Safe Motion Planning and Control Framework for Automated Vehicles with Zonotopic TRMPC

Model mismatches can cause multi-dimensional uncertainties for the receding horizon control strategies of automated vehicles(AVs).The uncertainties may lead to potentially hazardous behaviors when the AV tracks ideal trajectories that are individually optimized by the AV's planning layer.To address this issue,this study proposes a safe motion planning and control(SMPAC)framework for AVs.For the control layer,a dynamic model including multi-dimensional uncertainties is established.A zonotopic tube-based robust model predictive control scheme is proposed to constrain the uncertain system in a bounded minimum robust positive invariant set.A flexible tube with varying cross-sections is constructed to reduce the controller conservatism.For the planning layer,a concept of safety sets,representing the geometric boundaries of the ego vehicle and obstacles under uncertainties,is proposed.The safety sets provide the basis for the subsequent evaluation and ranking of the generated trajectories.An efficient collision avoidance algorithm decides the desired trajectory through the intersection detection of the safety sets between the ego vehicle and obstacles.A numerical simulation and hardware-in-the-loop experiment validate the effectiveness and real-time performance of the SMPAC.The result of two driving scenarios indicates that the SMPAC can guarantee the safety of automated driving under multi-dimensional uncertainties.

Repulsive firefly algorithm-based optimal switching device placement in power distribution systems

To achieve optimal configuration of switching devices in a power distribution system,this paper proposes a repulsive firefly algorithm-based optimal switching device placement method.In this method,the influence of territorial repulsion during firefly courtship is considered.The algorithm is practically applied to optimize the position and quantity of switching devices,while avoiding its convergence to the local optimal solution.The experimental simulation results have showed that the proposed repulsive firefly algorithm is feasible and effective,with satisfying global search capability and convergence speed,holding potential applications in setting value calculation of relay protection and distribution network automation control.

Grazing effects on the relationship between plant functional diversity and soil carbon sequestration regulated by livestock species

Grazing exerts a profound influence on both the plant diversity and productivity of grasslands,while simultaneously exerting a significant impact on regulating grassland soil carbon sequestration.Moreover,besides altering the taxonomic diversity of plant communities,grazing can also affect their diversity of functional traits.However,we still poorly understand how grazing modifies the relationship between plant functional diversity(FD)and soil carbon sequestration in grassland ecosystems.Here,we conducted a grazing manipulation experiment to investigate the effects of different grazing regimes(no grazing,sheep grazing(SG)and cattle grazing(CG))on the relationships between plant FD and soil carbon sequestration in meadow and desert steppe.Our findings showed that different livestock species changed the relationships between plant FD and soil organic carbon(SOC)in the meadow steppe.SG decoupled the originally positive relationship between FD and SOC,whereas CG changed the relationship from positive to negative.In the desert steppe,both SG and CG strengthened the positive relationship between FD and SOC.Our study illuminates the considerable impact of livestock species on the intricate mechanisms of soil carbon sequestration,primarily mediated through the modulation of various measures of functional trait diversity.In ungrazed meadows and grazed deserts,maintaining high plant FD is conducive to soil carbon sequestration,whereas in grazed meadows and ungrazed deserts,this relationship may disappear or even reverse.By measuring the traits and controlling the grazing activities,we can accurately predict the carbon sequestration potential in grassland ecosystems.

