Design, Implementation and Evaluation of Ultrasonic Measurement System using ROS and MQTT

Performing inspection tasks in industrial environment require high accuracy systems. Capabilities of this system should have potential to minimize operator involvement in hazardous areas. Currently, operation of ultrasonic thickness (UT) measurement cannot be monitored and controlled by robot pilot. One operator should be responsible to inform pilot while pilot is forcing robot to measure the thickness of surface. This article presents designing and implementation of a UT measurement system that can be visualized and controlled by users and pilot simultaneously through an interface between Robotic Operating System (ROS) and Message Queue Telemetry Transport (MQTT). MQTT is one of the data communication protocols for Internet of Things (IoT). The interface between ROS and MQTT is called ROS-MQTT bridge. Moreover, we make a comparison between ROS-MQTT bridge and client signal for each topic by using normalized cross correlation method. We used two samples of steel, with and without coating. The results show that the normalized cross-correlation of 1 for thickness numbers between two signals in client and ROS-MQTT bridge sides. The client side received thickness number with less than 1 millisecond delay. Also, it is same for another topic such as dispenser. The contribution of this work is to develop UT measurement system with other sensors such as LiDAR sensors and camera to control robot motion. The second contribution is to assist robot pilot and other users to visualize and control the UT measurement system remotely from safe area.