Principal design of the femoro-tibial joint in the main groups of arthropoda and possible implications for robotics limbs

Abstract The anatomy of the femoro-tibial joint of the walking legs in four representatives of the main groups of Arthropoda (Myriapoda, Chelicerata, Crustacea and Insecta) is examined. Using the method resembling reverse engineering the principal structure of the femoro-tibial joint is reconstructed and analysed. The segmentation of the walking leg, position of the articulation and its functional role in locomotion are discussed. Three morpho-functional types of walking legs are defined: angular leg (Crustacea and Insecta), bow-like leg (Chelicerata) and arcuate leg (Myriapoda). The relationship between the type and position of the articulation, muscles (actuators), and the type of flexion-extension are analysed and discussed. Principal design of the articulation in the femoro-tibial joint is described and two types of leverage (class 1 and 3) are determined. Following this, two types of kinematic pairs are determined: revolute (hinge) joint in Myriapoda and Chelicerata, and indirect hinge (or suspended joint) in Crustacea and Insecta. The principle of the hingeless leg joint of insects and crustaceans is reproduced in the form of an artificial bioinspired joint model.