Paper 6: Design of an Artificial Elbow: An Electromechanical Solution

This paper presents an outline of the power and energy requirements of a human elbow and gives a discussion on the means by which these requirements can be met. Reasons are given for the choice of a system using batteries for energy storage and direct electric drive by a motor and gearbox. The gearbox is of an unusual type, using ‘harmonic drive’ elements, which permit the motor to be installed transversally at the elbow. The gear reduction unit is described in detail. The paper also discusses the problems inherent in controlling a motor with large stall current in such a way that most efficient use is made of the energy stored in the battery, and two control circuits are described which meet the requirements.