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Xi Zeng,Shi-ming Ji,Ming-sheng Jin,Da-peng Tan,Jue-hui Li,Wen-tao Zeng 한국정밀공학회 2014 International Journal of Precision Engineering and Vol. No.
In order to improve material removal rate of laser hardening workpiece and also make machining tool suitable for free-form surface,a new method based on the softness consolidation abrasives (SCA) is put forward, which means the abrasives are consolidated onthe outer layer of pneumatic wheel to achieve the softness-machining. Binder selecting test shows that acidic silicone is proved tosuit for consolidating particles in cutting process. Combined with robot, the machining system has been established. The machiningeffects of SCA are investigated when it faces with workpiece of different hardness. According to the Preston predicted model, thesimulation results of stress and velocity are proven by analysis of average roughness in the contact region. The contrastive machiningexperimental results show that SCA can supply high cutting stress for material removal and fit for freeform surface’s machining byself-adjustment of flexible body.
Ming Xi Li,Fei Cai,Shi Hong Zhang 한국물리학회 2013 Current Applied Physics Vol.13 No.7
The AleTieN films deposited by multi-arc ion plating have been annealed in vacuum within the range of 700-1100 ℃. X-ray diffraction results showed that the structure of the films underwent the formation of coherent c-TiN and c-AlN for the annealing temperatures were up to 900 ℃. A new phase AlTix (x = 0.50,0.56, 3) was observed after annealing. The X-ray photoelectron spectroscopy results showed the intensity of TieAl bonds decreased as annealing temperatures increased, indicating the decomposition of (Al, Ti)N into c-TiN and c-AlN were at the expense of TieAl bonds. Differential scanning calorimetry experiments were used to investigate the dynamic behavior of the films during annealing process and the results showed that the N2 formed as a consequence of the phase transformation process. The release of the N2resulted in the peeling of the films from the substrates. The film exhibited a maximum hardness of 39 GPa after 900 ℃ annealing due to the formation of coherent c-TiN and c-AlN phases. In addition, we also investigated the influence of vacuum annealing on adhesive strength.
Development of an automated guidance system for rice transplanter1
( Fang-ming Zhang ),( Xi-ming Feng ),( Yuan Li ),( Beom-soo Shin ),( Ru-jiang Shou ) 한국농업기계학회 2012 한국농업기계학회 학술발표논문집 Vol.17 No.1
An automated guidance system was developed on a rice transplanter. A distributed embedded computer system, one ECC and 5 ECUs, was constructed. Two Kalman filters were formed. The 1<sup>st</sup> one, named as global Kalman filter, integrated data of a RTK-GPS, a strapdown attitude sensor, and two encoders. The 2<sup>nd</sup> one, named as local Kalman filter, integrated data of a strapdown attitude sensor and two encoders. A PID controller was applied to row following control, whose offset RMS could less than 4 cm at speed of 1.2 m/s. A U-turn controller was also designed that it could control the transplanter in a go-turn-back mode.
( Fang Ming Zhang ),( Beom Soo Shin ),( Xi Ming Feng ),( Yuan Li ),( Ri Jiang Shou ) 한국농업기계학회 2013 바이오시스템공학 Vol.38 No.4
Purpose: It is not easy to drive a rice-transplanter avoiding underlapped or overlapped transplanting in paddy fields. An automated guidance system for the riding-type rice-transplanter would be necessary to operate the rice-transplanter autonomously or to assist the beginning drivers as a driving aid. Methods: A prototype of guidance system was composed of embedded computers, RTK-GPS, and a power-steering mechanism. Two Kalman filters were adopted to overcome sparse positioning data (1 Hz) from the RTK-GPS. A global Kalman filter estimated the posture of rice-transplanter every one second, and a local Kalman filter calculated the posture from every new estimation of the global Kalman filter with an interval of 200 ms. A PID controller was applied to the row-following mode control. A control method of U-turning mode was developed as well. A stepping motor with a reduction gear set was used to rotate the shaft of steering wheel. Results:Test trials for U-turning and row-following modes were done in a paddy field after some parameters have been tuned at the ground speed range of 0.3 ~ 1.2 m/s. The minimum RMS error of offset was 3.13 cm at the ground speed of 0.3 m/s while the maximum RMS error was 13.01 cm at 1.2 m/s. The offset RMS error tended to increase as the ground speed increased. The target point distance, LT also affected the system performance and PID controller parameters should be adjusted on different ground speeds. Conclusions: A target angle-based PID controller plus stationary steering angle controller made it possible for the rice-transplanter to steer autonomously by following a reference line accurately and even on U-turning mode. However, as condition in paddy fields is very complicated, the system should control the ground speed that prevents it from deviating too much due to ditch and slope.
