Using angular speed measurement with hall effect sensors to observe grinding operation with flexible robot

Abstract: Hydro-Quebec has developed and implemented a portable robotic technology to facilitate the maintenance of hydraulic turbines. To improve the quality of the grinding, it is thus necessary to reduce the vibrations caused by the flexibility of the portable robot «SCOMPI». Steady vibration responses of the dynamic model during grinding shows repeating and high frequency impacts between the wheel and workpiece. High speed camera observations confirm the existence of a vibro-impact process. From our experiments, it is shown that angular speed signal can be very useful for monitoring grinding, by detecting the exact location on the wheel and energy content of each impact. These detections can allow online modification of the commands of the robot, such as normal force or feed speed, so as to better control the material removal rate. A comparison between built in Hall effect sensors and added encoder shows too many differences, and even if the first results are promising, an improved encoder need to be designed.