Highly accurate dynamic position measurement for wheeled mobile robot using laser beacon measurement system

The present research concerns a compensation method for dynamic measurement error(DME)using the laser beacon measurement system(LBMS), which is necessary for highly accurate positioning control and trajectory tracking control of a wheeled mobile robot (WMR). The LBMS uses particular laser beacons, each of which emits two symmetrical laser beams traveling in opposite directions around the beacon and is placed at two reference positions. Receiving beams from these beacons, a photo sensor incorporated in the sensor unit of a WMR yields four time intervals that are necessary to calculate the position of the WMR. From four time intervals, the position of a standing WMR can be measured with high accuracy by LBMS. However, using this method, the position of a moving WMR can't be measured as accurately, because the above-mentioned four time intervals change slightly owing to motion of the WMR, and DME arises consequently. The proposed method compensates the position of a moving WMR measured by LBMS, making use of the DME calculated from four different time intervals. In this paper, we report on this compensation method which has been found to yield satisfactory results in terms of accuracy and repeatability after various simulations and experiments.