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Although the bat is blind from birth, it catches flies on the fly! It is clear that debugging its ultrasound system took millions of years of evolution. And parking sensors - electronic devices whose work is based on the same principle, are still hard to compete with nature. But they also cope with some tasks. How good - we'll see.
Automotive parking sensors use ultrasonic waves with a frequency of 38–42 kHz. Piezosensors (emitters, they are also receivers) are usually located in bumpers, their work is controlled by an electronic unit. The principle of echolocation is simple: the ultrasonic signal sent by the sensors according to a certain algorithm is reflected from the obstacle and returned. Electronics recalculates the signal transit time to the distance to the object and displays it on the screen in the form of an icon (“track”) and in meters. The driver can also judge the distance by the signal of the buzzer: the sound intensity increases as you approach the obstacle. Most systems can detect a threat no further than a meter and a half, some models warn with a voice, and at a critical moment they simply yell: “Stop!”. Very convincing.
The information content of the system depends on the number of sensors and their location. At least two on the rear bumper. But this sub-blind version with a dead zone in the middle is less and less popular. Four sensors on one bumper see much better, there are practically no unseeable zones.
In some devices, four sensors are on the front bumper. When reversing, two extreme ones work - they control the space on the sides of the machine, so that when maneuvering you do not catch anything with the front wing. Two averages track the space as you move forward.
But even the best electronic eyes can fail if an obstacle is hidden, for example, in the grass, behind a curtain of dense fog or heavy rain, snowfall. Even dust can reflect an ultrasonic signal and mask the danger. In addition, objects with a small reflective surface - for example, the end of a pipe directed toward the sensor - are detected even by the device, often only at the last moment. Animal fur is also reluctant to reflect ultrasound waves; trusting in electronics, run into a nonchalant dog for a short time or, God forbid, look at a man in a fur coat tucked at the curb.
By the way, look at the bumpers of cars equipped with this very useful option - as a rule, you will see on them a lot of traces of contact with obstacles. So recklessly rely on the all-seeing eye is not worth it.
To prove this, we will conduct a test. Six parking sensors made in China (others, it seems, just simply do not exist) will demonstrate their abilities in practice.
TESTS
Test one. "Accuracy"
Obstacle - a panel of laminated plywood with dimensions of 0.1 × 1.0 m is placed vertically at a distance of 1.0; 0.5 and 0.3 m from the sensors and compare these values with the readings of the parking sensors. First, at an air temperature of 21 ºС. It turned out that the SHO-ME Y-2612P did not show a distance of less than 0.4 m. Maybe this is logical: there is nothing to cuddle! The rest completely coped with the task - with an error of 5–8 cm. At a temperature of –4 ºС, the measurement accuracy remained practically unchanged. Good result.
The second test. "Vigilance"
Mask the target with water mist from the spray gun. A water cloud hangs in front of the sensor, the target is gradually moving closer to it. At a distance of 0.5 m from the bumper, all subjects found danger and warned about it. But first of all, the AVILINE MP-218LCD-Y8 and PARK MASTER 8BJ12 systems reacted to it.
The third test. "Vitality."
We’ll stick the sensor with a piece of paper (it will simulate pollution or, for example, a leaf that has accidentally adhered to a tree) - can it see through the object? Alas, I could not! But parking sensors with self-diagnostics detected a blind sensor - and each warned the owner in his own way. Not equipped with such a function simply did not see the obstacles. Moral: Keep the sensors clean. Or rely only on yourself.
The fourth test. "Fur"
The fur absorbs ultrasonic waves well! Parktronic with low sensitivity may not see such a target at all. The PARK MASTER 8BJ12 system recognized danger in half a meter. The rest also managed, but found a catch 10 cm "later." Total 0.4-0.5 m before the collision. We consider it acceptable.
The fifth test. Stealth
The target was positioned horizontally, deflecting its plane by 45º to reflect the waves up. The deception did not succeed: all the subjects easily found it at a distance of 0.5 m. It’s also not bad.
The sixth test. "Chamber"
Closed space. Drive into a cramped garage in reverse and in the dark, focusing on appliances, was not at all easy. We managed, but in a traditional way - focusing on mirrors and side lights. Here, all parking devices are more or less crazy, there is no hope for them.
The seventh test. "Vis."
The sensors of the two systems were arranged in two parallel lines, at a distance of 1.0 m. By gradually turning them, false alarms were detected. It turned out that glitches are slipping through everyone, but the devices almost do not interfere with each other, except for the "eye to eye" position. And the best in this test was the FLASHPOINT FP800Z.
DEVICES
SPAL EASY-1000 PS8
SPAL EASY-1000 PS8
Price 6300 rub
+ Volume adjustment of sound alerts. There is an air temperature indicator (but why is it here?).
- Poor attachment of the display and sensor connectors to the central unit. When moving backwards, the front sensors do not work. No self-diagnosis of sensors.
AVILINE MP-218LCD-Y8
AVILINE MP-218LCD-Y8
Price 6500 rub
+ Contrast display with convenient mount. Each sensor has its own scale. Automatically filters interference and adjusts to the height of the sensors above the ground, for example, when loading the trunk. Reliable connection of sensor connectors and unit. There is an adjustment of signal sensitivity.
- The monitor is not disconnected. No self-diagnosis of sensors.
FLASHPOINT FP800Z - SP
FLASHPOINT FP800Z
Price 5990 rub
+ Display on a convenient ball joint, can be installed anywhere. The choice of voice or sound alerts with volume control. Self-diagnosis of sensors. AWS system, automatically warning by emergency lights of those who are parking nearby. Legible instruction.
- Weak connectors on the central unit. If the AWS system is parked for a long period of time and if the battery trips frequently, the battery may be deeply discharged.
PARK MASTER 8BJ12
PARK MASTER 8BJ12
Price 6340 rub
+ Contrast display. The function of preventing false alarms. Self-diagnosis function of sensors.
- Unreliable display mount. Sensors are weak in the bumper. The sound volume is not adjustable.
SHO-ME Y-2612
SHO-ME Y-2612
Price 2400 rub
+ Contrast informative display. The sound and monitor are muted. Four types of stands for sensors allow you to properly orient them during installation.
- No self-diagnosis of sensors. Poor connection of the sensor connectors to the unit. Sensors are weak in the bumper. The minimum measured distance is 0.4 m.
ULTRAVOX V-308
ULTRAVOX V-308
Price 4630 rub
+ Contrast informative display. Self-diagnosis of sensors. Select a sound or voice alert and turn off the display. When loading a car, it takes into account its drawdown. Good mounting sensors in the bumper. Reliable connection of block sensor connectors.
- Inconvenient display mount. No installation instructions.
