The mechanical design of a passively adapting exoskeleton for the lower arm

Lifting patients is a demanding task for care providers. In addition, the number of patients is rising and the number of people with obesity is expanding. Current lifting aids are single purpose and time consuming to use. Exoskeletons can fulfill the demand for a versatile and easy to use lifting aid. A drawback of a typical exoskeleton is that in order to function correctly the axes need to be aligned to the human joints, which is time consuming. Furthermore, an exoskeleton for healthcare must reduce the reaction forces in the user while lifting. It is chosen to design an exoskeleton, which requires no adjustment and can cope with power enhancement. The goal of this paper is to design an exoskeleton that is fast, easy to use and reduces the reaction forces in the user. A design is proposed which easily fits different sized users. In addition the reaction forces in the human skeleton are eliminated. The model is tested by means of a demonstrator. Elastic tension elements are used as a gravity compensator. By reducing the potential energy fluctuation the required external input is reduced. Optimizing a number of design parameters leads to a calculated moment reduction of 98.8% and moment fluctuation reduction of 96.8%. This is the first exoskeleton to combine fast to use design with high-energy efficiency gravity compensation.BMDBioMechanical EngineeringMechanical, Maritime and Materials Engineerin