Consider the design and implementation of an electro-hydraulic control system for a robotic excavator, namely the Lancaster University computerized and intelligent excavator (LUCIE). The excavator was developed to aut...Consider the design and implementation of an electro-hydraulic control system for a robotic excavator, namely the Lancaster University computerized and intelligent excavator (LUCIE). The excavator was developed to autonomously dig trenches without human intervention. One stumbling block is the achievement of adequate, accurate, quick and smooth movement under automatic control, which is difficult for traditional control algorithm, e.g. PI/PID. A gain scheduling design, based on the true digital proportional-integral-plus (PIP) control methodology, was utilized to regulate the nonlinear joint dynamics. Simulation and initial field tests both demonstrated the feasibility and robustness of proposed technique to the uncertainties of parameters, time delay and load disturbances, with the excavator arm directed along specified trajectories in a smooth, fast and accurate manner. The tracking error magnitudes for oblique straight line and horizontal straight line are less than 20 mm and 50 mm, respectively, while the velocity reaches 9 m/min.展开更多
The indirect vector controlled IM （induction motor） drive involves decoupling of the stator current into torque and flux producing components. This paper proposes the implementation of a fuzzy logic control scheme a...The indirect vector controlled IM （induction motor） drive involves decoupling of the stator current into torque and flux producing components. This paper proposes the implementation of a fuzzy logic control scheme applied to a two d-q current components model of an induction motor. An intelligent based on fuzzy logic controller is developed with the help of knowledge rule base for efficient control. The performance of fuzzy logic controller is compared with that of the proportional integral controller in terms of the settling time and dynamic response to sudden load changes. The harmonic pattern of the output current is evaluated for both fixed gain proportional integral controller and the fuzzy logic based controller. The performance of the IM drive has been analyzed under steady state and transient conditions. Simulation results of both the controllers are presented for comparison.展开更多
We presented a quantity judgment task that involved comparing two sequentially presented sets of items to preschoolers and chimpanzees using nearly identical procedures that excluded verbal instructions to children. T...We presented a quantity judgment task that involved comparing two sequentially presented sets of items to preschoolers and chimpanzees using nearly identical procedures that excluded verbal instructions to children. Trial difficulty in this task reflected the ratio difference between sets of discrete items where larger ratios （e.g., 0.80 as from comparing 4 to 5） were more difficult than smaller ones （e.g., 0.50 as from comparing 4 to 8）. Children also completed verbal-based tasks probing the relationskip between counting proficiency and performance on the quantity judgment task of sequentially presented identical sized items. Both species＇ performance was best when ratios between comparison sets were small regardless of set size in all types of tasks. Generally, chimpanzees and older children performed better than younger children except at larger ratios. Children＇s counting proficiency was not related to success in choosing the larger of two quantities of identical-sized items. These results indicate that chimpanzees and children share an approximate number sense that is reflected through analog magnitude estimation when comparing quantities [Current Zoology 57 （4）： 419-428, 2011].展开更多
基金Project(K5117827)supported by Scientific Research Foundation for the Returned Overseas Chinese ScholarsProject(08KJB510021)supported by the Natural Science Research Council of Jiangsu Province,China+1 种基金Project(Q3117918)supported by Scientific Research Foundation for Young Teachers of Soochow University,ChinaProject(60910001)supported by National Natural Science Foundation of China
文摘Consider the design and implementation of an electro-hydraulic control system for a robotic excavator, namely the Lancaster University computerized and intelligent excavator (LUCIE). The excavator was developed to autonomously dig trenches without human intervention. One stumbling block is the achievement of adequate, accurate, quick and smooth movement under automatic control, which is difficult for traditional control algorithm, e.g. PI/PID. A gain scheduling design, based on the true digital proportional-integral-plus (PIP) control methodology, was utilized to regulate the nonlinear joint dynamics. Simulation and initial field tests both demonstrated the feasibility and robustness of proposed technique to the uncertainties of parameters, time delay and load disturbances, with the excavator arm directed along specified trajectories in a smooth, fast and accurate manner. The tracking error magnitudes for oblique straight line and horizontal straight line are less than 20 mm and 50 mm, respectively, while the velocity reaches 9 m/min.
文摘The indirect vector controlled IM （induction motor） drive involves decoupling of the stator current into torque and flux producing components. This paper proposes the implementation of a fuzzy logic control scheme applied to a two d-q current components model of an induction motor. An intelligent based on fuzzy logic controller is developed with the help of knowledge rule base for efficient control. The performance of fuzzy logic controller is compared with that of the proportional integral controller in terms of the settling time and dynamic response to sudden load changes. The harmonic pattern of the output current is evaluated for both fixed gain proportional integral controller and the fuzzy logic based controller. The performance of the IM drive has been analyzed under steady state and transient conditions. Simulation results of both the controllers are presented for comparison.
基金We wish to acknowledge the staff at the Berry College Child Development Center and Georgia State University Language Research Center for their support in data collection. Research with chimpanzees was supported by grants from the National Institutes of Health （HD 38051 and HD 060563） and the National Science Foundation （BCS 0924811）. The authors thank Mary Beran and John Kelley for their assistance in conducting experimental sessions with chimpanzees, and the staff at the Berry College Child Development Center for data collection with preschoolers. We thank Carla Moldavan for helpful comments pertaining to early childhood mathematical curricula.
文摘We presented a quantity judgment task that involved comparing two sequentially presented sets of items to preschoolers and chimpanzees using nearly identical procedures that excluded verbal instructions to children. Trial difficulty in this task reflected the ratio difference between sets of discrete items where larger ratios （e.g., 0.80 as from comparing 4 to 5） were more difficult than smaller ones （e.g., 0.50 as from comparing 4 to 8）. Children also completed verbal-based tasks probing the relationskip between counting proficiency and performance on the quantity judgment task of sequentially presented identical sized items. Both species＇ performance was best when ratios between comparison sets were small regardless of set size in all types of tasks. Generally, chimpanzees and older children performed better than younger children except at larger ratios. Children＇s counting proficiency was not related to success in choosing the larger of two quantities of identical-sized items. These results indicate that chimpanzees and children share an approximate number sense that is reflected through analog magnitude estimation when comparing quantities [Current Zoology 57 （4）： 419-428, 2011].
