Elliptical machines using adjustable linkages

Abstract

Elliptical machines are exercising or training machines that are used to imitate walking, jogging, running, or climbing exercises. Different from treadmill machines, elliptical machine users never leave their feet away from the pedals, which reduces the pressures to the ankle, knee, and hip joints, and significantly decreases the impact injuries of joints. The configuration of the elliptical motion commonly mimics the natural paths of the ankle, knee, and hip joints for walking, jogging or running, which further lowers the strains and stresses on the joints. In addition to the lower joint impact, a unique feature of elliptical machines is their integrated leg and arm movements that provide full-body (dual lower and upper body) exercises. Users of elliptical machines not only exercise their legs but also push and pull the handlebars to strengthen their arms. Unlike treadmills, ellipticals are usually self-powered by user-generated motion and do not need motor and belt conveyance. They have cost and maintenance advantages over treadmills. This thesis research is on analyzing and simulating elliptical machines. The closed elliptical trajectories of elliptical machines are generated through their linkages. The shapes of the closed trajectories depend on the linkage types and dimensions. The relationships between linkage dimensions and elliptical shapes and sizes are complicated and are difficult to represent using analytical expressions. The complexities and difficulties put challenges on designing elliptical machines. The elliptical trajectory including stride length of an elliptical machine needs to meet the requirements for different exercises, and various short and tall people with a wide range of arm or leg sizes. If an elliptical machine has fixed linkage dimensions, its elliptical trajectory has only one shape and size, which does not provide flexibility. For an elliptical machine to have flexibility, its linkage has to be adjustable. Adjustable linkages are more difficult to analyze and synthesize than linkages without adjustability. This thesis research is motivated to surmount the challenges facing elliptical machines. The research objective is to improve the performances of the current elliptical machines. In this thesis research, different types of elliptical machines (front, rear, and central arrangements) without and with adjustability will be analyzed. Their elliptical output motions will be simulated and compared. The research results from this thesis research will provide useful guidelines for developing and promoting elliptical machines