# Review of Autonomous Intelligent Vehicles for Urban Driving and Parking
## 2 Advanced Driver-Assistance System  
Prior to fully autonomous driving, the technology of advanced driver-assistance systems (ADASs) is briefly discussed. ADASs can help with monitoring, braking, and warning tasks to enhance safety conditions on the road. ADASs can perform parking assistance or monitoring. Connected technologies such as V2X and V2I, streetlights and traffic information, together with ADASs, can create a safer road for drivers and pedestrians. As ADASs continue to strive for more benefits, it is known that governments may soon require vehicles to install essential ADASs and their components over the next few years. It is necessary to highlight that the ADASs discussed here refer to technology to assist the driver during driving rather than an autonomously driven car. Current driver-assistance systems are gradually being equipped with more advanced technology. Most systems aim to provide parking assistance, forward collision warnings, lane-departure warnings, adaptive cruise control, and driver drowsiness detection [46]. Parking assistance systems aim to provide safe and comfortable backward parking. These systems work by reading data such as the magnitude of steering wheel rotation, speed, and lateral acceleration from the vehicle's electronic stability control system to generate the backward parking trajectory. The rear camera then captures the vehicle's rear view, and the trajectory is integrated into the view and displayed on the in-car monitor. Such a reference provides the driver with the information of where the vehicle is heading and prevents a crash while reversing. Forward collision avoidance systems are designed to provide the driver with a visual and audible warning when they are too close to a vehicle ahead [47]. In general, such systems monitor the vehicle's speed and the speed of the vehicle in front of it while measuring the distance between the two vehicles to analyze if there is a risk of collision [48]. Monitoring can be achieved using vision-based sensors, GPS, radar, or LiDAR [49]. Current technology for lane changing focuses primarily on blind-spot identification and warning [50]. The lane-change assistant recognizes vehicles in the blind spot and warns the driver when changing lanes [51]. A lane-departure warning system usually estimates the vehicle's relative position on the road using a camera to track road markings. The system then provides an alert to prevent an unintended lane departure using audible, visual, or haptic steering wheel feedback [52; 53; 54]. Such systems have already been rolled out in several commercial vehicles by Volvo, Mercedes, Audi, BMW, Nissan, and Honda [52; 53]. Adaptive cruise control (ACC) is an enhancement of the traditional cruise control (CC) system that improves driver convenience, reduces driver workload, and has the potential to improve vehicle safety [55]. Current ACC systems are intelligent systems that control a vehicle's acceleration and deceleration to maintain pace with the preceding car or travel at the desired speed [55; 56]. Such systems are achieved with the data collected from onboard sensors such as an infrared laser, radar, and video sensors [57]. Abnormal driving is usually caused by fatigue, recklessness, and/or drunkenness [58]. A driver with any of these conditions usually exhibits a specific change in behavior or body movement. When a driver is drowsy, they will usually perform actions such as rapid and constant blinking, nodding or swinging their head, and frequent yawning [59]. On the other hand, a drunk driver intoxicated by alcohol usually develops the habit of sudden acceleration or deceleration with a delayed response. Reckless driving is also similar to drunk driving to a certain degree. The driver may be awake but affected by emotional factors, thereby exhibiting sudden acceleration or deceleration and violating the speed limit [58]. Therefore, a driver monitoring system can be achieved by monitoring the driver directly or indirectly.