For a distributed drive electric vehicle（DDEV） driven by four in-wheel motors, advanced vehicle dynamic control methods can be realized easily because motors can be controlled independently, quickly and precisely. A...For a distributed drive electric vehicle（DDEV） driven by four in-wheel motors, advanced vehicle dynamic control methods can be realized easily because motors can be controlled independently, quickly and precisely. And direct yaw-moment control（DYC） has been widely studied and applied to vehicle stability control. Good vehicle handling performance： quick yaw rate transient response, small overshoot, high steady yaw rate gain, etc, is required by drivers under normal conditions, which is less concerned, however. Based on the hierarchical control methodology, a novel control system using direct yaw moment control for improving handling performance of a distributed drive electric vehicle especially under normal driving conditions has been proposed. The upper-loop control system consists of two parts： a state feedback controller, which aims to realize the ideal transient response of yaw rate, with a vehicle sideslip angle observer; and a steering wheel angle feedforward controller designed to achieve a desired yaw rate steady gain. Under the restriction of the effect of poles and zeros in the closed-loop transfer function on the system response and the capacity of in-wheel motors, the integrated time and absolute error（ITAE） function is utilized as the cost function in the optimal control to calculate the ideal eigen frequency and damper coefficient of the system and obtain optimal feedback matrix and feedforward matrix. Simulations and experiments with a DDEV under multiple maneuvers are carried out and show the effectiveness of the proposed method： yaw rate rising time is reduced, steady yaw rate gain is increased, vehicle steering characteristic is close to neutral steer and drivers burdens are also reduced. The control system improves vehicle handling performance under normal conditions in both transient and steady response. State feedback control instead of model following control is introduced in the control system so that the sense of control intervention to drivers is relieved.展开更多
Background: Beflex is an active fixation atrial and ventricular lead with a retractable screw;X-Fine is a passive fixation ventricular lead. These two bradycardia lead models were evaluated in the FINE study, an obser...Background: Beflex is an active fixation atrial and ventricular lead with a retractable screw;X-Fine is a passive fixation ventricular lead. These two bradycardia lead models were evaluated in the FINE study, an observational prospective trial conducted in France and Spain. Methods: Patients enlisted for pacemaker or defibrillator implants were enrolled. The primary objective was to assess acute dislodgement rates at the 3-month follow-up visit. Safety and electrical performances of the leads were assessed in acute conditions at implant and at the follow-up visit up to three months later. A handling questionnaire was submitted to implanting investigators immediately after implant. Results: A total of 2254 patients were enrolled in 95 centers;investigators implanted 1153 active atrial leads, mainly in the right atrium;1021 active right ventricular leads, mainly in the septum and 712 passive right ventricular leads, mainly in the apex. After a mean follow-up of 54.9 ± 37.6 days, dislodgement rates were 1.0% and 1.6% for atrial and ventricular active, and 3.2% for ventricular passive leads. No unexpected adverse reactions were observed during the course of the study and the electrical performances at implant and follow-up visits remained within normal ranges. Overall, most investigators (84%) rated leads’ handling as superior (better or best) to what observed with other bradycardia leads. Conclusion: Different bradycardia leads showed a dislodgement rate of 1.0% and 1.6% for atrial and ventricular active leads, and 3.2% for ventricular passive leads, at 3-month follow-up. Acute safety and electrical performances were within expected ranges and very good handling performances were observed.展开更多
The current investigations primarily focus on using advanced suspensions to overcome the tradeo design of ride comfort and handling performance for mining vehicles. It is generally realized by adjusting spring sti nes...The current investigations primarily focus on using advanced suspensions to overcome the tradeo design of ride comfort and handling performance for mining vehicles. It is generally realized by adjusting spring sti ness or damping parameters through active control methods. However, some drawbacks regarding control complexity and uncertain reliability are inevitable for these advanced suspensions. Herein, a novel passive hydraulically interconnected suspension(HIS) system is proposed to achieve an improved ride-handling compromise of mining vehicles. A lumped-mass vehicle model involved with a mechanical–hydraulic coupled system is developed by applying the free-body diagram method. The transfer matrix method is used to derive the impedance of the hydraulic system, and the impedance is integrated to form the equation of motions for a mechanical–hydraulic coupled system. The modal analysis method is employed to obtain the free vibration transmissibilities and force vibration responses under di erent road excitations. A series of frequency characteristic analyses are presented to evaluate the isolation vibration performance between the mining vehicles with the proposed HIS and the conventional suspension. The analysis results prove that the proposed HIS system can e ectively suppress the pitch motion of sprung mass to guarantee the handling performance, and favorably provide soft bounce sti ness to improve the ride comfort. The distribution of dynamic forces between the front and rear wheels is more reasonable, and the vibration decay rate of sprung mass is increased e ectively. This research proposes a new suspension design method that can achieve the enhanced cooperative control of bounce and pitch motion modes to improve the ride comfort and handling performance of mining vehicles as an e ective passive suspension system.展开更多
