Aiming at the issue of yaw and rollover stability control for off-road vehicles with non-pneumatic mechanical elastic wheel(MEW),an integrated control system based on fuzzy differential braking is developed.By simplif...Aiming at the issue of yaw and rollover stability control for off-road vehicles with non-pneumatic mechanical elastic wheel(MEW),an integrated control system based on fuzzy differential braking is developed.By simplifying the structure of the MEW,a corresponding fitting brush tire model is constructed and its longitudinal and lateral tire force expressions are set up,respectively.Then,a nonlinear vehicle simulation model with MEW is established to validate the proposed control scheme based on Carsim.The designed yaw and rollover control system is a two-level structure with the upper additional moment controller,which utilizes a predictive load transfer ratio(PLTR)as the rollover index.In order to design the upper integrated control algorithm,fuzzy proportional-integral-derivative(PID)is adopted to coordinate the yaw and rollover control,simultaneously.And the lower control allocator realizes the additional moment to the vehicle by differential braking.Finally,a Carsim-simulink co-simulation model is constructed,and simulation results show that the integrated control system could improve the vehicle yaw and roll stability,and prevent rollover happening.展开更多
Abstract: The current method to solve the problem of active suspension control for a vehicle is often dealt with a quarter-car or half-car model. But it is not enough to use this kind of model for practical applicatio...Abstract: The current method to solve the problem of active suspension control for a vehicle is often dealt with a quarter-car or half-car model. But it is not enough to use this kind of model for practical applications. In this paper, based on considering the influence of factors such as, seat and passengers, a MDOF(multi-degree-of-freedom) model describing the vehicle motion is set up. The MODF model, which is 8DOF of four independent suspensions and four wheel tracks, is more applicable by comparison of its analysis result with some conventional vehicle models. Therefore, it is more suitable to use the 8DOF full-car model than a conventional 4DOF half-car model in the active control design for car vibration. Based on the derived 8DOF model, a controller is designed by using LQ (linear quadratic ) control theory, and the appropriate control scheme is selected by testing various performance indexes. Computer simulation is carried out for a passenger car running on a road with step disturbance and random road disturbance expressed by Power Spectral Density (PSD). Vibrations corresponding to ride comfort are derived under the foregoing road disturbances. The response results for uncontrolled and controlled system are compared. The response of vehicle vibration is greatly suppressed and quickly damped, which testifies the effect of the active suspension. The results achieved for various controllers are compared to investigate the influence of different control schemes on the control effect.展开更多
In order to improve the yaw stability of the vehicle with active front steering system, an adaptive PID-type fuzzy control scheme is designed to make the yaw rate tracking the desired values as close as possible. A 2-...In order to improve the yaw stability of the vehicle with active front steering system, an adaptive PID-type fuzzy control scheme is designed to make the yaw rate tracking the desired values as close as possible. A 2-DOF vehicle model with active front steering is built firstly, and then the fuzzy PID controller is designed in detail. The simulation investigations of the yaw stability with different steering ma- neuvers are performed. The simulation results show the effectiveness of the fuzzy PID controller for improving the vehicle's yaw stability.展开更多
With the help of engineering technologies, there are varieties of medical supports such as surgical simulations, preoperative plans, intraoperative supports, and diagnostic explanations. In order to perform preoperati...With the help of engineering technologies, there are varieties of medical supports such as surgical simulations, preoperative plans, intraoperative supports, and diagnostic explanations. In order to perform preoperative plans, the simulation model of the target organ is necessary, and is usually generated from some fine images obtained by imaging devices such as CT (computed tomography) or MRI (magnetic resonance imaging). These devices, however, are very large and it is difficult to use them during the surgery although there is a kind of MRI that can be used during operations. On the other hand, there is a device called Ultrasonography (US Echo). It is so handy and can be easily used during operations without radiation or magnetic effect. US images, however, are not usually used for the construction of 3D model for preoperative plans since there are so many noises in the image, and the quality of the image is not so good compared to the images obtained by CT or MRI. Therefore, the authors have tried to construct 3D volumetric shape model from just two 2D US (ultrasound) images, which are the horizontal and vertical cross-section images of the target organ. Their concrete target organ and surgery are the aorta and AAE (annuloaortic ectasia), respectively. With some technologies of image processing, the boundary of the aorta is extracted for both cross-section images, and the thickness of the aorta is estimated. These processes are applied to not only the aorta wall but also the aorta valve. Finally, the aorta shape model can be constructed by inserting the estimated horizontal aorta images into the estimated vertical one. The constructed model has three dimensions so that it can be viewed from any point of view.展开更多
