Calibration of the Ultrasonic Sensor-Range Finder by the Laser Interferometer

Ultrasonic sensors are often used as range finders [1]. Their main disadvantage is the lack of measurement accuracy, as it is due to the negative impact of the environment in which the sound propagates. Parameters and values of characteristics (the main of which is the optical density) can’t be constant and can change during measurements. An important disadvantage is the limitation of the measured distance to values from 3 cm to 40 cm. It should also be noted the following disadvantages of ultrasonic sensors. The surfaces, which are characterized by a porous structure, absorb ultrasound well; therefore, it is difficult to measure the distance to them. If the distance to a surface at an angle to the beam or a spherical surface is to be measured, the obtained results may be inaccurate. The same problems await us when measuring the distance to the wall covered with foam. As result, the errors of such sensors – range finders are accessed as 4 cm for the measured distance 20 cm – 1400 cm [2] error ~20 % for 20 cm) that seems to be insufficient for robot application. These shortcomings require experimenters not only to take into account the above parameters while applying the ultrasonic sensors – range finders but to ensure the metrological unity of measurements with their help as well as to prove the exactness of the studied sensors. The latter can be achieved by developing metrological equipment for calibration of ultrasonic sensors range finders.