Low-cost IMU and odometer tightly coupled integration with Robust Kalman filter for underground 3-D pipeline mapping

A low-cost IMU and odometer integration system is developed in this paper for underground pipeline mapping. A tightly coupled integration between IMU and odometer is implemented to decrease the error caused by the odometer installation attitude error and scale factor error. Besides this, a novel approach to this application of using a Robust Kalman filter is developed to remove the effect of odometer measurement outliers due to the wheel-slip. Compared with the loosely coupled integration method, the use of loosely coupled integration with scale factor correction, tightly coupled integration and tightly coupled with Robust Kalman filter provide a horizontal position improvement of 11%, 41% and 43%, respectively. Similarly, the height accuracy is improved by 14%, 50% and 57%. Moreover, after applying the Robust Kalman filter, the positioning error caused by wheel-slip is reduced to 0.61 m in the horizontal plan, and 0.11 m in the height.