입력 다듬기기법을 이용한 유연관절을 갖는 로봇의 잔류진동 제거

This paper addresses the residual vibration problem of robots due to joint flexibility excited by fast accelerations, which has not been easily solved with conventional closed loop controllers. In this paper, an open loop input shaping technique, proposed by singer, has been applied to a 3 DOF robot with joint flexibility. In conjunction to the technique, a closed loop controller based on time-delay controller was also used. The results of simulations and experiments showed that the technique is quite effective for suppressing the residual vibration

미세조류 당화액으로부터 순차적 기질 활용을 통한 에탄올과 DagA 생산공정 개발

학위논문(박사) - 한국과학기술원 : 생명화학공학과, 2016.2 ,[x, 124 p. :]Microalgal hydrolysate, an alternative carbon source, could be used as a feedstock for the production of valuable bioproducts such as biofuel and biochemicals. The acid hydrolysate of Nannochloropsis oceanica contains 7 different sugars of glucose, galactose, xylose, rhamnose, ribose, mannose and fucose. At first, DagA, a β-agarase was produced by cultivating a recombinant Streptomyces lividans in a glucose medium or a mixed-sugar medium simulating microalgae hydrolysate. The optimum composition of glucose medium was identified as 25 g/L glucose, 10 g/L yeast extract, and 5 $g/L MgCl_2·6H_2O$. With this, a DagA activity of 7.26 U/mL was obtained. It was tried to produce DagA in mixed-sugar medium mimicking N. oceanica hydrolysate. When a mixed-sugar medium containing 25 g/L of sugars was used, a DagA activity of 4.81 U/mL was obtained with very low substrate utilization efficiency due to the catabolic repression of glucose against the other sugars. When glucose and galactose were removed from the medium, an unexpectedly high DagA activity of about 8.7 U/mL was obtained even though a smaller amount of sugars were used. It is recommended for better substrate utilization and process economics that glucose and galactose should be eliminated from the medium being consumed for some other useful applications before the production of DagA. A novel two-step fermentation process based on sequential utilization of sugars in the mixed-sugar medium has been proposed. In the first step, glucose was consumed by Saccharomyces cerevisiae together with galactose and mannose producing ethanol. In the second step, DagA was produced by the recombinant S. lividans from the residual sugars of xylose, rhamnose and ribose. Fucose was not consumed. By adopting this two-step process, the overall substrate utilization efficiency was increased approximately 3-fold with a nearly 2-fold improvement of DagA production, let alone the additional benefit of ethanol production. Afore-mentioned two-step fermentation process was studied by using real microalgal hydrolysate. To prepare microalgal hydrolysate, 100 g/L lipid-extracted N. oceanica biomass was treated with 1.5 N $HNO_3$ or $H_2SO_4$ at 120 ℃ for 60 min. The N. oceanica hydrolysate treated by nitric acid was desalted by electrodialysis. When a membrane with a molecular weight cut-off of 300, about 98 % salts were removed from N. oceanica hydrolysate. Although, the total salt concentration was low enough, yeast cells in the first stage did not show a substantial level of growth probably due to still remaining inhibitory compounds. The N. oceanica hydrolysate treated by sulfuric acid was neutralized with $CaCO_3$. In this step, sulfate was removed in the form of gypsum. The treated hydrolysate containing total 7.01 g/L of 7 different monosugars: 2.19 g/L glucose, 1.12 g/L galactose, 1.32 g/L mannose, 0.47 g/L xylose, 0.50 g/L rhamnose, 0.86 g/L ribose and 0.55 g/L fucose was used for the sequential production of ethanol and DagA. In the first step, 1.30 g/L of ethanol was produced by S. cerevisiae with complete utilization of glucose, galactose and mannose. In the second step, 3.6 U/mL of DagA was produced by S. lividans with complete utilization of the residual sugars except fucose. Consequently, an overall substrate utilization of as high as 92.2 % was obtained. The unconsumed fucose has a potential to be a high-value-added product with many applications once recovered.한국과학기술원 :생명화학공학과

Implementation of universal robot controller and application to redundant robot

학위논문(석사) - 한국과학기술원 : 정밀공학과, 1993.2, [ [ii], 36, [2] p. ]한국과학기술원 : 정밀공학과

비선형-시변 시스템의 잔류진동제거를 위한 학습 입력다듬기에 대한 연구

학위논문(박사) - 한국과학기술원 : 기계공학전공, 2001.8, [ xi, 139 p. ]It is well known that conventional Input Shaping Technique (IST) is not very effective in suppressing residual vibrations for nonlinear and time varying systems. In an effort to increase the effectiveness for such systems, this thesis presents Learning Input Shaping Technique (LIST) which iteratively updates the parameters of IST from previous trials. Simulations are presented for four different cases: (1) when the natural frequency or damping of a system is not estimated well; (2) when a system has time varying vibration; (3) when a system has nonlinear flexibility; and (4) when a closed loop system includes a saturation element in the loop. LIST is experimented on a six D.O.F industrial robot to evaluate its effectiveness. The results of the simulations and the experiment show that the residual vibrations become considerably smaller as iteration goes on, thereby demonstrating the effectiveness of LIST. The results of LIST is compared to that of time varying IST (TVIST), which changes the IST parameters in real time according to an estimated frequency.한국과학기술원 : 기계공학전공