Cut-in Conditions Research Articles

Generation of a scenario library for testing driver-automation cooperation safety under cut-in working conditions

To improve the efficiency of safety tests of driver-automation cooperation, a method for generating a scenario library is proposed that considers the probability of scenario occurrence and driver-handling challenges in real driving situations. First, the original scenario data under cut-in conditions stored in a time series are extracted from the scenario data set. Then, a mathematical performance index is used to model the scenario and a significance function in terms of the occurrence frequency of the scenario, and the performance challenge between the driver and the vehicle is established. Next, the important scenario set is extracted from the original scenario set by constructing and optimizing a significance auxiliary function. Finally, the extracted important scenario sets are filtered by using the significance function values of the scenarios to generate a scenario library. Simulation results show that the proposed method for scenario library generation can effectively identify scenarios with potential adventure during driver-automation cooperation and thus accelerate safety tests compared with traditional methods.

Research on Accelerated Testing of Cut-In Condition of Electric Automated Vehicles Based on Monte Carlo Simulation

Electric automated vehicles are zero-emission, energy-saving, and environmentally friendly vehicles, and testing and verification is an important means to ensure their safety. Because of the scarcity of dangerous scenarios in natural driving roads, it is required to conduct accelerated tests and evaluations for electric automated vehicles. According to the scenario data of the natural road in cut-in conditions, we used the kernel density estimation method to calculate the probability distribution of the scenario parameters. Additionally, we used the Metropolis–Hastings algorithm to sample based on the probability distribution of the parameters, and the Euclidean distance was combined with the paired combination to accelerate the simulation test process. The critical scenarios were screened out by the safety indicator, and the feature distribution of the critical scenario parameters was analyzed based on the Euclidean distance clustering method, so as to design importance sampling parameters and carry out importance sampling. The study obtained the distribution characteristics of critical scenario parameters under cut-in conditions and found that the importance sampling method can accelerate the test under the condition of ensuring that the relative error is small, and the improved accelerated simulation method makes the overall calculation amount smaller.

Ecological control strategy for cooperative autonomous vehicle in mixed traffic considering linear stability

Purpose This paper aims to present a cooperative adaptive cruise control, called stable smart driving model (SSDM), for connected and autonomous vehicles (CAVs) in mixed traffic streams with human-driven vehicles. Design/methodology/approach Considering the linear stability, SSDM is able to provide smooth deceleration and acceleration in the vehicle platoons with or without cut-in. Besides, the calibrated Virginia tech microscopic energy and emission model is applied in this study to investigate the impact of CAVs on the fuel consumption of the vehicle platoon and traffic flows. Under the cut-in condition, the SSDM outperforms ecological SDM and SDM in terms of stability considering different desired time headways. Moreover, single-lane vehicle dynamics are simulated for human-driven vehicles and CAVs. Findings The result shows that CAVs can reduce platoon-level fuel consumption. SSDM can save the platoon-level fuel consumption up to 15%, outperforming other existing control strategies. Considering the single-lane highway with merging, the higher market penetration of SSDM-equipped CAVs leads to less fuel consumption. Originality/value The proposed rule-based control method considered linear stability to generate smoother deceleration and acceleration curves. The research results can help to develop environmental-friendly control strategies and lay the foundation for the new methods.

Antioxidant Activity and Probiotic Proliferation and Acidifying Activity of Intracellular Polysaccharides from the Shaggy Ink Cap Medicinal Mushroom, Coprinus comatus (Agaricomycetes), under Optimal Polysaccharide Synthase Activity.

For the first time, polysaccharide synthase activity was used as the cut-in condition in this study and the fermentation conditions of Coprinus comatus intracellular polysaccharide (IPS) were further optimized. The optimal conditions were 23.65 g/L of carbon source, 47.44 g/L of nitrogen source, and pH 5.73. C. comatus IPS was obtained under the optimal conditions and its antioxidant properties were evaluated. Next, in vitro proliferation and Lactobacillus rhamnosus acidifying activity were assessed. IPS had good antioxidant properties and could promote the growth and acid production of probiotics. The antioxidant properties and probiotic proliferation and acidifying activity of IPS were improved to a certain extent under the optimal conditions. Thus, our findings contribute to establishing a novel fermentation process that can produce IPS with better performance. Meanwhile, IPS has great application potential in medicine.

