Working principle and installation points of reversing radar
The full name of the reversing radar is "reversing anti-collision radar", also called "parking auxiliary device", or "reversing computer warning system". The device can judge the distance of obstacles and advise the situation of obstacles around the vehicle to improve the safety of reversing.
First, working principle
Reversing radar is a parking safety auxiliary device, which is composed of ultrasonic sensor (commonly known as probe), controller and display, alarm (horn or buzzer) and other parts, as shown in Figure 1. Ultrasonic sensor is the core component of the whole reversing system. Its function is to send and receive ultrasonic waves. Its structure is shown in Figure 2. At present, the commonly used probe operating frequency of 40kHz, 48kHz and 58kHz three kinds. Generally speaking, the higher the frequency, the higher the sensitivity, but the horizontal and vertical direction of the detection Angle is smaller, so generally use 40kHz probe
Astern radar adopts ultrasonic ranging principle. When the vehicle is put into reverse gear, the reversing radar automatically enters the working state. Under the control of the controller, the probe installed on the rear bumper sends ultrasonic waves and generates echo signals when encountering obstacles. After receiving the echo signals from the sensor, the controller carries out data processing, thus calculating the distance between the vehicle body and obstacles and judging the position of obstacles.
Reversing radar circuit composition block diagram as shown in figure 3, MCU (MicroprocessorControlUint) through the scheduled program design, control the corresponding electronic analog switch drive transmission circuit, ultrasonic sensors work. Ultrasonic echo signals are processed by special receiving, filtering and amplifying circuits, and then detected by the 10 ports of MCU. When receiving the signal of the full part of the sensor, the system obtains the nearest distance through a specific algorithm, and drives the buzzer or display circuit to remind the driver of the nearest obstacle distance and azimuth.
The main function of the reversing radar system is to assist parking, exit the reverse gear or stop working when the relative moving speed exceeds a certain speed (usually 5km/h).
[Tip] Ultrasonic wave refers to the sound wave that exceeds the range of human hearing (above 20kHz). It has the characteristics of high frequency, straight line propagation, good directivity, small diffraction, strong penetration, slow propagation speed (about 340m/s) and so on. Ultrasonic waves travel through opaque solids and can penetrate to a depth of tens of meters. When ultrasonic meets impurities or interfaces, it will produce reflected waves, which can be used to form depth detection or ranging, and thus can be made into a ranging system.
