Abstract: An indoor positioning method for robots is presented to improve the precision of displacement measurement using only low-cost inertial measurement units (IMUs). Firstly, a high-fidelity displacement estimation for linear motion is proposed. A new robot motion model is designed as well as an axis alignment that only uses a single axis of the accelerometer. The integral error of velocity is eliminated by a new subsection calculation method. Two complementary IMUs are combined by assigning them different weights to obtain high accuracy displacement results. Secondly, an orientation estimation based on a fusion filter for the steering motion is proposed. Experiments show that the proposed method significantly improves the accuracy of linear motion measurement and is effective for the indoor positioning of a robot.