Research on Suspension Gravity Compensation System of Lunar Rover with Magnetic Levitation Servo

In order to overcome the shortcomings of the traditional sling suspension method,such as complex structure of suspension truss,large running resistance,and low precision of position servo system,a gravity compensation method of lunar rover based on the combination of active suspension and active position following of magnetic levitation is proposed,and the overall design is carried out.The dynamic model of the suspension module of microgravity compensation system was established,and the decoupling control between the constant force component and the position servo component was analyzed and verified.The constant tension control was achieved by using hybrid force/position control.The position following control was realized by using fuzzy adaptive PID(proportional⁃integral⁃differential)control.The stable suspension control was realized based on the principle of force balance.The simulation results show that the compensation accuracy of constant tension could reach more than 95%,the position deviation was less than 5 mm,the position deviation angle was less than 0.025°,and the air gap recovered stability within 0.1 s.The gravity compensation system has excellent dynamic performance and can meet the requirements of microgravity simulation experiment of lunar rover.

Establishment of genomic library technology mediated by non-homologous end joining mechanism in Yarrowia lipolytica

Genomic variants libraries are conducive to obtain dominant strains with desirable phenotypic traits.The non-homologous end joining(NHEJ),which enables foreign DNA fragments to be randomly integrated into different chromosomal sites,shows prominent capability in genomic libraries construction.In this study,we established an efficient NHEJ-mediated genomic library technology in Yarrowia lipolytica through regulation of NHEJ repair process,employment of defective Ura marker and optimization of iterative transformations,which enhanced genes integration efficiency by 4.67,22.74 and 1.87 times,respectively.We further applied this technology to create high lycopene producing strains by multi-integration of heterologous genes of CrtE,CrtB and CrtI,with 23.8 times higher production than rDNA integration through homologous recombination(HR).The NHEJ-mediated genomic library technology also achieved random and scattered integration of loxP and vox sites,with the copy number up to 65 and 53,respectively,creating potential for further application of recombinase mediated genome rearrangement in Y.lipolytica.This work provides a high-efficient NHEJ-mediated genomic library technology,which enables random and scattered genomic integration of multiple heterologous fragments and rapid generation of diverse strains with superior phenotypes within 96 h.This novel technology also lays an excellent foundation for the development of other genetic technologies in Y.lipolytica.