Recently, attempts have been made to construct actuators with similar behaviour to natural muscles. However the results have been inadequate for application to practical prostheses. For example, muscle wire, which has too low an efficiency to be powered by batteries and McKibben muscles which require two power supplies, one electric and one pneumatic. Electrochemical muscles are still in the development stage and cannot yet be used for prostheses. In this paper, a new electromechanical actuator is presented, which provides rectilinear movement and linear characteristics. This electromechanical actuator is based on a ball screw and rare earth magnet coreless motors. The system has been characterised and some of the most important results are that it produces a force of 167N while developing a velocity of 7x10(-3)m/s. The force developed is proportional to the current drained. Its efficiency is about 32%, its total mass 0.19kg and it is light and compact enough to be used in practical clinical prosthesis.
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