In this paper, design, mathematical modeling, modeling-based control implementation of wearable lower limb robotic exoskeleton are presented, which can assist people with mobility impairments during the transition between sit to stand (STS) or walking. This is also based on 12V high torque DC gear motors being strategically placed at the hip and knee joints to offer mechanical support. The surface electromyography (EMG) electrodes are connected to a microcontroller, which uses them to detect human intention for system actuation, while two 9-DOF Inertial Measurement Units (IMUs) are used to measure real-time joint trajectories. A Proportional-Integral-Derivative (PID) control algorithm is implemented to modulate the PWM signals sent to IBT-2 motor drivers – the outputs must be smooth, coordinated and adaptive. The DC motors have inherent self-locking characteristics of the worm gear ensuring the steady posture. Experimental assessments show that the DC gear motor system can reliably provide up to 6 Nm of torque and decrease the user effort by ~40% to facilitate mobility of the lower limb. Moreover, study describes future directions for changing the architecture into a high torque servo motor configuration for improved dynamic performance.

Keywords—DC Gear Motor, Lower Limb Exoskeleton, EMG Sensor, IMU Posture Tracking, STM32 Microcontroller, PID Controller, Sit-to-Stand (STS) Assistance, Wearable Robotics