Experimental validation of compliance models for LADD transmission kinematics

Abstract

Introduces new compliance models for LADD (linear to angular displacement device) transmissions which reduce, by an order of magnitude, inelastic model errors of up to 18% full scale over force and position operating ranges. Elastic models introduced so far were all based on fiber elasticity, which show an increase an LADD length from the inelastic length with force. The authors show that in experiments the opposite is true. The LADD is always shorter than predicted from the inelastic model. As the load force increases, the LADD length approaches the inelastic length. The authors found the cause for this fundamentally different elastic behavior to be fiber bending. The authors also employ one of the new models to improve the prediction of the kinematics of a CLADD, which consists of two concentric LADD devices. The new LADD models are essential for the design of LADD based systems, the online estimation of LADD forces, and accurate control.