Depth: Robots have a lot of knowledge about obstacle avoidance, and what are the tricks of sensors and algorithms?

Avoidancemeans to moveRobotDuring walking, throughsensorWhen sensing the presence of static or dynamic obstacles on its planned route, follow certainalgorithmUpdate the path in real time, bypass obstacles, and finally reach the goal point.

What sensors are commonly used for obstacle avoidance?

Whether it is for navigation planning or obstacle avoidance, sensing the surrounding environment information is the first step. As far as obstacle avoidance is concerned, mobile robots need to obtain information on obstacles around themselves through sensors in real time, including information such as size, shape, and location. There are various sensors used for obstacle avoidance, each with different principles and characteristics. At present, the common ones are mainly vision sensors, laser sensors, infrared sensors, ultrasonic sensors, etc. Below I briefly introduce the basic working principle of these sensors.

Ultrasound

The basic principle of the ultrasonic sensor is to measure the time of flight of the ultrasonic wave, and the distance is measured by d=vt/2, where d is the distance, v is the speed of sound, and t is the time of flight. Since the speed of ultrasonic waves in the air is related to temperature and humidity, changes in temperature and humidity and other factors need to be taken into account in a more accurate measurement.

The above picture is a schematic representation of the ultrasonic sensor signal. A piezoelectric or electrostatic transmitter generates an ultrasonic pulse with a frequency of several tens of kHz to form a wave packet. The system detects reverse acoustic waves higher than a certain threshold, and uses the measured flight time to calculate the distance after detection. The ultrasonic sensor generally has a short operating distance, and the ordinary effective detection distance is several meters, but there will be a minimum detection blind area of ​​about tens of millimeters. Due to its low cost, simple implementation method and mature technology, ultrasonic sensors are commonly used sensors in mobile robots. Ultrasonic sensors also have some disadvantages, first look at the picture below.

Because sound travels in a cone, the distance we actually measure is not a point, but the distance to the closest object within a certain cone angle.