Design, Control, and Evaluation of a Modular Variable Configuration Rehabilitation Robot for Early Physical Therapy

This paper proposes a modular variable configuration rehabilitation robot (MVCRR), aiming to meet the needs of multi-functional, full-cycle rehabilitation. MVCRR integrates a lower-limb training module and a-sit-to-stand module, offering 16 actuated degrees of freedom and supporting four rehabilitation postures: supine, sitting, standing, and sit-to-stand transition, while integrating the functions of typical rehabilitation devices. Meanwhile, a split–reassembly mechanism is designed to enable flexible bedside deployment, while compact scissor mechanisms and optimized actuation design improve adaptability and efficiency. In addition, a distributed bilateral coordination control architecture is established, and a unified human–robot interaction control framework is developed based on a multi posture dynamic model library, enabling compliant, assist-as needed control. Eight active and passive training modes are designed, covering gait reconstruction, muscle strengthening, posture transitions, and bilateral coordination. Experimental results demonstrate high-accuracy joint tracking (RMSE ≤ 0.0083 rad) and torque regulation (RMSE ≤ 1.6848 Nm), and good natural-gait reproduction (joint-angle RMSE ≤ 0.094 rad, r ≥ 0.897), validating the effectiveness of rehabilitation training across multiple postures. Overall, MVCRR establishes a systematic and intelligent integrated solution that supports multi-posture training and bedside deployment, demonstrating strong potential for clinical application.