Path-Following Control of Autonomous Vehicles Considering Coupling Effects and Multi-source System Uncertainties

Path-following control is one of the key technologies of autonomous vehicles,but the complex coupling effects and system uncertainties of vehicles can degrade their control performance.Accordingly,this study proposes targeted methods to solve different types of coupling in vehicle dynamics.First,the types of coupling are figured out and different handling strategies are proposed for each type,among which the coupling caused by steering angle,unsaturated tire forces,and load transfer can be treated as uncertainties in a unified form,such that the coupling effects can be treated in a decoupling way.Then,robust control methods for both lateral and longitudinal dynamics are proposed to deal with the uncertainties in dynamic and physical parameters.In lateral control,a robust feedback-feedforward scheme is utilized in lateral control to deal with such uncertainties.In longitudinal control,a radial basis function neural network-based adaptive sliding mode controller is introduced to deal with uncertainties and disturbances.In addition,the tire saturation coupling that cannot be handled by controllers is treated by a proposed speed profile.Simulation results based on the CarSim-Simulink joint platform evaluate the effectiveness and robustness of the proposed control method.The results show that compared with a well-designed robust controller,the velocity tracking performance,lateral tracking performance,and heading tracking performance improve by 55.68%,34.26%,and 52.41%,respectively,in the double-lane change maneuver,and increase by 87.79%,30.18%,and 9.68%,respectively,in the ramp maneuver.

Design,Modeling,and Characterization of a Tubular Linear Vibration Energy Harvester for Integrated Active Wheel System

A major source of electric vehicle energy loss is the vibration energy dissipated by the shock absorbers under irregular road excitation,which is particularly severe when active wheel systems are employed because their greater unsprung mass leads to greater shocks and vibrations.Therefore,a tubular linear energy harvester(TLEH)with a large stroke and low electromagnetic force ripple is designed to convert this vibration energy into electricity.The proposed TLEH employs a slotted external mover with three-phase winding coils and an internal stator with PMs to increase the stroke,adopts a fractional slot-per-pole configuration to reduce its size and improve the winding factor,and realizes significantly reduced cogging force by optimizing the incremental length of the armature core.A finite element model of the TLEH is first verified against a theoretical model and then used to investigate the influences of various road excitation frequencies and amplitudes on the electromotive force(EMF)waveforms and generated power,the efficiency and damping force according to load condition,and the energy recovery and nonlinear electromagnetic force characteristics of the TLEH.A resistance controller is then designed to realize a self-damping electromagnetic suspension.The results indicate that the EMF and the generated power waveforms depend on the excitation frequency and amplitude,the efficiency increases and the damping coefficient decreases with the increasing load resistance.

Simulation and Analysis on Overtaking Safety Assistance System Based on Vehicle-to-Vehicle Communication

Because of the complexity and variability of an intelligent vehicle’s driving environment,it is difficult for the application of the vehicular sensors to meet the needs of the surrounding environment information entirely.Vehicle-to-vehicle(V2V)communication technology is used by target vehicles to exchange information,and obtain the driving condition and driving intention of the front driver.To obtain environmental information outside the range of vehicular sensors in advance,in this paper,a vehicle overtaking assistance system is proposed based on V2V communication.The data,including the speed,position,direction angle and steering angle obtained using V2V communication,were preliminarily processed.Then,combined with an overtaking safety distance model,the vehicle parameters,driver’s driving intention and vehicle status information were entered into an overtaking security assistance system to determine the overtaking conditions.Fuzzy theory was used to control the parameters of the overtaking safety distance model.Finally,the overtaking safety assistance system was established and the proposed algorithm was tested using PreScan/MATLAB cooperative simulation software.The results showed that the proposed overtaking safety algorithm effectively provided a warning according to environmental change and the driver’s intention,which assisted the driver to overtake and avoid the occurrence of accidents,which improved the safety performance of the vehicle.

赏石是对自然艺术的表现活动

李隐龙是一位有独特视角的赏石写作者,激烈的言辞之下,是深入的思考,甚至是对潮流观点的直面式批判。多年前,本刊曾经发起过一场讨论——奇石究竟就是发现的艺术还是表达的艺术。在那个纸媒当道的年代,那场讨论旷日持久,双方各执一词,激烈辩论,引发过行业对赏石的深入思考。这次,李隐龙的这篇文章,直接将话题拨回到奇石的自然属性上。这个话题如同"贪吃蛇"的游戏,讨论是否会就此打住呢,留给大家结辩吧。