stacks, a new process of robot laser and side-milling compound drilling is proposed, which has the advantages of high surface quality, high precision of geometry and high efficiency. laser and side-milling compound drilling experiment of CFRP/TC4 laminated stacks was carried out, and the effect of process parameters on the processing quality was explored. A Ø15 mm high precision hole was drilled on an 8mm CFRP/TC4 laminated stacks. Experimental results show that laser-induced heat affected zone (HAZ) can greatly reduce the cutting force during the milling process, the average cutting force of CFRP is reduced by 60.8%, and the average cutting force of TC4 is reduced by 66.2%. The introduction of minimal quantity lubrication (MQL) can greatly improve the surface quality. The surface roughness (Sa) of CFRP and TC4 decreasing by 36.1% and 36.8%, respectively, compared with dry cutting, and both remaining below 3.2 μm. The minimum interlayer burrs of CFRP and TC4 are 26.734 μm and 60.802 μm respectively.

Carbon fiber reinforced polymer (CFRP) is widely used in aircraft manufacturing field because of superior physical and mechanical properties. Millions of connection holes require to be drilled on CFRP material, the cutting damage of holes has crucial effect on the aircraft performance. Robotic rotary ultrasonic drilling (RRUD) as a potential method is proposed to improve the drilling quality. Nevertheless, it is difficult to control the drilling temperature to avoid exceeding the glass transition temperature of the resin matrix in a dry cutting environment during RRUD. The minimum quantity lubrication (MQL) technology can improve cooling conditions and achieve temperature reduction effectively. In this paper, an investigation on cutting temperature during the processing method combining RRUD and MQL (RRUD&MQL) is carried out and a theoretical prediction model is established. Firstly, analysis on RRUD&MQL coupling friction reduction mechanism is conducted with consideration of periodic kinematics characteristic in RRUD and lubrication property of MQL droplets. After that, based on this friction reduction mechanism, thrust force is calculated and cutting temperature model is established. Finally, validation experiments results indicate that analytical cutting temperatures agree well with the experimental value, and the average of relative prediction error is 9.12%.

Carbon fiber-reinforcement plastics (CFRP) have been widely applied in modern aerospace industry with aluminum alloy in the form of thin-walled stacks due to their superior mechanical and physical properties. However, for CFRP, the heat accumulation occurs easily during countersinking process in consequence of low thermal conductivity. The surface thermal damage of CFRP caused by excessive heat would affect the fatigue and stealth performance of aircraft. Consequently, the countersinking temperature is an important indicator to judge the feasibility of CFRP countersinking process. In this paper, to investigate temperature of countersinking process, the application of rotary ultrasonic machining technology to CFRP/Al thin-walled stacks countersinking process under different stiffness conditions with drilling-countersinking integrated tool is carried out by FEA (Finite element analysis) and experiments. And the influences of cutting temperature on countersunk wall quality are discussed. The results demonstrate that the maximum countersinking temperature increases with the decrease of axial stiffness, and the ultrasonic vibration can effectively reduce maximum countersinking temperature by 22.9%-26.2%. Furthermore, analysis of the surface quality of countersunk wall shows that the countersunk wall roughness and defects gradually deteriorate with the increase of the maximum countersinking temperature. Meanwhile, the ultrasonic vibration can improve countersunk surface quality by reducing maximum countersinking temperature effectively.