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

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.