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Shuwei Qu,Ruiqin Li,Shaoping Bai,Shijie Liang 대한기계학회 2018 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.32 No.10
A unified model is proposed for the output accuracy of open-chain manipulators in consideration of joint clearance and structural parameters. First, the operator of the finite-displacement screw matrix and the combination operation are presented. Second, the joint clearance and structural parameters are described and analyzed with screw theory. A virtual screw is established for the joint clearance and structural parameter errors. Third, a unified model is built through the adjoint transformation of Lie groups in consideration of the two effectors of the virtual screw. The error pose is decomposed into orientation and position errors, which are obtained through the virtual screw. Finally, an open-chain manipulator with six degrees of freedom is analyzed based on the proposed model. The position and orientation errors are obtained with the trajectory that provided an intuitive geometric insight into the accuracy and exact maximal position and orientation errors.
Type synthesis for lower-mobility decoupled parallel mechanism with redundant constraints
Shuwei Qu,Ruiqin Li,Chunsheng Ma,Hong Li 대한기계학회 2021 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.35 No.6
A novel method for type synthesis of lower-mobility decoupled parallel mechanism with redundant constraints is proposed. Firstly, the definition of the redundant constraints is put forward. Then, number and topology structure synthesis is carried out based on the redundant constraints between the closed loop structure of parallel configuration. Next, the specific procedure for type synthesis of lower-mobility decoupled parallel mechanism is derived. Furthermore, the local freedom of the limbs was established through the relationship of motion-screw and constraint-screw between limbs. Finally, type synthesis of 2R1T decoupled parallel mechanism is established. The synthesized configuration theoretical output characteristics is a decoupled Jacobin matrix. The output characteristics are analyzed based on theoretical calculation and ADAMS simulation software. The simulation results and the theoretical calculation results are consistent. The proposed method can be applied to type synthesis of lower-mobility decoupled parallel mechanisms.
Shuwei LI,Jung Rae KIM 한국생물공학회 2021 한국생물공학회 학술대회 Vol.2021 No.10
The electron donor is essential to provide respiratory energy to the metabolism of living organisms. Although most microbes usually uptake electrons from soluble organic matter or reduced inorganic compounds (i.e. electron donors), some electroactive bacteria can directly uptake electrons from the solid electrode surface. However, most previous studies focus on reduction of C1, so far less is known about the metabolic shift and electron transfer mechanism of direct and indirect electron uptake in CO₂ fixation. In this study, we focused on polyhydroxybutyrate (PHB) as the target product from CO₂ electrosynthesis to examine the direct and indirect electron uptake of Rhodobacter sphaeroides. Our results show that R. sphaeroides converts more CO₂ into products (i.e., PHB) by direct electron uptake, but the cell grow slowly compare to indirect electron uptake. Notably, although cells growth is retarded, and both Rubisco form I and form II are highly down-regulated in direct electron uptake, but the NADH depend isocitrate dehydrogenase expression is stimulated by direct electron uptake. The Direct electron uptake and CO₂ fixation also occurs under dark conditions, uncoupled from photosynthesis. Therefore, there may be an unknown CO₂ fixation pathway other than the Calvin cycle using direct electron uptake from cathode.