基金Supported by National Basic Research Program of China(973 Program,Grant No.2011CB711200)National Science and Technology Support Program of China(Grant No.2015BAG17B00)National Natural Science Foundation of China(Grant No.51475333)
文摘For a distributed drive electric vehicle（DDEV） driven by four in-wheel motors, advanced vehicle dynamic control methods can be realized easily because motors can be controlled independently, quickly and precisely. And direct yaw-moment control（DYC） has been widely studied and applied to vehicle stability control. Good vehicle handling performance： quick yaw rate transient response, small overshoot, high steady yaw rate gain, etc, is required by drivers under normal conditions, which is less concerned, however. Based on the hierarchical control methodology, a novel control system using direct yaw moment control for improving handling performance of a distributed drive electric vehicle especially under normal driving conditions has been proposed. The upper-loop control system consists of two parts： a state feedback controller, which aims to realize the ideal transient response of yaw rate, with a vehicle sideslip angle observer; and a steering wheel angle feedforward controller designed to achieve a desired yaw rate steady gain. Under the restriction of the effect of poles and zeros in the closed-loop transfer function on the system response and the capacity of in-wheel motors, the integrated time and absolute error（ITAE） function is utilized as the cost function in the optimal control to calculate the ideal eigen frequency and damper coefficient of the system and obtain optimal feedback matrix and feedforward matrix. Simulations and experiments with a DDEV under multiple maneuvers are carried out and show the effectiveness of the proposed method： yaw rate rising time is reduced, steady yaw rate gain is increased, vehicle steering characteristic is close to neutral steer and drivers burdens are also reduced. The control system improves vehicle handling performance under normal conditions in both transient and steady response. State feedback control instead of model following control is introduced in the control system so that the sense of control intervention to drivers is relieved.
文摘Background: Beflex is an active fixation atrial and ventricular lead with a retractable screw;X-Fine is a passive fixation ventricular lead. These two bradycardia lead models were evaluated in the FINE study, an observational prospective trial conducted in France and Spain. Methods: Patients enlisted for pacemaker or defibrillator implants were enrolled. The primary objective was to assess acute dislodgement rates at the 3-month follow-up visit. Safety and electrical performances of the leads were assessed in acute conditions at implant and at the follow-up visit up to three months later. A handling questionnaire was submitted to implanting investigators immediately after implant. Results: A total of 2254 patients were enrolled in 95 centers;investigators implanted 1153 active atrial leads, mainly in the right atrium;1021 active right ventricular leads, mainly in the septum and 712 passive right ventricular leads, mainly in the apex. After a mean follow-up of 54.9 ± 37.6 days, dislodgement rates were 1.0% and 1.6% for atrial and ventricular active, and 3.2% for ventricular passive leads. No unexpected adverse reactions were observed during the course of the study and the electrical performances at implant and follow-up visits remained within normal ranges. Overall, most investigators (84%) rated leads’ handling as superior (better or best) to what observed with other bradycardia leads. Conclusion: Different bradycardia leads showed a dislodgement rate of 1.0% and 1.6% for atrial and ventricular active leads, and 3.2% for ventricular passive leads, at 3-month follow-up. Acute safety and electrical performances were within expected ranges and very good handling performances were observed.
基金Supported by National Natural Science Foundation of China(Grant Nos.51805155,51675152)Foundation for Innovative Research Groups of National Natural Science Foundation of China(Grant No.51621004)Open Fund in the State Key Laboratory of Advanced Design and Manufacture for Vehicle Body(Grant No.71575005)
文摘The current investigations primarily focus on using advanced suspensions to overcome the tradeo design of ride comfort and handling performance for mining vehicles. It is generally realized by adjusting spring sti ness or damping parameters through active control methods. However, some drawbacks regarding control complexity and uncertain reliability are inevitable for these advanced suspensions. Herein, a novel passive hydraulically interconnected suspension(HIS) system is proposed to achieve an improved ride-handling compromise of mining vehicles. A lumped-mass vehicle model involved with a mechanical–hydraulic coupled system is developed by applying the free-body diagram method. The transfer matrix method is used to derive the impedance of the hydraulic system, and the impedance is integrated to form the equation of motions for a mechanical–hydraulic coupled system. The modal analysis method is employed to obtain the free vibration transmissibilities and force vibration responses under di erent road excitations. A series of frequency characteristic analyses are presented to evaluate the isolation vibration performance between the mining vehicles with the proposed HIS and the conventional suspension. The analysis results prove that the proposed HIS system can e ectively suppress the pitch motion of sprung mass to guarantee the handling performance, and favorably provide soft bounce sti ness to improve the ride comfort. The distribution of dynamic forces between the front and rear wheels is more reasonable, and the vibration decay rate of sprung mass is increased e ectively. This research proposes a new suspension design method that can achieve the enhanced cooperative control of bounce and pitch motion modes to improve the ride comfort and handling performance of mining vehicles as an e ective passive suspension system.
