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This paper presents the ACC system for autonomous trams, including three core processes: object detection, collision assessment and control. The system utilizes the YOLOX deep learning model for camera-based object detection and a clustering approach for LiDAR point clouds, integrating both outputs through a late fusion method for enhanced accuracy. The positions of objects and the tram are projected onto a data map to assess collision risk. This data map, which is a virtual 2D space configured with the track’s UTM coordinates and ROI lines, is used to determine whether objects are located within the ROI. The ACC system adjusts the tram’s speed to control acceleration or deceleration based on the relative distances of objects within the ROI. Experiments on a test track demonstrate effective collision avoidance and reliable ACC system operation under predefined scenarios.

Workload and distraction are problems that affect road driving and can cause very serious accidents. Drive assistance systems are very important to help drivers relieve fatigue of driving by increasing road safety and reducing the number of accidents. The Adaptive Cruise Control (ACC) is a useful driver assistance system to set and maintain a safe distance from the front vehicle, modulating speed and limiting sudden braking. However, the effects of the ACC on overall driver behaviour have not yet been thoroughly investigated. In this study, the authors assessed the influence of ACC on mental workload and attention of drivers in a real driving environment. The results of several evaluations were considered: subjective assessment of workload (NASA-TLX), physiological measurements of workload (brain activity through electroencephalographic technique and the analysis of visual behaviour through an eye monitoring device) and performance-based measurements (via Vbox Pro Video mounted on the vehicle). 52 drivers were involved in the study, 26 ACC experts and 26 non-experts, who drove along the ring road of Bologna (Tangenziale di Bologna) (Italy), both using ACC and manually, without the help of any device. During the test a secondary task was introduced: the sudden arrival of a braking car. Results showed that the use of ACC increased distraction when driving.

Transportation sector and its impacts on climate change have received much attention over the last decade. Energy-optimal vehicle control algorithms such as adaptive cruise control can potentially reduce fuel consumption and the consequential environmental impacts. Adaptive cruise control algorithms optimize vehicles’ speed to lower energy consumption considering several constraints, including safety, stability, and comfortability. A wide range of algorithms with different objectives and optimization mechanisms have been reported in the literature. Due to the high diversity of constraints and objectives, a comprehensive study of these algorithms is required. In recent literature reviews, there is no comprehensive summary of the adaptive cruise control algorithms’ features, classes, and objectives. This paper presents a holistic literature review of energy-optimal adaptive cruise control algorithms. We gathered relevant publications from well-eminent journals. Information on diversity and the number of publications will be presented to provide data on used references. For each paper, the objectives, features, and relevant classes of algorithms were extracted. Then a classification based on objectives is suggested, and mathematical formulas of representative studies are summarized to provide the required knowledge regarding mathematical modeling and optimization in this field. The study provides a useful insight into the development of the cruise control systems research field, revealing those scientific actors (i.e., authors, developers, and institutions) that have made the biggest research contribution to its development.

In this paper, we present an advanced adaptive cruise control (ACC) concept powered by Deep Reinforcement Learning (DRL) that generates safe, human-like, and comfortable car-following policies. Unlike the current trend in developing DRL-based ACC systems, we propose defining the action space of the DRL agent with discrete actions rather than continuous ones, since human drivers never set the throttle/brake pedal level to be actuated, but rather the required change of the current pedal levels. Through this human-like throttle-brake manipulation representation, we also define explicit actions for holding (keeping the last action) and coasting (no action), which are usually omitted as actions in ACC systems. Moreover, based on the investigation of a real-world driving dataset, we cast a novel reward function that is easy to interpret and personalized. The proposed reward enforces the agent to learn stable and safe actions, while also encouraging the holding and coasting actions, just like a human driver would. The proposed discrete action DRL agent is trained with action masking, and the reward terms are completely derived from the real-world dataset collected from a human driver. We present exhaustive comparative results to show the advantages of the proposed DRL approach in both simulation and scenarios extracted from real-world driving. We clearly show that the proposed policy imitates human driving significantly better and handles complex driving situations, such as cut-ins and cut-outs, implicitly, in comparison with a DRL agent trained with a widely-used reward function proposed for ACC, a model predictive control structure, and traditional car-following approaches.

This paper discusses the Adaptive Cruise Control (ACC) system, which is a solution that allows drivers to minimize the amount of time spent driving. It supports four different driving modes and regulates the acceleration and deceleration of the car in order to maintain a fixed speed or avoid a collision with another vehicle. Real-Time Publish-Subscribe (RTPS) middleware has emerged as one of the most efficient and practical options for the real solutions to the difficulties listed above. This paper proposes to develop a real-time system for integrating the various components of ACC, such as Information Cluster, Radar, Brake Switches, Cruise Switches, ACC Controller, Engine/Throttle Controller, Brake Controller, Brake Actuators, Speed Sensors, and Back Brake Lights. The exchange of data is through a RTPS Data Distribution Service (DDS) middleware. The design of the publish/subscribe model was explained in detail in this paper along with the proper Quality of Service (QoS) policies suggested to govern the behavior of the model.

