The effect of clearance on gear performance: An optimization study for a light-weight 3D-printed cycloidal drive

As the field of prosthetics moves away from traditional subtractive manufacturing methods toward more sustainable, customizable approaches like 3D printing, this study examines how varying clearance values in cycloidal drives impact their vibrational behavior. Cycloidal drives known for their high torque density and low backlash, are gaining traction as key reduction components in robotic prostheses, where minimizing vibration is essential for ensuring smooth gait transitions, reducing user fatigue, and improving long-term prosthetic wear comfort. This study investigates the vibrational performance of 3D-printed cycloidal drives by evaluating different clearances to optimize vibrational performance in robotic prostheses applications, specifically in robotic knee joints. In this research, three clearance values (0.2, 0.3, and 0.5 mm) were tested on a benchtop using 3D-printed cycloidal drives. With the retrieved raw gyroscope data, a combination of ANOVA and time-frequency analyses was employed to evaluate their vibrational performance across different speeds and load conditions. The study revealed that the 0.2 mm clearance, while effective at higher speeds, exhibited greater variance, and concentrated vibrational energy at lower speeds, which could cause localized stress and wear. The 0.3 mm clearance emerged as the most balanced, with minimal variance, evenly distributed vibrational energy, and greater durability, making it ideal for high-precision applications like prosthetic joints. In contrast, the 0.5 mm clearance exhibited erratic behavior, with excessive vibration and mechanical noise, making it the least favorable option.