Multi-level information fusion with motion constraints: Key to achieve high-precision gait analysis using low-cost inertial sensors

•Achieves high-precision gait analysis by using only low-cost inertial sensors.•Proposes a new multi-level information fusion architecture.•Involves data fusion from the sensor-level, single-foot level, and dual-foot level.•Extracts new human-walking constraints.•Achieved state-of-the-art for stride-length and foot-clearance estimation.