Order-of-magnitude increased range of constant force adjustment via section optimization

Abstract

An adjustable constant force environment is critical in engineering applications, including precision manipulation, surgical robots, and advanced manufacturing, all requiring a wider range of force regulation and adjustment. Traditional adjustable constant force mechanisms (ACFMs) have significant limitations in achieving a wide range of constant force (CF) adjustments due to factors like stress and interference. Existing ACFMs typically offer only a 2–4 times change in CF, which is insufficient. This research aims to provide an order-of-magnitude increase in CF adjustment range while remaining compact and preserving CF quality through section optimization. An analytical model demonstrates the efficacy of adjusting CF by an order-of-magnitude in prismatic and non-prismatic beams for CF adjustment method selection. Additionally, finite element analysis and design optimization of the non-prismatic serpentine beam with an out-of-plumbness imperfection angle and polynomial section description were conducted to maximize CF adjustability and quality. Experimental validation showed a 38 times change in CF adjustability for 5 percent variation in the CF, 18 times improvement in compactness, and high Energy Similarity Index $S_{CF}$ compared to the prismatic benchmark mechanism. This proposed system may be implemented in several applications, including load control, impact and vibration mitigation, space exercise, wearables, etc.