3D Model of the Upper Limb Link of a Variable-Length Exoskeleton with Controlled Rigidity and a Movable Pole for Construction Workers

Unloading the upper limbs of their bodies is a serious problem in preventing occupational diseases and increasing the productivity of construction workers. An effective approach to this task is the use of exoskeletons for the upper limbs, or exosuits for the entire musculoskeletal system of the builder. The proposed link model has seven possible movements: three translational movements of the pole, three rotations around the pole, and a change in the length of the link when the upper part moves relative to the pole. The dynamics of the link is described by Lagrange equations of the second kind, which constitute a system of seven ordinary differential equations of second order. To accelerate the compilation of motion equations, the quaternion algebra apparatus is used to obtain transition matrices from the previous coordinate system to the next system. The forces and moments necessary to realize given movements of the link are determined using program communication equations. The use of link structures based on the proposed model when combined into multi-link structures can be used in the development of exoskeletons for upper limbs that enhance the physical abilities of construction workers and in the creation of autonomous robots. © 2025 The Authors.