Today, advanced driver-assistance systems (ADAS) come up with different abilities. One of them is the adaptive cruise control (ACC) system. The ACC system is a continuation of research on cruise control (CC) system, which integrates spacing control with the existing velocity control on the CC system. The vehicles with an ACC system guarantee traffic safety while at the same time ensure a well-driving sense. Many studies have demonstrated numerous control techniques applied as ACC controllers to accomplish uncertainty and perturbation issues. Nevertheless, most of the existing papers assumed the model vehicle dynamics as a linear time-invariant (LTI) system while designing the ACC controller. This paper proposed an ACC controller using the gain scheduling technique to deal with the model vehicle dynamics as a linear parameter varying (LPV) system. The passenger vehicle’s mass varies during ACC operation depending on how many passengers or loads on the vehicle’s trunks. Later, the vehicle’s mass is estimated by recursive least square (RLS) with a forgetting factor. Then, the disk margin is utilized to provide the high-level robustness at each operating or “frozen” point. The robustness performance will be analyzed using the worst-case gain metric while the uncertainty is modeled by integral quadratic constraints (IQC). The LPV system behavior, such as the rate vehicle’s mass, is also considered in the analysis. The effectiveness algorithm is validated through joint simulation between Matlab/Simulink and PreScan. The last, the comparison performance between gain scheduling and fixed gain ACC controller is evaluated.

This paper proposes a defensive ecological adaptive cruise control (DEco-ACC) algorithm that is capable of reducing an ego vehicle’s dwelling time in the blind spot zones (BSZs) of its neighboring vehicles. To this end, a model predictive control is applied in the use of information such as speed, position, and blind spot zones about preceding and neighboring vehicles. The cost function of the DEco-ACC consists of tracking performance, control effort, and dwelling time in BSZs. Specifically, a continuous and one-time differentiable penalty function is introduced to handle the constraints regarding the BSZs. For optimizing and evaluating the performance of the proposed DEco-ACC, real-world traffic data from Next Generation Simulation (NGSIM) are used to analyze and generate car-following scenarios during highway driving. Especially, in consideration of the most probable case that one neighboring vehicle exists at one adjacent lane, a parametric study is conducted to investigate the impact of the weighting factors on the performance of the DEco-ACC. The simulation results from 100 cases demonstrate that on average, the DEco-ACC with optimized weighting factors can reduce the dwelling time in the neighboring vehicles’ BSZs by 46.3% without significant deterioration of fuel consumption (0.04% increase in average fuel consumption) and drivability, as compared to the Eco-ACC, whose primary objective is the minimization of fuel consumption during safe car-following.

This paper presents a personalized stochastic optimal adaptive cruise control (ACC) algorithm for automated vehicles (AVs) incorporating human drivers' risk-sensitivity under system and measurement uncertainties. The proposed controller is designed as a linear exponential-of-quadratic Gaussian (LEQG) problem, which utilizes the stochastic optimal control mechanism to feedback the deviation from the design car-following target. With the risk-sensitive parameter embedded in LEQG, the proposed method has the capability to characterize risk preference heterogeneity of each AV against uncertainties according to each human drivers' preference. Further, the established control theory can achieve both expensive control mode and non-expensive control mode via changing the weighting matrix of the cost function in LEQG to reveal different treatments on input. Simulation tests validate the proposed approach can characterize different driving behaviors and its effectiveness in terms of reducing the deviation from equilibrium state. The ability to produce different trajectories and generate smooth control of the proposed algorithm is also verified.

The decision-making system of intelligent vehicles is the core component of an advanced driving system for both passenger vehicles and commercial vehicles. Finding ways to improve decision-making strategies to suit the complex and unfamiliar environments is a standing problem for traditional rule-based methods. This paper proposes a semi-rule-based decision-making strategy for heavy intelligent vehicles based on the Deep Deterministic Policy Gradient algorithm. Firstly, according to the car-following characteristics, the problems of high dimensions and a large amount of data in vehicle action space and state space are solved by dimension reduction and interval reduction to accelerate the training process. Subsequently, an accurate three-axle vehicle load model is established to calculate the load transfer rate value and carry out active control to increase the roll stability of heavy vehicles at high-speed corners. Furthermore, the Deep Deterministic Policy Gradient algorithm is developed based on the reward function and update function to achieve adaptive cruise control objectives for heavy vehicles on different curvature roads. Finally, the effectiveness and robustness of the algorithm are verified through simulation experiments.