基金Project(11672127)supported by the National Natural Science Foundation of ChinaProject(NHAl3002)supported by the Major Exploration Project of the General Armaments Department of China+1 种基金Project(KYCX17_0240)supported by the Postgraduate Research&Practice Innovation Program of Jiangsu Province,ChinaProjects(NP2016412,NP2018403,NT2018002)supported by the Fundamental Research Funds for the Central Universities,China
文摘Aiming at the issue of yaw and rollover stability control for off-road vehicles with non-pneumatic mechanical elastic wheel(MEW),an integrated control system based on fuzzy differential braking is developed.By simplifying the structure of the MEW,a corresponding fitting brush tire model is constructed and its longitudinal and lateral tire force expressions are set up,respectively.Then,a nonlinear vehicle simulation model with MEW is established to validate the proposed control scheme based on Carsim.The designed yaw and rollover control system is a two-level structure with the upper additional moment controller,which utilizes a predictive load transfer ratio(PLTR)as the rollover index.In order to design the upper integrated control algorithm,fuzzy proportional-integral-derivative(PID)is adopted to coordinate the yaw and rollover control,simultaneously.And the lower control allocator realizes the additional moment to the vehicle by differential braking.Finally,a Carsim-simulink co-simulation model is constructed,and simulation results show that the integrated control system could improve the vehicle yaw and roll stability,and prevent rollover happening.
文摘Abstract: The current method to solve the problem of active suspension control for a vehicle is often dealt with a quarter-car or half-car model. But it is not enough to use this kind of model for practical applications. In this paper, based on considering the influence of factors such as, seat and passengers, a MDOF(multi-degree-of-freedom) model describing the vehicle motion is set up. The MODF model, which is 8DOF of four independent suspensions and four wheel tracks, is more applicable by comparison of its analysis result with some conventional vehicle models. Therefore, it is more suitable to use the 8DOF full-car model than a conventional 4DOF half-car model in the active control design for car vibration. Based on the derived 8DOF model, a controller is designed by using LQ (linear quadratic ) control theory, and the appropriate control scheme is selected by testing various performance indexes. Computer simulation is carried out for a passenger car running on a road with step disturbance and random road disturbance expressed by Power Spectral Density (PSD). Vibrations corresponding to ride comfort are derived under the foregoing road disturbances. The response results for uncontrolled and controlled system are compared. The response of vehicle vibration is greatly suppressed and quickly damped, which testifies the effect of the active suspension. The results achieved for various controllers are compared to investigate the influence of different control schemes on the control effect.
基金Supported by the National Natural Science Foundation of China (No.50705008)
文摘In order to improve the yaw stability of the vehicle with active front steering system, an adaptive PID-type fuzzy control scheme is designed to make the yaw rate tracking the desired values as close as possible. A 2-DOF vehicle model with active front steering is built firstly, and then the fuzzy PID controller is designed in detail. The simulation investigations of the yaw stability with different steering ma- neuvers are performed. The simulation results show the effectiveness of the fuzzy PID controller for improving the vehicle's yaw stability.
文摘With the help of engineering technologies, there are varieties of medical supports such as surgical simulations, preoperative plans, intraoperative supports, and diagnostic explanations. In order to perform preoperative plans, the simulation model of the target organ is necessary, and is usually generated from some fine images obtained by imaging devices such as CT (computed tomography) or MRI (magnetic resonance imaging). These devices, however, are very large and it is difficult to use them during the surgery although there is a kind of MRI that can be used during operations. On the other hand, there is a device called Ultrasonography (US Echo). It is so handy and can be easily used during operations without radiation or magnetic effect. US images, however, are not usually used for the construction of 3D model for preoperative plans since there are so many noises in the image, and the quality of the image is not so good compared to the images obtained by CT or MRI. Therefore, the authors have tried to construct 3D volumetric shape model from just two 2D US (ultrasound) images, which are the horizontal and vertical cross-section images of the target organ. Their concrete target organ and surgery are the aorta and AAE (annuloaortic ectasia), respectively. With some technologies of image processing, the boundary of the aorta is extracted for both cross-section images, and the thickness of the aorta is estimated. These processes are applied to not only the aorta wall but also the aorta valve. Finally, the aorta shape model can be constructed by inserting the estimated horizontal aorta images into the estimated vertical one. The constructed model has three dimensions so that it can be viewed from any point of view.