The HC-SR04 Ultrasonic Sensor is a very affordable proximity/distance sensor that has been used mainly for object avoidance in various robotics projects. It essentially gives your Arduino eyes / special awareness and can prevent your robot from crashing or falling off a table. It has also been used in blind stick applications, water level sensing, and even as a parking sensor. Continue reading Distance Measurement using Ultrasonic Sensor HC-SR04 and Arduino