A compliant rotating joint for deployable wings on small UAVs

Recent interest in small Unmanned Air Vehicles (UAVs) has led to advances in wing technologies. Deployable wings reduce required storage space while providing greater range during flight. This paper presents a compliant rotating joint which is bistable and features a locking characteristic that prevents the wing from reverting back to the undeployed configuration during flight. The two stable positions occur at local strain energy minima about 90 degrees apart, but can be adjusted by the designer. A pseudo rigid body model is illustrated for the joint, based on a four-bar linkage. Such a joint mechanism can be designed for any wing, by using the pseudo rigid body model to optimize link lengths and position the instant center appropriately. In addition, the mechanism can be cut out within a single plane for ease of manufacture and assembly.