Using Ultrasonic Tactile Sensor for Materials Recognition On Thin Wall Objects in Assembly Lines

One of the important tasks of robots is object recognition without human intervention. The main aim of this study is developing an ultrasonic sensor to recognize the materials of thin wall objects. This study is based on the physics rules in ultrasonic that ultrasonic velocities, longitudinal and transverse velocities, are altered in different materials because of differences in their elastic modulus. Obviously applying forces by robot to an object walls should be in harmony with their elastic modules and kind of materials, especially thin wall objects. The novelty of this research is related to using an especial probe for omitting the effect of near field by using a delay line made of a column of water in plastic membrane. The ultrasonic sensors with delay lines make it possible to detect the material of thin wall objects. The measured ultrasonic velocities are compared with standard ones to detect objects materials. The results of experiments are very promising and confirm that it is possible to detect plates made of St 11, copper, with 1 m thickness