Improved Solar Operation Control for a Solar Cooling System of an IT Center

In this contribution, a model predictive control algorithm is developed, which allows an increase of the solar operating hours of a solar cooling system without a negative impact on the auxiliary electricity demand, e.g., for heat rejection in a dry cooler. An improved method of the characteristic equations for single-effect H 2 O / LiBr absorption chillers is used in combination with a simple dry-cooler model to describe the part load behavior of both components. The aim of the control strategy is to find a cut-in and a cut-off condition for the solar heat operation (SHO) of an absorption chiller cooling assembly (i.e., including all the supply pumps and the dry cooler) under the constraint that the specific electricity demand during SHO is lower than the electricity demand of a reference cooling technology (e.g., a compression chiller cooling assembly). Especially for the cut-in condition, the model predictive control algorithm calculates a minimum driving temperature, which has to be reached by the solar collector and storage in order to cover the cooling load with a low cooling water temperature but restricted auxiliary electricity demand. Measurements at a solar cooling system for an IT center were used for the testing and a first evaluation of the control algorithm.

A new adaptive cruise control strategy and its stabilization effect on traffic flow

Connected and autonomous vehicle (CAV) technologies are likely to be gradually implemented over time. In this paper, an adaptive cruise control, named Smart Driver Model (SDM), is proposed to describe the autonomous vehicles flow. The stability criteria is proposed for SDM to judge the stability of homogeneous traffic flow. Numerical simulations were conducted to verify the results of the theoretical analysis. Single-lane vehicle dynamics in a traffic stream with connected and autonomous vehicles are simulated by varying model parameters. Simulation results are consistent with the results of linear stability analysis. As a result, a set of parameters is proposed to investigate the stabilization effect of the proposed model on homogeneous traffic flow considering realistic driving cycle and cut-in condition. By simulating a platoon with a lead vehicle which follows the Urban Dynamometer Driving Schedule (UDDS), we find out that the proposed model can stabilize the traffic flow with proposed parameters. The results from simulation and linear stability analysis show that SDM outperforms the IDM-ACC and the ACC proposed by Milanés and Shladover in terms of stabilization effect on homogeneous traffic flow. The simulation result shows that the SDM-equipped vehicles are able to stabilize the homogeneous traffic flow under cut-in condition.

Characteristic Study of Milling Force in Cut-In Process of Hard Milling Die Steel

This article takes common material Cr12MoV for automobile panel die as research object, aiming at difficulties when tool cutting in workpiece which are caused by high material hardness in maching, based on simulation software DEFORM-3D, a high precision simulation model of cut-in process in hard milling die steel is established, and the accuracy of the model is verified by tests, the milling force cut-in process in hard milling die steel is studied, the influence law of different cutting parameters and cut-in angles on milling force in milling cutter cutting in workpiece is analyzed, and the optimized cut-in angles are obtained, this study provides a reference for further optimization of cut-in conditions, reducing tool early damage and improving processing efficiency.

Modeling and Testing of a Novel Aeroelastic Flutter Energy Harvester

This paper proposes a novel piezoelectric energy harvesting device driven by aeroelastic flutter vibrations of a simple pin connected flap and beam. The system is subject to a modal convergence flutter response above a critical wind speed and then oscillates in a limit cycle at higher wind speeds. A linearized analytical model of the device is derived to include the effects of the three-way coupling between the structural, unsteady aerodynamic, and electrical aspects of the system. A stability analysis of this model is presented to determine the frequency and wind speed at the onset of the flutter instability, which dictates the cut-in conditions for energy harvesting. In order to estimate the electrical output of the energy harvester, the amplitude and frequency of the flutter limit cycle are also investigated. The limit cycle behavior is simulated in the time domain with a semi-empirical nonlinear model that accounts for the effects of the dynamic stall over the flap at large deflections. Wind tunnel test results are presented to determine the empirical aerodynamic model coefficients and to characterize the power output and flutter frequency of the energy harvester as functions of incident wind speed.