The tracking problem of nonholonomic mobile robots with uncertainties is investigated in this paper. An uncertain model of the nonholonomic kinematic system is presented based on the visual feedback and the state and ...The tracking problem of nonholonomic mobile robots with uncertainties is investigated in this paper. An uncertain model of the nonholonomic kinematic system is presented based on the visual feedback and the state and input transformations for a kind of mobile robots in chained form with uncertainties. Two transformations are exploited based on the idea of backstepping and the structure of tracking error system. Then, both an adaptive control law and a dynamic feedback robust controller are designed to track the desired trajectory by using Lyapunov direct method and the extended Barbalat Lemma. The asymptotic convergence of a closed-loop error system is proved rigorously. Finally, simulation results demonstrate the effectiveness of the proposed strategies.展开更多
The pinhole gamma camera is the basis of the newly developed method of high-resolution pinhole single photon emission computed tomography (SPECT). In this paper, a pinhole gamma camera system was examined using the ch...The pinhole gamma camera is the basis of the newly developed method of high-resolution pinhole single photon emission computed tomography (SPECT). In this paper, a pinhole gamma camera system was examined using the channel model of information theory. The model pinhole gamma camera was simplified from a noisy, lossy channel to a noiseless, lossless channel by assuming a plane source. An approximate formula of average mutual information for the pinhole gamma camera was then derived from the model. Imaging experiments validated the applicability of the analytic formula. The findings demonstrated that the pinhole gamma camera can be adequately described using the channel model of information theory, and that average mutual information can be considered a figure of merit for the optimizing design of the pinhole gamma camera.展开更多
Distributed source coding （DSC） is applied to interferential multispectral image compression owing to strong correlation among the image frames. Many DSC systems in the literature use feedback channel （FC） to cont...Distributed source coding （DSC） is applied to interferential multispectral image compression owing to strong correlation among the image frames. Many DSC systems in the literature use feedback channel （FC） to control rate at the decoder, which limits the application of DSC. Upon an analysis of the image data, a rate control approach is proposed to avoid FC. Low-complexity motion compensation is applied first to estimate side information at the encoder. Using a polynomial fitting method, a new mathematical model is then derived to estimate rate based on the correlation between the source and side information. The experimental results show that our estimated rate is a good approximation to the actual rate required by FC while incurring a little bit-rate overhead. Our compression scheme performs comparable with the FC based DSC system and outperforms JPEG2000 significantly.展开更多
A system for a type of nonholonomic wheeled mobile robots equipped with an uncalibrated camera fixed to the ceiling is investigated.Based on the visual feedback and the state-input transformation,models of uncertain c...A system for a type of nonholonomic wheeled mobile robots equipped with an uncalibrated camera fixed to the ceiling is investigated.Based on the visual feedback and the state-input transformation,models of uncertain chained form systems are presented for the robot-camera systems.Then,new smooth time-varying feedback controllers are proposed to exponentially stabilize the uncertain chained system by using state-scaling and control theories for two cases.The exponential stabilities of the closed-loop uncertain systems are rigorously proved.Simulation results demonstrate the effectiveness of the proposed strategies.展开更多
基金Supported by National Natural Science Foundation of China(61374040,61304004,61473179)Scientific Innovation Program(13Z Z115)+2 种基金Hujiang Foundation of China(C14002)Graduate Innovation Program of Shanghai(54-13-302-102)and the Natural Science Foundation of Shandong Province(ZR2013FM012,ZR2014FM007)
文摘The tracking problem of nonholonomic mobile robots with uncertainties is investigated in this paper. An uncertain model of the nonholonomic kinematic system is presented based on the visual feedback and the state and input transformations for a kind of mobile robots in chained form with uncertainties. Two transformations are exploited based on the idea of backstepping and the structure of tracking error system. Then, both an adaptive control law and a dynamic feedback robust controller are designed to track the desired trajectory by using Lyapunov direct method and the extended Barbalat Lemma. The asymptotic convergence of a closed-loop error system is proved rigorously. Finally, simulation results demonstrate the effectiveness of the proposed strategies.
文摘The pinhole gamma camera is the basis of the newly developed method of high-resolution pinhole single photon emission computed tomography (SPECT). In this paper, a pinhole gamma camera system was examined using the channel model of information theory. The model pinhole gamma camera was simplified from a noisy, lossy channel to a noiseless, lossless channel by assuming a plane source. An approximate formula of average mutual information for the pinhole gamma camera was then derived from the model. Imaging experiments validated the applicability of the analytic formula. The findings demonstrated that the pinhole gamma camera can be adequately described using the channel model of information theory, and that average mutual information can be considered a figure of merit for the optimizing design of the pinhole gamma camera.
基金Supported by the National Natural Science Foundation of China （No. 60532060 60672117）, the Program for Changjiang Scholars and Innovative Research Team in University （PCS1TR）.
文摘Distributed source coding （DSC） is applied to interferential multispectral image compression owing to strong correlation among the image frames. Many DSC systems in the literature use feedback channel （FC） to control rate at the decoder, which limits the application of DSC. Upon an analysis of the image data, a rate control approach is proposed to avoid FC. Low-complexity motion compensation is applied first to estimate side information at the encoder. Using a polynomial fitting method, a new mathematical model is then derived to estimate rate based on the correlation between the source and side information. The experimental results show that our estimated rate is a good approximation to the actual rate required by FC while incurring a little bit-rate overhead. Our compression scheme performs comparable with the FC based DSC system and outperforms JPEG2000 significantly.
基金supported by the National Natural Science Foundation of China under Grant Nos.61374040,61304004 and 61473179the Natural Science Foundation of Shandong Province under Grant Nos.ZR2013FM012 and ZR2014FM007
文摘A system for a type of nonholonomic wheeled mobile robots equipped with an uncalibrated camera fixed to the ceiling is investigated.Based on the visual feedback and the state-input transformation,models of uncertain chained form systems are presented for the robot-camera systems.Then,new smooth time-varying feedback controllers are proposed to exponentially stabilize the uncertain chained system by using state-scaling and control theories for two cases.The exponential stabilities of the closed-loop uncertain systems are rigorously proved.Simulation results demonstrate the effectiveness of the proposed strategies.
