Who is more reliable in the infrared and laser of robots and drones?

With the rise of new concept systems such as Robot, Drone, automated guided vehicles, and autonomous driving, there is a need for stimuli ranging and obstacle avoidance (Obstacle Avoidance) technology.

 The ranging is the basis of obstacle avoidance, and there are a variety of techniques to achieve ranging, including Radio Frequency; RF, Ultrasonic, Infrared, and Laser. Each of these technologies has its own advantages and disadvantages, and the costs are also different.

1. Infrared angle ranging principle

The general infrared ranging is based on the principle of triangulation. The infrared emitter emits an infrared beam at a certain angle. After encountering the object, the light will be reversed. After the reflected light is detected, the object distance D can be calculated through the geometric triangle relationship of the structure. Common infrared sensors measure distances are relatively close. In addition, for transparent or near-black objects, the infrared sensor cannot detect the distance.

2. Laser phase difference ranging principle

The common lidar is based on ToF (time of flight). The distance d=ct/2 is measured by measuring the flight time of the laser, where d is the distance, c is the speed of light, and t is from transmission to reception. time interval. A laser radar includes a transmitter and a receiver, the transmitter illuminates the target with a laser, and the receiver receives the reversed light wave.

There are also different methods for measuring flight time, such as using a pulsed laser; another type of continuous laser wave that emits frequency modulation, and measuring the time by measuring the difference frequency between the received reflected waves.

A simpler solution is to measure the phase shift of the reflected light. The sensor emits a certain amount of modulated light at a known frequency and measures the phase shift between the transmitted and inverted signals.

Lidar's measuring distance can reach tens of meters or even hundreds of meters, the angular resolution is high, usually can reach a few tenths of a degree, and the accuracy of ranging is also high. However, the confidence of the measured distance is inversely proportional to the square of the amplitude of the received signal. Therefore, blackbody or long-distance object distance measurements are not as good as bright, close-range objects. And, for transparent materials, such as glass, Lidar can't do anything about it. In addition, due to the complexity of the structure and the high cost of the device, the cost of the laser radar is also high.

According to the research institute, laser ranging technology is difficult to replace infrared or ultrasonic technology because of its high price. It is difficult to replace infrared or ultrasonic technology in the indoor slow moving system. However, the laser has high accuracy and long detectable distance. Outdoor high-speed mobile systems, such as high-speed driving, drone flying, etc.