Adaptive cruise control (ACC) systems are designed to provide longitudinal assistance for drivers to enhance safety and reduce workload. As the core of all ACC control algorithms, the spacing policy plays a crucial role in various aspects. This paper presents a comprehensive survey on spacing policies for existing ACC solutions in the literature. The objectives of this paper are to clarify the operating mechanisms and characteristics of the common spacing policies, and to reveal their advantages and shortcomings by means of a comparative study. In this survey, the general evaluation criteria for spacing policies are first introduced. Then, the existing spacing policies are categorized into different types according to their operating mechanisms, and their characteristics are carefully reviewed and explained. A comparative study is followed to analyze the performances of five typical spacing policies in the literature, including the constant spacing policy, constant time headway, traffic flow stability, constant safety factor and human driving behavior spacing policies. The contents provided in this paper serve as a tool for understanding current ACC spacing policies, and pave the way for future ACC enhancement.

Recent years, advanced driver assistance system (ADAS) has been highly developed and widely used. Among various ADAS techniques adaptive cruise control (ACC) is the fundamental of longitudinal control. The tradeoffs among safety, comfort and traffic efficiency are the main issue in ACC design process. In this study, large amount of road tests was carried out to explore the circumstance characteristics in ACC usages scenarios. Based on statistical analysis of road test data, a method for ACC safety performance evaluation is proposed. Furthermore, the effects of parameters such as following distance, jerk limit and time delay to ACC safety performance are discussed. Finally, a way of ACC parameter designing is developed, this method can obtain best comfort and traffic efficiency after safety request is guaranteed. In this study, regulations and realistic constrains of production vehicles are considered. Different from theoretical simulation, production-oriented ACC system is restricted in maximum deceleration, maximum braking jerk, detection latency, actuation latency, calculation capacity etc. For this reason, all the analysis is based on statistical results and requests from actual products, no computationally expensive optimal method is implemented. The proposed method may not get optimal results in theoretical simulation but is very instructive in production-oriented ACC system design.

During the car following process, in order to improve ACC ability to coordinate various goals and adaptability in a complex and variable driving environment, the variable time headway spacing strategy and multi-objective adaptive cruise control algorithm are studied. Aiming at the deceleration adaptability, an improved variable time headway strategy is proposed, which adjusts the value of acceleration weight according to the deceleration duration and deceleration changes to increase the relative distance between the two vehicles in deceleration conditions. In order to improve the multi-objective coordination ability, the longitudinal kinematics model between the two vehicles is established, the objective function and constraints considering multiple factors are designed, and the relaxation factor vector is introduced to soften the boundary of different hard constraints to solve the problem with no feasible solution. Based on model predictive control theory, the objective function is converted into a multi-constrained quadratic programming problem in the rolling optimization process, and an improved particle swarm algorithm is used to solve the function. Through numerical simulation, the results show that the improved ACC algorithm can effectively improve the safety of the vehicle during deceleration, as well as the fuel economy, comfort and tracking ability under cycling conditions. The effectiveness of the algorithm is verified by the joint simulation of MATLAB/Simulink and CarSim.

Vehicle-borne millimeter wave radar sensor may malfunction during signal acquisition and transmission process, which will affect the decision of adaptive cruise control (ACC) system and the safe driving of vehicles. However, adding other redundant environment-aware devices will increases costs. Therefore, in this paper, an active fault tolerant control of ACC system considering vehicle-borne millimeter wave radar sensor failure is proposed. Sensor faults are taken as discrete events, and the mixed logical dynamical (MLD) model of ACC upper control system is built which includes both the fault-free dynamics and the fault dynamics of the system. Then, the active fault tolerant control model of ACC system is established based on model predictive control (MPC) framework. Compared with the existing researches, this work emphasizes on the active fault tolerant control without adding other redundant environment-aware devices, which has not been fully revealed by the existing researches and is important to the industrial application. Moreover, the active fault tolerant control method can be easily ported to other driver assistance system besides ACC. The simulation results show that the vehicle equipped with the active fault tolerant ACC system can still drive safely and smoothly without being affected by radar sensor failures, which demonstrates its great significance to improve vehicle's own intelligence and ensure the safe driving instead of relying entirely on sensors.

The influence of (cooperative) adaptive cruise control (CACC/ACC) on rear-end crashes have been conducted by some previous studies. However, they usually did not consider the degeneration from stable CACC to unstable ACC when vehicle-to-vehicle (V2V) communication is not available. California PATH program validated the instability of ACC system by using real experimental data, which might have negative impacts on safety. Therefore, this paper evaluated the impacts of degeneration of CACC vehicles on rear-end crash risks. A micro-simulation based method was adopted to evaluate rear-end crash risks with the increase of the CACC market penetration rate (MPR). The results obtained were quite different from those in previous studies and showed that the rear-end crash risks of the full MDV flow increase before CACC MPR increases to a certain level. It was found that the instability of ACC vehicles might be the main factor for the negative results. The results of this paper provide helpful insight into the management of CACC vehicular flow in the V2V communication environment.