Command Structure Design of a Robot for the Vibro-Acoustic with Scanning Testing

Abstract

This paper is presenting the command system improvement of a scanning robot for acoustical testing. The evaluation of noise emitted by an object by measuring the acoustic intensity according with the ISO 9614-3:2002 international standard requires displacement of the probe on spatial trajectories with constant speed and maintaining the spatial orientation of the probe. In a previous work a robot was design by the authors for performing this task, including a unit with 3 translations and an orientation unit with 2 rotations.The practical tests of the first system shown high difficulties in maintaining the constant speed due to the robot dimensions and inertia. Also the noise produced by the translational units during scanning was too high. The system is improved by adding 1 degree of freedom at the orientation unit, reduction of noise and new software version. The new mechanical structure is the subject of another paper. This article is presenting the control system of the robot based on Festo controllers, DSP board and programs derived using LabVIEW. The new version is based on a positioning of the scanning unit in the vicinity of the scanning plane, using translation axis, and then the displacement of the acoustic probe for scanning using only the orientation unit, having DC motors, much lower inertia. This allowed a better control of scanning and lower noise.