What are the methods for a car to judge distance?
3 Answers
Methods for a car to judge distance include: 1. Judging distance based on rearview mirrors; 2. Using wheel position to judge distance; 3. Judging distance based on parking sensors. The method for judging distance based on rearview mirrors is as follows: 1. When the car image occupies the entire rearview mirror, the distance is 3m; 2. When the car image occupies two-thirds of the rearview mirror, the distance is 5m; 3. When the car image occupies half of the rearview mirror, the distance is 9m; 4. When the car image occupies one-third of the rearview mirror, the distance is 12m. The method for judging distance based on parking sensors is: Determining the distance through sound. Parking sensors emit beeps at a certain frequency, and the frequency increases as the obstacle gets closer. When the beeping frequency becomes faster and is accompanied by a continuous sound, it indicates that the vehicle is getting closer to the obstacle.
When driving, I mainly rely on my eyes to judge distance, simply put, by observing changes in the size and position of objects to estimate. For example, if there's a car ahead, I'll notice how big it appears; if it changes from large to small quickly, it means it's getting closer. On rainy or foggy days, when visibility is poor, I need to be more cautious and slow down. Experience tells me not to focus on just one spot—scan the entire road and use roadside utility poles or trees as reference points to roughly estimate the distance to my car. Binocular vision is also practical, where the slight angle difference between the two eyes makes distant objects appear slightly different, helping the brain calculate distance instinctively. However, don't rely solely on this—maintaining a safe following distance is the most reliable. Generally, keep a distance in meters equal to your speed in kilometers per hour. After years of driving this way, I've stayed safe without accidents, and with practice, it becomes very accurate.
I research new automotive technologies, and modern vehicles determine distances through the collaboration of multiple sensors. For example, radar systems installed at the front of the car emit radio waves that bounce back, and the time taken is used to calculate the distance, which is applied in adaptive cruise control to maintain a safe following distance. Ultrasonic sensors around the vehicle measure short distances to assist with parking, while rear and side-view cameras identify objects and determine their distance through image processing. Additionally, LiDAR is used in combination for precise calculations in autonomous driving. These systems operate in all weather conditions, outperforming human vision, especially in harsh weather, making them more reliable. I've tested these features in a new car—blind spot monitoring alerts about approaching vehicles from behind, and automatic braking reduces collision risks. Although sensors occasionally give false alerts, they significantly enhance safety overall. Don't forget to clean the equipment during maintenance.
