Real-Time Trajectory Compensation of a Parallel Motion Platform Using Low-Cost IMU Sensing and Hybrid Proportional-Fuzzy Control

Accurate platform-orientation feedback is important for trajectory tracking in parallel motion platforms, but high-precision measurement systems can be costly. This study develops a low-cost inertial measurement unit (IMU)-based feedback compensation framework for a three-axis parallel motion platform. A GY-9250 IMU integrated with an STM32 microcontroller provides roll and pitch estimates through Kalman filtering of gyroscope and accelerometer measurements. Inverse kinematics maps the estimated orientation into actuator coordinates to formulate posture-derived displacement errors. The hybrid controller combines proportional control based on encoder-derived actuator tracking errors with single-input fuzzy compensation based on the posture-derived displacement errors. The framework is implemented using an NI CompactRIO controller (National Instruments Corporation, Austin, TX, USA) and evaluated through circular orientation trajectories with different periods and angular amplitudes. Relative to proportional control at the same gain of Kp = 2, the hybrid controller reduces RMS angular tracking error by 0.6%, 30.0%, and 62.3% in three tested conditions, but increases it by 34.4% in the fourth condition. These results demonstrate condition-dependent benefits rather than consistent superiority over proportional control. Independent dynamic attitude validation, between-run variability, and end-to-end execution timing remain unquantified. The study provides a practical implementation of low-cost orientation-feedback compensation and identifies the need for further validation of its accuracy, repeatability, and timing characteristics.