Adaptive Multiple MPC for a Wind Farm with DFIG
Xiao-ming LI,Xi ZHANG,Zhong-wei LIN,Yu-guang NIU,Ming-yang LI,Noel Vishal Nathan 대한전기학회 2016 Journal of Electrical Engineering & Technology Vol.11 No.5
For low investment and flexible control, doubly fed induction generator (DFIG) is becoming the dominant type that is been used in the wind farms (WFs) today. The report researches about the rotor-side controller of DFIG where all design is based on the single machine infinite bus (SMIB) model. The interactions between the different generators have not been considered in the SMIB model, and the desired performance cannot be obtained by using the controller based on this model. In this situation, an adaptive decentralized-coordinated multiple model predictive control (ADM-MPC) is proposed. First, the interaction measurement method is developed to obtain the interaction measurement model of DFIG, where the interactions between the different generators have been considered. Next, an adaptive multiple MPC based on the obtained interaction measurement method of DFIG is employed to control the rotor-side converter of DFIG. In order to cope with the stochastic disturbance of wind turbine, the augment state structure is employed to improve the tracking control performance. An artificial neural network (ANN) trained online is employed as a weighting controller to cope with the nonlinearities and large operating range of DFIG. A simple, generic renewable power system (RPS) is used to demonstrate contributions. The results of both dominant eigenvalue analysis and time response simulations are represented to illustrate contributions to system damping and transient stability that the DFIG based WF can make with the proposed ADM-MPC controller.
Development of a Prototype of Guidance System for Rice-transplanter
Zhang, Fang-Ming,Shin, Beom-Soo,Feng, Xi-Ming,Li, Yuan,Shou, Ru-Jiang Korean Society for Agricultural Machinery 2013 바이오시스템공학 Vol.38 No.4
Purpose: It is not easy to drive a rice-transplanter avoiding underlapped or overlapped transplanting in paddy fields. An automated guidance system for the riding-type rice-transplanter would be necessary to operate the rice-transplanter autonomously or to assist the beginning drivers as a driving aid. Methods: A prototype of guidance system was composed of embedded computers, RTK-GPS, and a power-steering mechanism. Two Kalman filters were adopted to overcome sparse positioning data (1 Hz) from the RTK-GPS. A global Kalman filter estimated the posture of rice-transplanter every one second, and a local Kalman filter calculated the posture from every new estimation of the global Kalman filter with an interval of 200 ms. A PID controller was applied to the row-following mode control. A control method of U-turning mode was developed as well. A stepping motor with a reduction gear set was used to rotate the shaft of steering wheel. Results: Test trials for U-turning and row-following modes were done in a paddy field after some parameters have been tuned at the ground speed range of 0.3 ~ 1.2 m/s. The minimum RMS error of offset was 3.13 cm at the ground speed of 0.3 m/s while the maximum RMS error was 13.01 cm at 1.2 m/s. The offset RMS error tended to increase as the ground speed increased. The target point distance, LT also affected the system performance and PID controller parameters should be adjusted on different ground speeds. Conclusions: A target angle-based PID controller plus stationary steering angle controller made it possible for the rice-transplanter to steer autonomously by following a reference line accurately and even on U-turning mode. However, as condition in paddy fields is very complicated, the system should control the ground speed that prevents it from deviating too much due to ditch and slope.